/*********************************************************
 *  Simple Node.js module for using the Bing Search API  *
 *********************************************************/

// Require dependencies
var request = require('request'),
    url = require('url'),
    _ = require('underscore'),
    qs = require('querystring');

/**
 * @param {Object} options  Options to all Bing calls, allows overriding of
 *        rootUri, accKey (Bing API key), userAgent, reqTimeout
 * @returns {Bing}
 * @constructor
 */
var Bing = function (options) {

    if (!(this instanceof Bing)) return new Bing(options);

    var defaults = {

        //Bing Search API URI
        rootUri: "https://api.datamarket.azure.com/Bing/Search/v1/",

        //Account Key
        accKey: null,

        //Bing UserAgent
        userAgent: 'Bing Search Client for Node.js',

        //Request Timeout
        reqTimeout: 5000,

        // Number of results (limited to 50 by API)
        top: 50,

        // Number of skipped results (pagination)
        skip: 0

    };

    //merge options passed in with defaults
    this.options = _.extend(defaults, options);

    this.searchVertical = function (query, vertical, options, callback) {
        if (typeof options === 'function') {
            callback = options;
        }
        if (typeof callback != 'function') {
            throw "Error: Callback function required!";
        }

        // Create a copy of the options, to avoid permanent overwrites
        var opts = JSON.parse(JSON.stringify(this.options));

        if (typeof options === 'object') {
            _.extend(opts, options);
        }

        var reqUri = opts.rootUri + vertical + "?$format=json&" + qs.stringify({
            "Query": "'" + query + "'"
        }) + "&$top=" + opts.top + "&$skip=" + opts.skip + (opts.sources ? "&Sources=%27" + opts.sources + "%27" : '') + (opts.newssortby ? "&NewsSortBy=%27" + opts.newssortby + "%27" : '') + (opts.newscategory ? "&NewsCategory=%27" + opts.newscategory + "%27" : '') + (opts.newslocationoverride ? "&NewsLocationOverride=%27" + opts.newslocationoverride + "%27" : '') + (opts.market ? "&Market=%27" + opts.market + "%27" : '') + (opts.adult ? "&Adult=%27" + opts.adult + "%27" : '') + (opts.imagefilters ? '&' + qs.stringify({
            "ImageFilters": "'" + opts.imagefilters + "'"
        }) : '') + (opts.videofilters ? '&' + qs.stringify({
            "VideoFilters": "'" + opts.videofilters + "'"
        }) : '');

        request({
            uri: reqUri,
            method: opts.method || "GET",
            headers: {
                "User-Agent": opts.userAgent
            },
            auth: {
                user: opts.accKey,
                pass: opts.accKey
            },
            timeout: opts.reqTimeout

        }, function (err, res, body) {

            if (res && res.statusCode !== 200) {
                err = new Error(body);
            } else {

                // Parse body, if body
                body = typeof body === 'string' ? JSON.parse(body) : body;
            }

            callback(err, res, body);
        });
    };

};


/**
 * @callback requestCallback
 * @param {String} error     Error evaluates to true when an error has occurred.
 * @param {Object} response  Response object from the Bing call.
 * @param {Object} body      JSON of the response.
 */


/**
 * Performs a Bing search in the Web vertical.
 *
 * @param {String} query              Query term to search for.
 *
 * @param {Object} options            Options to command, allows overriding
 *                                    of rootUri, accKey (Bing API key),
 *                                    userAgent, reqTimeout, top, skip
 *
 * @param {requestCallback} callback  Callback called with (potentially
 *                                    json-parsed) response.
 *
 * @function
 */
Bing.prototype.web = function (query, options, callback) {
    this.searchVertical(query, "Web", options, callback);
};

// Alias Bing.search to Bing.web
// Note: Keep this for compatibility with older versions
Bing.prototype.search = Bing.prototype.web;


/**
 * Performs a Bing search in the Composite vertical.
 *
 * @param {String} query              Query term to search for.
 *
 * @param {Object} options            Options to command, allows overriding
 *                                    of rootUri, accKey (Bing API key),
 *                                    userAgent, reqTimeout, top, skip,
 *
 * @param {requestCallback} callback  Callback called with (potentially
 *                                    json-parsed) response.
 * @function
 */
Bing.prototype.composite = function (query, options, callback) {
    this.searchVertical(query, "Composite", options, callback);
};

/**
 * Performs a Bing search in the News vertical.
 *
 * @param {String} query              Query term to search for.
 *
 * @param {Object} options            Options to command, allows overriding
 *                                    of rootUri, accKey (Bing API key),
 *                                    userAgent, reqTimeout, top, skip,
 *
 * @param {requestCallback} callback  Callback called with (potentially
 *                                    json-parsed) response.
 * @function
 */
Bing.prototype.news = function (query, options, callback) {
    this.searchVertical(query, "News", options, callback);
};

/**
 * Performs a Bing search in the Video vertical.
 *
 * @param {String} query              Query term to search for.
 *
 * @param {Object} options            Options to command, allows overriding
 *                                    of rootUri, accKey (Bing API key),
 *                                    userAgent, reqTimeout, top, skip,
 *
 * @param {requestCallback} callback  Callback called with (potentially
 *                                    json-parsed) response.
 * @function
 */
Bing.prototype.video = function (query, options, callback) {
    if (options && typeof options === 'object' && options.videofilters && typeof options.videofilters === 'object') {
        var filterQuery = '';
        var filters = Object.keys(options.videofilters);
        filters.map(function (key, i) {
            filterQuery += capitalizeFirstLetter(key) + ':';
            filterQuery += capitalizeFirstLetter(options.videofilters[key]);
            if (i < filters.length - 1)
                filterQuery += '+';
        });
        options.videofilters = filterQuery;
    }
    this.searchVertical(query, "Video", options, callback);
};



/**
 * Performs a Bing search in the Images vertical.
 *
 * @param {String} query              Query term to search for.
 *
 * @param {Object} options            Options to command, allows overriding of
 *                                    rootUri, accKey (Bing API key),
 *                                    userAgent, reqTimeout, top, skip,
 *                                    imagefilters
 *
 * @param {requestCallback} callback  Callback called with (potentially
 *                                    json-parsed) response.
 * @function
 */
Bing.prototype.images = function (query, options, callback) {
    if (options && typeof options === 'object' && options.imagefilters && typeof options.imagefilters === 'object') {
        var filterQuery = '';
        var filters = Object.keys(options.imagefilters);
        filters.map(function (key, i) {
            filterQuery += capitalizeFirstLetter(key) + ':';
            filterQuery += capitalizeFirstLetter(options.imagefilters[key]);
            if (i < filters.length - 1)
                filterQuery += '+';
        });
        options.imagefilters = filterQuery;
    }
    this.searchVertical(query, "Image", options, callback);
};

function capitalizeFirstLetter(s) {
    return s.charAt(0).toUpperCase() + s.slice(1);
}

module.exports = Bing;