<?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\Fedi;

/**
 * タイムライン（data/ap/timeline.jsonl に1行1件の索引）
 *
 * 各行：t（時刻）、type（note/boost）、object（投稿のID）、actor（投稿者又はブーストした人）、
 *       author（投稿者）、vis（公開範囲）、aud（to+cc）、local（ローカルの投稿か）、reply（返信先）、tags
 */
final class Timeline {
  /** 1ページの件数 */
  public const PAGE = 20;

  private static function file(): string {
    return Fedi::path('timeline.jsonl');
  }

  /**
   * 全部の行（古い順）
   */
  public static function entries(): array {
    $file = self::file();
    if (!is_file($file)) return [];
    $out = [];
    foreach (file($file, FILE_IGNORE_NEW_LINES | FILE_SKIP_EMPTY_LINES) ?: [] as $line) {
      $e = json_decode($line, true);
      if (is_array($e)) $out[] = $e;
    }
    return $out;
  }

  /**
   * 投稿・ブーストを追加する
   *
   * @param array $obj  Note（ローカルならtoObject()の結果）
   * @param string|null $booster  ブーストした人（ブーストの場合）
   * @param int|float|null $t  時刻
   */
  public static function add(array $obj, ?string $booster = null, int|float|null $t = null): void {
    $id = Fedi::id($obj['id'] ?? null);
    $author = Fedi::id($obj['attributedTo'] ?? null);
    if ($id === null || $author === null) return;
    $to = Fedi::ids($obj['to'] ?? []);
    $cc = Fedi::ids($obj['cc'] ?? []);
    $tags = [];
    foreach ($obj['tag'] ?? [] as $tag) {
      if (is_array($tag) && ($tag['type'] ?? '') === 'Hashtag') $tags[] = mb_strtolower(ltrim((string)($tag['name'] ?? ''), '#'));
    }
    $e = [
      't' => $t ?? (strtotime((string)($obj['published'] ?? '')) ?: time()),
      'type' => $booster ? 'boost' : 'note',
      'object' => $id,
      'actor' => $booster ?? $author,
      'author' => $author,
      'vis' => Fedi::visibility($to, $cc, Fedi::id(self::followersOf($author))),
      'aud' => array_values(array_unique(array_merge($to, $cc))),
      'local' => Fedi::isLocal($id),
      'reply' => Fedi::id($obj['inReplyTo'] ?? null),
      'tags' => $tags,
    ];
    if ($booster) $e['t'] = $t ?? time();

    self::rewrite(function(array $list) use ($e): array {
      // 同じ投稿（又は同じ人の同じブースト）は1回だけ
      foreach ($list as $x) {
        if ($x['type'] === $e['type'] && $x['object'] === $e['object'] && $x['actor'] === $e['actor']) return $list;
      }
      $list[] = $e;
      return $list;
    });
  }

  /**
   * 編集された投稿のタグと宛先を更新する
   */
  public static function refresh(array $obj): void {
    $id = Fedi::id($obj['id'] ?? null);
    if ($id === null) return;
    $tags = [];
    foreach ($obj['tag'] ?? [] as $tag) {
      if (is_array($tag) && ($tag['type'] ?? '') === 'Hashtag') $tags[] = mb_strtolower(ltrim((string)($tag['name'] ?? ''), '#'));
    }
    $aud = array_values(array_unique(array_merge(Fedi::ids($obj['to'] ?? []), Fedi::ids($obj['cc'] ?? []))));
    self::rewrite(fn(array $list) => array_map(fn($x) => $x['object'] === $id ? ['tags' => $tags, 'aud' => $aud] + $x : $x, $list));
  }

  /**
   * 投稿（とそのブースト）を消す
   */
  public static function remove(string $objectId, ?string $booster = null): void {
    self::rewrite(fn(array $list) => array_values(array_filter($list, function($x) use ($objectId, $booster) {
      if ($x['object'] !== $objectId) return true;
      return $booster !== null && !($x['type'] === 'boost' && $x['actor'] === $booster);
    })));
  }

  /**
   * アクターの投稿を全部消す（アカウントの削除・ブロック）
   */
  public static function removeActor(string $actor): void {
    self::rewrite(fn(array $list) => array_values(array_filter($list, fn($x) => $x['actor'] !== $actor && $x['author'] !== $actor)));
  }

