/**
 * 小游戏 zip Bundle 存储补丁。
 *
 * 背景：微信等小游戏本地缓存满时，引擎 unzip 失败后会调异步 clearLRU（每 500ms 删一个文件），
 * 空间未腾出前无法重试解压，导致 loadBundle 永久挂起；坏缓存写入 cacheList.json 后重启仍命中。
 *
 * 本文件在 GameLaunch 最早阶段 monkey-patch 引擎 cacheManager：
 * 1. 新增 clearLRUImmediate — 同步删 LRU 缓存（无 setTimeout）
 * 2. 重写 unzipAndCacheBundle — 存储不足时同步清缓存并立即重试解压
 *
 * 测试时在控制台过滤关键字：CacheManagerPatch
 *
 * @see Cocos 3.8.8 platforms/minigame/common/engine/cache-manager.js
 */
import { assetManager, path } from "cc";

declare global {
    interface Window {
        fsUtils?: MinigameFsUtils;
    }
}

/** 小游戏引擎适配层注入的文件系统工具（window.fsUtils） */
interface MinigameFsUtils {
    fs?: { unlinkSync?(filePath: string): void };
    rmdirSync(dirPath: string, recursive?: boolean): Error | null;
    makeDirSync(dirPath: string, recursive?: boolean): Error | null;
    unzip(zipFilePath: string, targetPath: string, onComplete: (err: Error | null) => void): void;
    isOutOfStorage(errMsg: string): boolean;
}

/** 引擎 cacheManager 运行时扩展字段（TS 公开类型未暴露，运行时有） */
interface CacheManagerLike {
    cacheDir: string;
    autoClear: boolean;
    outOfStorage: boolean;
    cachedFiles: {
        forEach(cb: (val: { bundle: string; url: string; lastTime: number }, key: string) => void): void;
        add(key: string, val: { bundle: string; url: string; lastTime: string | number }): void;
        remove(key: string): unknown;
    };
    _isZipFile(url: string): boolean;
    _write(): void;
    clearLRU(): void;
    clearLRUImmediate?(): void;
    unzipAndCacheBundle(
        id: string,
        zipFilePath: string,
        cacheBundleRoot: string,
        onComplete: (err: Error | null, targetPath?: string) => void,
        retryCount?: number
    ): void;
}

/** 日志前缀，控制台过滤：CacheManagerPatch */
const LOG_TAG = "[CacheManagerPatch]";

/** 存储不足时 unzip 最大重试次数（每次重试前同步清 1/3 LRU） */
const MAX_UNZIP_STORAGE_RETRIES = 5;

/** 解压目标目录后缀，避免同毫秒多次解压路径冲突 */
let unzipPathSuffix = 0;

function log(message: string, detail?: unknown): void {
    if (detail !== undefined) {
        console.log(LOG_TAG, message, detail);
    } else {
        console.log(LOG_TAG, message);
    }
}

function warn(message: string, detail?: unknown): void {
    if (detail !== undefined) {
        console.warn(LOG_TAG, message, detail);
    } else {
        console.warn(LOG_TAG, message);
    }
}

function logError(message: string, detail?: unknown): void {
    if (detail !== undefined) {
        console.error(LOG_TAG, message, detail);
    } else {
        console.error(LOG_TAG, message);
    }
}

/** 统计 cachedFiles 条目数 */
function countCachedFiles(cm: CacheManagerLike): number {
    let count = 0;
    cm.cachedFiles.forEach(() => {
        count++;
    });
    return count;
}

/**
 * 获取小游戏平台 fsUtils。
 * 仅在小游戏环境存在；Web 预览等环境为 null，补丁自动跳过。
 */
function getFsUtils(): MinigameFsUtils | null {
    const fsUtils = (globalThis as typeof globalThis & { fsUtils?: MinigameFsUtils }).fsUtils;
    return fsUtils ?? null;
}

