Discussion: Drush pm-download is too restrictive for dog's objectives

Looks like Sam (sdboyer) is working on this in the custom-dl branch.

For anyone interested, I include the dog-dl code I made for myself.

I hope it can be useful for the dog-dl development

It supports the d.o. repository,
example: drush dog-dl --branch=devel libraries
local git repositories:
drush dog-dl --branch=devel /home/git/drupal/my_module.git sites/all/modules/my_module
and non-d.o. remote repositories
drush dog-dl --branch=devel https://github.com/kete/tiny_mce.git sites/all/libraries/tiny_mce

Specifying a local branch is required for this code

function drush_dog_dl($project = '', $target = '') {
  // First ensure we have a clean working copy
  $output = _dog_git_invoke('status --porcelain', DRUPAL_ROOT);
  if ($output) {
    return drush_set_error('DRUSH_DOG_DIRTY_TREE', dt("You have uncommitted changes in your working copy; dog-dl requires a clean working copy to run:\n!changes", array('!changes'=>$output)));
  }

  if (empty($project)) {
    return drush_set_error('DRUSH_DOG_PROJECT_MISSING', dt('A project must be specified.'));
  }

  // If the project doesn't contain a slash or backslash character
  // assume it's a drupal project
  if (strpos($project, '/') === FALSE && strpos($project, '\\') === FALSE) {
    $version = pm_parse_project_version(array($project));
    $version = reset($version);
    $xml = _drush_pm_get_release_history_xml($version);
    switch($xml->terms->term[0]->value) {
      case 'Modules':
        $contrib_type = 'modules';
        break;
      case 'Themes':
        $contrib_type = 'themes';
        break;
      default:
        drush_log('Unknown project type', 'error');
    }
    $release = pm_parse_release($version, $xml);
    $short_name = $xml->short_name;
    $upstream_ref = $release['tag'];
    if (isset($release['version_extra']) &&
    $release['version_extra'] == 'dev') {
      // branch tags need the 'upstream/' prefix;
      $upstream_ref = 'upstream/' . $upstream_ref;
    }
    $upstream = 'git://git.drupal.org/project/' . $short_name . '.git';
    if (empty($target)) {
      $target = 'sites/all/' . $contrib_type . '/' . $short_name;
    }
  }
  else {
    $upstream_ref = drush_get_option('upstream-ref', 'HEAD');
    $upstream = $project;
    if (empty($target)) {
      return drush_set_error('DRUSH_DOG_TARGET MISSING', dt('A target must be specified for non drupal projects.'));
    }
  }
  // Check for and resolve a relative target path
  if (substr($target, 0, 1) != '/' && substr($target, 1, 2) != ':\\') {
    $target = DRUPAL_ROOT . '/' . $target;
  }

  if (file_exists($target)) {
    return drush_set_error('DRUSH_DOG_TARGET_EXISTS', dt('Target directory !target already exists.', array('!target'=>$target)));
  }

  try {
    $remoteinfo = _dog_git_invoke('ls-remote ' . drush_escapeshellarg($upstream) . ' 7.0');
  }
  catch (Exception $e) {
    return drush_set_error('DRUSH_DOG_INVALID_UPSTREAM', dt("Upstream URI '%upstream' is not a Git repository.", array('%upstream' => $upstream)));
  }
  
  // @todo Add option for repository validation?
  //if (strpos($remoteinfo, '497914920385b7016ac9c9367e0198530787adf2') !== 0) {
  //  drush_log("Upstream URI '$upstream' is not a valid Drupal core repository.", 'error');
  //  return bad_dog();
  //}

  // Build the base clone command.
  $cmd = 'clone -q -o upstream --no-hardlinks ';

  // Use a refcache if drush has one specified
  if ($refcache = drush_get_option('git_reference_cache')) {
    $cmd .= "--reference $refcache ";
  }

  // add the clone uri and target dir
  $cmd .= escapeshellarg($upstream);

  // add the target output dir
  if (!empty($target)) {
    $cmd .= ' ' . escapeshellarg($target);
  }

  drush_log("Cloning '$upstream' into '$target'.", 'info');

  try {
    // Do the clone
    _dog_git_invoke($cmd);
  }
  catch (Exception $e) {
    return drush_set_error('DRUSH_DOG_GIT_INVOCATION_ERROR', dt("Clone of upstream repository failed."));
  }

  if (!empty($short_name)) {
    $proj_name = $short_name . '-' . $release['tag'];
  }
  else {
    $proj_name = $upstream;
  }

  drush_log("Successfully installed project $proj_name in $target.", 'success');

  // Create the appropriate local branch based on the requested start point
  $localbranch = drush_get_option('branch', 'master');

  $old = trim(_dog_git_invoke('symbolic-ref HEAD | cut -c 12-', $target));

  _dog_git_invoke('checkout -b ' . escapeshellarg($localbranch) . ' ' . escapeshellarg($upstream_ref), $target);
  _dog_git_invoke('branch -D ' . $old, $target);

  // Set the collab uri
  $collab = drush_get_option('collab', $upstream);
  _dog_git_invoke('remote add collab ' . escapeshellarg($collab), $target);

  // Add the submodule if it's in a subdirectory of DRUPAL_ROOT
  if (substr($target, 0, strlen(DRUPAL_ROOT)) == DRUPAL_ROOT) {
    $target_relative = substr($target, strlen(DRUPAL_ROOT) + 1);
    $cmd = 'submodule add ';
    $cmd .= escapeshellarg($upstream) . ' ';
    $cmd .= escapeshellarg($target_relative);
    _dog_git_invoke($cmd, DRUPAL_ROOT);

    // Add and commit .gitmodules and the new project
    $new_files = '.gitmodules ' . $target_relative . ' ' . dirname($target_relative);
    _dog_git_invoke('add -- ' . $new_files, DRUPAL_ROOT);
    _dog_git_invoke('commit -m "Add project ' . $proj_name . '" -o -- ' . $new_files, DRUPAL_ROOT);
  }
}