Synnefo

// Copyright 2011 GRNET S.A. All rights reserved.

// 

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// without modification, are permitted provided that the following

// conditions are met:

// 

//   1. Redistributions of source code must retain the above

//      copyright notice, this list of conditions and the following

//      disclaimer.

// 

//   2. Redistributions in binary form must reproduce the above

//      copyright notice, this list of conditions and the following

//      disclaimer in the documentation and/or other materials

//      provided with the distribution.

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// THIS SOFTWARE IS PROVIDED BY GRNET S.A. ``AS IS'' AND ANY EXPRESS

// OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED

// WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR

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// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF

// USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED

// AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT

// LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN

// ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE

// POSSIBILITY OF SUCH DAMAGE.

// 

// The views and conclusions contained in the software and

// documentation are those of the authors and should not be

// interpreted as representing official policies, either expressed

// or implied, of GRNET S.A.

// 

;(function(root){

    // root

    var root = root;

    // setup namepsaces

    var snf = root.synnefo = root.synnefo || {};

    var sync = snf.sync = snf.sync || {};

    var api = snf.api = snf.api || {};

    var storage = snf.storage = snf.storage || {};

    // shortcuts

    var bb = Backbone;

    // logging

    var logger = new snf.logging.logger("SNF-API");

    var debug = _.bind(logger.debug, logger)

    // method map

    var methodMap = {

        'create': 'POST',

        'update': 'PUT',

        'delete': 'DELETE',

        'read'  : 'GET',

        'head'  : 'HEAD'

    };

    // custom getUrl function

    // handles url retrieval based on the object passed

    // on most occasions in the synnefo api this will call

    // the model/collection url method

    var getUrl = function(object, options, method) {

        if (!(object && object.url)) return null;

        return _.isFunction(object.url) ? object.url(options, method) : object.url;

    };

    // Call history (set of api paths with the dates the path last called)

    var api_history = api.requests = api.requests || {};

    var addApiCallDate = function(url, d, method) {

        if (d === undefined) { d = Date() };

        var path = snf.util.parseUri(url).path;

        var key = path + "_" + method;

        // TODO: check if d is very old date

        api_history[key] = d;

        return api_history[path]

    }

    var clearApiCallDate = function(url, method) {

        var path = snf.util.parseUri(url).path;

        var key = path + "_" + method;

        api_history[key] = false;

        return api_history[path]

    }

    var api_errors = api.errors = api.errors || [];

    var add_api_error = function(settings, data) {

        api_errors.push({url:settings.url, date:new Date, settings:settings, data:data})

    }

    var setChangesSince = function(url, method) {

        var path = snf.util.parseUri(url).path;

        var d = api_history[path + "_" + method];

        if (d) {

            // subtract threshold

            d = new Date(d - synnefo.config.changes_since_alignment);

            url = url + "?changes-since=" + snf.util.ISODateString(d);

        }

        return url;

    }

    // custom sync method

    // appends global ajax handlers

    // handles changed-since url parameter based on api path

    api.sync = function(method, model, options) {

        var type = methodMap[method];

        if (model && (model.skipMethods || []).indexOf(method) >= 0) {

            throw "Model does not support " + method + " calls";

        }

        if (!options.url) {

            var urlobject = model;

            // fallback to collection url for item creation

            if (method == "create" && model.isNew && model.isNew()) {

                urlobject = model.collection;

            }

            options.url = getUrl(urlobject, options, method) || urlError();

            if (urlobject && urlobject.supportIncUpdates) {

                if (!options.refresh) {

                  options.url = setChangesSince(options.url, type);

                  options._detect_change_by_response_code = true;

                } 

            }

            if (!options.refresh && options.cache === undefined) {

                options.cache = true;

            }

        }

        // default error options

        options.critical = options.critical === undefined ? true : options.critical;

        options.display = options.display === undefined ? true : options.display;

        if (api.stop_calls && !options.no_skip) {

            return;

        }

        var success = options.success || function(){};

        var error = options.error || function(){};

        var complete = options.complete || function(){};

        var before_send = options.beforeSend || function(){};

        // custom json data.

        if (options.data && model && (method == 'create' || method == 'update')) {

            options.contentType = 'application/json';

            options.data = JSON.stringify(options.data);

        }

        options.data = _.isEmpty(options.data) ? undefined : options.data;

        var api_params = {};

        var api_options = _.extend(api_params, options, {

            success: api.handlerWrapper(api.successHandler, success, "success"),

            error: api.handlerWrapper(api.errorHandler, error, "error"),

            complete: api.handlerWrapper(api.completeHandler, complete, "complete"),

            beforeSend: api.handlerWrapper(api.beforeSendHandler, before_send, "beforeSend"),

            cache: options.cache || false,

            timeout: options.timeout || snf.config.ajax_timeout || window.TIMEOUT || 5000

        });

        return bb.sync(method, model, api_options);

