# file.js

    const _ = require('underscore');
    const cos = require('./uploader/cos');
    const qiniu = require('./uploader/qiniu');
    const s3 = require('./uploader/s3');
    const AVError = require('./error');
    const AVRequest = require('./request')._request;
    const Promise = require('./promise');
    const { tap, transformFetchOptions } = require('./utils');
    const debug = require('debug')('leancloud:file');
    const parseBase64 = require('./utils/parse-base64');

    module.exports = function(AV) {
      const hexOctet = () =>
        Math.floor((1 + Math.random()) * 0x10000)
          .toString(16)
          .substring(1);

      // port from browserify path module
      // since react-native packager won't shim node modules.
      const extname = path => {
        if (!_.isString(path)) return '';
        return path.match(
          /^(\/?|)([\s\S]*?)((?:\.{1,2}|[^\/]+?|)(\.[^.\/]*|))(?:[\/]*)$/
        )[4];
      };

      const b64Digit = number => {
        if (number < 26) {
          return String.fromCharCode(65 + number);
        }
        if (number < 52) {
          return String.fromCharCode(97 + (number - 26));
        }
        if (number < 62) {
          return String.fromCharCode(48 + (number - 52));
        }
        if (number === 62) {
          return '+';
        }
        if (number === 63) {
          return '/';
        }
        throw new Error('Tried to encode large digit ' + number + ' in base64.');
      };

      var encodeBase64 = function(array) {
        var chunks = [];
        chunks.length = Math.ceil(array.length / 3);
        _.times(chunks.length, function(i) {
          var b1 = array[i * 3];
          var b2 = array[i * 3 + 1] || 0;
          var b3 = array[i * 3 + 2] || 0;

          var has2 = i * 3 + 1 < array.length;
          var has3 = i * 3 + 2 < array.length;

          chunks[i] = [
            b64Digit((b1 >> 2) & 0x3f),
            b64Digit(((b1 << 4) & 0x30) | ((b2 >> 4) & 0x0f)),
            has2 ? b64Digit(((b2 << 2) & 0x3c) | ((b3 >> 6) & 0x03)) : '=',
            has3 ? b64Digit(b3 & 0x3f) : '=',
          ].join('');
        });
        return chunks.join('');
      };

      /**
       * An AV.File is a local representation of a file that is saved to the AV
       * cloud.
       * @param name {String} The file's name. This will change to a unique value
       *     once the file has finished saving.
       * @param data {Array} The data for the file, as either:
       *     1. an Array of byte value Numbers, or
       *     2. an Object like { base64: "..." } with a base64-encoded String.
       *     3. a Blob(File) selected with a file upload control.
       *     4. a Buffer in Node.js runtime.
       *     5. a Stream in Node.js runtime.
       *
       *        For example:<pre>
       * var fileUploadControl = $("#profilePhotoFileUpload")[0];
       * if (fileUploadControl.files.length > 0) {
       *   var file = fileUploadControl.files[0];
       *   var name = "photo.jpg";
       *   var file = new AV.File(name, file);
       *   file.save().then(function() {
       *     // The file has been saved to AV.
       *   }, function(error) {
       *     // The file either could not be read, or could not be saved to AV.
       *   });
       * }</pre>
       *
       * @class
       * @param [mimeType] {String} Content-Type header to use for the file. If
       *     this is omitted, the content type will be inferred from the name's
       *     extension.
       */
      AV.File = function(name, data, mimeType) {
        this.attributes = {
          name,
          url: '',
          metaData: {},
          // 用来存储转换后要上传的 base64 String
          base64: '',
        };

        if (_.isString(data)) {
          throw new TypeError(
            'Creating an AV.File from a String is not yet supported.'
          );
        }
        if (_.isArray(data)) {
          this.attributes.metaData.size = data.length;
          data = { base64: encodeBase64(data) };
        }

        this._extName = '';
        this._data = data;
        this._uploadHeaders = {};

        if (
          process.env.CLIENT_PLATFORM === 'ReactNative' ||
          process.env.CLIENT_PLATFORM === 'Weapp'
        ) {
          if (data && data.blob) {
            this._extName = extname(data.blob.uri);
          }
        }

        if (typeof Blob !== 'undefined' && data instanceof Blob) {
          if (data.size) {
            this.attributes.metaData.size = data.size;
          }
          if (data.name) {
            this._extName = extname(data.name);
          }
        }

