#!/usr/bin/env php
<?php

// This is the minimalist denialist implementation that doesn't check it's
// pre-conditions and will screw up if you don't know what you're doing.

/**
 * Manage the current working directory as a stack.
 */
class DirStack {
  protected $dirs;

  function __construct($dirs = array()) {
    $this->dirs = $dirs;
  }

  function push($dir) {
    $this->dirs[] = getcwd();
    if (!chdir($dir)) {
      throw new Exception("Failed to chdir($dir)");
    }
  }

  function pop() {
    $oldDir = array_pop($this->dirs);
    chdir($oldDir);
  }
}

class Givi {

  /**
   * @var string 'checkout', 'begin', 'help', etc
   */
  protected $action;

  /**
   * @var string
   */
  protected $baseBranch;

  /**
   * @var array ($repoName => $gitRef)
   */
  protected $branches;

  /**
   * @var string
   */
  protected $civiRoot = '.';

  /**
   * @var int
   */
  protected $drupalVersion = 7;

  /**
   * @var bool
   */
  protected $dryRun = FALSE;

  /**
   * @var bool
   */
  protected $fetch = FALSE;

  /**
   * @var bool
   */
  protected $rebase = FALSE;

  /**
   * @var array ($repoName => $relPath)
   */
  protected $repos;

  /**
   * @var array, non-hyphenated arguments after the basedir
   */
  protected $arguments;

  /**
   * @var string, the name of this program
   */
  protected $program;

  /**
   * @var DirStack
   */
  protected $dirStack;

  function __construct() {
    $this->dirStack = new DirStack();
    $this->repos = array(
      'core' => '.',
      'packages' => 'packages',
      'joomla' => 'joomla',
      'drupal' => 'drupal',
      'wordpress' => 'WordPress',
    );
  }

  function main($args) {
    if (!$this->parseOptions($args)) {
      printf("Error parsing arguments\n");
      $this->doHelp();
      return FALSE;
    }

    // All operations relative to civiRoot
    $this->dirStack->push($this->civiRoot);

    // Filter branch list based on what repos actually exist
    foreach (array_keys($this->repos) as $repo) {
      if (!is_dir($this->repos[$repo])) {
        unset($this->repos[$repo]);
      }
    }
    if (!isset($this->repos['core']) || !isset($this->repos['packages'])) {
      return $this->returnError("Root appears to be invalid -- missing too many repos. Try --root=<dir>\n");
    }

    // Run the action
    switch ($this->action) {
      case 'checkout':
        call_user_func_array(array($this, 'doCheckoutAll'), $this->arguments);
        break;
      case 'fetch':
        call_user_func_array(array($this, 'doFetchAll'), $this->arguments);
        break;
      case 'status':
        call_user_func_array(array($this, 'doStatusAll'), $this->arguments);
        break;
      case 'begin':
        call_user_func_array(array($this, 'doBegin'), $this->arguments);
        break;
      case 'resume':
        call_user_func_array(array($this, 'doResume'), $this->arguments);
        break;
      case 'help':
      case '':
        $this->doHelp();
        break;
      default:
        return $this->returnError("unrecognized action: {$this->action}\n");
    }

    $this->dirStack->pop();
  }

  /**
   * @param $args
   * @return bool
   */
  function parseOptions($args) {
    $this->branches = array();
    $this->arguments = array();

    foreach ($args as $arg) {
      if ($arg == '--fetch') {
        $this->fetch = TRUE;
      }
      elseif ($arg == '--rebase') {
        $this->rebase = TRUE;
      }
      elseif ($arg == '--dry-run' || $arg == '-n') {
        $this->dryRun = TRUE;
      }
      elseif (preg_match('/^--d([678])/', $arg, $matches)) {
        $this->drupalVersion = $matches[1];
      }
      elseif (preg_match('/^--root=(.*)/', $arg, $matches)) {
        $this->civiRoot = $matches[1];
      }
      elseif (preg_match('/^--(core|packages|joomla|drupal|wordpress)=(.*)/', $arg, $matches)) {
        $this->branches[$matches[1]] = $matches[2];
      }
      elseif (preg_match('/^-/', $arg)) {
        printf("unrecognized argument: %s\n", $arg);
        return FALSE;
      }
      else {
        $this->arguments[] = $arg;
      }
    }

    $this->program = @array_shift($this->arguments);
    $this->action = @array_shift($this->arguments);
    return TRUE;
  }

  function doHelp() {
    $program = basename($this->program);
    echo "Givi - Coordinate git checkouts across CiviCRM repositories\n";
    echo "Usage:\n";
    echo "  $program [options] checkout <branch>\n";
    echo "  $program [options] fetch\n";
    echo "  $program [options] status\n";
    echo "  $program [options] begin <base-branch> [--core=<new-branch>|--drupal=<new-branch>|...] \n";
    echo "  $program [options] resume [--rebase] <base-branch> [--core=<custom-branch>|--drupal=<custom-branch>|...] \n";
    echo "Actions:\n";
    echo "  checkout: Checkout same branch name on all repos\n";
    echo "  fetch: Fetch remote changes on all repos\n";
    echo "  status: Display status on all repos\n";
    echo "  begin: Begin work on a new branch on some repo (and use base-branch for all others)\n";
    echo "  resume: Resume work on an existing branch on some repo (and use base-branch for all others)\n";
    echo "Common options:\n";
    echo "  --dry-run: Don't do anything; only print commands that would be run\n";
    echo "  --d6: Specify that Drupal branches should use 6.x-* prefixes\n";
    echo "  --d7: Specify that Drupal branches should use 7.x-* prefixes (default)\n";
    echo "  --fetch: Fetch the latest code before creating, updating, or checking-out anything\n";
    echo "  --root=X: Specify CiviCRM root directory (default: .)\n";
    echo "Special options:\n";
    echo "  --core=X: Specify the branch to use on the core repository\n";
    echo "  --packages=X: Specify the branch to use on the packages repository\n";
    echo "  --drupal=X: Specify the branch to use on the drupal repository\n";
    echo "  --joomla=X: Specify the branch to use on the joomla repository\n";
    echo "  --wordpress=X: Specify the branch to use on the wordpress repository\n";
    echo "  --rebase: Perform a rebase before starting work\n";
    echo "Known repositories:\n";
    foreach ($this->repos as $repo => $relPath) {
      printf("  %-12s: %s\n", $repo, realpath($this->civiRoot . DIRECTORY_SEPARATOR . $relPath));
    }
    echo "When using 'begin' or 'resume' with a remote base-branch, most repositories\n";
    echo "will have a detached HEAD. Only repos with an explicit branch will be real,\n";
    echo "local branches.\n";
  }

