require('require-yaml');
const gulp = require('gulp');
const fs = require('fs-extra');
const exec = require('child_process').exec;
const PluginError = require('plugin-error');
const argv = require('minimist')(process.argv.slice(2));
const log = require('fancy-log');

// Configuration

let isWindows = /^win/.test(process.platform);

if (argv.NODE_ENV)
    process.env.NODE_ENV = argv.NODE_ENV;

let env = process.env.NODE_ENV ? process.env.NODE_ENV : 'development';

let langs = ['es', 'en'];
let srcDir = './front';
let modulesDir = './modules';
let servicesDir = './services';
let modules = require('./modules.yml');

let wpConfig = require('./webpack.config.yml');
let buildDir = wpConfig.buildDir;
let devServerPort = wpConfig.devServerPort;

let nginxDir = `${servicesDir}/nginx`;
let proxyConf = require(`${nginxDir}/config.yml`);
let proxyEnvFile = `${nginxDir}/config.${env}.yml`;

if (fs.existsSync(proxyEnvFile))
    Object.assign(proxyConf, require(proxyEnvFile));

let defaultService = proxyConf.main;
let defaultPort = proxyConf.defaultPort;

// Development

const nginx = gulp.series(nginxStart);
nginx.description = `Starts/restarts the nginx process`;

const localesRoutes = gulp.parallel(locales, routes);
localesRoutes.description = `Builds locales and routes`;

const front = gulp.series(buildClean, gulp.parallel(localesRoutes, watch, webpackDevServer));
front.description = `Starts frontend service`;

const back = gulp.series(dockerStart, backOnly, nginx);
back.description = `Starts backend and database service`;

const defaultTask = gulp.parallel(front, back);
defaultTask.description = `Starts all application services`;

function backOnly(done) {
    let app = require(`./loopback/server/server`);
    app.start(defaultPort);
    app.on('started', done);
}
backOnly.description = `Starts backend service`;

// backend tests

function backendUnitTest() {
    let app = require(`./loopback/server/server`);

    let specFiles = [
        'back/**/*.spec.js',
        'loopback/**/*.spec.js',
        'modules/*/back/**/*.spec.js'
    ];

    const jasmine = require('gulp-jasmine');
    const reporters = require('jasmine-reporters');
    let options = {errorOnFail: false};

    if (argv.junit || argv.j)
        options.reporter = new reporters.JUnitXmlReporter();

    return gulp.src(specFiles)
        .pipe(jasmine(options))
        .on('jasmineDone', function() {
            app.disconnect();
        });
}
backendUnitTest.description = `Runs the backend tests only, can receive args --junit or -j to save reports on a xml file`;

const dockerAndBackTest = gulp.series(docker, backendUnitTest);
dockerAndBackTest.description = `Restarts database and runs the backend tests`;

function backTest(done) {
    const nodemon = require('gulp-nodemon');

    nodemon({
        script: 'node_modules/.bin/gulp',
        args: ['dockerAndBackTest'],
        watch: ['loopback', 'modules/*/back/**', 'back'],
        done: done
    });
}
backTest.description = `Watches for changes in modules to execute backTest task`;

// end to end tests

function e2eOnly() {
    const jasmine = require('gulp-jasmine');

    if (argv.show || argv.s)
        process.env.E2E_SHOW = true;

    return gulp.src('./e2e/tests.js')
        .pipe(jasmine({reporter: 'none'}));
}
e2eOnly.description = `Runs the e2e tests only`;

e2e = gulp.series(docker, e2eOnly);
e2e.description = `Restarts database and runs the e2e tests`;

function smokesOnly() {
    const jasmine = require('gulp-jasmine');
    return gulp.src('./e2e/smokes-tests.js')
        .pipe(jasmine({reporter: 'none'}));
}
smokesOnly.description = `Runs the smokes tests only`;

smokes = gulp.series(docker, smokesOnly);
smokes.description = `Restarts database and runs the smokes tests`;

const clean = gulp.parallel(buildClean, nginxClean);
clean.description = 'Cleans all generated project files';

function install() {
    const install = require('gulp-install');
    const print = require('gulp-print');

    let packageFiles = ['front/package.json', 'print/package.json'];
    return gulp.src(packageFiles)
        .pipe(print(filepath => {
            return `Installing packages in ${filepath}`;
        }))
        .pipe(install({
            npm: ['--no-package-lock']
        }));
}
install.description = `Installs node dependencies in all directories`;

const i = gulp.series(install);
i.description = `Alias for the 'install' task`;

// Deployment

const build = gulp.series(clean, gulp.parallel(localesRoutes, webpack, nginxConf));
build.description = `Generates binaries and configuration files`;

function buildClean() {
    const del = require('del');
    const files = [
        `${buildDir}/*`
    ];
    return del(files, {force: true});
}
buildClean.description = `Cleans all files generated by the 'build' task`;