        /* NODE-ONLY:start */
        if (data instanceof require('stream') && data.path) {
          this._extName = extname(data.path);
        }
        if (Buffer.isBuffer(data)) {
          this.attributes.metaData.size = data.length;
        }
        /* NODE-ONLY:end */

        let owner;
        if (data && data.owner) {
          owner = data.owner;
        } else if (!AV._config.disableCurrentUser) {
          try {
            owner = AV.User.current();
          } catch (error) {
            if ('SYNC_API_NOT_AVAILABLE' !== error.code) {
              throw error;
            }
          }
        }

        this.attributes.metaData.owner = owner ? owner.id : 'unknown';

        this.set('mime_type', mimeType);
      };

      /**
       * Creates a fresh AV.File object with exists url for saving to AVOS Cloud.
       * @param {String} name the file name
       * @param {String} url the file url.
       * @param {Object} [metaData] the file metadata object.
       * @param {String} [type] Content-Type header to use for the file. If
       *     this is omitted, the content type will be inferred from the name's
       *     extension.
       * @return {AV.File} the file object
       */
      AV.File.withURL = function(name, url, metaData, type) {
        if (!name || !url) {
          throw new Error('Please provide file name and url');
        }
        var file = new AV.File(name, null, type);
        //copy metaData properties to file.
        if (metaData) {
          for (var prop in metaData) {
            if (!file.attributes.metaData[prop])
              file.attributes.metaData[prop] = metaData[prop];
          }
        }
        file.attributes.url = url;
        //Mark the file is from external source.
        file.attributes.metaData.__source = 'external';
        return file;
      };

      /**
       * Creates a file object with exists objectId.
       * @param {String} objectId The objectId string
       * @return {AV.File} the file object
       */
      AV.File.createWithoutData = function(objectId) {
        var file = new AV.File();
        file.id = objectId;
        return file;
      };

      _.extend(
        AV.File.prototype,
        /** @lends AV.File.prototype */ {
          className: '_File',

          _toFullJSON(seenObjects, full = true) {
            var json = _.clone(this.attributes);
            AV._objectEach(json, function(val, key) {
              json[key] = AV._encode(val, seenObjects, undefined, full);
            });
            AV._objectEach(this._operations, function(val, key) {
              json[key] = val;
            });

            if (_.has(this, 'id')) {
              json.objectId = this.id;
            }
            _(['createdAt', 'updatedAt']).each(key => {
              if (_.has(this, key)) {
                const val = this[key];
                json[key] = _.isDate(val) ? val.toJSON() : val;
              }
            });
            if (full) {
              json.__type = 'File';
            }
            return json;
          },

          /**
           * Returns a JSON version of the file with meta data.
           * Inverse to {@link AV.parseJSON}
           * @since 2.0.0
           * @return {Object}
           */
          toFullJSON(seenObjects = []) {
            return this._toFullJSON(seenObjects);
          },

          /**
           * Returns a JSON version of the object.
           * @return {Object}
           */
          toJSON(key, holder, seenObjects = [this]) {
            return this._toFullJSON(seenObjects, false);
          },

          /**
           * Gets a Pointer referencing this file.
           * @private
           */
          _toPointer() {
            return {
              __type: 'Pointer',
              className: this.className,
              objectId: this.id,
            };
          },

          /**
           * Returns the ACL for this file.
           * @returns {AV.ACL} An instance of AV.ACL.
           */
          getACL() {
            return this._acl;
          },

          /**
           * Sets the ACL to be used for this file.
           * @param {AV.ACL} acl An instance of AV.ACL.
           */
          setACL(acl) {
            if (!(acl instanceof AV.ACL)) {
              return new AVError(AVError.OTHER_CAUSE, 'ACL must be a AV.ACL.');
            }
            this._acl = acl;
            return this;
          },

          /**
           * Gets the name of the file. Before save is called, this is the filename
           * given by the user. After save is called, that name gets prefixed with a
           * unique identifier.
           */
          name() {
            return this.get('name');
          },

          /**
           * Gets the url of the file. It is only available after you save the file or
           * after you get the file from a AV.Object.
           * @return {String}
           */
          url() {
            return this.get('url');
          },

          /**
           * Gets the attributs of the file object.
           * @param {String} The attribute name which want to get.
           * @returns {Any}
           */
          get(attrName) {
            switch (attrName) {
              case 'objectId':
                return this.id;
              case 'url':
              case 'name':
              case 'mime_type':
              case 'metaData':
              case 'createdAt':
              case 'updatedAt':
                return this.attributes[attrName];
              default:
                return this.attributes.metaData[attrName];
            }
          },

