reste.js

var main = function() {

    var reste = this;

    // setup vars
    var config = {},
        requestHeaders = [];

    // generic log handler in DEV mode
    function log(message) {
        if (config.debug && message) {
            console.log('::RESTE::' + message);
        }
    }

    // generic log handler in DEV mode
    function warn(message) {
        if (config.debug && message) {
            console.warn('::RESTE::' + message);
        }
    }

    // sets up the config, headers, adds methods
    reste.config = function(args) {

        config = args;

        reste.setRequestHeaders(config.requestHeaders);

        config.methods.forEach(function(method) {
            reste.addMethod(method);
        });

        if (config.models) {

            initModels();

            config.models.forEach(function(model) {
                reste.addModel(model);
            });
        }

    };

    reste.setUrl = function(url) {
        config.url = url || config.url;
    };

    reste.getUrl = function() {
        return config.url;
    };

    // makes an http request to a URL, as a POST / GET / currently,
    // passing params and callback
    function makeHttpRequest(args, onLoad, onError) {

        function isJSON(str) {
            try {
                JSON.parse(str);
            } catch (e) {
                return false;
            }
            return true;
        }

        function parseJSON(text) {
            if (isJSON(text)) {
                return JSON.parse(text);
            } else {
                return text;
            }
        }

        // debug the url
        if (args.url.indexOf('http') >= 0) {
            log(args.url);
        } else {
            log((config.url ? config.url + args.url : args.url));
        }

        if (args.params) {
            log(JSON.stringify(args.params));
        }

        // create a client
        var http = Ti.Network.createHTTPClient();

        reste.clearCookies = function() {
            if (http)
                http.clearCookies(config.url);
        };

        var formEncode = false;

        //set some defaults
        http.setTimeout(config.timeout || 10000);

        if (_.has(config, 'validatesSecureCertificate')) {
            http.setValidatesSecureCertificate(config.validatesSecureCertificate);
        }

        // open the url and check if we're overrding with
        // a local http based url

        if (args.url.indexOf('http') >= 0) {
            http.open(args.method, args.url);
        } else {
            http.open(args.method, (config.url ? config.url + args.url : args.url));
        }

        // load up any global request headers
        requestHeaders.forEach(function(header) {
            if (header.name === 'Content-Type' && header.value === 'application/x-www-form-urlencoded') {
                formEncode = true;
            }

            http.setRequestHeader(header.name, typeof header.value === 'function' ? header.value() : header.value);

            log('Setting global header - ' + header.name + ': ' + ( typeof header.value === 'function' ? header.value() : header.value));
        });

        // non-global headers
        if (args.headers) {
            // load up any request headers
            for (var header in args.headers) {
                if (header === 'Content-Type' && args.headers[header] === 'application/x-www-form-urlencoded') {
                    formEncode = true;
                } else if (header === 'Content-Type' && args.headers[header] === 'application/json') {
                    formEncode = false;
                }

                http.setRequestHeader(header, typeof args.headers[header] === 'function' ? args.headers[header]() : args.headers[header]);

                log('Setting local header - ' + header + ': ' + ( typeof args.headers[header] === 'function' ? args.headers[header]() : args.headers[header]));
            }
        }

        // security manager (Pro / Enterprise)
        if (_.has(config, 'securityManager')) {
            http.setSecurityManager(config.securityManager);
        }

        // events
        http.onload = function(e) {
            // get the response parsed
            var response = parseJSON(http.responseText);

            if (config.onLoad) {
                config.onLoad(response, onLoad);
            } else if (onLoad) {
                onLoad(response);
            }

        };

        http.onerror = function(e) {
            e.url = args.url;

            function retry() {
                log('Retrying...');
                makeHttpRequest(args, onLoad, onError);
            }

            var error;

            if (config.errorsAsObjects) {
                error = e;
                error.content = parseJSON(http.responseText);
                warn('Errors will be returned as objects.');
            } else {
                error = parseJSON(http.responseText);
                warn('Future versions of RESTe will return errors as objects. Use config.errorsAsObjects = true to support this now and update your apps!');
            }

