<?php
/*
 +--------------------------------------------------------------------+
 | CiviCRM version 4.5                                                |
 +--------------------------------------------------------------------+
 | Copyright CiviCRM LLC (c) 2004-2014                                |
 +--------------------------------------------------------------------+
 | This file is a part of CiviCRM.                                    |
 |                                                                    |
 | CiviCRM is free software; you can copy, modify, and distribute it  |
 | under the terms of the GNU Affero General Public License           |
 | Version 3, 19 November 2007 and the CiviCRM Licensing Exception.   |
 |                                                                    |
 | CiviCRM is distributed in the hope that it will be useful, but     |
 | WITHOUT ANY WARRANTY; without even the implied warranty of         |
 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.               |
 | See the GNU Affero General Public License for more details.        |
 |                                                                    |
 | You should have received a copy of the GNU Affero General Public   |
 | License and the CiviCRM Licensing Exception along                  |
 | with this program; if not, contact CiviCRM LLC                     |
 | at info[AT]civicrm[DOT]org. If you have questions about the        |
 | GNU Affero General Public License or the licensing of CiviCRM,     |
 | see the CiviCRM license FAQ at http://civicrm.org/licensing        |
 +--------------------------------------------------------------------+
*/

/**
 *
 * @package CRM
 * @copyright CiviCRM LLC (c) 2004-2014
 * $Id$
 *
 */
class CRM_Dedupe_Merger {

  // FIXME: consider creating a common structure with cidRefs() and eidRefs()
  // FIXME: the sub-pages references by the URLs should
  // be loaded dynamically on the merge form instead
  /**
   * @return array
   */
  static function relTables() {
    static $relTables;

    $config = CRM_Core_Config::singleton();
    if ($config->userSystem->is_drupal) {
      $userRecordUrl = CRM_Utils_System::url('user/%ufid');
      $title = ts('%1 User: %2; user id: %3', array(1 => $config->userFramework, 2 => '$ufname', 3 => '$ufid'));
    }
    elseif ($config->userFramework == 'Joomla') {
      $userRecordUrl = $config->userFrameworkVersion > 1.5 ? $config->userFrameworkBaseURL . "index.php?option=com_users&view=user&task=user.edit&id=" . '%ufid' : $config->userFrameworkBaseURL . "index2.php?option=com_users&view=user&task=edit&id[]=" . '%ufid';
      $title = ts('%1 User: %2; user id: %3', array(1 => $config->userFramework, 2 => '$ufname', 3 => '$ufid'));
    }

    if (!$relTables) {
      $relTables = array(
        'rel_table_contributions' => array(
          'title' => ts('Contributions'),
          'tables' => array('civicrm_contribution', 'civicrm_contribution_recur', 'civicrm_contribution_soft'),
          'url' => CRM_Utils_System::url('civicrm/contact/view', 'reset=1&force=1&cid=$cid&selectedChild=contribute'),
        ),
        'rel_table_contribution_page' => array(
          'title' => ts('Contribution Pages'),
          'tables' => array('civicrm_contribution_page'),
          'url' => CRM_Utils_System::url('civicrm/admin/contribute', 'reset=1&cid=$cid'),
        ),
        'rel_table_memberships' => array(
          'title' => ts('Memberships'),
          'tables' => array('civicrm_membership', 'civicrm_membership_log', 'civicrm_membership_type'),
          'url' => CRM_Utils_System::url('civicrm/contact/view', 'reset=1&force=1&cid=$cid&selectedChild=member'),
        ),
        'rel_table_participants' => array(
          'title' => ts('Participants'),
          'tables' => array('civicrm_participant'),
          'url' => CRM_Utils_System::url('civicrm/contact/view', 'reset=1&force=1&cid=$cid&selectedChild=participant'),
        ),
        'rel_table_events' => array(
          'title' => ts('Events'),
          'tables' => array('civicrm_event'),
          'url' => CRM_Utils_System::url('civicrm/event/manage', 'reset=1&cid=$cid'),
        ),
        'rel_table_activities' => array(
          'title' => ts('Activities'),
          'tables' => array('civicrm_activity', 'civicrm_activity_contact'),
          'url' => CRM_Utils_System::url('civicrm/contact/view', 'reset=1&force=1&cid=$cid&selectedChild=activity'),
        ),
        'rel_table_relationships' => array(
          'title' => ts('Relationships'),
          'tables' => array('civicrm_relationship'),
          'url' => CRM_Utils_System::url('civicrm/contact/view', 'reset=1&force=1&cid=$cid&selectedChild=rel'),
        ),
        'rel_table_custom_groups' => array(
          'title' => ts('Custom Groups'),
          'tables' => array('civicrm_custom_group'),
          'url' => CRM_Utils_System::url('civicrm/admin/custom/group', 'reset=1'),
        ),
        'rel_table_uf_groups' => array(
          'title' => ts('Profiles'),
          'tables' => array('civicrm_uf_group'),
          'url' => CRM_Utils_System::url('civicrm/admin/uf/group', 'reset=1'),
        ),
        'rel_table_groups' => array(
          'title' => ts('Groups'),
          'tables' => array('civicrm_group_contact'),
          'url' => CRM_Utils_System::url('civicrm/contact/view', 'reset=1&force=1&cid=$cid&selectedChild=group'),
        ),
        'rel_table_notes' => array(
          'title' => ts('Notes'),
          'tables' => array('civicrm_note'),
          'url' => CRM_Utils_System::url('civicrm/contact/view', 'reset=1&force=1&cid=$cid&selectedChild=note'),
        ),
        'rel_table_tags' => array(
          'title' => ts('Tags'),
          'tables' => array('civicrm_entity_tag'),
          'url' => CRM_Utils_System::url('civicrm/contact/view', 'reset=1&force=1&cid=$cid&selectedChild=tag'),
        ),
        'rel_table_mailings' => array(
          'title' => ts('Mailings'),
          'tables' => array('civicrm_mailing', 'civicrm_mailing_event_queue', 'civicrm_mailing_event_subscribe'),
          'url' => CRM_Utils_System::url('civicrm/mailing', 'reset=1&force=1&cid=$cid'),
        ),
        'rel_table_cases' => array(
          'title' => ts('Cases'),
          'tables' => array('civicrm_case_contact'),
          'url' => CRM_Utils_System::url('civicrm/contact/view', 'reset=1&force=1&cid=$cid&selectedChild=case'),
        ),
        'rel_table_grants' => array(
          'title' => ts('Grants'),
          'tables' => array('civicrm_grant'),
          'url' => CRM_Utils_System::url('civicrm/contact/view', 'reset=1&force=1&cid=$cid&selectedChild=grant'),
        ),
        'rel_table_pcp' => array(
          'title' => ts('PCPs'),
          'tables' => array('civicrm_pcp'),
          'url' => CRM_Utils_System::url('civicrm/contribute/pcp/manage', 'reset=1'),
        ),
        'rel_table_pledges' => array(
          'title' => ts('Pledges'),
          'tables' => array('civicrm_pledge', 'civicrm_pledge_payment'),
          'url' => CRM_Utils_System::url('civicrm/contact/view', 'reset=1&force=1&cid=$cid&selectedChild=pledge'),
        ),
        'rel_table_users' => array(
          'title' => $title,
          'tables' => array('civicrm_uf_match'),
          'url' => $userRecordUrl,
        ),
      );

      $relTables += self::getMultiValueCustomSets('relTables');

      // Allow hook_civicrm_merge() to adjust $relTables
      CRM_Utils_Hook::merge('relTables', $relTables);
    }
    return $relTables;
  }

  /**
   * Returns the related tables groups for which a contact has any info entered
   */
  static function getActiveRelTables($cid) {
    $cid = (int) $cid;
    $groups = array();