          /**
           * Set the metaData of the file object.
           * @param {Object} Object is an key value Object for setting metaData.
           * @param {String} attr is an optional metadata key.
           * @param {Object} value is an optional metadata value.
           * @returns {String|Number|Array|Object}
           */
          set(...args) {
            const set = (attrName, value) => {
              switch (attrName) {
                case 'name':
                case 'url':
                case 'mime_type':
                case 'base64':
                case 'metaData':
                  this.attributes[attrName] = value;
                  break;
                default:
                  // File 并非一个 AVObject，不能完全自定义其他属性，所以只能都放在 metaData 上面
                  this.attributes.metaData[attrName] = value;
                  break;
              }
            };

            switch (args.length) {
              case 1:
                // 传入一个 Object
                for (var k in args[0]) {
                  set(k, args[0][k]);
                }
                break;
              case 2:
                set(args[0], args[1]);
                break;
            }
            return this;
          },

          /**
           * Set a header for the upload request.
           * For more infomation, go to https://url.leanapp.cn/avfile-upload-headers
           *
           * @param {String} key header key
           * @param {String} value header value
           * @return {AV.File} this
           */
          setUploadHeader(key, value) {
            this._uploadHeaders[key] = value;
            return this;
          },

          /**
           * <p>Returns the file's metadata JSON object if no arguments is given.Returns the
           * metadata value if a key is given.Set metadata value if key and value are both given.</p>
           * <p><pre>
           *  var metadata = file.metaData(); //Get metadata JSON object.
           *  var size = file.metaData('size');  // Get the size metadata value.
           *  file.metaData('format', 'jpeg'); //set metadata attribute and value.
           *</pre></p>
           * @return {Object} The file's metadata JSON object.
           * @param {String} attr an optional metadata key.
           * @param {Object} value an optional metadata value.
           **/
          metaData(attr, value) {
            if (attr && value) {
              this.attributes.metaData[attr] = value;
              return this;
            } else if (attr && !value) {
              return this.attributes.metaData[attr];
            } else {
              return this.attributes.metaData;
            }
          },

          /**
           * 如果文件是图片，获取图片的缩略图URL。可以传入宽度、高度、质量、格式等参数。
           * @return {String} 缩略图URL
           * @param {Number} width 宽度，单位：像素
           * @param {Number} heigth 高度，单位：像素
           * @param {Number} quality 质量，1-100的数字，默认100
           * @param {Number} scaleToFit 是否将图片自适应大小。默认为true。
           * @param {String} fmt 格式，默认为png，也可以为jpeg,gif等格式。
           */

          thumbnailURL(
            width,
            height,
            quality = 100,
            scaleToFit = true,
            fmt = 'png'
          ) {
            const url = this.attributes.url;
            if (!url) {
              throw new Error('Invalid url.');
            }
            if (!width || !height || width <= 0 || height <= 0) {
              throw new Error('Invalid width or height value.');
            }
            if (quality <= 0 || quality > 100) {
              throw new Error('Invalid quality value.');
            }
            const mode = scaleToFit ? 2 : 1;
            return (
              url +
              '?imageView/' +
              mode +
              '/w/' +
              width +
              '/h/' +
              height +
              '/q/' +
              quality +
              '/format/' +
              fmt
            );
          },

          /**
           * Returns the file's size.
           * @return {Number} The file's size in bytes.
           **/
          size() {
            return this.metaData().size;
          },

          /**
           * Returns the file's owner.
           * @return {String} The file's owner id.
           */
          ownerId() {
            return this.metaData().owner;
          },

          /**
           * Destroy the file.
           * @param {AuthOptions} options
           * @return {Promise} A promise that is fulfilled when the destroy
           *     completes.
           */
          destroy(options) {
            if (!this.id) {
              return Promise.reject(new Error('The file id does not eixst.'));
            }
            var request = AVRequest(
              'files',
              null,
              this.id,
              'DELETE',
              null,
              options
            );
            return request;
          },

          /**
           * Request Qiniu upload token
           * @param {string} type
           * @return {Promise} Resolved with the response
           * @private
           */
          _fileToken(type, authOptions) {
            let name = this.attributes.name;

            let extName = extname(name);
            if (!extName && this._extName) {
              name += this._extName;
              extName = this._extName;
            }
            // Create 16-bits uuid as qiniu key.
            const key =
              hexOctet() +
              hexOctet() +
              hexOctet() +
              hexOctet() +
              hexOctet() +
              extName;
            const data = {
              key,
              name,
              keep_file_name: authOptions.keepFileName,
              ACL: this._acl,
              mime_type: type,
              metaData: this.attributes.metaData,
            };
            this._qiniu_key = key;
            return AVRequest('fileTokens', null, null, 'POST', data, authOptions);
          },

