// Put this file to your FunScript output folder.
var gulp = require('gulp'),
    concat = require('gulp-concat'),
    uglify = require('gulp-uglify'),
    sourcemaps = require('gulp-sourcemaps');

var jsfile = {
    targetPath: '',
    //This is your FunScript-generated .js-file:
    sources: ['generated.js']
};

function minifyJs() {
    return gulp.src(jsfile.sources)
        .pipe(sourcemaps.init())
        .pipe(concat('/generated.min.js'))
        .pipe(uglify())
        .pipe(sourcemaps.write('/.'))
        .pipe(gulp.dest(jsfile.targetPath));
}

// If you call this from f-sharp-script, use this task
gulp.task('minifyJs', minifyJs);

// Or...
// npm install --save-dev gulp gulp-concat gulp-uglify gulp-sourcemaps

// If you just run "gulp" from command-line:
// Gulp monitors modifications of this generated.js -file (defined in jsfile.sources) and minifies it on the fly
gulp.task('default', function () {
    gulp.watch(jsfile.sources, ['minifyJs']);
});

// This is just optional helper if you would like to run Gulp from the FunScript.
let private dir file = Path.Combine(System.Environment.CurrentDirectory, file)
let private execute (cmd,parameter) = System.Diagnostics.Process.Start(cmd, parameter).WaitForExit()    

let writeTempFile code =
    let generatedTemp = dir "generated.js"
    if File.Exists generatedTemp then
        File.Delete generatedTemp
    File.WriteAllText(generatedTemp, code)
    generatedTemp
    
let installGulpComponents path = 
    let nodePath = @"c:\Program Files\nodejs\npm.cmd"
    let install = nodePath, "install --save-dev gulp gulp-concat gulp-uglify gulp-sourcemaps"
    execute install

let minify file = 
    let gulpPath = dir @"node_modules\.bin\gulp.cmd"
    if not <| File.Exists(gulpPath) then
        installGulpComponents gulpPath
    
    let minifiedTemp = dir "generated.min.js"
    if File.Exists minifiedTemp then 
        File.Delete minifiedTemp

    let gulpTask = "minifyJs";
    execute (gulpPath,gulpTask)
    let result = minifiedTemp |> File.ReadAllText
    result

let minified = 
    let temp = writeTempFile code
    minify temp