  /**
   * 古い行を消す（cronのapcleanup）。ローカルの投稿は消さない
   *
   * @param int $days  この日数より古いリモートの行を消す
   * @return array  消したリモートのオブジェクトのID
   */
  public static function prune(int $days): array {
    $limit = time() - $days * 86400;
    $removed = [];
    self::rewrite(function(array $list) use ($limit, &$removed): array {
      $keep = [];
      foreach ($list as $x) {
        if (!$x['local'] && $x['t'] < $limit) $removed[] = $x['object'];
        else $keep[] = $x;
      }
      return $keep;
    });
    return array_values(array_unique($removed));
  }

  /**
   * 古いリモートのデータを消す（cronのapcleanup）
   *
   * @param int $days  この日数より古いリモートの投稿とキャッシュを消す
   * @return \Result
   */
  public static function cleanup(int $days = 90): \Result {
    $removed = self::prune($days);
    // 他の行（ブースト等）から使われていなければ、保存したオブジェクトも消す
    $used = [];
    foreach (self::entries() as $e) $used[$e['object']] = true;
    $n = 0;
    foreach ($removed as $id) {
      if (!isset($used[$id])) {
        Remote::forget($id);
        $n++;
      }
    }
    // タイムラインに無い古いオブジェクト（検索やプロフィールで取得した物）
    $limit = time() - $days * 86400;
    foreach (glob(Fedi::path('remote/objects/').'*.json') ?: [] as $f) {
      if (filemtime($f) < $limit) {
        $obj = Fedi::read($f, null);
        if (!$obj || !isset($used[$obj['id'] ?? ''])) {
          @unlink($f);
          $n++;
        }
      }
    }
    // 古いキャッシュ
    foreach (['remote/actors/', 'remote/webfinger/'] as $dir) {
      foreach (glob(Fedi::path($dir).'*.json') ?: [] as $f) if (filemtime($f) < $limit) @unlink($f);
    }
    // 画像のキャッシュ（期限切れ）
    $old = time() - Remote::IMAGE_TTL;
    foreach (glob(Fedi::path('remote/media/').'*') ?: [] as $f) if (filemtime($f) < $old) @unlink($f);
    return \Result::Success("古い投稿{$n}件を削除しました。", ['removed' => $n]);
  }

  /**
   * タイムラインを読む
   *
   * @param string $scope  home, local, federated, user, actor, tag
   * @param string|null $viewer  見ているローカルのユーザー（未ログインならnull）
   * @param array $opt  user/actor/tag：対象、before：この時刻より前、limit
   * @return array  [項目の配列, 次のページのbefore（無ければnull）]
   *                項目：['entry' => 行, 'object' => Note]
   */
  public static function query(string $scope, ?string $viewer, array $opt = []): array {
    $before = (int)($opt['before'] ?? PHP_INT_MAX);
    $limit = (int)($opt['limit'] ?? self::PAGE);
    $me = $viewer !== null ? Fedi::actorUrl($viewer) : null;
    $target = $opt['user'] ?? $opt['actor'] ?? null;
    if (isset($opt['user'])) $target = Fedi::actorUrl($opt['user']);

    $entries = self::entries();
    usort($entries, fn($a, $b) => $b['t'] <=> $a['t']);

    $out = [];
    $next = null;
    $seen = [];
    foreach ($entries as $e) {
      if ($e['t'] >= $before) continue;
      $ok = match ($scope) {
        'home' => $me !== null && ($e['actor'] === $me || $e['author'] === $me || in_array($me, $e['aud'], true)
                                   || Actor::isFollowing($viewer, $e['actor'])),
        'local' => $e['local'] && $e['type'] === 'note' && $e['vis'] === 'public',
        'federated' => $e['type'] === 'note' && $e['vis'] === 'public',
        'user', 'actor' => $e['actor'] === $target && in_array($e['vis'], ['public', 'unlisted', 'followers', 'direct'], true),
        'tag' => $e['type'] === 'note' && in_array(mb_strtolower((string)($opt['tag'] ?? '')), $e['tags'] ?? [], true)
                 && in_array($e['vis'], ['public', 'unlisted'], true),
        default => false,
      };
      if (!$ok || !self::canSee($viewer, $e)) continue;
      if ($viewer !== null && (Actor::isBlocked($viewer, $e['actor']) || Actor::isBlocked($viewer, $e['author']))) continue;
      if (Actor::isDomainBlocked($e['author'])) continue;

