<?php
/*************************************************************
# 076 License

Copyright (c) テクニカル諏訪子

Permission is hereby granted to any person obtaining a copy of the software
Little Beast (the "Software") to use, modify, merge, copy, publish, distribute,
sublicense, and/or sell copies of the Software, subject to the following conditions:

    1. **Origin Attribution**:
       - You must not misrepresent the origin of the Software; you must not claim
         you created the original Software.
       - If the Software is used in a product, you must either:
         a. Provide clear attribution in the product's documentation, user interface,
            or other visible areas, **OR**
         b. Pay the original developers a fee they specify in writing.
    2. **Usage Restriction**:
       - The Software, or any derivative works, dependencies, or libraries
         incorporating it, must not be used for censorship or to suppress freedom of
         speech, expression, or creativity. Prohibited uses include, but are not
         limited to:
         - Censorship of so-called "hate speech", visuals, non-mainstream opinions,
           ideas, or objective reality.
         - Tools or systems designed to restrict access to information or
           artistic works.
    3. **Notice Preservation**:
       - This license and the above copyright notice must remain intact in all copies
         of the source code.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF
CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE
OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 */
namespace Std\Lib\Git;

/**
 * SSH（git clone git@host:user/repo.git、git push）
 *
 * sshdのauthorized_keysのcommand=から呼ぶスクリプトで使う。SSH_ORIGINAL_COMMANDは
 * 「git-upload-pack 'user/repo.git'」又は「git-receive-pack 'user/repo.git'」。
 * プロトコルv2はGIT_PROTOCOL（sshd_configのAcceptEnv GIT_PROTOCOLが必要）。
 */
final class Ssh {
  /**
   * コマンドを解析する
   *
   * @return array|null  [サービス（git-upload-pack又はgit-receive-pack）, パス]
   */
  public static function parse(string $command): ?array {
    if (!preg_match('/^(git[ -](?:upload-pack|receive-pack|upload-archive))\s+(.+)$/s', trim($command), $m)) return null;
    $service = str_replace('git ', 'git-', $m[1]);
    $arg = trim($m[2]);
    // シェルの引用符（'…'、'\''）
    if (str_starts_with($arg, "'")) {
      if (!preg_match("/^'((?:[^']|'\\\\'')*)'$/s", $arg, $q)) return null;
      $arg = str_replace("'\\''", "'", $q[1]);
    } else if (str_starts_with($arg, '"')) {
      $arg = trim($arg, '"');
    }
    $path = preg_replace('#^(~/|/)+#', '', $arg);
    if ($path === '' || str_contains($path, "\0") || preg_match('#(^|/)\.\.(/|$)#', $path)) return null;
    return [$service, $path];
  }

  /**
   * SSHのコマンドを処理する
   *
   * @param string $command  SSH_ORIGINAL_COMMAND
   * @param callable $open  fn(string $path, bool $write): ?Repository（アクセスの確認。nullならリポジトリが無い・権限が無い）
   * @param array $opt  receive（ReceivePackのオプション）、agent
   * @return int  終了コード
   */
  public static function handle(string $command, callable $open, array $opt = [], $in = null, $out = null, $err = null): int {
    $in ??= STDIN;
    $out ??= STDOUT;
    $err ??= STDERR;
    $p = self::parse($command);
    if ($p === null || $p[0] === 'git-upload-archive') {
      fwrite($err, "このコマンドは使えません。\n");
      return 1;
    }
    [$service, $path] = $p;
    $write = $service === 'git-receive-pack';
    try {
      $repo = $open($path, $write);
    } catch (GitException $e) {
      $repo = null;
    }
    if (!$repo instanceof Repository) {
      fwrite($err, "リポジトリ「{$path}」が有りません、又は".($write ? 'プッシュする' : '読む')."権限が有りません。\n");
      return 1;
    }
    $agent = ['agent' => (string)($opt['agent'] ?? 'LittleBeast')];
    try {
      if ($write) {
        (new ReceivePack($repo, $agent + ($opt['receive'] ?? [])))->serve($in, $out, false);
      } else {
        $version = str_contains((string)getenv('GIT_PROTOCOL'), 'version=2') ? 2 : 0;
        (new UploadPack($repo, $agent))->serve($in, $out, false, $version);
      }
    } catch (GitException $e) {
      fwrite($err, $e->getMessage()."\n");
      return 1;
    }
    return 0;
  }
}