/**
 * 同步删除单条缓存对应的磁盘文件/目录。
 * - zip bundle 解压后是目录 → rmdirSync
 * - 普通文件 / zip 包本身 → unlinkSync
 */
function removePathOrFileSync(cm: CacheManagerLike, originUrl: string, localPath: string): boolean {
    const fsUtils = getFsUtils();
    if (!fsUtils) {
        warn("removePathOrFileSync: fsUtils missing", { originUrl, localPath });
        return false;
    }
    if (cm._isZipFile(originUrl)) {
        if (cm._isZipFile(localPath)) {
            try {
                fsUtils.fs?.unlinkSync?.(localPath);
                log("removed file (zip)", { originUrl: path.basename(originUrl), localPath });
                return true;
            } catch (e) {
                warn("unlinkSync zip failed", { localPath, error: e });
                return false;
            }
        }
        const rmErr = fsUtils.rmdirSync(localPath, true);
        if (rmErr) {
            warn("rmdirSync failed", { localPath, error: rmErr.message });
            return false;
        }
        log("removed dir (unzipped bundle)", { originUrl: path.basename(originUrl), localPath });
        return true;
    }
    try {
        fsUtils.fs?.unlinkSync?.(localPath);
        log("removed file", { originUrl: path.basename(originUrl), localPath });
        return true;
    } catch (e) {
        warn("unlinkSync failed", { localPath, error: e });
        return false;
    }
}

/**
 * 按引擎 clearLRU 相同规则筛选待删缓存条目：
 * 1. 遍历 cachedFiles，跳过正在使用的 zip bundle
 * 2. 按 lastTime 升序（最久未用在前）
 * 3. 总数 ≥ 3 取最旧 1/3；< 3 则全取
 */
function collectLruCandidates(cm: CacheManagerLike): Array<{ originUrl: string; url: string; lastTime: number }> {
    const allCandidates: Array<{ originUrl: string; url: string; lastTime: number }> = [];
    let skippedInUse = 0;
    cm.cachedFiles.forEach((val, key) => {
        let skip = false;
        if (cm._isZipFile(key)) {
            assetManager.bundles.forEach((bundle) => {
                if (bundle.base.indexOf(val.url) !== -1) {
                    skip = true;
                }
            });
            if (skip) {
                skippedInUse++;
                return;
            }
        }
        allCandidates.push({ originUrl: key, url: val.url, lastTime: val.lastTime });
    });
    allCandidates.sort((a, b) => a.lastTime - b.lastTime);
    const totalEligible = allCandidates.length;
    if (allCandidates.length >= 3) {
        allCandidates.length = Math.floor(allCandidates.length / 3);
    }
    log("collectLruCandidates", {
        totalInCache: countCachedFiles(cm),
        eligible: totalEligible,
        skippedInUseZipBundle: skippedInUse,
        toRemove: allCandidates.length,
        rule: totalEligible >= 3 ? "remove oldest 1/3" : "remove all eligible",
    });
    return allCandidates;
}

/**
 * 给 cacheManager 挂载 clearLRUImmediate。
 * 与引擎 clearLRU 筛选逻辑相同，但同步删除磁盘文件并立即写回 cacheList.json，
 * 不经过 setTimeout(deferredDelete, deleteInterval)。
 */
function installClearLRUImmediate(cm: CacheManagerLike): void {
    cm.clearLRUImmediate = function clearLRUImmediate(this: CacheManagerLike): void {
        const beforeCount = countCachedFiles(this);
        warn("clearLRUImmediate start", {
            cacheDir: this.cacheDir,
            cachedCount: beforeCount,
            outOfStorage: this.outOfStorage,
            autoClear: this.autoClear,
        });
        const caches = collectLruCandidates(this);
        if (caches.length === 0) {
            warn("clearLRUImmediate: nothing to remove");
            return;
        }
        let diskOk = 0;
        let diskFail = 0;
        for (let i = 0, l = caches.length; i < l; i++) {
            const item = caches[i];
            const cacheKey = `${assetManager.utils.getUuidFromURL(item.originUrl)}@native`;
            (assetManager as unknown as { files: { remove(key: string): void } }).files.remove(cacheKey);
            this.cachedFiles.remove(item.originUrl);
            if (removePathOrFileSync(this, item.originUrl, item.url)) {
                diskOk++;
            } else {
                diskFail++;
            }
        }
        this._write();
        this.outOfStorage = false;
        const afterCount = countCachedFiles(this);
        warn("clearLRUImmediate done", {
            removedFromIndex: caches.length,
            diskOk,
            diskFail,
            cachedCountBefore: beforeCount,
            cachedCountAfter: afterCount,
            outOfStorage: this.outOfStorage,
        });
    };
}