    $relTables = self::relTables();
    $cidRefs = self::cidRefs();
    $eidRefs = self::eidRefs();
    foreach ($relTables as $group => $params) {
      $sqls = array();
      foreach ($params['tables'] as $table) {
        if (isset($cidRefs[$table])) {
          foreach ($cidRefs[$table] as $field) {
            $sqls[] = "SELECT COUNT(*) AS count FROM $table WHERE $field = $cid";
          }
        }
        if (isset($eidRefs[$table])) {
          foreach ($eidRefs[$table] as $entityTable => $entityId) {
            $sqls[] = "SELECT COUNT(*) AS count FROM $table WHERE $entityId = $cid AND $entityTable = 'civicrm_contact'";
          }
        }
        foreach ($sqls as $sql) {
          if (CRM_Core_DAO::singleValueQuery($sql) > 0) {
            $groups[] = $group;
          }
        }
      }
    }
    return array_unique($groups);
  }

  /**
   * Return tables and their fields referencing civicrm_contact.contact_id explicitly
   */
  static function cidRefs() {
    static $cidRefs;
    if (!$cidRefs) {
      $sql = "
SELECT
    table_name,
    column_name
FROM information_schema.key_column_usage
WHERE
    referenced_table_schema = database() AND
    referenced_table_name = 'civicrm_contact' AND
    referenced_column_name = 'id';
      ";
      $dao = CRM_Core_DAO::executeQuery($sql);
      while ($dao->fetch()) {
        $cidRefs[$dao->table_name][] = $dao->column_name;
      }

      // FixME for time being adding below line statically as no Foreign key constraint defined for table 'civicrm_entity_tag'
      $cidRefs['civicrm_entity_tag'][] = 'entity_id';
      $dao->free();

      // Allow hook_civicrm_merge() to adjust $cidRefs
      CRM_Utils_Hook::merge('cidRefs', $cidRefs);
    }
    return $cidRefs;
  }

  /**
   * Return tables and their fields referencing civicrm_contact.contact_id with entity_id
   */
  static function eidRefs() {
    static $eidRefs;
    if (!$eidRefs) {
      // FIXME: this should be generated dynamically from the schema
      // tables that reference contacts with entity_{id,table}
      $eidRefs = array(
        'civicrm_acl' => array('entity_table' => 'entity_id'),
        'civicrm_acl_entity_role' => array('entity_table' => 'entity_id'),
        'civicrm_entity_file' => array('entity_table' => 'entity_id'),
        'civicrm_log' => array('entity_table' => 'entity_id'),
        'civicrm_mailing_group' => array('entity_table' => 'entity_id'),
        'civicrm_note' => array('entity_table' => 'entity_id'),
      );

      // Allow hook_civicrm_merge() to adjust $eidRefs
      CRM_Utils_Hook::merge('eidRefs', $eidRefs);
    }
    return $eidRefs;
  }

  /**
   * We treat multi-valued custom sets as "related tables" similar to activities, contributions, etc.
   * @param string $request 'relTables' or 'cidRefs'
   * @see CRM-13836
   */
  static function getMultiValueCustomSets($request) {
    static $data = NULL;
    if ($data === NULL) {
      $data = array(
        'relTables' => array(),
        'cidRefs' => array(),
      );
      $result = civicrm_api3('custom_group', 'get', array(
        'is_multiple' => 1,
        'extends' => array('IN' => array('Individual', 'Organization', 'Household', 'Contact')),
        'return' => array('id', 'title', 'table_name', 'style'),
      ));
      foreach($result['values'] as $custom) {
        $data['cidRefs'][$custom['table_name']] = array('entity_id');
        $urlSuffix = $custom['style'] == 'Tab' ? '&selectedChild=custom_' . $custom['id'] : '';
        $data['relTables']['rel_table_custom_' . $custom['id']] = array(
          'title' => $custom['title'],
          'tables' => array($custom['table_name']),
          'url' => CRM_Utils_System::url('civicrm/contact/view', 'reset=1&force=1&cid=$cid' . $urlSuffix),
        );
      }
    }
    return $data[$request];
  }

  /**
   * Tables which require custom processing should declare functions to call here.
   * Doing so will override normal processing.
   */
  static function cpTables() {
    static $tables;
    if (!$tables) {
      $tables = array(
        'civicrm_case_contact' => array('CRM_Case_BAO_Case' => 'mergeContacts'),
        'civicrm_group_contact' => array('CRM_Contact_BAO_GroupContact' => 'mergeGroupContact'),
        // Empty array == do nothing - this table is handled by mergeGroupContact
        'civicrm_subscription_history' => array(),
        'civicrm_relationship' => array('CRM_Contact_BAO_Relationship' => 'mergeRelationships'),
      );
    }
    return $tables;
  }

  /**
   * return payment related table.
   */
  static function paymentTables() {
    static $tables;
    if (!$tables) {
      $tables = array('civicrm_pledge', 'civicrm_membership', 'civicrm_participant');
    }

    return $tables;
  }

  /**
   * return payment update Query.
   */
  static function paymentSql($tableName, $mainContactId, $otherContactId) {
    $sqls = array();
    if (!$tableName || !$mainContactId || !$otherContactId) {
      return $sqls;
    }

    $paymentTables = self::paymentTables();
    if (!in_array($tableName, $paymentTables)) {
      return $sqls;
    }

    switch ($tableName) {
      case 'civicrm_pledge':
        $sqls[] = "
    UPDATE  IGNORE  civicrm_contribution contribution
INNER JOIN  civicrm_pledge_payment payment ON ( payment.contribution_id = contribution.id )
INNER JOIN  civicrm_pledge pledge ON ( pledge.id = payment.pledge_id )
       SET  contribution.contact_id = $mainContactId
     WHERE  pledge.contact_id = $otherContactId";
        break;

      case 'civicrm_membership':
        $sqls[] = "
    UPDATE  IGNORE  civicrm_contribution contribution
INNER JOIN  civicrm_membership_payment payment ON ( payment.contribution_id = contribution.id )
INNER JOIN  civicrm_membership membership ON ( membership.id = payment.membership_id )
       SET  contribution.contact_id = $mainContactId
     WHERE  membership.contact_id = $otherContactId";
        break;

      case 'civicrm_participant':
        $sqls[] = "
    UPDATE  IGNORE  civicrm_contribution contribution
INNER JOIN  civicrm_participant_payment payment ON ( payment.contribution_id = contribution.id )
INNER JOIN  civicrm_participant participant ON ( participant.id = payment.participant_id )
       SET  contribution.contact_id = $mainContactId
     WHERE  participant.contact_id = $otherContactId";
        break;
    }

    return $sqls;
  }

  /**
   * @param $mainId
   * @param $otherId
   * @param $tableName
   * @param array $tableOperations
   * @param string $mode
   *
   * @return array
   */
  static function operationSql($mainId, $otherId, $tableName, $tableOperations = array(), $mode = 'add') {
    $sqls = array();
    if (!$tableName || !$mainId || !$otherId) {
      return $sqls;
    }


    switch ($tableName) {
      case 'civicrm_membership':
        if (array_key_exists($tableName, $tableOperations) && $tableOperations[$tableName]['add'])
        break;
      if ($mode == 'add') {
        $sqls[] = "
DELETE membership1.* FROM civicrm_membership membership1
 INNER JOIN  civicrm_membership membership2 ON membership1.membership_type_id = membership2.membership_type_id
             AND membership1.contact_id = {$mainId}
             AND membership2.contact_id = {$otherId} ";
      }
      if ($mode == 'payment') {
        $sqls[] = "
DELETE contribution.* FROM civicrm_contribution contribution
INNER JOIN  civicrm_membership_payment payment ON payment.contribution_id = contribution.id
INNER JOIN  civicrm_membership membership1 ON membership1.id = payment.membership_id
            AND membership1.contact_id = {$mainId}
INNER JOIN  civicrm_membership membership2 ON membership1.membership_type_id = membership2.membership_type_id
            AND membership2.contact_id = {$otherId}";
      }
      break;

      case 'civicrm_uf_match':
        // normal queries won't work for uf_match since that will lead to violation of unique constraint,
        // failing to meet intended result. Therefore we introduce this additonal query:
        $sqls[] = "DELETE FROM civicrm_uf_match WHERE contact_id = {$mainId}";
        break;
    }

    return $sqls;
  }

  /**
   * Based on the provided two contact_ids and a set of tables, move the
   * belongings of the other contact to the main one.
   *
   * @static
   */
  static function moveContactBelongings($mainId, $otherId, $tables = FALSE, $tableOperations = array()) {
    $cidRefs = self::cidRefs();
    $eidRefs = self::eidRefs();
    $cpTables = self::cpTables();
    $paymentTables = self::paymentTables();
    $membershipMerge = FALSE; // CRM-12695

