<?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\Gitler;

use Std\Lib\Git\GitException;
use Std\Lib\Git\Repository;
use Std\Lib\Git\Walk;
use Std\Lib\Markdown;
use Result;

/**
 * Gitlerのイシュー（リポジトリの中のgitler/）
 *
 *   issues.json  索引（次の番号、イシュー毎の概要、リモートのID => [番号, コメント]）
 *   issues/{番号}.json  イシュー（本文、コメント、出来事、通知を受け取るユーザー（subscribers：ユーザー名 => bool））
 *   labels.json、milestones.json
 *
 * 書く者：local（{user}）、remote（{actor, name, handle, icon, url}、Fediverse）、commit（{commit, name}）。
 * 本文はMarkdown（htmlがtrueならリモートのHTML、受け取った時に安全にした物）。
 * プルリクエストも同じ番号のイシュー（pull：Pullsを参照）。インラインのコメントはpath・side・line・commit等を持ち、
 * レビュー（reviews：id、author、state（commented、approved、changes）、body、at、commit）に属する。
 */
final class Issues {
  public const MAX_TITLE = 200;
  public const MAX_BODY = 65536;
  /** プッシュで見るコミットの最大数 */
  private const MAX_PUSH_COMMITS = 500;
  /** 「fixes #3」等（英語のGitHubと同じ言葉） */
  private const CLOSE_RE = '/\b(?:close[sd]?|fix(?:e[sd])?|resolve[sd]?)\s*:?\s+#(\d+)\b/i';

  private string $dir;
  /** ロックの深さ（同じプロセスで2回ロックしない） */
  private int $depth = 0;

  public function __construct(public readonly Repository $repo) {
    $this->dir = $repo->path.'/gitler';
  }

  public static function open(string $owner, string $name): self {
    return new self(Gitler::open($owner, $name));
  }

  //////// 読む

  /** 索引（next、issues：番号 => 概要、remote：リモートのID => [番号, コメントのID]） */
  public function index(): array {
    $j = json_decode((string)@file_get_contents($this->dir.'/issues.json'), true);
    $j = is_array($j) ? $j : [];
    return ['next' => max(1, (int)($j['next'] ?? 1)), 'issues' => is_array($j['issues'] ?? null) ? $j['issues'] : [], 'remote' => is_array($j['remote'] ?? null) ? $j['remote'] : []];
  }

  /** 開いている・閉じたイシューの数 */
  /** 開いている・閉じた数（$pullならプルリクエスト） */
  public function counts(bool $pull = false): array {
    $c = ['open' => 0, 'closed' => 0];
    foreach ($this->index()['issues'] as $s) if (!empty($s['pull']) === $pull) $c[$s['state'] === 'closed' ? 'closed' : 'open']++;
    return $c;
  }

  /**
   * 探す
   *
   * @param array $f  state（open、closed、all）、label（ID）、milestone（ID、0は無し）、assignee、author、q、sort（created、updated、comments）、
   *                  pull（trueならプルリクエストだけ、falseならイシューだけ、既定はfalse、nullなら両方）
   * @return array  概要の配列（新しい順）
   */
  public function search(array $f = []): array {
    $state = $f['state'] ?? 'open';
    $q = mb_strtolower(trim((string)($f['q'] ?? '')));
    $out = [];
    $pull = array_key_exists('pull', $f) ? $f['pull'] : false;
    foreach ($this->index()['issues'] as $s) {
      if ($pull !== null && !empty($s['pull']) !== $pull) continue;
      if ($state !== 'all' && $s['state'] !== $state) continue;
      if (isset($f['label']) && !in_array((int)$f['label'], $s['labels'], true)) continue;
      if (isset($f['milestone']) && (int)($s['milestone'] ?? 0) !== (int)$f['milestone']) continue;
      if (isset($f['assignee']) && !in_array($f['assignee'], $s['assignees'], true)) continue;
      if (isset($f['author']) && $s['authorKey'] !== $f['author']) continue;
      if ($q !== '' && !str_contains(mb_strtolower($s['title']), $q) && ltrim($q, '#') !== (string)$s['number']) continue;
      $out[] = $s;
    }
    $key = match ($f['sort'] ?? 'created') { 'updated' => 'updated', 'comments' => 'comments', default => 'number' };
    usort($out, fn($a, $b) => $b[$key] <=> $a[$key] ?: $b['number'] <=> $a['number']);
    return $out;
  }

  public function get(int $n): ?array {
    if ($n < 1) return null;
    $j = json_decode((string)@file_get_contents($this->file($n)), true);
    return is_array($j) && ($j['number'] ?? 0) === $n ? $j : null;
  }

