define(["jquery", "core", "async-runner"], function($, core, asyncRunner) {

	var oauthParams = undefined;

	var tumblrHelper = {};

	// Only used to check the offline status
	function connect(task) {
		task.onRun(function() {
			if(core.isOffline === true) {
				task.error(new Error("Operation not available in offline mode."));
				return;
			}
			task.chain();
		});
	}

	// Try to authenticate with Oauth
	function authenticate(task) {
		var authWindow = undefined;
		var intervalId = undefined;
		task.onRun(function() {
			if (oauthParams !== undefined) {
				task.chain();
				return;
			}
			var serializedOauthParams = localStorage["tumblrOauthParams"];
			if(serializedOauthParams !== undefined) {
				oauthParams = JSON.parse(serializedOauthParams);
				task.chain();
				return;
			}
			core.showMessage("Please make sure the Tumblr authorization popup is not blocked by your browser.");
			var errorMsg = "Failed to retrieve a token from Tumblr.";
			// We add time for user to enter his credentials
			task.timeout = ASYNC_TASK_LONG_TIMEOUT;
			var oauth_object = undefined;
			function getOauthToken() {
				$.getJSON(TUMBLR_PROXY_URL + "request_token", function(data) {
					if(data.oauth_token !== undefined) {
						oauth_object = data;
						task.chain(getVerifier);
					}
					else {
						task.error(new Error(errorMsg));
					}
				});
			}
			function getVerifier() {
				localStorage.removeItem("tumblrVerifier");
				authWindow = core.popupWindow(
					'tumblr-oauth-client.html?oauth_token=' + oauth_object.oauth_token,
					'stackedit-tumblr-oauth', 800, 600);
				authWindow.focus();
				intervalId = setInterval(function() {
					if(authWindow.closed === true) {
						clearInterval(intervalId);
						authWindow = undefined;
						intervalId = undefined;
						oauth_object.oauth_verifier = localStorage["tumblrVerifier"];
						if(oauth_object.oauth_verifier === undefined) {
							task.error(new Error(errorMsg));
							return;
						}
						localStorage.removeItem("tumblrVerifier");
						task.chain(getAccessToken);
					}
				}, 500);
			}
			function getAccessToken() {
				$.getJSON(TUMBLR_PROXY_URL + "access_token", oauth_object, function(data) {
					if(data.access_token !== undefined && data.access_token_secret !== undefined) {
						localStorage["tumblrOauthParams"] = JSON.stringify(data);
						oauthParams = data;
						task.chain();
					}
					else {
						task.error(new Error(errorMsg));
					}
				});
			}
			task.chain(getOauthToken);
		});
		task.onError(function() {
			if(intervalId !== undefined) {
				clearInterval(intervalId);
			}
			if(authWindow !== undefined) {
				authWindow.close();
			}
		});
	}

	tumblrHelper.upload = function(blogHostname, postId, tags, format, title, content, callback) {
		callback = callback || core.doNothing;
		var task = asyncRunner.createTask();
		connect(task);
		authenticate(task);
		task.onRun(function() {
			var data = $.extend({
				blog_hostname: blogHostname,
				post_id: postId,
				tags: tags,
				format: format,
				title: title,
				content: content
			}, oauthParams);
			$.ajax({
				url : TUMBLR_PROXY_URL + "post",
				data: data,
				type: "POST",
				dataType : "json",
				timeout : AJAX_TIMEOUT
			}).done(function(post, textStatus, jqXHR) {
				postId = post.id;
				task.chain();
			}).fail(function(jqXHR) {
				var error = {
					code: jqXHR.status,
					message: jqXHR.statusText
				};
				// Handle error
				if(error.code === 404 && postId !== undefined) {
					error = 'Post ' + postId + ' not found on Tumblr.|removePublish';
				}
				handleError(error, task);
			});
		});
		task.onSuccess(function() {
			callback(undefined, postId);
		});
		task.onError(function(error) {
			callback(error);
		});
		asyncRunner.addTask(task);
	};
	
	function handleError(error, task) {
		var errorMsg = undefined;
		if (error) {
			console.error(error);
			// Try to analyze the error
			if (typeof error === "string") {
				errorMsg = error;
			}
			else {
				errorMsg = "Could not publish on Tumblr.";
				if (error.code === 401 || error.code === 403) {
					oauthParams = undefined;
					localStorage.removeItem("tumblrOauthParams");
					errorMsg = "Access to Tumblr account is not authorized.";
					task.retry(new Error(errorMsg), 1);
					return;
				} else if (error.code <= 0) {
					core.setOffline();
					errorMsg = "|stopPublish";
				}
			}
		}
		task.error(new Error(errorMsg));
	}

	return tumblrHelper;
});