    $affected = array_merge(array_keys($cidRefs), array_keys($eidRefs));
    if ($tables !== FALSE) {
      // if there are specific tables, sanitize the list
      $affected = array_unique(array_intersect($affected, $tables));
    }
    else {
      // if there aren't any specific tables, don't affect the ones handled by relTables()
      $relTables = self::relTables();
      $handled = array();
      foreach ($relTables as $params) {
        $handled = array_merge($handled, $params['tables']);
      }
      $affected = array_diff($affected, $handled);
      /**
       * CRM-12695
       * Set $membershipMerge flag only once
       * while doing contact related migration
       * to call addMembershipToRealtedContacts()
       * function only once.
       * Since the current function (moveContactBelongings) is called twice
       * with & without parameters $tables & $tableOperations
       */
      // retrieve main contact's related table(s)
      $activeMainRelTables = CRM_Dedupe_Merger::getActiveRelTables($mainId);
      // check if membership table exists in main contact's related table(s)
      if (in_array('rel_table_memberships', $activeMainRelTables)) {
        $membershipMerge = TRUE; // set membership flag - CRM-12695
      }
    }

    $mainId = (int) $mainId;
    $otherId = (int) $otherId;

    $sqls = array();
    foreach ($affected as $table) {
      // Call custom processing function for objects that require it
      if (isset($cpTables[$table])) {
        foreach ($cpTables[$table] as $className => $fnName) {
          $className::$fnName($mainId, $otherId, $sqls);
        }
        // Skip normal processing
        continue;
      }

      // use UPDATE IGNORE + DELETE query pair to skip on situations when
      // there's a UNIQUE restriction on ($field, some_other_field) pair
      if (isset($cidRefs[$table])) {
        foreach ($cidRefs[$table] as $field) {
          // carry related contributions CRM-5359
          if (in_array($table, $paymentTables)) {
            $paymentSqls = self::paymentSql($table, $mainId, $otherId);
            $sqls = array_merge($sqls, $paymentSqls);

            if (!empty($tables) && !in_array('civicrm_contribution', $tables)) {
              $payOprSqls = self::operationSql($mainId, $otherId, $table, $tableOperations, 'payment');
              $sqls = array_merge($sqls, $payOprSqls);
            }
          }

          $preOperationSqls = self::operationSql($mainId, $otherId, $table, $tableOperations);
          $sqls = array_merge($sqls, $preOperationSqls);

          $sqls[] = "UPDATE IGNORE $table SET $field = $mainId WHERE $field = $otherId";
          $sqls[] = "DELETE FROM $table WHERE $field = $otherId";
        }
      }
      if (isset($eidRefs[$table])) {
        foreach ($eidRefs[$table] as $entityTable => $entityId) {
          $sqls[] = "UPDATE IGNORE $table SET $entityId = $mainId WHERE $entityId = $otherId AND $entityTable = 'civicrm_contact'";
          $sqls[] = "DELETE FROM $table WHERE $entityId = $otherId AND $entityTable = 'civicrm_contact'";
        }
      }
    }

    // Allow hook_civicrm_merge() to add SQL statements for the merge operation.
    CRM_Utils_Hook::merge('sqls', $sqls, $mainId, $otherId, $tables);

    // call the SQL queries in one transaction
    $transaction = new CRM_Core_Transaction();
    foreach ($sqls as $sql) {
      CRM_Core_DAO::executeQuery($sql, array(), TRUE, NULL, TRUE);
    }
    // CRM-12695
    if ($membershipMerge) {
      // call to function adding membership to related contacts
      CRM_Dedupe_Merger::addMembershipToRealtedContacts($mainId);
    }
    $transaction->commit();
  }

  /**
   * Find differences between contacts.
   *
   * @param array $main contact details
   * @param array $other contact details
   *
   * @return array
   * @static
   */
  static function findDifferences($main, $other) {
    $result = array(
      'contact' => array(),
      'custom' => array(),
    );
    foreach (self::getContactFields() as $validField) {
      if (CRM_Utils_Array::value($validField, $main) != CRM_Utils_Array::value($validField, $other)) {
        $result['contact'][] = $validField;
      }
    }

    $mainEvs = CRM_Core_BAO_CustomValueTable::getEntityValues($main['id']);
    $otherEvs = CRM_Core_BAO_CustomValueTable::getEntityValues($other['id']);
    $keys = array_unique(array_merge(array_keys($mainEvs), array_keys($otherEvs)));
    foreach ($keys as $key) {
      // Exclude multi-value fields CRM-13836
      if (strpos($key, '_')) {
        continue;
      }
      $key1 = CRM_Utils_Array::value($key, $mainEvs);
      $key2 = CRM_Utils_Array::value($key, $otherEvs);
      if ($key1 != $key2) {
        $result['custom'][] = $key;
      }
    }
    return $result;
  }

  /**
   * Function to batch merge a set of contacts based on rule-group and group.
   *
   * @param  int $rgid rule group id
   * @param  int $gid group id
   * @param  string $mode helps decide how to behave when there are conflicts.
   *                              A 'safe' value skips the merge if there are any un-resolved conflicts.
   *                              Does a force merge otherwise.
   * @param  boolean $autoFlip wether to let api decide which contact to retain and which to delete.
   *
   *
   * @param bool $redirectForPerformance
   *
   * @return array|bool
   * @internal param array $cacheParams prev-next-cache params based on which next pair of contacts are computed.
   *                              Generally used with batch-merge.
   * @static
   * @access public
   */
  static function batchMerge($rgid, $gid = NULL, $mode = 'safe', $autoFlip = TRUE, $redirectForPerformance = FALSE) {
    $contactType = CRM_Core_DAO::getFieldValue('CRM_Dedupe_DAO_RuleGroup', $rgid, 'contact_type');
    $cacheKeyString = "merge {$contactType}";
    $cacheKeyString .= $rgid ? "_{$rgid}" : '_0';
    $cacheKeyString .= $gid ? "_{$gid}" : '_0';
    $join = "LEFT JOIN civicrm_dedupe_exception de ON ( pn.entity_id1 = de.contact_id1 AND
                                                             pn.entity_id2 = de.contact_id2 )";

    $limit = $redirectForPerformance ? 75 : 1;
    $where = "de.id IS NULL LIMIT {$limit}";

    $dupePairs = CRM_Core_BAO_PrevNextCache::retrieve($cacheKeyString, $join, $where);
    if (empty($dupePairs) && !$redirectForPerformance) {
      // If we haven't found any dupes, probably cache is empty.
      // Try filling cache and give another try.
      CRM_Core_BAO_PrevNextCache::refillCache($rgid, $gid, $cacheKeyString);
      $dupePairs = CRM_Core_BAO_PrevNextCache::retrieve($cacheKeyString, $join, $where);
    }

    $cacheParams = array(
      'cache_key_string' => $cacheKeyString,
      'join' => $join,
      'where' => $where,
    );
    return CRM_Dedupe_Merger::merge($dupePairs, $cacheParams, $mode, $autoFlip, $redirectForPerformance);
  }

  /**
   * Function to merge given set of contacts. Performs core operation.
   *
   * @param  array $dupePairs set of pair of contacts for whom merge is to be done.
   * @param  array $cacheParams prev-next-cache params based on which next pair of contacts are computed.
   *                              Generally used with batch-merge.
   * @param  string $mode helps decide how to behave when there are conflicts.
   *                             A 'safe' value skips the merge if there are any un-resolved conflicts.
   *                             Does a force merge otherwise (aggressive mode).
   * @param  boolean $autoFlip wether to let api decide which contact to retain and which to delete.
   *
   *
   * @param bool $redirectForPerformance
   *
   * @return array|bool
   * @static
   * @access public
   */
  static function merge($dupePairs = array(
    ), $cacheParams = array(), $mode = 'safe',
    $autoFlip = TRUE, $redirectForPerformance = FALSE
  ) {
    $cacheKeyString = CRM_Utils_Array::value('cache_key_string', $cacheParams);
    $resultStats = array('merged' => array(), 'skipped' => array());

