/*!
 * router
 * Copyright(c) 2013 Roman Shtylman
 * Copyright(c) 2014 Douglas Christopher Wilson
 * MIT Licensed
 */

'use strict'

/**
 * Module dependencies.
 * @private
 */

var flatten = require('array-flatten').flatten
var Layer = require('./layer')
var methods = require('methods')

/**
 * Module variables.
 * @private
 */

var slice = Array.prototype.slice

/**
 * Expose `Route`.
 */

module.exports = Route

/**
 * Initialize `Route` with the given `path`,
 *
 * @param {String} path
 * @api private
 */

function Route (path) {
  this.path = path
  this.stack = []

  // route handlers for various http methods
  this.methods = Object.create(null)
}

/**
 * @private
 */

Route.prototype._handlesMethod = function _handlesMethod (method) {
  if (this.methods._all) {
    return true
  }

  // normalize name
  var name = method.toLowerCase()

  if (name === 'head' && !this.methods.head) {
    name = 'get'
  }

  return Boolean(this.methods[name])
}

/**
 * @return {array} supported HTTP methods
 * @private
 */

Route.prototype._methods = function _methods () {
  var methods = Object.keys(this.methods)

  // append automatic head
  if (this.methods.get && !this.methods.head) {
    methods.push('head')
  }

  for (var i = 0; i < methods.length; i++) {
    // make upper case
    methods[i] = methods[i].toUpperCase()
  }

  return methods
}

/**
 * dispatch req, res into this route
 *
 * @private
 */

Route.prototype.dispatch = function dispatch (req, res, done) {
  var idx = 0
  var stack = this.stack
  if (stack.length === 0) {
    return done()
  }

  var method = req.method.toLowerCase()
  if (method === 'head' && !this.methods.head) {
    method = 'get'
  }

  req.route = this

  next()

  function next (err) {
    // signal to exit route
    if (err && err === 'route') {
      return done()
    }

    // signal to exit router
    if (err && err === 'router') {
      return done(err)
    }

    // no more matching layers
    if (idx >= stack.length) {
      return done(err)
    }

    var layer
    var match

    // find next matching layer
    while (match !== true && idx < stack.length) {
      layer = stack[idx++]
      match = !layer.method || layer.method === method
    }

    // no match
    if (match !== true) {
      return done(err)
    }

    if (err) {
      layer.handleError(err, req, res, next)
    } else {
      layer.handleRequest(req, res, next)
    }
  }
}

/**
 * Add a handler for all HTTP verbs to this route.
 *
 * Behaves just like middleware and can respond or call `next`
 * to continue processing.
 *
 * You can use multiple `.all` call to add multiple handlers.
 *
 *   function check_something(req, res, next){
 *     next()
 *   }
 *
 *   function validate_user(req, res, next){
 *     next()
 *   }
 *
 *   route
 *   .all(validate_user)
 *   .all(check_something)
 *   .get(function(req, res, next){
 *     res.send('hello world')
 *   })
 *
 * @param {array|function} handler
 * @return {Route} for chaining
 * @api public
 */

Route.prototype.all = function all (handler) {
  var callbacks = flatten(slice.call(arguments))

  if (callbacks.length === 0) {
    throw new TypeError('argument handler is required')
  }

  for (var i = 0; i < callbacks.length; i++) {
    var fn = callbacks[i]

    if (typeof fn !== 'function') {
      throw new TypeError('argument handler must be a function')
    }

    var layer = Layer('/', {}, fn)
    layer.method = undefined

    this.methods._all = true
    this.stack.push(layer)
  }

  return this
}

methods.forEach(function (method) {
  Route.prototype[method] = function (handler) {
    var callbacks = flatten(slice.call(arguments))

    if (callbacks.length === 0) {
      throw new TypeError('argument handler is required')
    }

    for (var i = 0; i < callbacks.length; i++) {
      var fn = callbacks[i]

      if (typeof fn !== 'function') {
        throw new TypeError('argument handler must be a function')
      }

      var layer = Layer('/', {}, fn)
      layer.method = method

      this.methods[method] = true
      this.stack.push(layer)
    }

    return this
  }
})