  /** リモートのIDのイシューとコメント（[番号, コメントのID又はnull]） */
  public function findRemote(string $id): ?array {
    $r = $this->index()['remote'][$id] ?? null;
    return is_array($r) ? [(int)$r[0], $r[1] === null ? null : (int)$r[1]] : null;
  }

  //////// 書く

  /**
   * イシューを作る
   *
   * @param array $author  書いた者
   * @param array $opt  html（本文がHTML）、remoteId、labels、assignees、milestone、pull（プルリクエストの情報）
   */
  public function create(array $author, string $title, string $body, array $opt = []): Result {
    $title = self::cleanTitle($title);
    if ($title === '') return Result::Error('題名を入力して下さい。');
    if (strlen($body) > self::MAX_BODY) return Result::Error('本文が長過ぎます。');
    return $this->locked(function() use ($author, $title, $body, $opt): Result {
      $idx = $this->index();
      if (isset($opt['remoteId']) && isset($idx['remote'][$opt['remoteId']])) return Result::Error('既に有ります。', ['number' => (int)$idx['remote'][$opt['remoteId']][0]]);
      $n = $idx['next'];
      $now = time();
      $issue = [
        'number' => $n, 'title' => $title, 'body' => $body, 'html' => !empty($opt['html']), 'author' => $author, 'state' => 'open',
        'created' => $now, 'updated' => $now, 'closed' => null, 'labels' => $this->validLabels($opt['labels'] ?? []),
        'assignees' => array_values(array_unique(array_map('strval', $opt['assignees'] ?? []))), 'milestone' => $this->validMilestone($opt['milestone'] ?? null),
        'remoteId' => $opt['remoteId'] ?? null, 'comments' => [], 'events' => [], 'seq' => 1, 'subscribers' => [],
      ];
      if (isset($opt['pull'])) $issue += ['pull' => $opt['pull'], 'reviews' => []];
      // 作った人と担当者は通知を受け取る
      foreach (array_merge(isset($author['user']) ? [$author['user']] : [], $issue['assignees']) as $u) $issue['subscribers'][$u] = true;
      $idx['next'] = $n + 1;
      if ($issue['remoteId'] !== null) $idx['remote'][$issue['remoteId']] = [$n, null];
      $this->save($issue, $idx);
      return Result::Success('イシューを作りました。', ['number' => $n, 'issue' => $issue]);
    });
  }

  /**
   * イシューを変える（$fnはイシューを受け取って新しいイシューを返す、nullなら何もしない）
   *
   * @return array|null  新しいイシュー
   */
  public function update(int $n, callable $fn): ?array {
    return $this->locked(function() use ($n, $fn): ?array {
      $issue = $this->get($n);
      if ($issue === null) return null;
      $new = $fn($issue);
      if (!is_array($new)) return null;
      $new['updated'] = time();
      $idx = $this->index();
      // リモートのIDの索引を作り直す
      foreach ($idx['remote'] as $id => [$num]) if ((int)$num === $n) unset($idx['remote'][$id]);
      if (($new['remoteId'] ?? null) !== null) $idx['remote'][$new['remoteId']] = [$n, null];
      foreach ($new['comments'] as $c) if (($c['remoteId'] ?? null) !== null) $idx['remote'][$c['remoteId']] = [$n, $c['id']];
      $this->save($new, $idx);
      return $new;
    });
  }

  /** 題名と本文を変える */
  public function edit(int $n, array $by, string $title, string $body): Result {
    $title = self::cleanTitle($title);
    if ($title === '') return Result::Error('題名を入力して下さい。');
    if (strlen($body) > self::MAX_BODY) return Result::Error('本文が長過ぎます。');
    $issue = $this->update($n, function(array $i) use ($by, $title, $body): array {
      if ($i['title'] !== $title) $i['events'][] = ['type' => 'title', 'by' => $by, 'at' => time(), 'from' => $i['title'], 'to' => $title];
      $i['title'] = $title;
      $i['body'] = $body;
      $i['edited'] = time();
      return $i;
    });
    return $issue ? Result::Success('保存しました。', ['issue' => $issue]) : Result::Error('イシューが有りません。');
  }