    // we don't want dupe caching to get reset after every-merge, and therefore set the
    // doNotResetCache flag
    $config = CRM_Core_Config::singleton();
    $config->doNotResetCache = 1;

    while (!empty($dupePairs)) {
      foreach ($dupePairs as $dupes) {
        CRM_Utils_Hook::merge('flip', $dupes, $dupes['dstID'], $dupes['srcID']);
        $mainId = $dupes['dstID'];
        $otherId = $dupes['srcID'];
        $isAutoFlip = CRM_Utils_Array::value('auto_flip', $dupes, $autoFlip);
        // if we can, make sure that $mainId is the one with lower id number
        if ($isAutoFlip && ($mainId > $otherId)) {
          $mainId = $dupes['srcID'];
          $otherId = $dupes['dstID'];
        }
        if (!$mainId || !$otherId) {
          // return error
          return FALSE;
        }

        // Generate var $migrationInfo. The variable structure is exactly same as
        // $formValues submitted during a UI merge for a pair of contacts.
        $rowsElementsAndInfo = &CRM_Dedupe_Merger::getRowsElementsAndInfo($mainId, $otherId);

        $migrationInfo = &$rowsElementsAndInfo['migration_info'];

        // add additional details that we might need to resolve conflicts
        $migrationInfo['main_details'] = &$rowsElementsAndInfo['main_details'];
        $migrationInfo['other_details'] = &$rowsElementsAndInfo['other_details'];
        $migrationInfo['main_loc_block'] = &$rowsElementsAndInfo['main_loc_block'];
        $migrationInfo['rows'] = &$rowsElementsAndInfo['rows'];

        // go ahead with merge if there is no conflict
        if (!CRM_Dedupe_Merger::skipMerge($mainId, $otherId, $migrationInfo, $mode)) {
          CRM_Dedupe_Merger::moveAllBelongings($mainId, $otherId, $migrationInfo);
          $resultStats['merged'][] = array('main_d' => $mainId, 'other_id' => $otherId);
        }
        else {
          $resultStats['skipped'][] = array('main_d' => $mainId, 'other_id' => $otherId);
        }

        // delete entry from PrevNextCache table so we don't consider the pair next time
        // pair may have been flipped, so make sure we delete using both orders
        CRM_Core_BAO_PrevNextCache::deletePair($mainId, $otherId, $cacheKeyString);
        CRM_Core_BAO_PrevNextCache::deletePair($otherId, $mainId, $cacheKeyString);

        CRM_Core_DAO::freeResult();
        unset($rowsElementsAndInfo, $migrationInfo);
      }

      if ($cacheKeyString && !$redirectForPerformance) {
        // retrieve next pair of dupes
        $dupePairs = CRM_Core_BAO_PrevNextCache::retrieve($cacheKeyString,
          $cacheParams['join'],
          $cacheParams['where']
        );
      }
      else {
        // do not proceed. Terminate the loop
        unset($dupePairs);
      }
    }
    return $resultStats;
  }

  /**
   * A function which uses various rules / algorithms for choosing which contact to bias to
   * when there's a conflict (to handle "gotchas"). Plus the safest route to merge.
   *
   * @param  int $mainId main contact with whom merge has to happen
   * @param  int $otherId duplicate contact which would be deleted after merge operation
   * @param  array $migrationInfo array of information about which elements to merge.
   * @param  string $mode helps decide how to behave when there are conflicts.
   *                                 A 'safe' value skips the merge if there are any un-resolved conflicts.
   *                                 Does a force merge otherwise (aggressive mode).
   *
   * @return bool
   * @static
   * @access public
   */
  static function skipMerge($mainId, $otherId, &$migrationInfo, $mode = 'safe') {
    $conflicts = array();
    $migrationData = array(
      'old_migration_info' => $migrationInfo,
      'mode' => $mode,
    );
    $allLocationTypes = CRM_Core_PseudoConstant::get('CRM_Core_DAO_Address', 'location_type_id');

    foreach ($migrationInfo as $key => $val) {
      if ($val === "null") {
        // Rule: no overwriting with empty values in any mode
        unset($migrationInfo[$key]);
        continue;
      }
      elseif ((in_array(substr($key, 5), CRM_Dedupe_Merger::getContactFields()) or
          substr($key, 0, 12) == 'move_custom_'
        ) and $val != NULL) {
        // Rule: if both main-contact has other-contact, let $mode decide if to merge a
        // particular field or not
        if (!empty($migrationInfo['rows'][$key]['main'])) {
          // if main also has a value its a conflict
          if ($mode == 'safe') {
            // note it down & lets wait for response from the hook.
            // For no response skip this merge
            $conflicts[$key] = NULL;
          }
          elseif ($mode == 'aggressive') {
            // let the main-field be overwritten
            continue;
          }
        }
      }
      elseif (substr($key, 0, 14) == 'move_location_' and $val != NULL) {
        $locField = explode('_', $key);
        $fieldName = $locField[2];
        $fieldCount = $locField[3];

        // Rule: resolve address conflict if any -
        if ($fieldName == 'address') {
          $mainNewLocTypeId = $migrationInfo['location'][$fieldName][$fieldCount]['locTypeId'];
          if (!empty($migrationInfo['main_loc_address']) &&
              array_key_exists("main_{$mainNewLocTypeId}", $migrationInfo['main_loc_address'])) {
            // main loc already has some address for the loc-type. Its a overwrite situation.

            // look for next available loc-type
            $newTypeId = NULL;
            foreach ($allLocationTypes as $typeId => $typeLabel) {
              if (!array_key_exists("main_{$typeId}", $migrationInfo['main_loc_address'])) {
                $newTypeId = $typeId;
              }
            }
            if ($newTypeId) {
              // try insert address at new available loc-type
              $migrationInfo['location'][$fieldName][$fieldCount]['locTypeId'] = $newTypeId;
            }
            elseif ($mode == 'safe') {
              // note it down & lets wait for response from the hook.
              // For no response skip this merge
              $conflicts[$key] = NULL;
            }
            elseif ($mode == 'aggressive') {
              // let the loc-type-id be same as that of other-contact & go ahead
              // with merge assuming aggressive mode
              continue;
            }
          }
        }
        elseif ($migrationInfo['rows'][$key]['main'] == $migrationInfo['rows'][$key]['other']) {
          // for loc blocks other than address like email, phone .. if values are same no point in merging
          // and adding redundant value
          unset($migrationInfo[$key]);
        }
      }
    }

    // A hook to implement other algorithms for choosing which contact to bias to when
    // there's a conflict (to handle "gotchas"). fields_in_conflict could be modified here
    // merge happens with new values filled in here. For a particular field / row not to be merged
    // field should be unset from fields_in_conflict.
    $migrationData['fields_in_conflict'] = $conflicts;
    CRM_Utils_Hook::merge('batch', $migrationData, $mainId, $otherId);
    $conflicts = $migrationData['fields_in_conflict'];

    if (!empty($conflicts)) {
      foreach ($conflicts as $key => $val) {
        if ($val === NULL and $mode == 'safe') {
          // un-resolved conflicts still present. Lets skip this merge.
          return TRUE;
        }
        else {
          // copy over the resolved values
          $migrationInfo[$key] = $val;
        }
      }
    }
    return FALSE;
  }

  /**
   * A function to build an array of information required by merge function and the merge UI.
   *
   * @param  int $mainId main contact with whom merge has to happen
   * @param  int $otherId duplicate contact which would be deleted after merge operation
   *
   * @return array|bool|int
   * @static
   * @access public
   */
  static function getRowsElementsAndInfo($mainId, $otherId) {
    $qfZeroBug = 'e8cddb72-a257-11dc-b9cc-0016d3330ee9';

    // Fetch contacts
    foreach (array('main' => $mainId, 'other' => $otherId) as $moniker => $cid) {
      $params = array('contact_id' => $cid, 'version' => 3, 'return' => array_merge(array('display_name'), self::getContactFields()));
      $result = civicrm_api('contact', 'get', $params);

      if (empty($result['values'][$cid]['contact_type'])) {
        return FALSE;
      }
      $$moniker = $result['values'][$cid];
    }

    static $fields = array();
    if (empty($fields)) {
      $fields = CRM_Contact_DAO_Contact::fields();
      CRM_Core_DAO::freeResult();
    }

