<?php

declare(strict_types=1);

namespace app\common\service\game;

/** ID-only progress policy. No framework, database, filesystem writes or network. */
final class TangDetectiveProgress
{
    public const MAX_BODY_BYTES = 32768;
    private array $catalog;
    private array $chapters = [];
    private array $cardIds = [];

    public function __construct(?array $catalog = null)
    {
        $this->catalog = $catalog ?? require dirname(__DIR__, 4) . '/config/tang_detective.php';
        foreach ($this->catalog['chapters'] as $chapter) {
            $this->chapters[$chapter['chapter_id']] = $chapter;
            $this->cardIds[] = $chapter['memory_card_id'];
        }
    }

    public function catalog(): array
    {
        return $this->catalog;
    }

    public function defaultProgress(): array
    {
        return [
            'completedHotspots' => (object) [],
            'completedChapters' => [],
            'lastChapter' => 1,
            'collectedMemoryCards' => [],
            'comicReaderByChapter' => (object) [],
            'lastPageId' => '',
        ];
    }

    public function defaultState(int $userId): array
    {
        if ($userId <= 0) {
            throw new TangDetectiveProgressException('AUTH_REQUIRED', '请先登录');
        }
        return [
            'user_id' => $userId,
            'schema_version' => 1,
            'content_version' => 'season-01',
            'revision' => 0,
            'story_generation' => 0,
            'progress' => $this->defaultProgress(),
        ];
    }

    /** Decode raw JSON so objects, lists, integers and booleans stay distinct. */
    public function decodeRequest(string $raw): array
    {
        if (strlen($raw) > self::MAX_BODY_BYTES) {
            throw new TangDetectiveProgressException('PAYLOAD_TOO_LARGE', '存档请求超过大小限制');
        }
        try {
            $decoded = json_decode($raw, false, 12, JSON_THROW_ON_ERROR);
        } catch (\JsonException $exception) {
            $this->invalid('存档请求不是有效的 JSON 对象');
        }
        $source = $this->record($decoded, [
            'schema_version', 'content_version', 'base_revision', 'story_generation',
            'request_id', 'operation', 'progress',
        ], true);
        if ($source['schema_version'] !== 1 || $source['content_version'] !== 'season-01') {
            throw new TangDetectiveProgressException('UNSUPPORTED_CONTENT_VERSION', '存档版本不匹配，请更新后再试');
        }
        $this->boundedInteger($source['base_revision'], 0, 2147483646);
        $this->boundedInteger($source['story_generation'], 0, 2147483646);
        if (!is_string($source['request_id']) || !preg_match('/\A[A-Za-z0-9_-]{16,64}\z/D', $source['request_id'])) {
            $this->invalid('存档请求标识无效');
        }
        if (!in_array($source['operation'], ['replace', 'reset_story'], true)) {
            $this->invalid('存档操作无效');
        }
        $progress = $this->normalizeProgress($source['progress']);
        if ($source['operation'] === 'reset_story') {
            $empty = $this->defaultProgress();
            $empty['collectedMemoryCards'] = $progress['collectedMemoryCards'];
            if ($this->encode($empty) !== $this->encode($progress)) {
                $this->invalid('重新开始请求必须清空故事进度');
            }
        }
        return [
            'schema_version' => 1,
            'content_version' => 'season-01',
            'base_revision' => $source['base_revision'],
            'story_generation' => $source['story_generation'],
            'request_id' => $source['request_id'],
            'operation' => $source['operation'],
            'progress' => $progress,
        ];
    }