  /**
   * コメントを追加する
   *
   * @param array $opt  html、remoteId
   */
  public function comment(int $n, array $author, string $body, array $opt = []): Result {
    if (trim($body) === '') return Result::Error('コメントを入力して下さい。');
    if (strlen($body) > self::MAX_BODY) return Result::Error('コメントが長過ぎます。');
    $added = null;
    $issue = $this->update($n, function(array $i) use ($author, $body, $opt, &$added): ?array {
      if (isset($opt['remoteId'])) foreach ($i['comments'] as $c) if (($c['remoteId'] ?? null) === $opt['remoteId']) return null;
      $added = ['id' => (int)$i['seq'], 'author' => $author, 'body' => $body, 'html' => !empty($opt['html']), 'created' => time(), 'updated' => time(),
                'remoteId' => $opt['remoteId'] ?? null];
      $i['seq'] = (int)$i['seq'] + 1;
      $i['comments'][] = $added;
      // コメントした人は通知を受け取る（止めていても）
      if (isset($author['user'])) $i['subscribers'][$author['user']] = true;
      return $i;
    });
    if ($issue === null || $added === null) return Result::Error('コメント出来ません。');
    return Result::Success('コメントしました。', ['issue' => $issue, 'comment' => $added]);
  }

  /**
   * プルリクエストの行へのコメント
   *
   * @param array $at  path、side（old、new）、line、commit、hunk（表示用の前の行）、replyTo（スレッドの最初のコメント）、pending（レビューの下書き）
   */
  public function inlineComment(int $n, array $author, string $body, array $at): Result {
    if (trim($body) === '') return Result::Error('コメントを入力して下さい。');
    if (strlen($body) > self::MAX_BODY) return Result::Error('コメントが長過ぎます。');
    $added = null;
    $issue = $this->update($n, function(array $i) use ($author, $body, $at, &$added): ?array {
      if (!isset($i['pull'])) return null;
      $root = null;
      if (!empty($at['replyTo'])) {
        foreach ($i['comments'] as $c) if ($c['id'] === (int)$at['replyTo'] && isset($c['path'])) $root = $c;
        if ($root === null) return null;
      }
      $added = ['id' => (int)$i['seq'], 'author' => $author, 'body' => $body, 'html' => false, 'created' => time(), 'updated' => time(), 'remoteId' => null,
                'path' => (string)($root['path'] ?? $at['path']), 'side' => ($root['side'] ?? $at['side']) === 'old' ? 'old' : 'new', 'line' => (int)($root['line'] ?? $at['line']),
                'commit' => (string)($root['commit'] ?? $at['commit']), 'hunk' => $root !== null ? [] : array_values(array_map('strval', (array)($at['hunk'] ?? []))),
                'replyTo' => $root !== null ? $root['id'] : null, 'review' => null, 'pending' => !empty($at['pending'])];
      $i['seq'] = (int)$i['seq'] + 1;
      $i['comments'][] = $added;
      if (isset($author['user'])) $i['subscribers'][$author['user']] = true;
      return $i;
    });
    if ($issue === null || $added === null) return Result::Error('コメント出来ません。');
    return Result::Success('コメントしました。', ['issue' => $issue, 'comment' => $added]);
  }