/**
 * 重写引擎 unzipAndCacheBundle。
 * 解压失败且报错为「存储空间不足」时：调 clearLRUImmediate 同步腾空间 → 立即递归重试；
 * 不再调引擎异步 clearLRU + 直接 onComplete(err) 让上层卡死。
 */
function installUnzipAndCacheBundle(cm: CacheManagerLike, fsUtils: MinigameFsUtils): void {
    cm.unzipAndCacheBundle = function unzipAndCacheBundle(
        this: CacheManagerLike,
        id: string,
        zipFilePath: string,
        cacheBundleRoot: string,
        onComplete: (err: Error | null, targetPath?: string) => void,
        retryCount = 0
    ): void {
        const time = Date.now().toString();
        const targetPath = `${this.cacheDir}/${cacheBundleRoot}/${time}${unzipPathSuffix++}`;
        log("unzip start", {
            bundle: cacheBundleRoot,
            zipName: path.basename(id),
            retry: `${retryCount}/${MAX_UNZIP_STORAGE_RETRIES}`,
            zipFilePath,
            targetPath,
            cachedCount: countCachedFiles(this),
            outOfStorage: this.outOfStorage,
        });
        const mkdirErr = fsUtils.makeDirSync(targetPath, true);
        if (mkdirErr) {
            logError("makeDirSync failed before unzip", { targetPath, error: mkdirErr.message });
        }
        fsUtils.unzip(zipFilePath, targetPath, (err) => {
            if (err) {
                fsUtils.rmdirSync(targetPath, true);
                const outOfStorage = fsUtils.isOutOfStorage(err.message);
                warn("unzip failed", {
                    bundle: cacheBundleRoot,
                    zipName: path.basename(id),
                    retry: retryCount,
                    outOfStorage,
                    message: err.message,
                });
                if (outOfStorage && retryCount < MAX_UNZIP_STORAGE_RETRIES) {
                    this.outOfStorage = true;
                    if (this.autoClear !== false && this.clearLRUImmediate) {
                        this.clearLRUImmediate();
                    } else {
                        warn("skip clearLRUImmediate", {
                            autoClear: this.autoClear,
                            hasImmediate: !!this.clearLRUImmediate,
                        });
                    }
                    warn(`unzip out-of-storage → retry ${retryCount + 1}/${MAX_UNZIP_STORAGE_RETRIES}`, {
                        bundle: cacheBundleRoot,
                        zipName: path.basename(id),
                    });
                    cm.unzipAndCacheBundle(id, zipFilePath, cacheBundleRoot, onComplete, retryCount + 1);
                    return;
                }
                if (outOfStorage) {
                    logError("unzip gave up: out-of-storage retries exhausted", {
                        bundle: cacheBundleRoot,
                        zipName: path.basename(id),
                        maxRetries: MAX_UNZIP_STORAGE_RETRIES,
                        message: err.message,
                    });
                } else {
                    logError("unzip gave up: non-storage error (no retry)", {
                        bundle: cacheBundleRoot,
                        zipName: path.basename(id),
                        message: err.message,
                    });
                }
                onComplete?.(err);
                return;
            }
            this.cachedFiles.add(id, { bundle: cacheBundleRoot, url: targetPath, lastTime: time });
            this._write();
            this.outOfStorage = false;
            log("unzip ok", {
                bundle: cacheBundleRoot,
                zipName: path.basename(id),
                retry: retryCount,
                targetPath,
                cachedCount: countCachedFiles(this),
            });
            onComplete?.(null, targetPath);
        });
    };
}

/**
 * 入口：在 GameLaunch.start 最早阶段调用。
 * 仅在小游戏环境（cacheManager + fsUtils 均存在）生效；已打过补丁则跳过（幂等）。
 */
export function applyCacheManagerPatch(): void {
    const cm = assetManager.cacheManager as unknown as CacheManagerLike | null;
    const fsUtils = getFsUtils();
    if (!cm && !fsUtils) {
        log("skip patch: not minigame env (cacheManager & fsUtils both missing)");
        return;
    }
    if (!cm) {
        warn("skip patch: assetManager.cacheManager missing");
        return;
    }
    if (!fsUtils) {
        warn("skip patch: window.fsUtils missing");
        return;
    }
    if (typeof cm.clearLRUImmediate === "function") {
        log("skip patch: already applied");
        return;
    }
    installClearLRUImmediate(cm);
    installUnzipAndCacheBundle(cm, fsUtils);
    log("patch applied", {
        cacheDir: cm.cacheDir,
        autoClear: cm.autoClear,
        cachedCount: countCachedFiles(cm),
        maxUnzipRetries: MAX_UNZIP_STORAGE_RETRIES,
        replaced: ["clearLRUImmediate (new)", "unzipAndCacheBundle (override)"],
    });
}