    // get all contact subtypes
    $contactSubTypes = CRM_Contact_BAO_ContactType::subTypePairs(NULL, TRUE, '');

    // FIXME: there must be a better way
    foreach (array('main', 'other') as $moniker) {
      $contact = &$$moniker;
      $preferred_communication_method = CRM_Utils_array::value('preferred_communication_method', $contact);
      $value = empty($preferred_communication_method) ? array() : $preferred_communication_method;
      $specialValues[$moniker] = array(
        'preferred_communication_method' => $value,
        'contact_sub_type' => $value,
        'communication_style_id' => $value,
      );

      if (!empty($contact['preferred_communication_method'])){
      // api 3 returns pref_comm_method as an array, which breaks the lookup; so we reconstruct
      $prefCommList = is_array($specialValues[$moniker]['preferred_communication_method']) ?
        implode(CRM_Core_DAO::VALUE_SEPARATOR, $specialValues[$moniker]['preferred_communication_method']) :
        $specialValues[$moniker]['preferred_communication_method'];
        $specialValues[$moniker]['preferred_communication_method'] = CRM_Core_DAO::VALUE_SEPARATOR . $prefCommList . CRM_Core_DAO::VALUE_SEPARATOR;
      }
      $names = array(
        'preferred_communication_method' =>
        array(
          'newName' => 'preferred_communication_method_display',
          'groupName' => 'preferred_communication_method',
        ),
      );
      CRM_Core_OptionGroup::lookupValues($specialValues[$moniker], $names);

      if (!empty($contact['contact_sub_type'])) {
        $specialValues[$moniker]['contact_sub_type'] = implode(CRM_Core_DAO::VALUE_SEPARATOR, $contact['contact_sub_type']);

        // fix contact sub type label for contact with sub type
        $subtypes = array();
        foreach ($contact['contact_sub_type'] as $key => $value) {
          $subtypes[] = CRM_Utils_Array::retrieveValueRecursive($contactSubTypes, $value);
        }
        $contact['contact_sub_type_display'] = $specialValues[$moniker]['contact_sub_type_display'] = implode(', ', $subtypes);
      }

      if (!empty($contact['communication_style'])) {
        $specialValues[$moniker]['communication_style_id_display'] = $contact['communication_style'];
      }
    }

    static $optionValueFields = array();
    if (empty($optionValueFields)) {
      $optionValueFields = CRM_Core_OptionValue::getFields();
    }
    foreach ($optionValueFields as $field => $params) {
      $fields[$field]['title'] = $params['title'];
    }

    $diffs = self::findDifferences($main, $other);

    $rows = $elements = $relTableElements = $migrationInfo = array();

    foreach ($diffs['contact'] as $field) {
      foreach (array('main', 'other') as $moniker) {
        $contact = &$$moniker;
        $value = CRM_Utils_Array::value($field, $contact);
        if (isset($specialValues[$moniker][$field]) && is_string($specialValues[$moniker][$field])) {
          $value = CRM_Core_DAO::VALUE_SEPARATOR . trim($specialValues[$moniker][$field], CRM_Core_DAO::VALUE_SEPARATOR) . CRM_Core_DAO::VALUE_SEPARATOR;
        }
        $label = isset($specialValues[$moniker]["{$field}_display"]) ? $specialValues[$moniker]["{$field}_display"] : $value;
        if (!empty($fields[$field]['type']) && $fields[$field]['type'] == CRM_Utils_Type::T_DATE) {
          if ($value) {
            $value = str_replace('-', '', $value);
            $label = CRM_Utils_Date::customFormat($label);
          }
          else {
            $value = "null";
          }
        }
        elseif (!empty($fields[$field]['type']) && $fields[$field]['type'] == CRM_Utils_Type::T_BOOLEAN) {
          if ($label === '0') {
            $label = ts('[ ]');
          }
          if ($label === '1') {
            $label = ts('[x]');
          }
        }
        elseif ($field == 'individual_prefix' || $field == 'prefix_id') {
          $label = CRM_Utils_Array::value('individual_prefix', $contact);
          $value = CRM_Utils_Array::value('prefix_id', $contact);
          $field = 'prefix_id';
        }
        elseif ($field == 'individual_suffix' || $field == 'suffix_id') {
          $label = CRM_Utils_Array::value('individual_suffix', $contact);
          $value = CRM_Utils_Array::value('suffix_id', $contact);
          $field = 'suffix_id';
        }
        $rows["move_$field"][$moniker] = $label;
        if ($moniker == 'other') {
          //CRM-14334
          if ($value === NULL || $value == '') {
            $value = 'null';
          }
          if ($value === 0 or $value === '0') {
            $value = $qfZeroBug;
          }
          if (is_array($value) && empty($value[1])) {
            $value[1] = NULL;
          }
          $elements[] = array('advcheckbox', "move_$field", NULL, NULL, NULL, $value);
          $migrationInfo["move_$field"] = $value;
        }
      }
      $rows["move_$field"]['title'] = $fields[$field]['title'];
    }

    // handle location blocks.
    $locationBlocks = array('email', 'phone', 'address');
    $locations = array();

    foreach ($locationBlocks as $block) {
      foreach (array('main' => $mainId, 'other' => $otherId) as $moniker => $cid) {
        $cnt = 1;
        $values = civicrm_api($block, 'get', array('contact_id' => $cid, 'version' => 3));
        $count = $values['count'];
        if ($count) {
          if ($count > $cnt) {
            foreach ($values['values'] as $value) {
              if ($block == 'address') {
                CRM_Core_BAO_Address::fixAddress($value);
                $display = CRM_Utils_Address::format($value);
                $locations[$moniker][$block][$cnt] = $value;
                $locations[$moniker][$block][$cnt]['display'] = $display;
              }
              else {
                $locations[$moniker][$block][$cnt] = $value;
              }

              $cnt++;
            }
          }
          else {
            $id = $values['id'];
            if ($block == 'address') {
              CRM_Core_BAO_Address::fixAddress($values['values'][$id]);
              $display = CRM_Utils_Address::format($values['values'][$id]);
              $locations[$moniker][$block][$cnt] = $values['values'][$id];
              $locations[$moniker][$block][$cnt]['display'] = $display;
            }
            else {
              $locations[$moniker][$block][$cnt] = $values['values'][$id];
            }
          }
        }
      }
    }

    $allLocationTypes = CRM_Core_PseudoConstant::get('CRM_Core_DAO_Address', 'location_type_id');

    $mainLocBlock = $locBlockIds = array();
    $locBlockIds['main'] = $locBlockIds['other'] = array();
    foreach (array('Email', 'Phone', 'IM', 'OpenID', 'Address') as $block) {
      $name = strtolower($block);
      foreach (array('main', 'other') as $moniker) {
        $locIndex = CRM_Utils_Array::value($moniker, $locations);
        $blockValue = CRM_Utils_Array::value($name, $locIndex, array());
        if (empty($blockValue)) {
          $locValue[$moniker][$name] = 0;
          $locLabel[$moniker][$name] = $locTypes[$moniker][$name] = array();
        }
        else {
          $locValue[$moniker][$name] = TRUE;
          foreach ($blockValue as $count => $blkValues) {
            $fldName = $name;
            $locTypeId = $blkValues['location_type_id'];
            if ($name == 'im') {
              $fldName = 'name';
            }
            if ($name == 'address') {
              $fldName = 'display';
            }
            $locLabel[$moniker][$name][$count] = CRM_Utils_Array::value($fldName,
              $blkValues
            );
            $locTypes[$moniker][$name][$count] = $locTypeId;
            if ($moniker == 'main' && in_array($name, $locationBlocks)) {
              $mainLocBlock["main_$name$locTypeId"] = CRM_Utils_Array::value($fldName,
                $blkValues
              );
              $locBlockIds['main'][$name][$locTypeId] = $blkValues['id'];
            }
            else {
              $locBlockIds[$moniker][$name][$count] = $blkValues['id'];
            }
          }
        }
      }

      if ($locValue['other'][$name] != 0) {
        foreach ($locLabel['other'][$name] as $count => $value) {
          $locTypeId = $locTypes['other'][$name][$count];
          $rows["move_location_{$name}_$count"]['other'] = $value;
          $rows["move_location_{$name}_$count"]['main'] = CRM_Utils_Array::value($count,
            $locLabel['main'][$name]
          );
          $rows["move_location_{$name}_$count"]['title'] = ts('%1:%2:%3',
            array(
              1 => $block,
              2 => $count,
              3 => $allLocationTypes[$locTypeId]
            )
          );