// Webpack

function webpack(done) {
    const webpackCompile = require('webpack');
    const merge = require('webpack-merge');

    let wpConfig = require('./webpack.config.js');
    wpConfig = merge(wpConfig, {});

    let compiler = webpackCompile(wpConfig);

    compiler.run(function(err, stats) {
        if (err) throw new PluginError('webpack', err);
        log('[webpack]', stats.toString(wpConfig.stats));
        done();
    });
}
webpack.description = `Transpiles application into files`;

function webpackDevServer(done) {
    const webpack = require('webpack');
    const merge = require('webpack-merge');
    const WebpackDevServer = require('webpack-dev-server');

    let wpConfig = require('./webpack.config.js');
    wpConfig = merge(wpConfig, {});

    let devServer = wpConfig.devServer;

    for (let entryName in wpConfig.entry) {
        let entry = wpConfig.entry[entryName];
        let wdsAssets = [`webpack-dev-server/client?http://127.0.0.1:${devServer.port}/`];
        if (Array.isArray(entry))
            wdsAssets = wdsAssets.concat(entry);
        else
            wdsAssets.push(entry);
        wpConfig.entry[entryName] = wdsAssets;
    }

    let compiler = webpack(wpConfig);
    new WebpackDevServer(compiler, wpConfig.devServer)
        .listen(devServer.port, devServer.host, function(err) {
            if (err) throw new PluginError('webpack-dev-server', err);
            // TODO: Keep the server alive or continue?
            done();
        });
}
webpackDevServer.description = `Transpiles application into memory`;

// Locale

let localeFiles = [
    `${srcDir}/**/locale/*.yml`,
    `${modulesDir}/*/front/**/locale/*.yml`
];

/**
 * Mixes all locale files into one JSON file per module and language. It looks
 * recursively in all project directories for locale folders with per language
 * yaml translation files.
 *
 * @return {Stream} The merged gulp streams
 */
function locales() {
    const mergeJson = require('gulp-merge-json');
    const yaml = require('gulp-yaml');
    const merge = require('merge-stream');

    let streams = [];
    let localePaths = [];

    for (let mod of modules)
        localePaths[mod] = `${modulesDir}/${mod}`;

    let baseMods = ['core', 'auth', 'salix'];
    for (let mod of baseMods)
        localePaths[mod] = `${srcDir}/${mod}`;

    for (let mod in localePaths) {
        let path = localePaths[mod];
        for (let lang of langs) {
            let localeFiles = `${path}/**/locale/${lang}.yml`;
            streams.push(gulp.src(localeFiles)
                .pipe(yaml())
                .pipe(mergeJson({fileName: `${lang}.json`}))
                .pipe(gulp.dest(`${buildDir}/locale/${mod}`)));
        }
    }

    return merge(streams);
}
locales.description = `Generates client locale files`;

// Routes

let routeFiles = `${modulesDir}/*/front/routes.json`;

function routes() {
    const concat = require('gulp-concat');
    const wrap = require('gulp-wrap');

    return gulp.src(routeFiles)
        .pipe(concat('routes.js', {newLine: ','}))
        .pipe(wrap('var routes = [<%=contents%>\n];'))
        .pipe(gulp.dest(buildDir));
}
routes.description = 'Merges all module routes file into one file';

// Watch

function watch(done) {
    gulp.watch(routeFiles, gulp.series(routes));
    gulp.watch(localeFiles, gulp.series(locales));
    done();
}
watch.description = `Watches for changes in routes and locale files`;

// Docker

/**
 * Builds the database image and runs a container. It only rebuilds the
 * image when fixtures have been modified or when the day on which the
 * image was built is different to today. Some workarounds have been used
 * to avoid a bug with OverlayFS driver on MacOS.
 */
async function docker() {
    try {
        await execP('docker rm -fv salix-db');
    } catch (e) {}

    let d = new Date();
    let pad = v => v < 10 ? '0' + v : v;
    let stamp = `${d.getFullYear()}-${pad(d.getMonth() + 1)}-${pad(d.getDate())}`;
    await execP(`docker build --build-arg STAMP=${stamp} -t salix-db ./services/db`);

    let runChown = process.platform != 'linux';
    await execP(`docker run --env RUN_CHOWN=${runChown} -d --name salix-db -p 3306:3306 salix-db`);
    if (runChown) await dockerWait();
}
docker.description = `Builds the database image and runs a container`;