  /**
   * レビューを出す（その人の下書きのコメントをレビューに入れる）
   *
   * @param string $state  commented、approved、changes
   */
  public function submitReview(int $n, array $author, string $state, string $body, string $commit): Result {
    if (!in_array($state, ['commented', 'approved', 'changes'], true)) return Result::Error('不正なレビューです。');
    if (strlen($body) > self::MAX_BODY) return Result::Error('本文が長過ぎます。');
    $review = null;
    $key = self::authorKey($author);
    $issue = $this->update($n, function(array $i) use ($author, $state, $body, $commit, $key, &$review): ?array {
      if (!isset($i['pull'])) return null;
      $pending = array_filter($i['comments'], fn($c) => !empty($c['pending']) && self::authorKey($c['author']) === $key);
      if ($state === 'commented' && trim($body) === '' && empty($pending)) return null;
      $id = (int)($i['rseq'] ?? 1);
      $review = ['id' => $id, 'author' => $author, 'state' => $state, 'body' => $body, 'at' => time(), 'commit' => $commit];
      $i['rseq'] = $id + 1;
      $i['reviews'][] = $review;
      foreach ($i['comments'] as $k => $c) {
        if (!empty($c['pending']) && self::authorKey($c['author']) === $key) {
          $i['comments'][$k]['pending'] = false;
          $i['comments'][$k]['review'] = $id;
          $i['comments'][$k]['created'] = time();
        }
      }
      if (isset($author['user'])) $i['subscribers'][$author['user']] = true;
      return $i;
    });
    if ($issue === null || $review === null) return Result::Error('コメントを入力して下さい。');
    return Result::Success('レビューを出しました。', ['issue' => $issue, 'review' => $review]);
  }

  /** コメントを変える（nullなら削除） */
  public function editComment(int $n, int $id, ?string $body): ?array {
    if ($body !== null && (trim($body) === '' || strlen($body) > self::MAX_BODY)) return null;
    $found = null;
    $this->update($n, function(array $i) use ($id, $body, &$found): ?array {
      foreach ($i['comments'] as $k => $c) {
        if ($c['id'] !== $id) continue;
        $found = $c;
        if ($body === null) {
          array_splice($i['comments'], $k, 1);
        } else {
          $i['comments'][$k]['body'] = $body;
          $i['comments'][$k]['updated'] = time();
          $found = $i['comments'][$k];
        }
        return $i;
      }
      return null;
    });
    return $found;
  }

  /** 閉じる・開く（変わらなければnull） */
  public function setState(int $n, bool $open, array $by, array $extra = []): ?array {
    return $this->update($n, function(array $i) use ($open, $by, $extra): ?array {
      if (($i['state'] === 'open') === $open) return null;
      $i['state'] = $open ? 'open' : 'closed';
      $i['closed'] = $open ? null : time();
      $i['events'][] = ['type' => $open ? 'reopened' : 'closed', 'by' => $by, 'at' => time()] + $extra;
      return $i;
    });
  }

  /** ラベル・担当者・マイルストーン（書き込み権限の有る人） */
  public function triage(int $n, array $by, ?array $labels, ?array $assignees, int|false|null $milestone): ?array {
    return $this->update($n, function(array $i) use ($by, $labels, $assignees, $milestone): array {
      $at = time();
      if ($labels !== null) {
        $labels = $this->validLabels($labels);
        $add = array_values(array_diff($labels, $i['labels']));
        $remove = array_values(array_diff($i['labels'], $labels));
        if ($add || $remove) $i['events'][] = ['type' => 'labels', 'by' => $by, 'at' => $at, 'add' => $add, 'remove' => $remove];
        $i['labels'] = $labels;
      }
      if ($assignees !== null) {
        $assignees = array_values(array_unique(array_map('strval', $assignees)));
        $add = array_values(array_diff($assignees, $i['assignees']));
        $remove = array_values(array_diff($i['assignees'], $assignees));
        if ($add || $remove) $i['events'][] = ['type' => 'assignees', 'by' => $by, 'at' => $at, 'add' => $add, 'remove' => $remove];
        foreach ($add as $u) $i['subscribers'][$u] = true;
        $i['assignees'] = $assignees;
      }
      if ($milestone !== false) {
        $m = $this->validMilestone($milestone);
        if ($m !== $i['milestone']) $i['events'][] = ['type' => 'milestone', 'by' => $by, 'at' => $at, 'from' => $i['milestone'], 'to' => $m];
        $i['milestone'] = $m;
      }
      return $i;
    });
  }

  /** 通知を受け取る・止める（明示的に止めた人はtrueに戻るまで受け取らない） */
  public function subscribe(int $n, array $users, bool $on): ?array {
    return $this->update($n, function(array $i) use ($users, $on): array {
      foreach ($users as $u) $i['subscribers'][(string)$u] = $on;
      return $i;
    });
  }