            // if local error, handle it
            if (onError) {
                onError(error, retry);
            } else if (config.onError) {
                // otherwise go to global handler
                config.onError(error, retry);
            } else if (onLoad) {
                // otherwise revert to the onLoad callback
                onLoad(error, retry);
            } else {
                // and if reste's not specified, error!
                throw 'RESTe :: No error handler / callback for: ' + args.url;
            }
        };

        function send() {
            // go
            log(args.params);

            if (args.params && (args.method === 'POST' || args.method === 'PUT')) {
                if (formEncode) {
                    http.send(args.params);
                } else {
                    http.send(JSON.stringify(args.params));
                }
            } else {
                http.send();
            }
        }


        args.params = args.params || {};

        var beforePost = args.beforePost || config.beforePost;
        var beforeSend = args.beforeSend || config.beforeSend;

        if (args.method === 'POST' && typeof beforePost === 'function') {

            // initialise empty params in case it's undefined

            beforePost(args.params, function(e) {
                args.params = e;
                send();
            });

        } else if ( typeof beforeSend === 'function') {
            beforeSend(args.params, function(e) {
                args.params = e;
                send();
            });

        } else {
            send();
        }

    }

    // set Requestheaders
    reste.setRequestHeaders = function(headers) {
        requestHeaders = [];
        for (var header in headers) {
            requestHeaders.push({
                name : header,
                value : headers[header]
            });
        }
    };

    // change/add requestHeader
    reste.changeRequestHeader = function(header) {
        var changed = false;

        _.each(requestHeaders, function(item) {
            if (item.name === Object.keys(header)[0]) {
                item.value = header[Object.keys(header)[0]];
                changed = true;
            }
        });
        if (!changed) {
            // add it
            requestHeaders.push({
                name : Object.keys(header)[0],
                value : header[Object.keys(header)[0]]
            });
        }
    };

    // removes an item from the requestHeader
    reste.removeRequestHeaderItem = function(delItem) {
        requestHeaders = _.filter(requestHeaders, function(item) {
            return !(item.name === delItem);
        });
    };

    // add a new method
    reste.addMethod = function(args) {

        log(args.requestHeaders);

        reste[args.name] = function(params, onLoad, onError) {

            var body,
                method = 'GET',
                url,
                deferred;

            if (args.post)
                method = 'POST';
            if (args.get)
                method = 'GET';
            if (args.put)
                method = 'PUT';
            if (args.delete)
                method = 'DELETE';

            url = args[method.toLowerCase()] || args.get;

            if (config.Q && !onLoad && typeof (params) != 'function') {
                deferred = config.Q.defer();
                onLoad = deferred.resolve;
                onError = deferred.reject;
            }

            if (!onLoad && typeof (params) === 'function') {
                onLoad = params;
            } else {
                for (var param in params) {
                    if (param === 'body') {
                        body = params[param];
                    } else {
                        while (url.indexOf('<' + param + '>') >= 0) {
                            if ( typeof params[param] === 'object') {
                                url = url.replace('<' + param + '>', JSON.stringify(params[param]));
                            } else {
                                url = url.replace('<' + param + '>', params[param]);
                            }
                        }
                    }
                }
            }

            if (args.onLoad) {
                // save the original callback
                var originalOnLoad = onLoad;

                // change the callback to be the one specified
                onLoad = function(e) {
                    args.onLoad(e, originalOnLoad);
                };
            }

            if (args.onError) {
                // change the callback to be the one specified
                onError = function(e) {
                    args.onError(e, onLoad);
                };
            }

            if (args.expects) {
                // look for explicityly required parameters
                args.expects.forEach(function(expectedParam) {
                    if ((method === 'POST' && params.body) ? !params.body[expectedParam] : !params[expectedParam]) {
                        throw 'RESTe :: missing parameter ' + expectedParam + ' for method ' + args.name;
                    }
                });

                makeHttpRequest({
                    url : url,
                    method : method,
                    params : body,
                    headers : args.requestHeaders || args.headers,
                    beforePost : args.beforePost,
                    beforeSend : args.beforeSend
                }, onLoad, onError);