          $elements[] = array('advcheckbox', "move_location_{$name}_{$count}");
          $migrationInfo["move_location_{$name}_{$count}"] = 1;

          // make sure default location type is always on top
          $mainLocTypeId = CRM_Utils_Array::value($count, $locTypes['main'][$name], $locTypeId);
          $locTypeValues = $allLocationTypes;
          $defaultLocType = array($mainLocTypeId => $locTypeValues[$mainLocTypeId]);
          unset($locTypeValues[$mainLocTypeId]);

          // keep 1-1 mapping for address - location type.
          $js = NULL;
          if (in_array($name, $locationBlocks) && !empty($mainLocBlock)) {
            $js = array('onChange' => "mergeBlock('$name', this, $count );");
          }
          $elements[] = array(
            'select', "location[{$name}][$count][locTypeId]", NULL,
            $defaultLocType + $locTypeValues, $js,
          );
          // keep location-type-id same as that of other-contact
          $migrationInfo['location'][$name][$count]['locTypeId'] = $locTypeId;

          if ($name != 'address') {
            $elements[] = array('advcheckbox', "location[{$name}][$count][operation]", NULL, ts('add new'));
            // always use add operation
            $migrationInfo['location'][$name][$count]['operation'] = 1;
          }
        }
      }
    }

    // add the related tables and unset the ones that don't sport any of the duplicate contact's info
    $config = CRM_Core_Config::singleton();
    $mainUfId = CRM_Core_BAO_UFMatch::getUFId($mainId);
    $mainUser = NULL;
    if ($mainUfId) {
      // d6 compatible
      if ($config->userSystem->is_drupal == '1' && function_exists($mainUser)) {
        $mainUser = user_load($mainUfId);
      }
      elseif ($config->userFramework == 'Joomla') {
        $mainUser = JFactory::getUser($mainUfId);
      }
    }
    $otherUfId = CRM_Core_BAO_UFMatch::getUFId($otherId);
    $otherUser = NULL;
    if ($otherUfId) {
      // d6 compatible
      if ($config->userSystem->is_drupal == '1' && function_exists($mainUser)) {
        $otherUser = user_load($otherUfId);
      }
      elseif ($config->userFramework == 'Joomla') {
        $otherUser = JFactory::getUser($otherUfId);
      }
    }

    $relTables = CRM_Dedupe_Merger::relTables();
    $activeRelTables = CRM_Dedupe_Merger::getActiveRelTables($otherId);
    $activeMainRelTables = CRM_Dedupe_Merger::getActiveRelTables($mainId);
    foreach ($relTables as $name => $null) {
      if (!in_array($name, $activeRelTables) &&
        !(($name == 'rel_table_users') && in_array($name, $activeMainRelTables))
      ) {
        unset($relTables[$name]);
        continue;
      }

      $relTableElements[] = array('checkbox', "move_$name");
      $migrationInfo["move_$name"] = 1;

      $relTables[$name]['main_url'] = str_replace('$cid', $mainId, $relTables[$name]['url']);
      $relTables[$name]['other_url'] = str_replace('$cid', $otherId, $relTables[$name]['url']);
      if ($name == 'rel_table_users') {
        $relTables[$name]['main_url'] = str_replace('%ufid', $mainUfId, $relTables[$name]['url']);
        $relTables[$name]['other_url'] = str_replace('%ufid', $otherUfId, $relTables[$name]['url']);
        $find = array('$ufid', '$ufname');
        if ($mainUser) {
          $replace = array($mainUfId, $mainUser->name);
          $relTables[$name]['main_title'] = str_replace($find, $replace, $relTables[$name]['title']);
        }
        if ($otherUser) {
          $replace = array($otherUfId, $otherUser->name);
          $relTables[$name]['other_title'] = str_replace($find, $replace, $relTables[$name]['title']);
        }
      }
      if ($name == 'rel_table_memberships') {
        $elements[] = array('checkbox', "operation[move_{$name}][add]", NULL, ts('add new'));
        $migrationInfo["operation"]["move_{$name}"]['add'] = 1;
      }
    }
    foreach ($relTables as $name => $null) {
      $relTables["move_$name"] = $relTables[$name];
      unset($relTables[$name]);
    }

    // handle custom fields
    $mainTree = CRM_Core_BAO_CustomGroup::getTree($main['contact_type'], CRM_Core_DAO::$_nullObject, $mainId, -1,
      CRM_Utils_Array::value('contact_sub_type', $main)
    );
    $otherTree = CRM_Core_BAO_CustomGroup::getTree($main['contact_type'], CRM_Core_DAO::$_nullObject, $otherId, -1,
      CRM_Utils_Array::value('contact_sub_type', $other)
    );
    CRM_Core_DAO::freeResult();

    foreach ($otherTree as $gid => $group) {
      $foundField = FALSE;
      if (!isset($group['fields'])) {
        continue;
      }

      foreach ($group['fields'] as $fid => $field) {
        if (in_array($fid, $diffs['custom'])) {
          if (!$foundField) {
            $rows["custom_group_$gid"]['title'] = $group['title'];
            $foundField = TRUE;
          }
          if (!empty($mainTree[$gid]['fields'][$fid]['customValue'])) {
            foreach ($mainTree[$gid]['fields'][$fid]['customValue'] as $valueId => $values) {
              $rows["move_custom_$fid"]['main'] = CRM_Core_BAO_CustomGroup::formatCustomValues($values,
                $field, TRUE
              );
            }
          }
          $value = "null";
          if (!empty($otherTree[$gid]['fields'][$fid]['customValue'])) {
            foreach ($otherTree[$gid]['fields'][$fid]['customValue'] as $valueId => $values) {
              $rows["move_custom_$fid"]['other'] = CRM_Core_BAO_CustomGroup::formatCustomValues($values,
                $field, TRUE
              );
              if ($values['data'] === 0 || $values['data'] === '0') {
                $values['data'] = $qfZeroBug;
            }
              $value = ($values['data']) ? $values['data'] : $value;
          }
          }
          $rows["move_custom_$fid"]['title'] = $field['label'];

          $elements[] = array('advcheckbox', "move_custom_$fid", NULL, NULL, NULL, $value);
          $migrationInfo["move_custom_$fid"] = $value;
        }
      }
    }
    $result = array(
      'rows' => $rows,
      'elements' => $elements,
      'rel_table_elements' => $relTableElements,
      'main_loc_block' => $mainLocBlock,
      'rel_tables' => $relTables,
      'main_details' => $main,
      'other_details' => $other,
      'migration_info' => $migrationInfo,
    );

    $result['main_details']['loc_block_ids'] = $locBlockIds['main'];
    $result['other_details']['loc_block_ids'] = $locBlockIds['other'];

    return $result;
  }

  /**
   * Based on the provided two contact_ids and a set of tables, move the belongings of the
   * other contact to the main one - be it Location / CustomFields or Contact .. related info.
   * A superset of moveContactBelongings() function.
   *
   * @param  int $mainId main contact with whom merge has to happen
   * @param  int $otherId duplicate contact which would be deleted after merge operation
   *
   * @param $migrationInfo
   *
   * @return bool
   * @static
   * @access public
   */
  static function moveAllBelongings($mainId, $otherId, $migrationInfo) {
    if (empty($migrationInfo)) {
      return FALSE;
    }

