#!/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;

  /**
   * @param array $dirs
   */
  public function __construct($dirs = array()) {
    $this->dirs = $dirs;
  }

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

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

}

/**
 * FIXME: Why am I doing this? Can't we get a proper build-system for little
 * CLI tools -- and then use prepackaged libraries?
 */
class PullRequest {

  /**
   * Given a link to a pull-request, determine which local repo
   * it applies to and fetch any metadata.
   *
   * @param string $url
   * @param array $repos list of locally known repos
   * @return PullRequest|NULL
   */
  public static function get($url, $repos) {
    foreach ($repos as $repo => $relPath) {
      if (preg_match("/^https:\/\/github.com\/(.*)\/(civicrm-{$repo})\/pull\/([0-9]+)(|\/commits|\/files)$/", $url, $matches)) {
        list ($full, $githubUser, $githubRepo, $githubPr) = $matches;

        $pr = new PullRequest();
        $pr->repo = $repo;
        $pr->data = HttpClient::getJson("https://api.github.com/repos/$githubUser/$githubRepo/pulls/$githubPr");
        if (empty($pr->data)) {
          return NULL;
        }

        return $pr;
      }
    }
    return NULL;
  }

  /**
   * @var string local repo name e.g. "core", "drupal"
   */
  public $repo;

  protected $data;

  /**
   * @return mixed
   */
  public function getNumber() {
    return $this->data->number;
  }

  /**
   * @return string name of the branch on the requestor's repo
   */
  public function getRequestorBranch() {
    return $this->data->head->ref;
  }

  /**
   * @return string URL of the requestor's repo
   */
  public function getRequestorRepoUrl() {
    return $this->data->head->repo->git_url;
  }

}

/**
 * Class Givi
 */
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 $force = FALSE;

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

  /**
   * @var string, the word 'all' or comma-delimited list of repo names
   */
  protected $repoFilter = 'all';

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

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

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

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

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

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

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

  /**
   * @param $args
   *
   * @throws Exception
   */
  public function main($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");
    }

    $this->repos = $this->filterRepos($this->repoFilter, $this->repos);

    // 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 'review':
        call_user_func_array(array($this, 'doReview'), $this->arguments);
        break;

      //case 'merge-forward':
      //  call_user_func_array(array($this, 'doMergeForward'), $this->arguments);
      //  break;

      case 'push':
        call_user_func_array(array($this, 'doPush'), $this->arguments);
        break;

      case 'help':
      case '':
        $this->doHelp();
        break;

      default:
        return $this->returnError("unrecognized action: {$this->action}\n");
    }

    if ($this->useSetup) {
      $this->run('core', $this->civiRoot . '/bin', 'bash', 'setup.sh');
    }
    elseif ($this->useGencode) {
      $this->run('core', $this->civiRoot . '/xml', 'php', 'GenCode.php');
    }

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

  /**
   * @param $args
   * @return bool
   */
  public function parseOptions($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') {
        $this->dryRun = TRUE;
      }
      elseif ($arg == '--force' || $arg == '-f') {
        $this->force = TRUE;
      }
      elseif ($arg == '--gencode') {
        $this->useGencode = TRUE;
      }
      elseif ($arg == '--setup') {
        $this->useSetup = 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('/^--repos=(.*)/', $arg, $matches)) {
        $this->repoFilter = $matches[1];
      }
      elseif (preg_match('/^--(core|packages|joomla|drupal|wordpress|backdrop)=(.*)/', $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;
  }

