// Gulp Tools
var gulp = require("gulp");
var webpackStream = require("webpack-stream");
var dtsBundle = require('dts-bundle');
var merge2 = require("merge2");
var through = require('through2');
var path = require("path");
var rename = require("gulp-rename");

// Gulp Helpers
var processDeclaration = require('../helpers/gulp-processModuleDeclarationToNamespace');
var addModuleExports = require("../helpers/gulp-addModuleExports");

// Import Build Config
var config = require("../config.json");

/**
 * Build the viewer
 */
var buildViewerLibrary = function(library, settings) {
    const sequence = [];
    var outputDirectory = config.build.outputDirectory + settings.build.distOutputDirectory;

    settings.build.outputs.forEach(out => {
        let wpConfig = require(settings.build.webpack);
        if (!out.minified) {
            wpConfig.mode = "development";
        }

        let wpBuild = webpackStream(wpConfig, require("webpack"));

        //shoud dtsBundle create the declaration?
        if (settings.build.dtsBundle) {
            let event = wpBuild
                .pipe(through.obj(function(file, enc, cb) {
                    // only declaration files
                    const isdts = /\.d\.ts$/.test(file.path);
                    if (isdts) this.push(file);
                    cb();
                }))
                .pipe(gulp.dest(outputDirectory));
            // dts-bundle does NOT support (gulp) streams, so files have to be saved and reloaded, 
            // until I fix it
            event.on("end", function() {
                // create the file
                dtsBundle.bundle(settings.build.dtsBundle);
                // process the declaration
                let fileLocation = path.join(path.dirname(settings.build.dtsBundle.main), settings.build.dtsBundle.out);
                processDeclaration(fileLocation, settings.build.processDeclaration);
            });
        }

        let build = wpBuild
            .pipe(through.obj(function(file, enc, cb) {
                // only pipe js files
                const isJs = /\.js$/.test(file.path);
                if (isJs) this.push(file);
                cb();
            }))
            .pipe(addModuleExports(library.moduleDeclaration, { subModule: false, extendsRoot: false, externalUsingBabylon: true, noBabylonInit: true }));

        function processDestination(dest) {
            var outputDirectory = config.build.outputDirectory + dest.outputDirectory;
            build = build
                .pipe(rename(dest.filename))
                .pipe(gulp.dest(outputDirectory));

            if (dest.addBabylonDeclaration) {
                // include the babylon declaration
                if (dest.addBabylonDeclaration === true) {
                    dest.addBabylonDeclaration = [config.build.declarationFilename];
                }
                var decsToAdd = dest.addBabylonDeclaration.map(function(dec) {
                    return config.build.outputDirectory + '/' + dec;
                });
                sequence.unshift(gulp.src(decsToAdd)
                    .pipe(rename(function(path) {
                        path.dirname = '';
                    }))
                    .pipe(gulp.dest(outputDirectory)))
            }
        }

        out.destinations.forEach(dest => {
            processDestination(dest);
        });

        sequence.push(build);

    });

    return merge2(sequence);
}

/**
 * Dynamic viewer module creation In Serie for WebPack leaks.
 */
function buildViewerLibraries(settings) {
    var tasks = settings.libraries.map(function(library) {
        var build = function(cb) {
            return buildViewerLibrary(library, settings);
        }
        return build;
    });

    return gulp.series.apply(this, tasks);
}


/**
 * Dynamic viewer module creation.
 */
config.viewerModules.map(function(module) {
    var settings = config[module];

    // Build the libraries.
    gulp.task(module, buildViewerLibraries(settings));
});