    $qfZeroBug = 'e8cddb72-a257-11dc-b9cc-0016d3330ee9';
    $relTables = CRM_Dedupe_Merger::relTables();
    $moveTables = $locBlocks = $tableOperations = array();
    foreach ($migrationInfo as $key => $value) {
      if ($value == $qfZeroBug) {
        $value = '0';
      }
      if ((in_array(substr($key, 5), CRM_Dedupe_Merger::getContactFields()) ||
        substr($key, 0, 12) == 'move_custom_') &&
        $value != NULL
      ) {
        $submitted[substr($key, 5)] = $value;
      }
      elseif (substr($key, 0, 14) == 'move_location_' and $value != NULL) {
        $locField = explode('_', $key);
        $fieldName = $locField[2];
        $fieldCount = $locField[3];
        $operation = CRM_Utils_Array::value('operation', $migrationInfo['location'][$fieldName][$fieldCount]);
        // default operation is overwrite.
        if (!$operation) {
          $operation = 2;
        }

        $locBlocks[$fieldName][$fieldCount]['operation'] = $operation;
        $locBlocks[$fieldName][$fieldCount]['locTypeId'] = CRM_Utils_Array::value('locTypeId', $migrationInfo['location'][$fieldName][$fieldCount]);
      }
      elseif (substr($key, 0, 15) == 'move_rel_table_' and $value == '1') {
        $moveTables = array_merge($moveTables, $relTables[substr($key, 5)]['tables']);
        if (array_key_exists('operation', $migrationInfo)) {
          foreach ($relTables[substr($key, 5)]['tables'] as $table) {
            if (array_key_exists($key, $migrationInfo['operation'])) {
              $tableOperations[$table] = $migrationInfo['operation'][$key];
            }
          }
        }
      }
    }


    // **** Do location related migration:
    if (!empty($locBlocks)) {
      $locComponent = array(
        'email' => 'Email',
        'phone' => 'Phone',
        'im' => 'IM',
        'openid' => 'OpenID',
        'address' => 'Address',
      );

      $primaryBlockIds = CRM_Contact_BAO_Contact::getLocBlockIds($mainId, array('is_primary' => 1));
      $billingBlockIds = CRM_Contact_BAO_Contact::getLocBlockIds($mainId, array('is_billing' => 1));

      foreach ($locBlocks as $name => $block) {
        if (!is_array($block) || CRM_Utils_System::isNull($block)) {
          continue;
        }
        $daoName = 'CRM_Core_DAO_' . $locComponent[$name];
        $primaryDAOId = (array_key_exists($name, $primaryBlockIds)) ? array_pop($primaryBlockIds[$name]) : NULL;
        $billingDAOId = (array_key_exists($name, $billingBlockIds)) ? array_pop($billingBlockIds[$name]) : NULL;

        foreach ($block as $blkCount => $values) {
          $locTypeId = CRM_Utils_Array::value('locTypeId', $values, 1);
          $operation = CRM_Utils_Array::value('operation', $values, 2);
          $otherBlockId = CRM_Utils_Array::value($blkCount,
            $migrationInfo['other_details']['loc_block_ids'][$name]
          );

          // keep 1-1 mapping for address - loc type.
          $idKey = $blkCount;
          if (array_key_exists($name, $locComponent)) {
            $idKey = $locTypeId;
          }

          if (isset($migrationInfo['main_details']['loc_block_ids'][$name])) {
          $mainBlockId = CRM_Utils_Array::value($idKey, $migrationInfo['main_details']['loc_block_ids'][$name]);
          }

          if (!$otherBlockId) {
            continue;
          }

          // for the block which belongs to other-contact, link the contact to main-contact
          $otherBlockDAO = new $daoName();
          $otherBlockDAO->id = $otherBlockId;
          $otherBlockDAO->contact_id = $mainId;
          $otherBlockDAO->location_type_id = $locTypeId;

          // if main contact already has primary & billing, set the flags to 0.
          if ($primaryDAOId) {
            $otherBlockDAO->is_primary = 0;
          }
          if ($billingDAOId) {
            $otherBlockDAO->is_billing = 0;
          }

          // overwrite - need to delete block which belongs to main-contact.
          if ($mainBlockId && ($operation == 2)) {
            $deleteDAO = new $daoName();
            $deleteDAO->id = $mainBlockId;
            $deleteDAO->find(TRUE);

            // if we about to delete a primary / billing block, set the flags for new block
            // that we going to assign to main-contact
            if ($primaryDAOId && ($primaryDAOId == $deleteDAO->id)) {
              $otherBlockDAO->is_primary = 1;
            }
            if ($billingDAOId && ($billingDAOId == $deleteDAO->id)) {
              $otherBlockDAO->is_billing = 1;
            }

            $deleteDAO->delete();
            $deleteDAO->free();
          }

          $otherBlockDAO->update();
          $otherBlockDAO->free();
        }
      }
    }

    // **** Do tables related migrations
    if (!empty($moveTables)) {
      CRM_Dedupe_Merger::moveContactBelongings($mainId, $otherId, $moveTables, $tableOperations);
      unset($moveTables, $tableOperations);
    }

    // **** Do contact related migrations
    CRM_Dedupe_Merger::moveContactBelongings($mainId, $otherId);

    // FIXME: fix gender, prefix and postfix, so they're edible by createProfileContact()
    $names['gender'] = array('newName' => 'gender_id', 'groupName' => 'gender');
    $names['individual_prefix'] = array('newName' => 'prefix_id', 'groupName' => 'individual_prefix');
    $names['individual_suffix'] = array('newName' => 'suffix_id', 'groupName' => 'individual_suffix');
    $names['communication_style'] = array('newName' => 'communication_style_id', 'groupName' => 'communication_style');
    $names['addressee'] = array('newName' => 'addressee_id', 'groupName' => 'addressee');
    $names['email_greeting'] = array('newName' => 'email_greeting_id', 'groupName' => 'email_greeting');
    $names['postal_greeting'] = array('newName' => 'postal_greeting_id', 'groupName' => 'postal_greeting');
    CRM_Core_OptionGroup::lookupValues($submitted, $names, TRUE);

    // fix custom fields so they're edible by createProfileContact()
    static $treeCache = array();
    if (!array_key_exists($migrationInfo['main_details']['contact_type'], $treeCache)) {
      $treeCache[$migrationInfo['main_details']['contact_type']] = CRM_Core_BAO_CustomGroup::getTree($migrationInfo['main_details']['contact_type'],
        CRM_Core_DAO::$_nullObject, NULL, -1
      );
    }
    $cgTree = &$treeCache[$migrationInfo['main_details']['contact_type']];

    $cFields = array();
    foreach ($cgTree as $key => $group) {
      if (!isset($group['fields'])) {
        continue;
      }
      foreach ($group['fields'] as $fid => $field) {
        $cFields[$fid]['attributes'] = $field;
      }
    }

    if (!isset($submitted)) {
      $submitted = array();
    }
    foreach ($submitted as $key => $value) {
      if (substr($key, 0, 7) == 'custom_') {
        $fid = (int) substr($key, 7);
        if (empty($cFields[$fid])) {
          continue;
        }
        $htmlType = $cFields[$fid]['attributes']['html_type'];
        switch ($htmlType) {
          case 'File':
            $customFiles[] = $fid;
            unset($submitted["custom_$fid"]);
            break;

          case 'Select Country':
          case 'Select State/Province':
            $submitted[$key] = CRM_Core_BAO_CustomField::getDisplayValue($value, $fid, $cFields);
            break;

          case 'CheckBox':
          case 'AdvMulti-Select':
          case 'Multi-Select':
          case 'Multi-Select Country':
          case 'Multi-Select State/Province':
            // Merge values from both contacts for multivalue fields, CRM-4385
            // get the existing custom values from db.
            $customParams = array('entityID' => $mainId, $key => TRUE);
            $customfieldValues = CRM_Core_BAO_CustomValueTable::getValues($customParams);
            if (!empty($customfieldValues[$key])) {
              $existingValue = explode(CRM_Core_DAO::VALUE_SEPARATOR, $customfieldValues[$key]);
              if (is_array($existingValue) && !empty($existingValue)) {
                $mergeValue = $submmtedCustomValue = array();
                if ($value) {
                  $submmtedCustomValue = explode(CRM_Core_DAO::VALUE_SEPARATOR, $value);
                }

                //hack to remove null and duplicate values from array.
                foreach (array_merge($submmtedCustomValue, $existingValue) as $k => $v) {
                  if ($v != '' && !in_array($v, $mergeValue)) {
                    $mergeValue[] = $v;
                  }
                }

