const Promise = require('bluebird');
const queryString = require('qs');
const xml2js = require('xml2js').parseString;

const errors = require('../errors')
    ,AppError = errors.AppError
    ,MalResultError = errors.MalResultError;

/** Random tools that have nowhere else to go */
export class Tools {
    constructor() {
    }

    /**
     * [getJSONParser pick the approriate JSON parser based on the content-type, dafault to dummy parser (return data as its)]
     * @type {[type]}
     */
    public getJSONParser = (contentType, cb = undefined) => {
        const my = this;
        return new Promise(function (resolve, reject) {
            let parser = my.defaultParser;
            
            if(!contentType) return reject(new AppError("No Content Type"));

            if(contentType.indexOf("text/xml") > -1)
                parser = my.xmlJSONParser;
             else if(contentType.indexOf("application/json") > -1)
                 parser = my.jsonParser;
            else if(contentType.indexOf("application/x-www-form-urlencoded") > -1)
                parser = my.formUrlEncodedJSONParser;

            return resolve(parser);
        }).nodeify(cb);
    }

    /**
     * [defaultParser default parsing data toString]
     * @type {[type]}
     */
    private defaultParser = (data, cb = undefined) => {
        return new Promise((resolve, reject) => {
            try{
                const parsedData = data.toString();
                return resolve(parsedData);
            }catch(err){
                return reject(new MalResultError("Unable to parse results: " + err.mesage));
            }
        }).nodeify(cb); 
    }
    /**
     * [xmlJSONParser parse JSON for content-type text/xml]
     * @return Promise resolving JSON parsed data
     *  or reject with AppError MalResult when fail to parse
     *  Support callback fallback
     */
    private xmlJSONParser = (data, cb = undefined) => {

        return new Promise((resolve, reject) => {
            xml2js(data, function (err, finalVal) {
                if(err) {
                    return reject(new MalResultError("Unable to parse results: " + err.mesage));
                }
                resolve(finalVal);
            })
        }).nodeify(cb);     
    }

    /**
     * [jsonParser parse JSON for content-type application/json]
     * @return Promise resolving JSON parsed data
     *  or reject with AppError MalResult when fail to parse
     *  Support callback fallback
     */
    private jsonParser = (data, cb = undefined) => {
        return new Promise((resolve, reject) => {
            try{
                const parsedData = JSON.parse(data)
                return resolve(parsedData);
            }catch(err){
                return reject(new MalResultError("Unable to parse results: " + err.mesage));
            }
        }).nodeify(cb);
    }

    /**
     * [formUrlEncodedJSONParser parse JSON for content-type application/x-www-form-urlencoded]
     * @return Promise resolving JSON parsed data
     *  or reject with AppError MalResult when fail to parse
     *  Support callback fallback
     */
    private formUrlEncodedJSONParser = (data, cb = undefined) => {
        return new Promise((resolve, reject) => {
            try{
                const parsedData = queryString.parse(data)
                return resolve(parsedData);
            }catch(err){
                return reject(new MalResultError("Unable to parse results: " + err.mesage));
            }
        }).nodeify(cb);
    }

}