    }

    api.timeouts_occured = 0;

    api.handlerWrapper = function(wrap, method, type) {

        var cb_type = type;

        return function() {

            var xhr = undefined;

            var handler_type = type;

            var args = arguments;

            var ajax_options = this;

            // save the request date to use it as a changes-since value

            // for opera because we are not able to determine

            // response date header for 304 requests

            if (handler_type == "beforeSend" && $.browser.opera) {

                this.date_send = new Date;

            }

            if (handler_type == "beforeSend") {

                arguments[0].setRequestHeader('X-Auth-Token', 

                                              synnefo.user.get_token());

            }

            // error with status code 0 in opera

            // act as 304 response

            if (handler_type == "error" && $.browser.opera) {

                if (arguments[0].status === 0 && arguments[1] === "error") {

                    arguments[0].status = 304;

                    arguments[1] = "notmodified";

                    response_type = "success";

                    xhr = arguments[0];

                }

            }

            // add error in api errors registry

            // api errors registry will be sent

            // if user reports an error using feedback form

            if (handler_type == "error") {

                // skip logging requested ?

                // if not log this error

                if (this.log_error !== false) {

                    add_api_error(this, arguments);

                }

            }

            // identify response status

            var status = 304;

            if (arguments[0]) {

                status = arguments[0].status;

            }

            // identify aborted request

            try {

                if (args[1] === "abort") {

                    api.trigger("abort");

                    return;

                }

            } catch(error) {

                console.error("error aborting", error);

            }

            // try to set the last request date

            // only for notmodified or succeed responses

            try {

                // identify xhr object

                xhr = xhr || args[2];

                // not modified response

                if (args[1] === "notmodified") {

                    if (xhr) {

                        // use date_send if exists (opera browser)

                        var d = this.date_send || xhr.getResponseHeader('Date');

                        if (d) { addApiCallDate(this.url, new Date(d), ajax_options.type); };

                    }

                    return;

                }

                // success response

                if (args[1] == "success" && handler_type == "success") {

                    try {

                        // use date_send if exists (opera browser)

                        var d = this.date_send || args[2].getResponseHeader('Date');

                        if (d) { addApiCallDate(this.url, new Date(d), ajax_options.type); };

                    } catch (err) {

                        console.error(err)

                    }

                }

            } catch (err) {

                console.error(err);

            }

            // dont call error callback for non modified responses

            if (arguments[1] === "notmodified") {

                return;

            }

            if (["beforeSend", "complete"].indexOf(cb_type) == -1 && 

                this._detect_change_by_response_code) {

                // trigger event to notify that a recurrent event

                // has returned status other than notmodified

                snf.api.trigger("change:recurrent");

            }

            // prepare arguments for error callbacks

            var cb_args = _.toArray(arguments);

            if (handler_type === "error") {

                cb_args.push(_.clone(this));

            }

            // determine if we need to call our callback wrapper

            var call_api_handler = true;

            // request handles errors by itself, s

            if (handler_type == "error" && this.skip_api_error) {

                call_api_handler = false

            }

            // aborted request, don't call error handler

            if (handler_type === "error" && args[1] === "abort") {

                call_api_handler = false;

            }

            // reset api call date, next call will be sent without changes-since

            // parameter set

            if (handler_type === "error") {

                if (args[1] === "error") {

                    clearApiCallDate(this.url, this.type);

                }

            }

            // call api call back and retrieve params to

            // be passed to the callback method set for

            // this type of response

            if (call_api_handler) {

                cb_args = wrap.apply(this, cb_args);

            }

            // call requested callback

            method.apply(this, _.toArray(cb_args));

        }

    }

    api.successHandler = function(data, status, xhr) {

        //debug("ajax success", arguments)

        // on success, update the last date we called the api url

        return [data, status, xhr];

    }

    api.errorHandler = function(event, xhr, settings, error) {

        // dont trigger api error until timeouts occured

        // exceed the skips_timeouts limit

        //

        // check only requests with skips_timeouts option set

        if (xhr === "timeout" && _.last(arguments).skips_timeouts) {

            var skip_timeouts = snf.config.skip_timeouts || 1;

            if (snf.api.timeouts_occured < skip_timeouts) {

                snf.api.timeouts_occured++;

                return;

            } else {

                // reset trigger error

                snf.api.timeouts_occured = 0;

                var args = _.toArray(arguments);

                api.trigger("error", args);

            }

        }

        // if error occured and changes-since is set for the request

        // skip triggering the error and try again without the changes-since

        // parameter set

        var url = snf.util.parseUri(this.url);

        if (url.query.indexOf("changes-since") > -1) {

            clearApiCallDate(this.url, this.type);

            return _.toArray(arguments);

        }

        // skip aborts, notmodified (opera)

        if (xhr === "error" || xhr === "timeout") {

            var args = _.toArray(arguments);

            api.trigger("error", args);

        }

        return _.toArray(arguments);

    }

    api.completeHandler = function(xhr, status) {

        //debug("ajax complete", arguments)

        return arguments;

    }

    api.beforeSendHandler = function(xhr, settings) {

        //debug("ajax beforeSend", arguments)

        // ajax settings

        var ajax_settings = this;

        return arguments;

    }

    // api call helper

    api.call = function(url, method, data, complete, error, success, options) {

            var self = this;

            error = error || function(){};

            success = success || function(){};

            complete = complete || function(){};

            var extra = data ? data._options || {} : {};

            // really ugly way to pass sync request options.

