'use strict';

var diff = require('diff');
var chalk = require('chalk');
var extend = require('extend-shallow');
var Template = require('template');
var Composer = require('composer');
var vfs = require('vinyl-fs');

var stack = require('./lib/stack');
var init = require('./lib/init');

/**
 * Initialize `Verb`
 *
 * @param {Object} `context`
 * @api private
 */

function Verb() {
  Template.apply(this, arguments);
  Composer.call(this, 'verb');
  init(this);
}

extend(Verb.prototype, Composer.prototype);
Template.extend(Verb.prototype);

/**
 * Set application defaults that may be overridden by the user.
 * This is a temporary method and should not be used.
 *
 * @param {String} `key`
 * @param {*} `value`
 * @api private
 */

Verb.prototype.defaults = function(key/*, value*/) {
  if (typeof key === 'object') {
    arguments[0] = {defaults: arguments[0]};
  } else {
    arguments[0] = 'defaults.' + arguments[0];
  }
  this.option.apply(this, arguments);
  return this;
};

/**
 * Glob patterns or filepaths to source files.
 *
 * ```js
 * verb.src('src/*.hbs', {layout: 'default'})
 * ```
 *
 * @param {String|Array} `glob` Glob patterns or file paths to source files.
 * @param {Object} `options` Options or locals to merge into the context and/or pass to `src` plugins
 * @api public
 */

Verb.prototype.src = function(glob, opts) {
  return stack.src(this, glob, opts);
};

/**
 * Specify a destination for processed files.
 *
 * ```js
 * verb.dest('dist')
 * ```
 *
 * @param {String|Function} `dest` File path or rename function.
 * @param {Object} `options` Options and locals to pass to `dest` plugins
 * @api public
 */

Verb.prototype.dest = function(dest, opts) {
  return stack.dest(this, dest, opts);
};

/**
 * Copy a `glob` of files to the specified `dest`.
 *
 * ```js
 * verb.task('assets', function() {
 *   verb.copy('assets/**', 'dist');
 * });
 * ```
 *
 * @param  {String|Array} `glob`
 * @param  {String|Function} `dest`
 * @return {Stream} Stream, to continue processing if necessary.
 * @api public
 */

Verb.prototype.copy = function(glob, dest, opts) {
  return vfs.src(glob, opts).pipe(vfs.dest(dest, opts));
};

/**
 * Display a visual representation of the difference between
 * two objects or strings.
 *
 * ```js
 * var doc = verb.views.docs['foo.md'];
 * verb.render(doc, function(err, content) {
 *   verb.diff(doc.orig, content);
 * });
 * ```
 *
 * @param {Object|String} `a`
 * @param {Object|String} `b`
 * @param {String} `methodName` Optionally pass a [jsdiff] method name to use. The default is `diffJson`
 * @api public
 */

Verb.prototype.diff = function(a, b, method) {
  method = method || 'diffJson';
  a = a || this.env;
  b = b || this.cache.data;
  diff[method](a, b).forEach(function (res) {
    var color = chalk.gray;
    if (res.added) {
      color = chalk.green;
    }
    if (res.removed) {
      color = chalk.red;
    }
    process.stderr.write(color(res.value));
  });
  console.log('\n');
};

/**
 * Expose `verb.Verb`
 */

Verb.prototype.Verb = Verb;

/**
 * Expose `verb`
 */

module.exports = new Verb();