  /** イシューを消す（番号は使い回さない） */
  public function delete(int $n): bool {
    return $this->locked(function() use ($n): bool {
      if ($this->get($n) === null) return false;
      $idx = $this->index();
      unset($idx['issues'][(string)$n]);
      foreach ($idx['remote'] as $id => [$num]) if ((int)$num === $n) unset($idx['remote'][$id]);
      $this->writeJson($this->dir.'/issues.json', $idx);
      @unlink($this->file($n));
      return true;
    });
  }

  //////// プッシュ

  /**
   * プッシュしたコミットのメッセージの「#3」をイシューに記録し、既定のブランチなら「fixes #3」等で閉じる
   *
   * @param array $updates  [参照, 前, 後]の配列
   * @param string $default  既定のブランチ（refs/heads/…）
   * @return array  閉じたイシューの番号
   */
  public function processPush(array $updates, string $default): array {
    $zero = $this->repo->zeroId();
    $closed = [];
    if (empty($this->index()['issues'])) return [];
    foreach ($updates as [$ref, $old, $new]) {
      if (!str_starts_with($ref, 'refs/heads/') || $new === $zero) continue;
      // 新しいブランチは他のブランチに無いコミットだけ
      $haves = $old !== $zero ? [$old] : array_values(array_filter($this->repo->refs->all('refs/heads/'), fn($id, $r) => $r !== $ref, ARRAY_FILTER_USE_BOTH));
      try {
        [$ids] = (new Walk($this->repo))->commitsBetween([$new], $haves);
      } catch (GitException) {
        continue;
      }
      // 古い順に
      foreach (array_reverse(array_slice($ids, 0, self::MAX_PUSH_COMMITS)) as $id) {
        $c = $this->repo->commit($id);
        if (!preg_match_all('/(?<![\w&\/])#(\d+)\b/', $c->message, $m)) continue;
        preg_match_all(self::CLOSE_RE, $c->message, $cm);
        $closes = array_map('intval', $cm[1]);
        $by = ['commit' => $id, 'name' => $c->author?->name ?? ''];
        foreach (array_unique(array_map('intval', $m[1])) as $n) {
          $close = $ref === $default && in_array($n, $closes, true) && empty($this->index()['issues'][$n]['pull']);
          $didClose = false;
          $this->update($n, function(array $i) use ($id, $c, $by, $close, $ref, &$didClose): ?array {
            // マージしたプルリクエスト自身のコミットは記録しない
            $seen = ($i['pull']['merged']['commit'] ?? '') === $id;
            foreach ($i['events'] as $e) if ($e['type'] === 'commit' && $e['commit'] === $id) $seen = true;
            if (!$seen) $i['events'][] = ['type' => 'commit', 'by' => $by, 'at' => time(), 'commit' => $id, 'subject' => $c->subject(), 'branch' => substr($ref, 11)];
            $didClose = $close && $i['state'] === 'open';
            if ($didClose) {
              $i['state'] = 'closed';
              $i['closed'] = time();
              $i['events'][] = ['type' => 'closed', 'by' => $by, 'at' => time(), 'commit' => $id];
            }
            return $seen && !$didClose ? null : $i;
          });
          if ($didClose) $closed[$n] = true;
        }
      }
    }
    return array_keys($closed);
  }

  //////// ラベルとマイルストーン

  /** ラベル（ID => name、color、description） */
  public function labels(): array {
    return $this->readList('labels.json', 'labels');
  }

  public function saveLabel(?int $id, string $name, string $color, string $description): Result {
    $name = trim(preg_replace('/[\x00-\x1f\x7f]/', '', $name));
    if ($name === '' || mb_strlen($name) > 50) return Result::Error('ラベルの名前は1〜50文字です。');
    if (!preg_match('/^#[0-9a-fA-F]{6}$/', $color)) return Result::Error('色が不正です。');
    return $this->locked(function() use ($id, $name, $color, $description): Result {
      $l = $this->readList('labels.json', 'labels', true);
      foreach ($l['labels'] as $k => $x) if ((int)$k !== $id && mb_strtolower($x['name']) === mb_strtolower($name)) return Result::Error("ラベル「{$name}」は既に有ります。");
      if ($id !== null && !isset($l['labels'][$id])) return Result::Error('ラベルが有りません。');
      $id ??= $l['next']++;
      $l['labels'][$id] = ['name' => $name, 'color' => strtolower($color), 'description' => mb_substr(trim($description), 0, 200)];
      $this->writeJson($this->dir.'/labels.json', $l);
      return Result::Success('保存しました。', ['id' => $id]);
    });
  }