                //keep state and country as array format.
                //for checkbox and m-select format w/ VALUE_SEPARATOR
                if (in_array($htmlType, array(
                  'CheckBox', 'Multi-Select', 'AdvMulti-Select'))) {
                  $submitted[$key] = CRM_Core_DAO::VALUE_SEPARATOR . implode(CRM_Core_DAO::VALUE_SEPARATOR,
                    $mergeValue
                  ) . CRM_Core_DAO::VALUE_SEPARATOR;
                }
                else {
                  $submitted[$key] = $mergeValue;
                }
              }
            }
            elseif (in_array($htmlType, array(
              'Multi-Select Country', 'Multi-Select State/Province'))) {
              //we require submitted values should be in array format
              if ($value) {
                $mergeValueArray = explode(CRM_Core_DAO::VALUE_SEPARATOR, $value);
                //hack to remove null values from array.
                $mergeValue = array();
                foreach ($mergeValueArray as $k => $v) {
                  if ($v != '') {
                    $mergeValue[] = $v;
                  }
                }
                $submitted[$key] = $mergeValue;
              }
            }
            break;

          default:
            break;
        }
      }
    }

    // **** Do file custom fields related migrations
    // FIXME: move this someplace else (one of the BAOs) after discussing
    // where to, and whether CRM_Core_BAO_File::deleteFileReferences() shouldn't actually,
    // like, delete a file...

    if (!isset($customFiles)) {
      $customFiles = array();
    }
    foreach ($customFiles as $customId) {
      list($tableName, $columnName, $groupID) = CRM_Core_BAO_CustomField::getTableColumnGroup($customId);

      // get the contact_id -> file_id mapping
      $fileIds = array();
      $sql = "SELECT entity_id, {$columnName} AS file_id FROM {$tableName} WHERE entity_id IN ({$mainId}, {$otherId})";
      $dao = CRM_Core_DAO::executeQuery($sql, CRM_Core_DAO::$_nullArray);
      while ($dao->fetch()) {
        $fileIds[$dao->entity_id] = $dao->file_id;
      }
      $dao->free();

      // delete the main contact's file
      if (!empty($fileIds[$mainId])) {
        CRM_Core_BAO_File::deleteFileReferences($fileIds[$mainId], $mainId, $customId);
      }

      // move the other contact's file to main contact
      //NYSS need to INSERT or UPDATE depending on whether main contact has an existing record
      if ( CRM_Core_DAO::singleValueQuery("SELECT id FROM {$tableName} WHERE entity_id = {$mainId}") ) {
      $sql = "UPDATE {$tableName} SET {$columnName} = {$fileIds[$otherId]} WHERE entity_id = {$mainId}";
      }
      else {
        $sql = "INSERT INTO {$tableName} ( entity_id, {$columnName} ) VALUES ( {$mainId}, {$fileIds[$otherId]} )";
      }
      CRM_Core_DAO::executeQuery($sql, CRM_Core_DAO::$_nullArray);

      if ( CRM_Core_DAO::singleValueQuery("
        SELECT id
        FROM civicrm_entity_file
        WHERE entity_table = '{$tableName}' AND file_id = {$fileIds[$otherId]}") ) {
        $sql = "
          UPDATE civicrm_entity_file
          SET entity_id = {$mainId}
          WHERE entity_table = '{$tableName}' AND file_id = {$fileIds[$otherId]}";
      }
      else {
        $sql = "
          INSERT INTO civicrm_entity_file ( entity_table, entity_id, file_id )
          VALUES ( '{$tableName}', {$mainId}, {$fileIds[$otherId]} )";
      }
      CRM_Core_DAO::executeQuery($sql, CRM_Core_DAO::$_nullArray);
    }

    // move view only custom fields CRM-5362
    $viewOnlyCustomFields = array();
    foreach ($submitted as $key => $value) {
      $fid = (int) substr($key, 7);
      if (array_key_exists($fid, $cFields) && !empty($cFields[$fid]['attributes']['is_view'])) {
        $viewOnlyCustomFields[$key] = $value;
      }
    }

    // special case to set values for view only, CRM-5362
    if (!empty($viewOnlyCustomFields)) {
      $viewOnlyCustomFields['entityID'] = $mainId;
      CRM_Core_BAO_CustomValueTable::setValues($viewOnlyCustomFields);
    }

    // **** Delete other contact & update prev-next caching
    $otherParams = array(
      'contact_id' => $otherId,
      'id' => $otherId,
      'version' => 3,
    );
    if (CRM_Core_Permission::check('merge duplicate contacts') &&
      CRM_Core_Permission::check('delete contacts')
    ) {
      // if ext id is submitted then set it null for contact to be deleted
      if (!empty($submitted['external_identifier'])) {
        $query = "UPDATE civicrm_contact SET external_identifier = null WHERE id = {$otherId}";
        CRM_Core_DAO::executeQuery($query);
      }

      civicrm_api('contact', 'delete', $otherParams);
      CRM_Core_BAO_PrevNextCache::deleteItem($otherId);
    }
    // FIXME: else part
    /*         else { */

    /*             CRM_Core_Session::setStatus( ts('Do not have sufficient permission to delete duplicate contact.') ); */

    /*         } */


    // **** Update contact related info for the main contact
    if (!empty($submitted)) {
      $submitted['contact_id'] = $mainId;

      //update current employer field
      if ($currentEmloyerId = CRM_Utils_Array::value('current_employer_id', $submitted)) {
        if (!CRM_Utils_System::isNull($currentEmloyerId)) {
          $submitted['current_employer'] = $submitted['current_employer_id'];
        } else {
          $submitted['current_employer'] = '';
        }
        unset($submitted['current_employer_id']);
      }

      //CRM-14312 include prefix/suffix from mainId if not overridden for proper construction of display/sort name
      if ( !isset($submitted['prefix_id']) && !empty($migrationInfo['main_details']['prefix_id']) ) {
        $submitted['prefix_id'] = $migrationInfo['main_details']['prefix_id'];
      }
      if ( !isset($submitted['suffix_id']) && !empty($migrationInfo['main_details']['suffix_id']) ) {
        $submitted['suffix_id'] = $migrationInfo['main_details']['suffix_id'];
      }

      CRM_Contact_BAO_Contact::createProfileContact($submitted, CRM_Core_DAO::$_nullArray, $mainId);
      unset($submitted);
    }

    return TRUE;
  }

  /**
   * @return array of field names which will be compared, so everything except ID.
   */
  static function getContactFields() {
    $contactFields = CRM_Contact_DAO_Contact::fields();
    $invalidFields = array('api_key', 'contact_is_deleted', 'created_date', 'display_name', 'hash', 'id', 'modified_date',
      'primary_contact_id', 'sort_name', 'user_unique_id');
    foreach ($contactFields as $field => $value) {
      if (in_array($field, $invalidFields)) {
        unset($contactFields[$field]);
      }
    }
    return array_keys($contactFields);
  }

  /**
   * Added for CRM-12695
   * Based on the contactId provided
   * add/update membership(s) to related contacts
   *
   * @param contactId
   */
  static function addMembershipToRealtedContacts($contactID) {
    $dao = new CRM_Member_DAO_Membership();
    $dao->contact_id = $contactID;
    $dao->is_test = 0;
    $dao->find();

    //checks membership of contact itself
    while ($dao->fetch()) {
      $relationshipTypeId = CRM_Core_DAO::getFieldValue('CRM_Member_DAO_MembershipType', $dao->membership_type_id, 'relationship_type_id', 'id');
      if ($relationshipTypeId) {
        $membershipParams = array(
          'id' => $dao->id,
          'contact_id' => $dao->contact_id,
          'membership_type_id' => $dao->membership_type_id,
          'join_date' => CRM_Utils_Date::isoToMysql($dao->join_date),
          'start_date' => CRM_Utils_Date::isoToMysql($dao->start_date),
          'end_date' => CRM_Utils_Date::isoToMysql($dao->end_date),
          'source' => $dao->source,
          'status_id' => $dao->status_id
        );
        // create/update membership(s) for related contact(s)
        CRM_Member_BAO_Membership::createRelatedMemberships($membershipParams, $dao);
      } // end of if relationshipTypeId
    }
  }
}