HackMD/public/js/google-drive-upload.js

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/**
* Helper for implementing retries with backoff. Initial retry
* delay is 1 second, increasing by 2x (+jitter) for subsequent retries
*
* @constructor
*/
var RetryHandler = function() {
this.interval = 1000; // Start at one second
this.maxInterval = 60 * 1000; // Don't wait longer than a minute
};
/**
* Invoke the function after waiting
*
* @param {function} fn Function to invoke
*/
RetryHandler.prototype.retry = function(fn) {
setTimeout(fn, this.interval);
this.interval = this.nextInterval_();
};
/**
* Reset the counter (e.g. after successful request.)
*/
RetryHandler.prototype.reset = function() {
this.interval = 1000;
};
/**
* Calculate the next wait time.
* @return {number} Next wait interval, in milliseconds
*
* @private
*/
RetryHandler.prototype.nextInterval_ = function() {
var interval = this.interval * 2 + this.getRandomInt_(0, 1000);
return Math.min(interval, this.maxInterval);
};
/**
* Get a random int in the range of min to max. Used to add jitter to wait times.
*
* @param {number} min Lower bounds
* @param {number} max Upper bounds
* @private
*/
RetryHandler.prototype.getRandomInt_ = function(min, max) {
return Math.floor(Math.random() * (max - min + 1) + min);
};
/**
* Helper class for resumable uploads using XHR/CORS. Can upload any Blob-like item, whether
* files or in-memory constructs.
*
* @example
* var content = new Blob(["Hello world"], {"type": "text/plain"});
* var uploader = new MediaUploader({
* file: content,
* token: accessToken,
* onComplete: function(data) { ... }
* onError: function(data) { ... }
* });
* uploader.upload();
*
* @constructor
* @param {object} options Hash of options
* @param {string} options.token Access token
* @param {blob} options.file Blob-like item to upload
* @param {string} [options.fileId] ID of file if replacing
* @param {object} [options.params] Additional query parameters
* @param {string} [options.contentType] Content-type, if overriding the type of the blob.
* @param {object} [options.metadata] File metadata
* @param {function} [options.onComplete] Callback for when upload is complete
* @param {function} [options.onProgress] Callback for status for the in-progress upload
* @param {function} [options.onError] Callback if upload fails
*/
var MediaUploader = function(options) {
var noop = function() {};
this.file = options.file;
this.contentType = options.contentType || this.file.type || 'application/octet-stream';
this.metadata = options.metadata || {
'title': this.file.name,
'mimeType': this.contentType
};
this.token = options.token;
this.onComplete = options.onComplete || noop;
this.onProgress = options.onProgress || noop;
this.onError = options.onError || noop;
this.offset = options.offset || 0;
this.chunkSize = options.chunkSize || 0;
this.retryHandler = new RetryHandler();
this.url = options.url;
if (!this.url) {
var params = options.params || {};
params.uploadType = 'resumable';
this.url = this.buildUrl_(options.fileId, params, options.baseUrl);
}
this.httpMethod = options.fileId ? 'PUT' : 'POST';
};
/**
* Initiate the upload.
*/
MediaUploader.prototype.upload = function() {
var self = this;
var xhr = new XMLHttpRequest();
xhr.open(this.httpMethod, this.url, true);
xhr.setRequestHeader('Authorization', 'Bearer ' + this.token);
xhr.setRequestHeader('Content-Type', 'application/json');
xhr.setRequestHeader('X-Upload-Content-Length', this.file.size);
xhr.setRequestHeader('X-Upload-Content-Type', this.contentType);
xhr.onload = function(e) {
if (e.target.status < 400) {
var location = e.target.getResponseHeader('Location');
this.url = location;
this.sendFile_();
} else {
this.onUploadError_(e);
}
}.bind(this);
xhr.onerror = this.onUploadError_.bind(this);
xhr.send(JSON.stringify(this.metadata));
};
/**
* Send the actual file content.