  public function deleteLabel(int $id): void {
    $this->locked(function() use ($id): void {
      $l = $this->readList('labels.json', 'labels', true);
      unset($l['labels'][$id]);
      $this->writeJson($this->dir.'/labels.json', $l);
    });
    foreach ($this->search(['state' => 'all', 'label' => $id]) as $s) {
      $this->update($s['number'], function(array $i) use ($id): array {
        $i['labels'] = array_values(array_diff($i['labels'], [$id]));
        return $i;
      });
    }
  }

  /** マイルストーン（ID => title、description、due（Y-m-d又は空）、state） */
  public function milestones(): array {
    return $this->readList('milestones.json', 'milestones');
  }

  public function saveMilestone(?int $id, string $title, string $description, string $due, string $state = 'open'): Result {
    $title = trim(preg_replace('/[\x00-\x1f\x7f]/', '', $title));
    if ($title === '' || mb_strlen($title) > 100) return Result::Error('マイルストーンの名前は1〜100文字です。');
    if ($due !== '' && (!preg_match('/^\d{4}-\d{2}-\d{2}$/', $due) || !checkdate((int)substr($due, 5, 2), (int)substr($due, 8, 2), (int)substr($due, 0, 4)))) return Result::Error('期日が不正です。');
    return $this->locked(function() use ($id, $title, $description, $due, $state): Result {
      $l = $this->readList('milestones.json', 'milestones', true);
      if ($id !== null && !isset($l['milestones'][$id])) return Result::Error('マイルストーンが有りません。');
      $id ??= $l['next']++;
      $l['milestones'][$id] = ['title' => $title, 'description' => mb_substr(trim($description), 0, 2000), 'due' => $due, 'state' => $state === 'closed' ? 'closed' : 'open'];
      $this->writeJson($this->dir.'/milestones.json', $l);
      return Result::Success('保存しました。', ['id' => $id]);
    });
  }

  public function deleteMilestone(int $id): void {
    $this->locked(function() use ($id): void {
      $l = $this->readList('milestones.json', 'milestones', true);
      unset($l['milestones'][$id]);
      $this->writeJson($this->dir.'/milestones.json', $l);
    });
    foreach ($this->search(['state' => 'all', 'milestone' => $id]) as $s) {
      $this->update($s['number'], function(array $i): array {
        $i['milestone'] = null;
        return $i;
      });
    }
  }

  //////// 表示

  /**
   * MarkdownをHTMLにする（安全なリンクだけ、「#3」をイシューへのリンクに）
   *
   * @param string $issuesUrl  イシューの一覧のURL（…/issues）
   */
  public static function render(string $text, string $issuesUrl): string {
    $html = Markdown::fromString($text)->parse();
    $html = (string)preg_replace_callback('/\s(href|src)="([^"]*)"/i', function(array $m): string {
      $url = html_entity_decode($m[2], ENT_QUOTES, 'UTF-8');
      return preg_match('~^(https?:|mailto:|#|/(?!/))~i', $url) ? " {$m[1]}=\"{$m[2]}\"" : " {$m[1]}=\"#\"";
    }, $html);
    return self::linkify($html, $issuesUrl);
  }

  /** HTMLの文字の部分（a、code、preの外）の「#3」、「@ユーザー」（居れば）とURLをリンクにする */
  public static function linkify(string $html, string $issuesUrl): string {
    $parts = preg_split('/(<[^>]*>)/', $html, -1, PREG_SPLIT_DELIM_CAPTURE);
    $depth = 0;
    foreach ($parts as $k => $p) {
      if ($p === '') continue;
      if ($p[0] === '<') {
        if (preg_match('~^<(/?)(a|code|pre)\b~i', $p, $m)) $depth = max(0, $depth + ($m[1] === '/' ? -1 : 1));
        continue;
      }
      if ($depth > 0) continue;
      $parts[$k] = (string)preg_replace_callback('~(https?://[^\s<>"]+[^\s<>".,;:!?)\]」。、])|(?<![\w&#/])#(\d+)\b|(?<![\w@/&.])@([A-Za-z0-9]+)(?![\w@]|\.\w)~u', function(array $m) use ($issuesUrl): string {
        if (($m[3] ?? '') !== '') return Gitler::user($m[3]) !== null ? '<a href="/gitler/'.$m[3].'">@'.$m[3].'</a>' : $m[0];
        if (($m[2] ?? '') !== '') return '<a href="'.htmlspecialchars($issuesUrl, ENT_QUOTES, 'UTF-8').'/'.$m[2].'">#'.$m[2].'</a>';
        return '<a href="'.$m[1].'" rel="nofollow noopener noreferrer">'.$m[1].'</a>';
      }, $p);
    }
    return implode('', $parts);
  }

