var _ = require('../util')
var transition = require('../transition')

/**
 * Append instance to target
 *
 * @param {Node} target
 * @param {Function} [cb]
 * @param {Boolean} [withTransition] - defaults to true
 */

exports.$appendTo = function (target, cb, withTransition) {
  return insert(
    this, target, cb, withTransition,
    append, transition.append
  )
}

/**
 * Prepend instance to target
 *
 * @param {Node} target
 * @param {Function} [cb]
 * @param {Boolean} [withTransition] - defaults to true
 */

exports.$prependTo = function (target, cb, withTransition) {
  target = query(target)
  if (target.hasChildNodes()) {
    this.$before(target.firstChild, cb, withTransition)
  } else {
    this.$appendTo(target, cb, withTransition)
  }
  return this
}

/**
 * Insert instance before target
 *
 * @param {Node} target
 * @param {Function} [cb]
 * @param {Boolean} [withTransition] - defaults to true
 */

exports.$before = function (target, cb, withTransition) {
  return insert(
    this, target, cb, withTransition,
    before, transition.before
  )
}

/**
 * Insert instance after target
 *
 * @param {Node} target
 * @param {Function} [cb]
 * @param {Boolean} [withTransition] - defaults to true
 */

exports.$after = function (target, cb, withTransition) {
  target = query(target)
  if (target.nextSibling) {
    this.$before(target.nextSibling, cb, withTransition)
  } else {
    this.$appendTo(target.parentNode, cb, withTransition)
  }
  return this
}

/**
 * Remove instance from DOM
 *
 * @param {Function} [cb]
 * @param {Boolean} [withTransition] - defaults to true
 */

exports.$remove = function (cb, withTransition) {
  var inDoc = this._isAttached && _.inDoc(this.$el)
  // if we are not in document, no need to check
  // for transitions
  if (!inDoc) withTransition = false
  var op
  var self = this
  var realCb = function () {
    if (inDoc) self._callHook('detached')
    if (cb) cb()
  }
  if (
    this._isBlock &&
    !this._blockFragment.hasChildNodes()
  ) {
    op = withTransition === false
      ? append
      : transition.removeThenAppend
    blockOp(this, this._blockFragment, op, realCb)
  } else {
    op = withTransition === false
      ? remove
      : transition.remove
    op(this.$el, this, realCb)
  }
  return this
}

/**
 * Shared DOM insertion function.
 *
 * @param {Vue} vm
 * @param {Element} target
 * @param {Function} [cb]
 * @param {Boolean} [withTransition]
 * @param {Function} op1 - op for non-transition insert
 * @param {Function} op2 - op for transition insert
 * @return vm
 */

function insert (vm, target, cb, withTransition, op1, op2) {
  target = query(target)
  var targetIsDetached = !_.inDoc(target)
  var op = withTransition === false || targetIsDetached
    ? op1
    : op2
  var shouldCallHook =
    !targetIsDetached &&
    !vm._isAttached &&
    !_.inDoc(vm.$el)
  if (vm._isBlock) {
    blockOp(vm, target, op, cb)
  } else {
    op(vm.$el, target, vm, cb)
  }
  if (shouldCallHook) {
    vm._callHook('attached')
  }
  return vm
}

/**
 * Execute a transition operation on a block instance,
 * iterating through all its block nodes.
 *
 * @param {Vue} vm
 * @param {Node} target
 * @param {Function} op
 * @param {Function} cb
 */

function blockOp (vm, target, op, cb) {
  var current = vm._blockStart
  var end = vm._blockEnd
  var next
  while (next !== end) {
    next = current.nextSibling
    op(current, target, vm)
    current = next
  }
  op(end, target, vm, cb)
}

/**
 * Check for selectors
 *
 * @param {String|Element} el
 */

function query (el) {
  return typeof el === 'string'
    ? document.querySelector(el)
    : el
}

/**
 * Append operation that takes a callback.
 *
 * @param {Node} el
 * @param {Node} target
 * @param {Vue} vm - unused
 * @param {Function} [cb]
 */

function append (el, target, vm, cb) {
  target.appendChild(el)
  if (cb) cb()
}

/**
 * InsertBefore operation that takes a callback.
 *
 * @param {Node} el
 * @param {Node} target
 * @param {Vue} vm - unused
 * @param {Function} [cb]
 */

function before (el, target, vm, cb) {
  _.before(el, target)
  if (cb) cb()
}

/**
 * Remove operation that takes a callback.
 *
 * @param {Node} el
 * @param {Vue} vm - unused
 * @param {Function} [cb]
 */

function remove (el, vm, cb) {
  _.remove(el)
  if (cb) cb()
}