/*!
 * Chai - message composition utility
 * Copyright(c) 2012-2013 Jake Luer <jake@alogicalparadox.com>
 * MIT Licensed
 */

/*!
 * Module dependancies
 */

var flag = require('./flag')
  , getActual = require('./getActual')
  , inspect = require('./inspect')
  , objDisplay = require('./objDisplay');

/**
 * ### .getMessage(object, message, negateMessage)
 *
 * Construct the error message based on flags
 * and template tags. Template tags will return
 * a stringified inspection of the object referenced.
 *
 * Messsage template tags:
 * - `#{this}` current asserted object
 * - `#{act}` actual value
 * - `#{exp}` expected value
 *
 * @param {Object} object (constructed Assertion)
 * @param {Arguments} chai.Assertion.prototype.assert arguments
 * @name getMessage
 * @api public
 */

module.exports = function (obj, args) {
  var negate = flag(obj, 'negate')
    , val = flag(obj, 'object')
    , expected = args[3]
    , actual = getActual(obj, args)
    , msg = negate ? args[2] : args[1]
    , flagMsg = flag(obj, 'message');

  msg = msg || '';
  msg = msg
    .replace(/#{this}/g, objDisplay(val))
    .replace(/#{act}/g, objDisplay(actual))
    .replace(/#{exp}/g, objDisplay(expected));

  return flagMsg ? flagMsg + ': ' + msg : msg;
};