/**
 * Does the minium effort to start the database container, if it doesn't exists
 * calls the 'docker' task, if it is started does nothing. Keep in mind that when
 * you do not rebuild the docker you may be using an outdated version of it.
 * See the 'docker' task for more info.
 */
async function dockerStart() {
    let state;
    try {
        let result = await execP('docker container inspect -f "{{json .State}}" salix-db');
        state = JSON.parse(result.stdout);
    } catch (err) {
        return await docker();
    }

    switch (state.Status) {
    case 'running':
        return;
    case 'exited':
        await execP('docker start salix-db');
        await dockerWait();
        return;
    default:
        throw new Error(`Unknown docker status: ${state.Status}`);
    }
}
dockerStart.description = `Starts the database container`;

function dockerWait() {
    return new Promise((resolve, reject) => {
        const mysql = require('mysql2');

        let interval = 100;
        let elapsedTime = 0;
        let maxInterval = 30 * 60 * 1000;

        log('Waiting for MySQL init process...');
        checker();

        async function checker() {
            elapsedTime += interval;
            let state;

            try {
                let result = await execP('docker container inspect -f "{{json .State}}" salix-db');
                state = JSON.parse(result.stdout);
            } catch (err) {
                return reject(new Error(err.message));
            }

            if (state.Status === 'exited')
                return reject(new Error('Docker exited, please see the docker logs for more info'));

            let conn = mysql.createConnection({
                host: 'localhost',
                user: 'root',
                password: 'root'
            });
            conn.on('error', () => {});
            conn.connect(err => {
                conn.destroy();
                if (!err) return resolve();

                if (elapsedTime >= maxInterval)
                    reject(new Error(`MySQL not initialized whithin ${elapsedTime} secs`));
                else
                    setTimeout(checker, interval);
            });
        }
    });
}
dockerWait.description = `Waits until database service is ready`;

// Nginx

let nginxConfFile = 'temp/nginx.conf';
let nginxTemp = `${nginxDir}/temp`;

async function nginxStart() {
    await nginxConf();
    let nginxBin = await nginxGetBin();

    if (isWindows)
        nginxBin = `start /B ${nginxBin}`;

    log(`Application available at http://${proxyConf.host}:${proxyConf.port}/`);
    await execP(`${nginxBin} -c "${nginxConfFile}" -p "${nginxDir}"`);
}
nginxStart.description = `Starts the nginx process`;

async function nginxStop() {
    try {
        let nginxBin = await nginxGetBin();
        await fs.stat(`${nginxTemp}/nginx.pid`);
        await execP(`${nginxBin} -c "${nginxConfFile}" -p "${nginxDir}" -s stop`);
    } catch (e) {}
}
nginxStop.description = `Stops the nginx process`;

/**
 * Generates the nginx configuration file. If NODE_ENV is defined and the
 * 'nginx.[environment].mst' file exists, it is used as a template, otherwise,
 * the 'nginx.mst' template file is used.
 */
async function nginxConf() {
    await nginxStop();
    const mustache = require('mustache');

    if (!await fs.exists(nginxTemp))
        await fs.mkdir(nginxTemp);

    let params = {
        services: modules,
        defaultService: defaultService,
        defaultPort: defaultPort,
        devServerPort: devServerPort,
        port: proxyConf.port,
        host: proxyConf.host
    };

    let confFile = `${nginxDir}/nginx.${env}.mst`;

    if (!await fs.exists(confFile))
        confFile = `${nginxDir}/nginx.mst`;

    let template = await fs.readFile(confFile, 'utf8');
    let nginxConfData = mustache.render(template, params);

    await fs.writeFile(`${nginxTemp}/nginx.conf`, nginxConfData);
}
nginxConf.description = `Generates the nginx configuration file`;

async function nginxClean() {
    await nginxStop();
    const del = require('del');
    return del([`${nginxTemp}/*`], {force: true});
}
nginxClean.description = `Cleans all files generated by nginx`;

async function nginxGetBin() {
    if (isWindows)
        return 'nginx';
    try {
        let nginxBin = '/usr/sbin/nginx';
        await fs.stat(nginxBin);
        return nginxBin;
    } catch (e) {
        return 'nginx';
    }
}

// Helpers

/**
 * Promisified version of exec().
 *
 * @param {String} command The exec command
 * @return {Promise} The promise
 */
function execP(command) {
    return new Promise((resolve, reject) => {
        exec(command, (err, stdout, stderr) => {
            if (err)
                reject(err);
            else {
                resolve({
                    stdout: stdout,
                    stderr: stderr
                });
            }
        });
    });
}

module.exports = {
    default: defaultTask,
    front,
    back,
    backOnly,
    backendUnitTest,
    dockerAndBackTest,
    backTest,
    e2eOnly,
    e2e,
    smokesOnly,
    smokes,
    clean,
    install,
    i,
    build,
    buildClean,
    nginxStart,
    nginx,
    nginxStop,
    nginxConf,
    nginxClean,
    webpack,
    webpackDevServer,
    locales,
    routes,
    localesRoutes,
    watch,
    docker,
    dockerStart,
    dockerWait
};