  public function doHelp() {
    $program = basename($this->program);
    echo "Givi - Coordinate git checkouts across CiviCRM repositories\n";
    echo "Scenario:\n";
    echo "  You have cloned and forked the CiviCRM repos. Each of the repos has two\n";
    echo "  remotes (origin + upstream). When working on a new PR, you generally want\n";
    echo "  to checkout official code (eg upstream/master) in all repos, but 1-2 repos\n";
    echo "  should use a custom branch (which tracks upstream/master).\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 "  $program [options] review <base-branch> <pr-url-1> <pr-url-2>...\n";
    #echo "  $program [options] merge-forward <maintenace-branch> <development-branch>\n";
    #echo "  $program [options] push <remote> <branch>[:<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 "  review: Test work provided by someone else's pull-request. (If each repo has related PRs, then you can link to each of them.)\n";
    #echo "  merge-forward: On each repo, merge changes from maintenance branch to development branch\n";
    #echo "  push: On each repo, push a branch to a remote (Note: only intended for use with merge-forward)\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 "  --d8: Specify that Drupal branches should use 8.x-* prefixes\n";
    echo "  -f: When switching branches, proceed even if the index or the working tree differs from HEAD. This is used to throw away local changes.\n";
    echo "  --fetch: Fetch the latest code before creating, updating, or checking-out anything\n";
    echo "  --repos=X: Restrict operations to the listed repos (comma-delimited list) (default: all)";
    echo "  --root=X: Specify CiviCRM root directory (default: .)\n";
    echo "  --gencode: Run xml/GenCode after checking out code\n";
    echo "  --setup: Run bin/setup.sh (incl xml/GenCode) after checking out code\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 "  --backdrop=X: Specify the branch to use on the backdrop 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";
  }

  /**
   * @param null $baseBranch
   *
   * @return bool
   */
  public function doCheckoutAll($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]);
      $this->run($repo, $relPath, 'git', 'checkout', $filteredBranch, $this->force ? '-f' : NULL);
    }
    return TRUE;
  }

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

  /**
   * @param null $baseBranch
   *
   * @return bool
   */
  public function doBegin($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) {
        $this->run($repo, $relPath, 'git', 'checkout', $filteredBranch, $this->force ? '-f' : NULL);
      }
      else {
        $this->run($repo, $relPath, 'git', 'checkout', '-b', $filteredBranch, $filteredBaseBranch, $this->force ? '-f' : NULL);
      }
    }

    return TRUE;
  }

  /**
   * @param null $baseBranch
   *
   * @return bool
   * @throws Exception
   */
  public function doResume($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) {
      $filteredBranch = $this->filterBranchName($repo, $branches[$repo]);
      $filteredBaseBranch = $this->filterBranchName($repo, $baseBranch);

      $this->run($repo, $relPath, 'git', 'checkout', $filteredBranch, $this->force ? '-f' : NULL);
      if ($filteredBranch != $filteredBaseBranch && $this->rebase) {
        list ($baseRemoteRepo, $baseRemoteBranch) = $this->parseBranchRepo($filteredBaseBranch);
        $this->run($repo, $relPath, 'git', 'pull', '--rebase', $baseRemoteRepo, $baseRemoteBranch);
      }
    }

    return TRUE;
  }

  /**
   * @param null $baseBranch
   *
   * @return bool
   */
  public function doReview($baseBranch = NULL) {
    if (!$this->doCheckoutAll($baseBranch)) {
      return FALSE;
    }

    $args = func_get_args();
    array_shift($args); // $baseBranch

    $pullRequests = array();
    foreach ($args as $prUrl) {
      $pullRequest = PullRequest::get($prUrl, $this->repos);
      if ($pullRequest) {
        $pullRequests[] = $pullRequest;
      }
      else {
        return $this->returnError("Invalid pull-request URL: $prUrl");
      }
    }

    foreach ($pullRequests as $pullRequest) {
      $repo = $pullRequest->repo;
      $branchName = 'pull-request-' . $pullRequest->getNumber();
      if ($this->hasLocalBranch($repo, $branchName)) {
        $this->run($repo, $this->repos[$repo], 'git', 'branch', '-D', $branchName);
      }
      $this->run($repo, $this->repos[$repo], 'git', 'checkout', '-b', $branchName); ## based on whatever was chosen by doCheckoutAll()
      $this->run($repo, $this->repos[$repo], 'git', 'pull', $pullRequest->getRequestorRepoUrl(), $pullRequest->getRequestorBranch());
    }

    return TRUE;
  }

  /**
   * @param $newBranchRepo
   * @param $newBranchNames
   *
   * @return bool
   */
  public function doPush($newBranchRepo, $newBranchNames) {
    if (!$newBranchRepo) {
      return $this->returnError("Missing <remote>\n");
    }
    if (!$newBranchNames) {
      return $this->returnError("Missing <branch>[:<branch>]\n");
    }
    if (FALSE !== strpos($newBranchNames, ':')) {
      list ($newBranchFromName, $newBranchToName) = explode(':', $newBranchNames);
      foreach ($this->repos as $repo => $relPath) {
        $filteredFromName = $this->filterBranchName($repo, $newBranchFromName);
        $filteredToName = $this->filterBranchName($repo, $newBranchToName);

