mail template gulpfile

/**
 * Created by pkosinski on 03.03.2016.
 */
var gulp = require('gulp'),
    sass = require('gulp-sass'),
    del = require('del'),
    runSequence = require('run-sequence'),
    replace = require('gulp-replace'),
    cache = require('gulp-cached'),
    htmlmin = require('gulp-htmlmin'),
    livereload = require('gulp-livereload'),
    premailer = require('gulp-premailer'),
    fileinclude = require('gulp-file-include');

var paths = {
    src: {
        sass: 'sample/sass/**/*.scss',
        css: 'sample/css/**/*.css',
        tmp: 'sample/tmp/**/*.html',
        templates: 'sample/template/**/*.html',
        preview: 'sample/preview/**/*.html',
        partials: 'sample/partials/**/*.html'
    },
    dest: {
        css: 'sample/styles/css',
        tmp: 'sample/tmp',
        preview: 'sample/preview'
    }
};

gulp.task('default', function () {
    gulp.watch([paths.src.templates, paths.src.partials, paths.src.css], ['watch']);
    gulp.watch(paths.src.sass, ['sass']);

    livereload.listen();
});

gulp.task('sass', function () {
    return gulp.src(paths.src.sass)
        .pipe(sass())
        .pipe(gulp.dest(paths.dest.css));
});


gulp.task('includePartials', function () {
    var fileIncludeConf = {
        basepath: '@root',
        context: {
            header: "'partials/header.html'",
            wrapper: "780",
            width: "690",
            grid: "690",
            col: "",
            col2: "345",    // gird cols
            col3: "230",
            col4: "172",
            col2img: "310",
            col3img: "200",
            col4img: "142",
            btnClass: ""
        }
    };

    return gulp.src(paths.src.templates)
        .pipe(fileinclude(fileIncludeConf)).on("error",errLog)
        .pipe(gulp.dest(paths.dest.tmp));
});
gulp.task('includeNonPremailingPartials', function () {
    var fileIncludeConf = {
        basepath: '@root',
        prefix: '##'
    };

    return gulp.src(paths.src.tmp)
        .pipe(fileinclude(fileIncludeConf))
        .pipe(gulp.dest(paths.dest.tmp));
});


gulp.task('clean', function () {
    cache.caches = {};
    return del([paths.dest.preview, paths.dest.tmp]);
});

gulp.task('premailer', function () {

    return gulp.src(paths.src.tmp)
        .pipe(premailer({escape_url_attributes: false}))
        .pipe(replace('%60', '`'))
        .pipe(replace('%5B', '['))
        .pipe(replace('%5D', ']'))
        .pipe(gulp.dest(paths.dest.tmp));
});

gulp.task('minify', function() {
    // https://github.com/kangax/html-minifier
    var htmlMinConfig = {
        collapseWhitespace: true,
        conservativeCollapse: true,
        keepClosingSlash: true,
        removeEmptyAttributes: true,
        preventAttributesEscaping: true,
        caseSensitive: true,
        minifyCSS: true,
        maxLineLength: 76
    };

    return gulp.src(paths.src.tmp)
        .pipe(htmlmin(htmlMinConfig)).on('error', errLog)
        .pipe(gulp.dest(paths.dest.tmp));
});

gulp.task('watch', function(cb) {
    return runSequence('includePartials', 'premailer', 'includeNonPremailingPartials', 'minify', 'updatePreview', cb);
});

gulp.task('updatePreview', function () {

    return gulp.src(paths.src.tmp)
        .pipe(cache('preview'))
        .pipe(gulp.dest(paths.dest.preview))
        .pipe(livereload());
});

/**
 * Creates new mail template previews
 */
gulp.task('build', function(cb) {
    return runSequence('clean', 'includePartials', 'premailer',
        'includeNonPremailingPartials', 'minify', 'updatePreview', cb);
});

function errLog(err) {
    return console.error(err);
}