/*global Dropbox */
define([
	"jquery",
	"underscore",
	"constants",
	"core",
	"utils",
	"storage",
	"logger",
	"settings",
	"eventMgr",
	"classes/AsyncTask"
], function($, _, constants, core, utils, storage, logger, settings, eventMgr, AsyncTask) {

	var client;
	var authenticated = false;

	var dropboxHelper = {};

	// Listen to offline status changes
	var isOffline = false;
	eventMgr.addListener("onOfflineChanged", function(isOfflineParam) {
		isOffline = isOfflineParam;
	});

	// Try to connect dropbox by downloading client.js
	function connect(task) {
		task.onRun(function() {
			if(isOffline === true) {
				client = undefined;
				return task.error(new Error("Operation not available in offline mode.|stopPublish"));
			}
			if(client !== undefined) {
				return task.chain();
			}
			$.ajax({
				url: "libs/dropbox.min.js",
				dataType: "script",
				timeout: constants.AJAX_TIMEOUT
			}).done(function() {
				client = new Dropbox.Client({
					key: settings.dropboxFullAccess === true ? constants.DROPBOX_APP_KEY : constants.DROPBOX_RESTRICTED_APP_KEY,
					secret: settings.dropboxFullAccess === true ? constants.DROPBOX_APP_SECRET : constants.DROPBOX_RESTRICTED_APP_SECRET
				});
				client.authDriver(new Dropbox.AuthDriver.Popup({
					receiverUrl: constants.BASE_URL + "html/dropbox-oauth-receiver.html",
					rememberUser: true
				}));
				task.chain();
			}).fail(function(jqXHR) {
				var error = {
					status: jqXHR.status,
					responseText: jqXHR.statusText
				};
				handleError(error, task);
			});
		});
	}

	// Try to authenticate with Oauth
	function authenticate(task) {
		task.onRun(function() {
			if(authenticated === true) {
				return task.chain();
			}
			var immediate = true;

			function oauthRedirect() {
				utils.redirectConfirm('You are being redirected to <strong>Dropbox</strong> authorization page.', function() {
					task.chain(localAuthenticate);
				}, function() {
					task.error(new Error('Operation canceled.'));
				});
			}

			function localAuthenticate() {
				if(immediate === false) {
					// If not immediate we add time for user to enter his
					// credentials
					task.timeout = constants.ASYNC_TASK_LONG_TIMEOUT;
				}
				else {
					client.reset();
				}
				client.authenticate({
					interactive: !immediate
				}, function(error, client) {
					// Success
					if(client.isAuthenticated() === true) {
						authenticated = true;
						return task.chain();
					}
					// If immediate did not work retry without immediate flag
					if(immediate === true) {
						immediate = false;
						return task.chain(oauthRedirect);
					}
					// Error
					task.error(new Error("Access to Dropbox account is not authorized."));
				});
			}

			task.chain(localAuthenticate);
		});
	}

	dropboxHelper.upload = function(path, content, callback) {
		var result;
		var task = new AsyncTask();
		connect(task);
		authenticate(task);
		task.onRun(function() {
			client.writeFile(path, content, function(error, stat) {
				if(!error) {
					result = stat;
					return task.chain();
				}
				// Handle error
				if(error.status === 400) {
					error = 'Could not upload document into path "' + path + '".';
				}
				handleError(error, task);
			});
		});
		task.onSuccess(function() {
			callback(undefined, result);
		});
		task.onError(function(error) {
			callback(error);
		});
		task.enqueue();
	};

	dropboxHelper.checkChanges = function(lastChangeId, callback) {
		var changes = [];
		var newChangeId = lastChangeId || 0;
		var task = new AsyncTask();
		connect(task);
		authenticate(task);
		task.onRun(function() {
			function retrievePageOfChanges() {
				client.pullChanges(newChangeId, function(error, pullChanges) {
					if(error) {
						return handleError(error, task);
					}
					// Retrieve success
					newChangeId = pullChanges.cursor();
					if(pullChanges.changes !== undefined) {
						changes = changes.concat(pullChanges.changes);
					}
					if(pullChanges.shouldPullAgain) {
						task.chain(retrievePageOfChanges);
					}
					else {
						task.chain();
					}
				});
			}

			task.chain(retrievePageOfChanges);
		});
		task.onSuccess(function() {
			callback(undefined, changes, newChangeId);
		});
		task.onError(function(error) {
			callback(error);
		});
		task.enqueue();
	};

