/**
 * minify all files matched by given glob pattern through terser. Requires `glob` to be installed:
 *
 * npm i glob --save-dev
 *
 * Place the scripts in your projects scripts folder, then add it to your package.json's scripts like this
 *
 * "mterser": "node scripts/mterser.js --glob dist/umd/*.js --compress --mangle --comments false",
 *
 * and run it by calling `npm run mterser`. A `terser` npm script should also be available, see `--terser-cmd` below.
 *
 * Options
 *
 * --glob       required    glob pattern to match source files
 * --terser-cmd optional    defaults to `npm run terser`. The npm script should exist and simple call "terser".
 * --dryrun     optional    Will only display the terser commands that are generated
 * --outdir     optional    When given, this is the folder that the generated files are placed in
 *
 * By default the minified filenames have `.min` inserted before the final `.js` extension. To change that behaviour,
 * modify the minifiedFilename and isFileMinified functions below.
 *
 */

let terserOptions = [],
    globPattern,
    outDir = null,
    dryRun = false,
    terserCommand = 'npm run terser';


const glob = require('glob'),
    {exec} = require('child_process'),
    terserOptionShortCuts = {
        "-V": "--version",
        "-p": "--parse",
        "-c": "--compress",
        "-m": "--mangle",
        "-f": "--format",
        "-o": "--output",
        "-d": "--define",
        "-e": "--enclose"
    },
    expandOptionName = option => option in terserOptionShortCuts ? terserOptionShortCuts[option] : option,
    isOption = string => string.slice(0, 2) === '--',
    type = string => /^true|false$/.test(string) ? string === 'true' : /^\d+$/.test(string) ? parseInt(string, 10) : string,
    minifiedFilename = filename => filename.replace(/\.js$/, '.min.js'),
    isFileMinified = filename => /\.min\.js$/.test(filename),
    args = process.argv.slice(2),
    terminator = '_____END_____';
args.push(terminator);

args.reduce((previous, current) => {
    if (previous && isOption(expandOptionName(previous))) {
        const option = expandOptionName(previous);

        if (option === '--glob') {
            globPattern = current;
        } else if (option === '--outdir') {
            outDir = current;
        } else if (option === '--terser-cmd') {
            terserCommand = current;
        } else if (option === '--dryrun') {
            dryRun = true;
        } else {
            terserOptions.push(previous);
            if (!isOption(expandOptionName(current)) && current !== terminator) {
                terserOptions.push(type(current));
            }
        }
    }
    return current;
}, null);

if (dryRun) {
    console.log('DRY RUN:');
}

glob(globPattern, {}, (error, files) => {
    if (error) {
        return console.log(`glob error : ${error}`);
    }
    files.forEach(file => {
        let input = file,
            output = minifiedFilename(file),
            options = [...terserOptions];
        if (outDir) {
            output = (outDir + '/' + output.split('/').pop()).replace(/\/{2,}/g, '/');
        }
        if (isFileMinified(file)) {
            return console.log(`skipping: ${file}`);
        }
        options.unshift(input);
        options.unshift('--');
        options.unshift(terserCommand);
        options.push('--output');
        options.push(output);
        if (dryRun) {
            return console.log(options.join(' '));
        }
        exec(options.join(' '));
    });
});