            // it works though....

            if (data && data._options) { delete data['_options'] };

            var base_url = snf.config.api_urls[this.api_type];

            var join = '/';

            // do not append trailling slash if already exists in url

            if (base_url[base_url.length - 1] == join) { join = '' }

            // prepare the params

            var params = {

                url: base_url + join + url,

                data: data,

                success: success,

                complete: function() { api.trigger("call"); complete(this) },

                error: error

            }

            params = _.extend(params, extra, options);

            this.sync(method, this, params);

        },

    _.extend(api, bb.Events);

    // helper for callbacks that need to get called

    // in fixed intervals

    api.updateHandler = function(options) {

        this.cb = options.callback;

        this.handler_id = options.id;

        // the interval with which we start

        this.interval = this.normal_interval = options.interval || 4000;

        // fast interval

        // set when faster() gets called

        this.fast_interval = options.fast || 1000;

        // after how many calls to increase the interval

        this.interval_increase_count = options.increase_after_calls || 0;

        // increase the timer by this value after interval_increase_count calls

        this.interval_increase = options.increase || 500;

        // maximum interval limit

        this.maximum_interval = options.max || 60000;

        // make a call before interval starts

        this.call_on_start = options.initial_call === undefined ? true : options.initial_call;

        this.increase_enabled = this.interval_increase_count === 0;

        if (this.increase_enabled) {

            this.maximum_interval = this.interval;

            this.interval_increase_count = 1;

        }

        // inner params

        this._called = 0;

        this._first_call_date = undefined;

        this.window_interval = undefined;

        // state params

        this.running = false;

        this.last_call = false;

        // helper for api calls

        // TODO: move this out of here :/

        if (options.is_recurrent) {

            snf.api.bind("change:recurrent", _.bind(function() {

                if (this.running) {

                    this.faster(true);

                }

            }, this));

        }

        // callback wrapper

        this._cb = function() {

            if (!this.running) { this.stop() }

            if (this._called >= this.interval_increase_count) {

                this._called = 0;

                this.slower(false);

            }

            this.cb();

            this.last_call = new Date;

            this._called++;

        };

        // start from faster timeout and start increasing

        this.faster = function(do_call) {

            if (!this.running) { return }

            this.interval = this.fast_interval;

            this.setInterval(do_call);

        }

        // slow down

        this.slower = function(do_call) {

            if (this.interval == this.maximum_interval) {

                // no need to increase

                return;

            }

            this.interval = this.interval + this.interval_increase;

            // increase timeout

            if (this.interval > this.maximum_interval) {

                this.interval = this.maximum_interval;

            }

            this.setInterval(do_call);

        }

        // reset internal

        this.setInterval = function(do_call) {

            this.trigger("clear");

            // reset times called

            this._called = 0;

            window.clearInterval(this.window_interval);

            this.window_interval = window.setInterval(_.bind(this._cb, this), this.interval);

            this.running = true;

            // if no do_call set, fallback to object creation option

            // else force what was requested

            var call = do_call === undefined ? this.call_on_start : do_call;

            if (this.last_call && do_call !== false) {

                var next_call = (this.interval - ((new Date) - this.last_call));

                if (next_call < this.interval/2) {

                    call = true;

                } else {

                    call = false;

                }

            }

            if (call) {

                this._cb();

            }

            return this;

        }

        this.start = function (call_on_start) {

            if (this.running) { this.stop() };

            this.setInterval(call_on_start);

            return this;

        }

        this.stop = function() {

            this.trigger("clear");

            window.clearInterval(this.window_interval);

            this.running = false;

            return this;

        }

    }

    // api error state

    api.stop_calls = false;

    api.STATES = { NORMAL:1, WARN:0, ERROR:-1 };

    api.error_state = api.STATES.NORMAL;

    // on api error update the api error_state

    api.bind("error", function() {

        if (snf.api.error_state == snf.api.STATES.ERROR) { return };

        var args = _.toArray(_.toArray(arguments)[0]);

        var params = _.last(args);

        if (params.critical) {

            snf.api.error_state = api.STATES.ERROR;

            snf.api.stop_calls = true;

        } else {

            snf.api.error_state = api.STATES.ERROR;

        }

        snf.api.trigger("change:error_state", snf.api.error_state);

    });

    // reset api error state

    api.bind("reset", function() {

        snf.api.error_state = api.STATES.NORMAL;

        snf.api.stop_calls = false;

        snf.api.trigger("change:error_state", snf.api.error_state);

    })

    // make it eventable

    _.extend(api.updateHandler.prototype, bb.Events);

})(this);