	dropboxHelper.downloadMetadata = function(paths, callback) {
		var result = [];
		var task = new AsyncTask();
		connect(task);
		authenticate(task);
		task.onRun(function() {
			function recursiveDownloadMetadata() {
				if(paths.length === 0) {
					return task.chain();
				}
				var path = paths[0];
				client.stat(path, function(error, stat) {
					if(stat) {
						result.push(stat);
						paths.shift();
						return task.chain(recursiveDownloadMetadata);
					}
					handleError(error, task);
				});
			}

			task.chain(recursiveDownloadMetadata);
		});
		task.onSuccess(function() {
			callback(undefined, result);
		});
		task.onError(function(error) {
			callback(error);
		});
		task.enqueue();
	};

	dropboxHelper.downloadContent = function(objects, callback) {
		var result = [];
		var task = new AsyncTask();
		connect(task);
		authenticate(task);
		task.onRun(function() {
			function recursiveDownloadContent() {
				if(objects.length === 0) {
					return task.chain();
				}
				var object = objects[0];
				result.push(object);
				var file;
				// object may be a file
				if(object.isFile === true) {
					file = object;
				}
				// object may be a change
				else if(object.wasRemoved !== undefined) {
					file = object.stat;
				}
				if(!file) {
					objects.shift();
					return task.chain(recursiveDownloadContent);
				}
				client.readFile(file.path, function(error, data) {
					if(_.isString(data)) {
						file.content = data;
						objects.shift();
						return task.chain(recursiveDownloadContent);
					}
					handleError(error, task);
				});
			}

			task.chain(recursiveDownloadContent);
		});
		task.onSuccess(function() {
			callback(undefined, result);
		});
		task.onError(function(error) {
			callback(error);
		});
		task.enqueue();
	};

	function handleError(error, task) {
		var errorMsg = true;
		if(error) {
			logger.error(error);
			// Try to analyze the error
			if(typeof error === "string") {
				errorMsg = error;
			}
			else {
				errorMsg = "Dropbox error (" + error.status + ": " + error.responseText + ").";

				if(error.status === 401 || error.status === 403) {
					authenticated = false;
					errorMsg = "Access to Dropbox account is not authorized.";
					return task.retry(new Error(errorMsg), 1);
				}
				else if(error.status === 400 && error.responseText.indexOf("oauth_nonce") !== -1) {
					// A bug I guess...
					_.each(_.keys(storage), function(key) {
						// We have to remove the Oauth cache from the
						// storage
						if(key.indexOf("dropbox-auth") === 0) {
							storage.removeItem(key);
						}
					});
					authenticated = false;
					return task.retry(new Error(errorMsg), 1);
				}
				else if(error.status <= 0) {
					client = undefined;
					authenticated = false;
					core.setOffline();
					errorMsg = "|stopPublish";
				}
			}
		}
		task.error(new Error(errorMsg));
	}

	var pickerLoaded = false;

	function loadPicker(task) {
		task.onRun(function() {
			if(pickerLoaded === true) {
				return task.chain();
			}
			function chooserRedirect() {
				utils.redirectConfirm('You are being redirected to <strong>Dropbox Chooser</strong> page.', function() {
					task.chain();
				}, function() {
					task.error(new Error('Operation canceled.'));
				});
			}

			$.ajax({
				url: "https://www.dropbox.com/static/api/1/dropbox.js",
				dataType: "script",
				timeout: constants.AJAX_TIMEOUT
			}).done(function() {
				pickerLoaded = true;
				task.chain(chooserRedirect);
			}).fail(function(jqXHR) {
				var error = {
					status: jqXHR.status,
					responseText: jqXHR.statusText
				};
				handleError(error, task);
			});
		});
	}

	dropboxHelper.picker = function(callback) {
		var paths = [];
		var task = new AsyncTask();
		// Add some time for user to choose his files
		task.timeout = constants.ASYNC_TASK_LONG_TIMEOUT;
		connect(task);
		loadPicker(task);
		task.onRun(function() {
			var options = {};
			options.multiselect = true;
			options.linkType = "direct";
			options.success = function(files) {
				for(var i = 0; i < files.length; i++) {
					var path = files[i].link;
					path = path.replace(/.*\/view\/[^\/]*/, "");
					paths.push(decodeURI(path));
				}
				task.chain();
			};
			options.cancel = function() {
				task.chain();
			};
			Dropbox.choose(options);
		});
		task.onSuccess(function() {
			callback(undefined, paths);
		});
		task.onError(function(error) {
			callback(error);
		});
		task.enqueue();
	};

	return dropboxHelper;
});