    /** Reject unknown fields; canonicalize only equivalent ordering of sets/maps. */
    public function normalizeProgress($value): array
    {
        $source = $this->record($value, [
            'completedHotspots', 'completedChapters', 'lastChapter',
            'collectedMemoryCards', 'comicReaderByChapter', 'lastPageId',
        ], true);
        $this->boundedInteger($source['lastChapter'], 1, count($this->chapters));
        $hotspots = $this->record($source['completedHotspots'], array_keys($this->chapters));
        $readers = $this->record($source['comicReaderByChapter'], array_keys($this->chapters));
        $finished = $this->idSet($source['completedChapters'], array_keys($this->chapters));
        $cards = $this->idSet($source['collectedMemoryCards'], $this->cardIds);
        $cleanHotspots = [];
        $cleanReaders = [];
        foreach ($this->chapters as $id => $chapter) {
            $events = $this->eventPrefix($hotspots[$id] ?? [], $chapter['hotspot_ids']);
            if (array_key_exists($id, $hotspots)) {
                $cleanHotspots[$id] = $events;
            }
            $isFinished = in_array($id, $finished, true);
            if (!array_key_exists($id, $readers)) {
                if ($events !== [] || $isFinished) {
                    $this->invalid('章节存档缺少一致的阅读状态');
                }
                continue;
            }
            $reader = $this->record($readers[$id], ['currentPageId', 'completedEventIds', 'chapterFinished'], true);
            $readerEvents = $this->eventPrefix($reader['completedEventIds'], $chapter['hotspot_ids']);
            if (!is_bool($reader['chapterFinished']) || $readerEvents !== $events
                || $reader['chapterFinished'] !== $isFinished
                || ($isFinished && count($events) !== 4)) {
                $this->invalid('章节完成状态与事件进度不一致');
            }
            $pageIndex = is_string($reader['currentPageId'])
                ? array_search($reader['currentPageId'], $chapter['page_ids'], true)
                : false;
            $lastUnlocked = $isFinished ? 7 : min(6, 2 + count($events));
            if ($pageIndex === false || $pageIndex > $lastUnlocked) {
                $this->invalid('阅读页码无效或尚未解锁');
            }
            $cleanReaders[$id] = [
                'currentPageId' => $reader['currentPageId'],
                'completedEventIds' => $readerEvents,
                'chapterFinished' => $reader['chapterFinished'],
            ];
        }
        if (!is_string($source['lastPageId'])) {
            $this->invalid('最后阅读页码无效');
        }
        $lastId = sprintf('S01-C%02d', $source['lastChapter']);
        if ($source['lastPageId'] !== '' && (
            !isset($cleanReaders[$lastId])
            || $cleanReaders[$lastId]['currentPageId'] !== $source['lastPageId']
        )) {
            $this->invalid('最后阅读页码与章节书签不一致');
        }
        return [
            'completedHotspots' => (object) $cleanHotspots,
            'completedChapters' => $finished,
            'lastChapter' => $source['lastChapter'],
            'collectedMemoryCards' => $cards,
            'comicReaderByChapter' => (object) $cleanReaders,
            'lastPageId' => $source['lastPageId'],
        ];
    }

    /** Called under the user's database row lock; request must be decodeRequest's result. */
    public function transition(array $current, array $request, string $lastRequestId = '', string $lastHash = ''): array
    {
        $hash = hash('sha256', $this->encode($request));
        if ($lastRequestId !== '' && hash_equals($lastRequestId, $request['request_id'])) {
            if (!hash_equals($lastHash, $hash)) {
                throw new TangDetectiveProgressException('IDEMPOTENCY_CONFLICT', '同一请求标识不能提交不同存档');
            }
            return ['state' => $current, 'request_hash' => $hash, 'idempotent' => true];
        }
        if ($request['base_revision'] !== $current['revision']
            || $request['story_generation'] !== $current['story_generation']) {
            throw new TangDetectiveProgressException('PROGRESS_CONFLICT', '存档已变化，请选择云端或本机进度');
        }
        if ($current['revision'] >= 2147483646 || $current['story_generation'] >= 2147483646) {
            throw new TangDetectiveProgressException('PROGRESS_CONFLICT', '存档版本超出范围，请联系管理员');
        }
        $next = $current;
        $next['progress'] = $request['progress'];
        if ($request['operation'] === 'reset_story') {
            $next['progress'] = $this->defaultProgress();
            $cards = array_unique(array_merge(
                $current['progress']['collectedMemoryCards'],
                $request['progress']['collectedMemoryCards']
            ));
            $next['progress']['collectedMemoryCards'] = array_values(array_intersect($this->cardIds, $cards));
            ++$next['story_generation'];
        }
        ++$next['revision'];
        return ['state' => $next, 'request_hash' => $hash, 'idempotent' => false];
    }

    public function encode(array $value): string
    {
        return json_encode($value, JSON_UNESCAPED_UNICODE | JSON_UNESCAPED_SLASHES | JSON_THROW_ON_ERROR);
    }

    private function record($value, array $allowed, bool $requireAll = false): array
    {
        if (!$value instanceof \stdClass) {
            $this->invalid('存档字段必须是对象');
        }
        $fields = get_object_vars($value);
        if (array_diff(array_keys($fields), $allowed) !== []
            || ($requireAll && array_diff($allowed, array_keys($fields)) !== [])) {
            $this->invalid('存档包含未知字段或缺少必要字段');
        }
        return $fields;
    }

    private function idSet($value, array $allowed): array
    {
        if (!is_array($value) || $value !== array_values($value) || count($value) > count($allowed)) {
            $this->invalid('存档标识列表无效');
        }
        $seen = [];
        foreach ($value as $id) {
            if (!is_string($id) || !in_array($id, $allowed, true) || isset($seen[$id])) {
                $this->invalid('存档包含非法或重复标识');
            }
            $seen[$id] = true;
        }
        return array_values(array_filter($allowed, static fn (string $id): bool => isset($seen[$id])));
    }

    private function eventPrefix($value, array $allowed): array
    {
        if (!is_array($value) || $value !== array_slice($allowed, 0, count($value))) {
            $this->invalid('事件进度必须是本章连续前缀');
        }
        return $value;
    }

    private function boundedInteger($value, int $minimum, int $maximum): void
    {
        if (!is_int($value) || $value < $minimum || $value > $maximum) {
            $this->invalid('存档整数参数无效');
        }
    }

    private function invalid(string $message): void
    {
        throw new TangDetectiveProgressException('INVALID_REQUEST', $message);
    }
}