  function doCheckoutAll($baseBranch = NULL) {
    if (!$baseBranch) {
      return $this->returnError("Missing <branch>\n");
    }
    $branches = $this->resolveBranches($baseBranch, $this->branches);
    if ($this->fetch) {
      $this->doFetchAll();
    }

    foreach ($this->repos as $repo => $relPath) {
      $filteredBranch = $this->filterBranchName($repo, $branches[$repo]);
      $this->run($relPath, 'git', 'checkout', $filteredBranch);
    }
    return TRUE;
  }

  function doStatusAll() {
    foreach ($this->repos as $repo => $relPath) {
      $this->run($relPath, 'git', 'status');
    }
    return TRUE;
  }

  function doBegin($baseBranch = NULL) {
    if (!$baseBranch) {
      return $this->returnError("Missing <base-branch>\n");
    }
    if (empty($this->branches)) {
      return $this->returnError("Must specify a custom branch for at least one repository.\n");
    }
    $branches = $this->resolveBranches($baseBranch, $this->branches);
    if ($this->fetch) {
      $this->doFetchAll();
    }

    foreach ($this->repos as $repo => $relPath) {
      $filteredBranch = $this->filterBranchName($repo, $branches[$repo]);
      $filteredBaseBranch = $this->filterBranchName($repo, $baseBranch);
      if ($filteredBranch == $filteredBaseBranch) {
        $this->run($relPath, 'git', 'checkout', $filteredBranch);
      }
      else {
        $this->run($relPath, 'git', 'checkout', '-b', $filteredBranch, $filteredBaseBranch);
      }
    }
  }

  function doResume($baseBranch = NULL) {
    if (!$baseBranch) {
      return $this->returnError("Missing <base-branch>\n");
    }
    if (empty($this->branches)) {
      return $this->returnError("Must specify a custom branch for at least one repository.\n");
    }
    $branches = $this->resolveBranches($baseBranch, $this->branches);
    if ($this->fetch) {
      $this->doFetchAll();
    }

    foreach ($this->repos as $repo => $relPath) {
      $this->run($relPath, 'git', 'checkout', $branches[$repo]);
      if ($branches[$repo] != $baseBranch && $this->rebase) {
        // FIXME: assumes
        list ($baseRemoteRepo, $baseRemoteBranch) = $this->parseBranchRepo($baseBranch);
        $this->run($relPath, 'git', 'pull', '--rebase', $baseRemoteRepo, $baseRemoteBranch);
      }
    }
  }

  /**
   * Given a ref name, determine the repo and branch
   *
   * FIXME: only supports $refs like "foo" (implicit origin) or "myremote/foo"
   *
   * @param $ref
   * @return array
   */
  function parseBranchRepo($ref, $defaultRemote = 'origin') {
    $parts = explode('/', $ref);
    if (count($parts) == 1) {
      return array($defaultRemote, $parts[1]);
    }
    elseif (count($parts) == 2) {
      return $parts;
    }
    else {
      throw new Exception("Failed to parse branch name ($ref)");
    }
  }

  /**
   * Run a command
   *
   * Any items after $command will be escaped and added to $command
   *
   * @param string $runDir
   * @param string $command
   * @return string
   */
  function run($runDir, $command) {
    $this->dirStack->push($runDir);

    $args = func_get_args();
    array_shift($args);
    array_shift($args);
    foreach ($args as $arg) {
      $command .= ' ' . escapeshellarg($arg);
    }
    printf("\nRUN [%s]: %s\n", $runDir, $command);
    if ($this->dryRun) {
      $r = NULL;
    } else {
      $r = system($command);
    }

    $this->dirStack->pop();
    return $r;
  }

  function doFetchAll() {
    foreach ($this->repos as $repo => $relPath) {
      $this->run($relPath, 'git', 'fetch', '--all');
    }
  }

  /**
   * @param string $default branch to use by default
   * @return array ($repoName => $gitRef)
   */
  function resolveBranches($default, $overrides) {
    $branches = $overrides;
    foreach ($this->repos as $repo => $relPath) {
      if (!isset($branches[$repo])) {
        $branches[$repo] = $default;
      }
    }
    return $branches;
  }

  function filterBranchName($repoName, $branchName) {
    if ($repoName == 'drupal') {
      $parts = explode('/', $branchName);
      $last = $this->drupalVersion . '.x-' . array_pop($parts);
      array_push($parts, $last);
      return implode('/', $parts);
    }
    return $branchName;
  }

  function returnError($message) {
    echo "ERROR: ", $message, "\n";
    $this->doHelp();
    return FALSE;
  }
}

$givi = new Givi();
$givi->main($argv);