const config = require('../config.json');
const logger = require('./logger.js');
const api = require('./api.js')
const constants = require('./constants.js');
const modep = require('./modep.js');
const http = require('http');

var server;

function start() {
    return new Promise(function (resolve, reject) {
        if (!server) {
            server = http.createServer();
        }
        server.listen(config.server.port, config.server.listen).on('listening', function () {
            logger.debug('server listening on ' + config.server.listen + ':' + config.server.port + '...');
            handleRequests();
        });
    });
}

function handleRequests() {
    server.on('request', function (request, response) {
        logger.request(request);
        if (request.url.endsWith('/')) {
            request.url = request.url.substring(0, request.url.length - 1);
        }
        var endpoint = api.getEndpoints().get(request.url);
        if (!endpoint) {
            var msg = 'endpoint \'' + request.url + '\' not defined';
            response.writeHead(501);
            response.end(msg);
            logger.debug(msg);
            return;
        }
        if (!endpoint.types.includes(request.method)) {
            var msg = 'endpoint \'' + request.url + '\' does not support ' + request.method + ' requests';
            response.writeHead(405);
            response.end(msg);
            logger.debug(msg);
            return;
        }
        if (request.method == constants.HTTP_GET) {
            handleGET(endpoint)
                .then(function (result) {
                    response.writeHead(200);
                    response.end(result);
                })
                .catch(function (err, code) {
                    if (!code) {
                        code = 500;
                    }
                    response.writeHead(code);
                    response.end(err);
                });
            return;
        }
        if (request.method == constants.HTTP_POST) {
            handlePOST(request, response)
                .then(function (result) {
                    response.writeHead(200);
                    response.end(result);
                })
                .catch(function (err, code) {
                    if (!code) {
                        code = 500;
                    }
                    response.writeHead(code);
                    response.end(err);
                });
            return;
        }
        var msg = 'endpoint \'' + request.url + '\' does not have any handlers for ' + request.method + ' requests';
        response.writeHead(405);
        response.end(msg);
        logger.debug(msg);
    });
}

function handleGET(endpoint) {
    return new Promise(function (resolve, reject) {
        if (!endpoint.method) {
            return reject('error: no method defined for endpoint \'' + endpoint.url + '\'');
        }
        endpoint.method(endpoint.args)
            .then(function (data) {
                return resolve(JSON.stringify(data))
            })
            .catch(reject);
    });
}

function handlePOST(request, response) {
    return new Promise(function (resolve, reject) {
        if (request.url.startsWith(constants.API_PEDALS)) {
            handlePOSTPedals(request)
                .then(resolve)
                .catch(reject);
            return;
        }
        if (request.url.startsWith(constants.API_PEDALBOARDS)) {
            handlePOSTPedalboards(request)
                .then(resolve)
                .catch(reject);
            return;
        }
        var msg = 'endpoint \'' + request.url + '\' is not yet implemented for ' + request.method + ' requests';
        response.writeHead(405);
        response.end(msg);
    });
}

function getPOSTParams(request) {
    return new Promise(function (resolve, reject) {
        var params = "";
        request.on("data", function (data) {
            params += data;
        });
        request.on("end", function () {
            return resolve(new URLSearchParams(params));
        });
    });
}

function handlePOSTPedals(request) {
    return new Promise(function (resolve, reject) {
        getPOSTParams(request)
            .then(function (params) {
                var pedalId = request.url.substring(request.url.lastIndexOf('/') + 1);
                var controlId = params.get('id');
                if (controlId == undefined) {
                    reject('error: could not handle POST - missing parameter \'id\'', 400)
                }
                var value = params.get('value');
                if (value == undefined) {
                    reject('error: could not handle POST - missing parameter \'value\'', 400)
                }
                modep.getPedalControlById(pedalId, controlId)
                    .then(function (control) {
                        modep.sendValueToControl(value, control);
                    })
                    .then(resolve)
                    .catch(reject);
            })
            .catch(reject);
    });
}

function handlePOSTPedalboards(request) {
    return new Promise(function (resolve, reject) {
        modep.setPedalboardById(request.url.substring(request.url.lastIndexOf('/') + 1))
            .then(resolve)
            .catch(reject);
    });
}

module.exports = {
    start
}