*
* @private
*/
MediaUploader.prototype.sendFile_ = function() {
var content = this.file;
var end = this.file.size;
if (this.offset || this.chunkSize) {
// Only bother to slice the file if we're either resuming or uploading in chunks
if (this.chunkSize) {
end = Math.min(this.offset + this.chunkSize, this.file.size);
}
content = content.slice(this.offset, end);
}
var xhr = new XMLHttpRequest();
xhr.open('PUT', this.url, true);
xhr.setRequestHeader('Content-Type', this.contentType);
xhr.setRequestHeader('Content-Range', "bytes " + this.offset + "-" + (end - 1) + "/" + this.file.size);
xhr.setRequestHeader('X-Upload-Content-Type', this.file.type);
if (xhr.upload) {
xhr.upload.addEventListener('progress', this.onProgress);
}
xhr.onload = this.onContentUploadSuccess_.bind(this);
xhr.onerror = this.onContentUploadError_.bind(this);
xhr.send(content);
};
/**
* Query for the state of the file for resumption.
*
* @private
*/
MediaUploader.prototype.resume_ = function() {
var xhr = new XMLHttpRequest();
xhr.open('PUT', this.url, true);
xhr.setRequestHeader('Content-Range', "bytes */" + this.file.size);
xhr.setRequestHeader('X-Upload-Content-Type', this.file.type);
if (xhr.upload) {
xhr.upload.addEventListener('progress', this.onProgress);
}
xhr.onload = this.onContentUploadSuccess_.bind(this);
xhr.onerror = this.onContentUploadError_.bind(this);
xhr.send();
};
/**
* Extract the last saved range if available in the request.
*
* @param {XMLHttpRequest} xhr Request object
*/
MediaUploader.prototype.extractRange_ = function(xhr) {
var range = xhr.getResponseHeader('Range');
if (range) {
this.offset = parseInt(range.match(/\d+/g).pop(), 10) + 1;
}
};
/**
* Handle successful responses for uploads. Depending on the context,
* may continue with uploading the next chunk of the file or, if complete,
* invokes the caller's callback.
*
* @private
* @param {object} e XHR event
*/
MediaUploader.prototype.onContentUploadSuccess_ = function(e) {
if (e.target.status == 200 || e.target.status == 201) {
this.onComplete(e.target.response);
} else if (e.target.status == 308) {
this.extractRange_(e.target);
this.retryHandler.reset();
this.sendFile_();
} else {
this.onContentUploadError_(e);
}
};
/**
* Handles errors for uploads. Either retries or aborts depending
* on the error.
*
* @private
* @param {object} e XHR event
*/
MediaUploader.prototype.onContentUploadError_ = function(e) {
if (e.target.status && e.target.status < 500) {
this.onError(e.target.response);
} else {
this.retryHandler.retry(this.resume_.bind(this));
}
};
/**
* Handles errors for the initial request.
*
* @private
* @param {object} e XHR event
*/
MediaUploader.prototype.onUploadError_ = function(e) {
this.onError(e.target.response); // TODO - Retries for initial upload
};
/**
* Construct a query string from a hash/object
*
* @private
* @param {object} [params] Key/value pairs for query string
* @return {string} query string
*/
MediaUploader.prototype.buildQuery_ = function(params) {
params = params || {};
return Object.keys(params).map(function(key) {
return encodeURIComponent(key) + '=' + encodeURIComponent(params[key]);
}).join('&');
};
/**
* Build the drive upload URL
*
* @private
* @param {string} [id] File ID if replacing
* @param {object} [params] Query parameters
* @return {string} URL
*/
MediaUploader.prototype.buildUrl_ = function(id, params, baseUrl) {
var url = baseUrl || 'https://www.googleapis.com/upload/drive/v2/files/';
if (id) {
url += id;
}
var query = this.buildQuery_(params);
if (query) {
url += '?' + query;
}
return url;
};