            } else {

                var m,
                    missing = [],
                    re = /(\<\w*\>)/g;

                //work out which parameters are required
                if (config.autoValidateParams) {

                    while (( m = re.exec(url)) !== null) {
                        if (m.index === re.lastIndex) {
                            re.lastIndex++;
                        }

                        missing.push(m[0]);
                    }

                }

                if (missing.length > 0) {
                    throw 'RESTe :: missing parameter/s ' + missing + ' for method ' + args.name;
                } else {

                    makeHttpRequest({
                        url : url,
                        method : method,
                        params : body,
                        headers : args.requestHeaders || args.headers,
                        beforePost : args.beforePost,
                        beforeSend : args.beforeSend
                    }, onLoad, onError);
                }
            }

            if (deferred) {
                return deferred.promise;
            }
        };
    };

    // Hacktastic section where we override the Alloy.createModel method
    // only call and run this section if we need it; if models are defined

    reste.createModel = function(name, attributes) {
        var model = new Backbone.Model(attributes);

        // if we have a config based transfor for th emodel
        // then attach this to the model, or create a default
        if (reste.modelConfig && reste.modelConfig[name] && reste.modelConfig[name].transform) {
            model.transform = function(model, transform) {
                if (transform) {
                    this.__transform = transform(this);
                } else {
                    this.__transform = reste.modelConfig[name].transform(this);
                }
                return this.__transform;
            };
        } else {
            model.transform = function(model, transform) {
                if (transform) {
                    this.__transform = transform(this);
                } else {
                    this.__transform = this.toJSON();
                }
                return this.__transform;
            };
        }

        model._type = name;
        return model;
    };

    reste.createCollection = function(name, content) {

        if (!Alloy.Collections[name]) {
            Alloy.Collections[name] = new Backbone.Collection();
        }

        if ( content instanceof Array) {
            // on-the-fly collection, so populate from array
            Alloy.Collections[name].reset(content);
            // and override fetch to trigger a change event
            Alloy.Collections[name].fetch = function() {
                Alloy.Collections[name].trigger('change');
            };
        } else {
            throw 'No Array specified for createCollection';
        }
    };

    function initModels() {

        // add a new model definition
        reste.addModel = function(args) {
            reste.modelConfig = reste.modelConfig || {};

            // storing a reference to the model definition in config
            reste.modelConfig[args.name] = args;

            var model = Backbone.Model.extend({
                _type : args.name,
                _method : args.name,
                transform : function(model, transform) {
                    if (transform) {
                        this.__transform = transform(this);
                    } else if (args.transform) {
                        this.__transform = args.transform(this);
                    } else {
                        this.__transform = this.toJSON();
                    }
                    return this.__transform;
                }
            });

            if (args.collections) {
                args.collections.forEach(function(collection) {
                    Alloy.Collections[collection.name] = Alloy.Collections[collection.name] || new Backbone.Collection();
                    Alloy.Collections[collection.name]._type = args.name;
                    Alloy.Collections[collection.name]._name = collection.name;
                    Alloy.Collections[collection.name].model = model;
                });
            }
        };

        // Intercept sync to handle collections / models
        Backbone.sync = function(method, model, options) {
            log('Backbone.sync: ' + method + ' ' + model._type);

            var modelConfig = reste.modelConfig[model._type];
            var body,
                onError;

            // if this is a collection, get the data and complete
            if ( model instanceof Backbone.Collection && modelConfig && modelConfig.collections) {
                var collectionConfig = _.where(modelConfig.collections, {
                name: model._name
                })[0];

                var methodCall = reste[collectionConfig.read];

                methodCall(options, function(response) {

                  if ((response != null) && (response != undefined)) {

                        // check if we have a return property
                        if (response[collectionConfig.content]) {

                            response[collectionConfig.content].forEach(function(item) {
                                item.id = item[modelConfig.id];
                            });

