gistfile1.txt

var gulp = require('gulp');
var sass = require('gulp-sass');
var browserSync = require('browser-sync').create();
var useref = require('gulp-useref');
var uglify = require('gulp-uglify');
var gulpIf = require('gulp-if');
var cssnano = require('gulp-cssnano');
var imagemin = require('gulp-imagemin');
var cache = require('gulp-cache');
var del = require('del');
var runSequence = require('run-sequence');
var nunjucksRender = require('gulp-nunjucks-render');


gulp.task('nunjucksRender', function() {
  return gulp.src('src/pages/**/*.+(html|njk)')
  .pipe(nunjucksRender({
    path: ['src/templates']
  }))
  .pipe(gulp.dest('src'))
});

gulp.task('sass', function(){
  return gulp.src('src/scss/**/*.scss')
    .pipe(sass()) // Converts Sass to CSS with gulp-sass
    .pipe(gulp.dest('src/css'))
    .pipe(browserSync.reload({
      stream: true
    }))
});

gulp.task('watch', ['browserSync', 'sass'], function (){
  gulp.watch('src/scss/**/*.scss', ['sass']); 
  // Reloads the browser whenever HTML or JS files change
  gulp.watch('src/*.html', browserSync.reload); 
  gulp.watch('src/js/**/*.js', browserSync.reload); 
  gulp.watch('src/templates/partials/*.njk', browserSync.reload); 

});

gulp.task('browserSync', function() {
  browserSync.init({
    server: {
      baseDir: 'src'
    },
  })
})

gulp.task('useref', function(){
  return gulp.src('src/*.html')
    .pipe(useref())
    .pipe(gulpIf('*.js', uglify()))
    // Minifies only if it's a CSS file
    .pipe(gulpIf('*.css', cssnano()))
    .pipe(gulp.dest('build'))
});

gulp.task('img', function(){
  return gulp.src('src/img/**/*.+(png|jpg|jpeg|gif|svg)')
  // Caching images that ran through imagemin
  .pipe(cache(imagemin({
      interlaced: true
    })))
  .pipe(gulp.dest('build/img'))
});

gulp.task('clean:build', function() {
  return del.sync('build');
})

gulp.task('build', function (callback) {
  runSequence('clean:build', 
    ['sass', 'useref', 'img'],
    callback
  )
})

gulp.task('default', function (callback) {
  runSequence(['sass','browserSync', 'nunjucksRender', 'watch'],
    callback
  )
})