          /**
           * @callback UploadProgressCallback
           * @param {XMLHttpRequestProgressEvent} event - The progress event with 'loaded' and 'total' attributes
           */
          /**
           * Saves the file to the AV cloud.
           * @param {AuthOptions} [options] AuthOptions plus:
           * @param {UploadProgressCallback} [options.onprogress] 文件上传进度，在 Node.js 中无效，回调参数说明详见 {@link UploadProgressCallback}。
           * @param {boolean} [options.keepFileName = false] 保留下载文件的文件名。
           * @return {Promise} Promise that is resolved when the save finishes.
           */
          save(options = {}) {
            if (this.id) {
              throw new Error('File is already saved.');
            }
            if (!this._previousSave) {
              if (this._data) {
                let mimeType = this.get('mime_type');
                this._previousSave = this._fileToken(mimeType, options).then(
                  uploadInfo => {
                    if (uploadInfo.mime_type) {
                      mimeType = uploadInfo.mime_type;
                      this.set('mime_type', mimeType);
                    }
                    this._token = uploadInfo.token;
                    return Promise.resolve()
                      .then(() => {
                        const data = this._data;
                        if (data && data.base64) {
                          return parseBase64(data.base64, mimeType);
                        }
                        if (data && data.blob) {
                          if (!data.blob.type && mimeType) {
                            data.blob.type = mimeType;
                          }
                          if (!data.blob.name) {
                            data.blob.name = this.get('name');
                          }
                          return data.blob;
                        }
                        if (typeof Blob !== 'undefined' && data instanceof Blob) {
                          return data;
                        }
                        /* NODE-ONLY:start */
                        if (data instanceof require('stream')) {
                          return data;
                        }
                        if (Buffer.isBuffer(data)) {
                          return data;
                        }
                        /* NODE-ONLY:end */
                        throw new TypeError('malformed file data');
                      })
                      .then(data => {
                        const _options = _.extend({}, options);
                        // filter out download progress events
                        if (options.onprogress) {
                          _options.onprogress = event => {
                            if (event.direction === 'download') return;
                            return options.onprogress(event);
                          };
                        }
                        switch (uploadInfo.provider) {
                          case 's3':
                            return s3(uploadInfo, data, this, _options);
                          case 'qcloud':
                            return cos(uploadInfo, data, this, _options);
                          case 'qiniu':
                          default:
                            return qiniu(uploadInfo, data, this, _options);
                        }
                      })
                      .then(tap(() => this._callback(true)), error => {
                        this._callback(false);
                        throw error;
                      });
                  }
                );
              } else if (
                this.attributes.url &&
                this.attributes.metaData.__source === 'external'
              ) {
                // external link file.
                const data = {
                  name: this.attributes.name,
                  ACL: this._acl,
                  metaData: this.attributes.metaData,
                  mime_type: this.mimeType,
                  url: this.attributes.url,
                };
                this._previousSave = AVRequest(
                  'files',
                  this.attributes.name,
                  null,
                  'post',
                  data,
                  options
                ).then(response => {
                  this.attributes.name = response.name;
                  this.attributes.url = response.url;
                  this.id = response.objectId;
                  if (response.size) {
                    this.attributes.metaData.size = response.size;
                  }
                  return this;
                });
              }
            }
            return this._previousSave;
          },

          _callback(success) {
            AVRequest('fileCallback', null, null, 'post', {
              token: this._token,
              result: success,
            }).catch(debug);
            delete this._token;
            delete this._data;
          },

          /**
           * fetch the file from server. If the server's representation of the
           * model differs from its current attributes, they will be overriden,
           * @param {Object} fetchOptions Optional options to set 'keys',
           *      'include' and 'includeACL' option.
           * @param {AuthOptions} options
           * @return {Promise} A promise that is fulfilled when the fetch
           *     completes.
           */
          fetch(fetchOptions, options) {
            var request = AVRequest(
              'files',
              null,
              this.id,
              'GET',
              transformFetchOptions(fetchOptions),
              options
            );
            return request.then(this._finishFetch.bind(this));
          },
          _finishFetch(response) {
            var value = AV.Object.prototype.parse(response);
            value.attributes = {
              name: value.name,
              url: value.url,
              mime_type: value.mime_type,
              bucket: value.bucket,
            };
            value.attributes.metaData = value.metaData || {};
            value.id = value.objectId;
            // clean
            delete value.objectId;
            delete value.metaData;
            delete value.url;
            delete value.name;
            delete value.mime_type;
            delete value.bucket;
            _.extend(this, value);
            return this;
          },
        }
      );
    };