                            if (options.success)  options.success(response[collectionConfig.content]);

                            Alloy.Collections[collectionConfig.name].trigger('sync');

                        } else {

                            // otherwise just return an array with the response
                            response.forEach(function(item) {
                                item.id = item[modelConfig.id];
                            });

                            if (options.success) options.success(response);

                            Alloy.Collections[collectionConfig.name].trigger('sync');
                        }
                  }
                }, function(response) {

                    if (options.error) {
                        options.error(response);
                    }

                });

            } else if ( model instanceof Backbone.Model) {

                if (model.get('id') && method === 'create') {
                    method = 'update';
                }

                if (method === 'update') {
                    params = {};

                    // if we're specifying attributes to changes
                    // just update those
                    if (options.changes) {
                        params.body = {};
                        for (var attr in options.changes) {
                            params.body[attr] = model.get(attr);
                        }
                    }

                    // update!
                    params[modelConfig.id] = model.get('id');

                    params.body = params.body || model.toJSON();

                    // remove any ids from the body
                    delete params.body.id;
                    delete params.body[modelConfig.id];

                    // change to change the attributes before sending
                    if (modelConfig.beforeUpdate) {
                        params.body = modelConfig.beforeUpdate(params.body);
                    }

                    options.error ? onError = function(e) {
                        options.error(e);
                    } : onError = null;

                    reste[modelConfig.update](params, function(e) {
                        // calls error handler if we have it defined and 201 returned
                        if (e.code > 200) {
                            onError(e);
                        } else {
                            // otherwise pass to success
                            options.success(e);
                        }
                    }, onError);
                }

                if (method === 'read') {

                    if (modelConfig.read) {

                        if (model[modelConfig.id]) {
                            options[modelConfig.id] = model[modelConfig.id];
                        } else if (model.get('id')) {
                            options[modelConfig.id] = model.get('id');
                        }

                        options.error ? onError = function(e) {
                            options.error(e);
                        } : onError = null;

                        reste[modelConfig.read](options, function(e) {

                            if (modelConfig.content) {

                                var result = e[modelConfig.content];

                                if (result.length === 1) {
                                    //result is an array with value as first entry
                                    options.success(result[0]);
                                }
                                else {
                                    //result is not an array
                                    options.success(result);
                                }
                            } else {
                                // calls error handler if we have it defined and 201+ returned
                                if (e.code > 200) {
                                    onError(e);
                                } else {
                                    // otherwise pass to success
                                    options.success(e);
                                }
                            }
                        }, onError);
                    }
                }

                if (method === 'create') {

                    body = model.toJSON();

                    // remove any ids from the body
                    delete body.id;
                    delete body[modelConfig.id];

                    // change to change the attributes before sending
                    if (modelConfig.beforeDelete) {
                        body = modelConfig.beforeDelete(body);
                    }

                    options.error ? onError = function(e) {
                        options.error(e);
                    } : onError = null;

                    reste[modelConfig.create]({
                        body : body
                    }, function(e) {
                        // calls error handler if we have it defined and 201+ returned

                        if (e.code > 200) {
                            onError(e);
                        } else {
                            // otherwise pass to success
                            e.id = e[modelConfig.id];
                            model.set('id', e[modelConfig.id]);
                            options.success(e);
                        }
                    }, onError);
                }

                if (method === 'delete') {

                    body = {};

                    body[modelConfig.id] = model.get('id');
                    body.body = model.toJSON();

                    // change to change the attributes before sending
                    if (modelConfig.beforeCreate) {
                        body.body = modelConfig.beforeCreate(body.body);
                    }

                    options.error ? onError = function(e) {
                        options.error(e);
                    } : onError = null;

                    reste[modelConfig.delete](body, function(e) {
                        // calls error handler if we have it defined and 201+ returned
                        if (e.code > 200) {
                            onError(e);
                        } else {
                            // otherwise pass to success
                            options.success(e);
                        }
                    }, onError);
                }
            }
        };
    }

    return reste;
};

module.exports = main;