class DownloadMgr{
    constructor() {
        console.log('DownloadMgr初始化');
        this.fUpdateCb = null;
        this.manifestUrl = null;
        this._storagePath = null; //存储路径
    }

    createDownLoad(manifestUrl, path, cb){
        if(!cc.sys.isNative) return;
        this.manifestUrl = manifestUrl;
        this.fUpdateCb = cb;
        this.savePath = path || "storagePath_0";
        this._storagePath = ((jsb.fileUtils ? jsb.fileUtils.getWritablePath() : '/') + this.savePath);

        this.versionCompareHandle = function(versionA, versionB){
            let vA = versionA.split('.');
            let vB = versionB.split('.');
            for(let i=0; i < vA.length; ++i){
                let a = parseInt(vA[i]);
                let b = parseInt(vB[i] || 0);
                if (a === b) {
                    continue;
                }
                else {
                    return a - b;
                }
            }
            if (vB.length > vA.length) {
                return -1;
            }
            else {
                return 0;
            }
        };

        this._am = new jsb.AssetsManager('', this._storagePath, this.versionCompareHandle);
        this._am.setVerifyCallback(function (path, asset) {
            var compressed = asset.compressed;
            var expectedMD5 = asset.md5;
            var relativePath = asset.path;
            var size = asset.size;
            if (compressed) {
                return true;
            }
            else {
                return true;
            }
        });
        
        if (cc.sys.os === cc.sys.OS_ANDROID) {
            this._am.setMaxConcurrentTask(2);
        }

        this._am.setEventCallback(this.updateCb.bind(this));

        if (this._am.getState() === jsb.AssetsManager.State.UNINITED) {
            // Resolve md5 url
            let url = this.manifestUrl.nativeUrl;
            if (cc.loader.md5Pipe) {
                url = cc.loader.md5Pipe.transformURL(url);
            }
            this._am.loadLocalManifest(url);
        }

        this._am.update();
        this.iFailDownCount = 0;
    }

    updateCb(event) {
        switch (event.getEventCode()) {
            case jsb.EventAssetsManager.ERROR_NO_LOCAL_MANIFEST:
                break;
            case jsb.EventAssetsManager.UPDATE_PROGRESSION:
                break;
            case jsb.EventAssetsManager.ERROR_DOWNLOAD_MANIFEST:
            case jsb.EventAssetsManager.ERROR_PARSE_MANIFEST:
                break;
            case jsb.EventAssetsManager.ALREADY_UP_TO_DATE:
                break;
            case jsb.EventAssetsManager.UPDATE_FINISHED:
                break;
            case jsb.EventAssetsManager.UPDATE_FAILED:
                if (this.iFailDownCount < 10) {
                    this._am.downloadFailedAssets();
                    this.iFailDownCount++;
                } else {
                    this.removeTemStorage();
                }
                break;
            case jsb.EventAssetsManager.ERROR_UPDATING:
                break;
            case jsb.EventAssetsManager.ERROR_DECOMPRESS:
                break;
            default:
                break;
        }

        if (this.fUpdateCb) {
            this.fUpdateCb(event);
        }
    }

    onDestroy() {
        this._am.setEventCallback(null);
    }

    removeTemStorage() {
        console.log("DownloadMgr removeTemStorage........");
    }

    getSearchPaths() {
        let newPaths = this._am.getLocalManifest().getSearchPaths();
        return newPaths;
    }

    
}

let instance = null;
DownloadMgr.getInstance = function(){
    if(!instance){
        instance = new DownloadMgr();
    }
    return instance;
}

export default DownloadMgr.getInstance();