        $this->run($repo, $relPath, 'git', 'push', $newBranchRepo, $filteredFromName . ':' . $filteredToName);
      }
    }
    else {
      foreach ($this->repos as $repo => $relPath) {
        $filteredName = $this->filterBranchName($repo, $newBranchNames);
        $this->run($repo, $relPath, 'git', 'push', $newBranchRepo, $filteredName);
      }
    }

    return TRUE;
  }

  /**
   * Determine if a branch exists locally
   *
   * @param string $repo
   * @param string $name branch name
   * @return bool
   */
  public function hasLocalBranch($repo, $name) {
    $path = $this->repos[$repo] . '/.git/refs/heads/' . $name;
    return file_exists($path);
  }

  /**
   * Given a ref name, determine the repo and branch
   *
   * FIXME: only supports $refs like "foo" (implicit origin) or "myremote/foo"
   *
   * @param $ref
   * @param string $defaultRemote
   *
   * @throws Exception
   * @return array
   */
  public function parseBranchRepo($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 $repoName
   * @param string $runDir
   * @param string $command
   *
   * @return string
   */
  public function run($repoName, $runDir, $command) {
    $this->dirStack->push($runDir);

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

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

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

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

  /**
   * @param $repoName
   * @param $branchName
   *
   * @return string
   */
  public function filterBranchName($repoName, $branchName) {
    if ($branchName == '') {
      return '';
    }
    if ($repoName == 'drupal') {
      $parts = explode('/', $branchName);
      $last = $this->drupalVersion . '.x-' . array_pop($parts);
      array_push($parts, $last);
      return implode('/', $parts);
    }
    if ($repoName == 'backdrop') {
      $parts = explode('/', $branchName);
      $last = '1.x-' . array_pop($parts);
      array_push($parts, $last);
      return implode('/', $parts);
    }
    return $branchName;
  }

  /**
   * @param string $filter e.g. "all" or "repo1,repo2"
   * @param array $repos ($repoName => $repoDir)
   *
   * @throws Exception
   * @return array ($repoName => $repoDir)
   */
  public function filterRepos($filter, $repos) {
    if ($filter == 'all') {
      return $repos;
    }

    $inclRepos = explode(',', $filter);
    $unknowns = array_diff($inclRepos, array_keys($repos));
    if (!empty($unknowns)) {
      throw new Exception("Unknown Repos: " . implode(',', $unknowns));
    }
    $unwanted = array_diff(array_keys($repos), $inclRepos);
    foreach ($unwanted as $repo) {
      unset($repos[$repo]);
    }
    return $repos;
  }

  /**
   * @param $message
   *
   * @return bool
   */
  public function returnError($message) {
    echo "\nERROR: ", $message, "\n\n";
    $this->doHelp();
    return FALSE;
  }

}

/**
 * Class HttpClient
 */
class HttpClient {
  /**
   * @param $url
   * @param $file
   *
   * @return bool
   */
  public static function download($url, $file) {
    // PHP native client is unreliable PITA for HTTPS
    if (exec("which wget")) {
      self::run('wget', '-q', '-O', $file, $url);
    }
    elseif (exec("which curl")) {
      self::run('curl', '-o', $file, $url);
    }

    // FIXME: really detect errors
    return TRUE;
  }

  /**
   * @param $url
   *
   * @return mixed
   */
  public static function getJson($url) {
    $file = tempnam(sys_get_temp_dir(), 'givi-json-');
    HttpClient::download($url, $file);
    $data = json_decode(file_get_contents($file));
    unlink($file);
    return $data;
  }

  /**
   * Run a command
   *
   * Any items after $command will be escaped and added to $command
   *
   * @param string $command
   *
   * @internal param string $runDir
   * @return string
   */
  public static function run($command) {
    $args = func_get_args();
    array_shift($args);
    foreach ($args as $arg) {
      $command .= ' ' . escapeshellarg($arg);
    }
    printf("\n\n\nRUN: %s\n", $command);
    $r = system($command);

    return $r;
  }

}

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