  /** 書いた者の比較用のキー（ローカルはユーザー名、リモートはアクターのURL） */
  public static function authorKey(array $a): string {
    return (string)($a['user'] ?? $a['actor'] ?? ('commit:'.($a['commit'] ?? '')));
  }

  //////// 内部

  private function file(int $n): string {
    return $this->dir.'/issues/'.$n.'.json';
  }

  private static function cleanTitle(string $t): string {
    return mb_substr(trim(preg_replace('/[\x00-\x1f\x7f]+/', ' ', $t)), 0, self::MAX_TITLE);
  }

  private function validLabels(array $ids): array {
    $all = $this->labels();
    return array_values(array_unique(array_filter(array_map('intval', $ids), fn($id) => isset($all[$id]))));
  }

  private function validMilestone(mixed $id): ?int {
    $id = (int)$id;
    return $id > 0 && isset($this->milestones()[$id]) ? $id : null;
  }

  /** ID => 物（$withNextなら[next, 名前 => ID => 物]） */
  private function readList(string $file, string $key, bool $withNext = false): array {
    $j = json_decode((string)@file_get_contents($this->dir.'/'.$file), true);
    $list = [];
    foreach ((array)($j[$key] ?? []) as $id => $x) if (is_array($x)) $list[(int)$id] = $x;
    return $withNext ? ['next' => max(1, (int)($j['next'] ?? 1), ...array_map(fn($id) => $id + 1, array_keys($list))), $key => $list] : $list;
  }

  /** イシューと索引を書く */
  private function save(array $issue, array $idx): void {
    $last = $issue['created'];
    foreach ($issue['comments'] as $c) $last = max($last, $c['created']);
    $idx['issues'][(string)$issue['number']] = [
      'number' => $issue['number'], 'title' => $issue['title'], 'state' => $issue['state'], 'author' => $issue['author'], 'authorKey' => self::authorKey($issue['author']),
      'created' => $issue['created'], 'updated' => $issue['updated'], 'closed' => $issue['closed'], 'labels' => $issue['labels'], 'assignees' => $issue['assignees'],
      'milestone' => $issue['milestone'], 'comments' => count(array_filter($issue['comments'], fn($c) => empty($c['pending']))), 'last' => $last,
      'pull' => isset($issue['pull']), 'merged' => !empty($issue['pull']['merged']),
    ];
    $this->repo->mkdir($this->dir.'/issues');
    $this->writeJson($this->file($issue['number']), $issue);
    $this->writeJson($this->dir.'/issues.json', $idx);
  }

  private function writeJson(string $file, array $data): void {
    $this->repo->mkdir(dirname($file));
    $this->repo->writeFile($file, (string)json_encode($data, JSON_UNESCAPED_UNICODE | JSON_UNESCAPED_SLASHES));
  }

  /** gitler/の中を書く間はロックする（Webとgitユーザーの両方から書けるロックファイル） */
  private function locked(callable $fn): mixed {
    if ($this->depth > 0) return $fn();
    $this->repo->mkdir($this->dir);
    $file = $this->dir.'/issues.lock';
    $new = !is_file($file);
    $lock = @fopen($file, 'c');
    if ($lock && $new) $this->repo->chmodFile($file);
    if ($lock) flock($lock, LOCK_EX);
    $this->depth++;
    try {
      return $fn();
    } finally {
      $this->depth--;
      if ($lock) {
        flock($lock, LOCK_UN);
        fclose($lock);
      }
    }
  }
}