      // 同じ投稿は1回だけ（ブーストと元の投稿等）
      if (isset($seen[$e['object']])) continue;
      $obj = self::object($e['object']);
      if ($obj === null) continue;
      $seen[$e['object']] = true;

      if (count($out) >= $limit) {
        $next = $out[count($out) - 1]['entry']['t'];
        break;
      }
      $out[] = ['entry' => $e, 'object' => $obj];
    }
    return [$out, $next];
  }

  /**
   * 見ているユーザーがこの投稿を見られるか
   */
  public static function canSee(?string $viewer, array $e): bool {
    if (in_array($e['vis'], ['public', 'unlisted'], true)) return true;
    if ($viewer === null) return false;
    $me = Fedi::actorUrl($viewer);
    if ($e['author'] === $me || in_array($me, $e['aud'], true)) return true;
    if ($e['vis'] !== 'followers') return false;
    // フォロワー限定：作者をフォローしている事
    $author = $e['author'];
    $local = Fedi::localUsername($author);
    return $local !== null ? Actor::isFollowedBy($local, $me) : Actor::isFollowing($viewer, $author);
  }

  /**
   * 投稿のオブジェクト（ローカル又は保存しているリモート）
   */
  public static function object(string $id): ?array {
    if (Fedi::isLocal($id)) {
      $ids = Fedi::localNoteId($id);
      $note = $ids ? Notes::get($ids[1]) : null;
      return $note ? Notes::toObject($note) : null;
    }
    return Remote::stored($id);
  }

  /**
   * ある投稿への返信（保存しているもの）
   */
  public static function replies(string $id): array {
    $out = [];
    foreach (self::entries() as $e) {
      if ($e['type'] === 'note' && $e['reply'] === $id) $out[] = $e;
    }
    usort($out, fn($a, $b) => $a['t'] <=> $b['t']);
    return $out;
  }

  /**
   * 文字で検索する（ローカルと保存しているリモートの、公開・未収載の投稿）
   */
  public static function search(string $q, ?string $viewer, int $limit = 40): array {
    $q = mb_strtolower(trim($q));
    if ($q === '') return [];
    $entries = self::entries();
    usort($entries, fn($a, $b) => $b['t'] <=> $a['t']);
    $out = [];
    foreach ($entries as $e) {
      if ($e['type'] !== 'note' || !self::canSee($viewer, $e)) continue;
      if ($viewer !== null && Actor::isBlocked($viewer, $e['author'])) continue;
      $obj = self::object($e['object']);
      if (!$obj) continue;
      $text = mb_strtolower(Html::text((string)($obj['content'] ?? '')).' '.($obj['summary'] ?? ''));
      if (!str_contains($text, $q)) continue;
      $out[] = ['entry' => $e, 'object' => $obj];
      if (count($out) >= $limit) break;
    }
    return $out;
  }

  ///////

  private static function rewrite(callable $fn): void {
    $file = self::file();
    $lock = fopen($file.'.lock', 'c');
    if ($lock) flock($lock, LOCK_EX);
    try {
      $list = $fn(self::entries());
      $tmp = $file.'.'.bin2hex(random_bytes(4)).'.tmp';
      $data = '';
      foreach ($list as $e) $data .= json_encode($e, JSON_UNESCAPED_SLASHES | JSON_UNESCAPED_UNICODE)."\n";
      file_put_contents($tmp, $data);
      rename($tmp, $file);
    } finally {
      if ($lock) {
        flock($lock, LOCK_UN);
        fclose($lock);
      }
    }
  }

  /** 投稿者のフォロワーのコレクション（分かれば） */
  private static function followersOf(string $author): ?string {
    if (Fedi::isLocal($author)) return $author.'/followers';
    $file = Fedi::path('remote/actors/'.sha1($author).'.json');
    $cached = Fedi::read($file, null);
    return $cached['doc']['followers'] ?? null;
  }
}