var cledit = require('./cleditCore')

function SelectionMgr(editor) {
  var debounce = cledit.Utils.debounce
  var contentElt = editor.$contentElt
  var scrollElt = editor.$scrollElt
  cledit.Utils.createEventHooks(this)

  var self = this
  var lastSelectionStart = 0
  var lastSelectionEnd = 0
  this.selectionStart = 0
  this.selectionEnd = 0
  this.cursorCoordinates = {}

  this.findContainer = function (offset) {
    var result = cledit.Utils.findContainer(contentElt, offset)
    if (result.container.nodeValue === '\n') {
      var hdLfElt = result.container.parentNode
      if (hdLfElt.className === 'hd-lf' && hdLfElt.previousSibling && hdLfElt.previousSibling.tagName === 'BR') {
        result.container = hdLfElt.parentNode
        result.offsetInContainer = Array.prototype.indexOf.call(result.container.childNodes, result.offsetInContainer === 0 ? hdLfElt.previousSibling : hdLfElt)
      }
    }
    return result
  }

  this.createRange = function (start, end) {
    var range = editor.$document.createRange()
    if (start === end) {
      end = start = isNaN(start) ? start : this.findContainer(start < 0 ? 0 : start)
    } else {
      start = isNaN(start) ? start : this.findContainer(start < 0 ? 0 : start)
      end = isNaN(end) ? end : this.findContainer(end < 0 ? 0 : end)
    }
    range.setStart(start.container, start.offsetInContainer)
    range.setEnd(end.container, end.offsetInContainer)
    return range
  }

  var adjustScroll
  var debouncedUpdateCursorCoordinates = debounce(function () {
    var coordinates = this.getCoordinates(this.selectionEnd, this.selectionEndContainer, this.selectionEndOffset)
    if (this.cursorCoordinates.top !== coordinates.top ||
      this.cursorCoordinates.height !== coordinates.height ||
      this.cursorCoordinates.left !== coordinates.left
    ) {
      this.cursorCoordinates = coordinates
      this.$trigger('cursorCoordinatesChanged', coordinates)
    }
    if (adjustScroll) {
      var scrollEltHeight = scrollElt.clientHeight;
      if (typeof adjustScroll === 'number') {
        scrollEltHeight -= adjustScroll
      }
      var adjustment = scrollEltHeight / 2 * editor.options.getCursorFocusRatio()
      var cursorTop = this.cursorCoordinates.top + this.cursorCoordinates.height / 2
      // Adjust cursorTop with contentElt position relative to scrollElt
      cursorTop += contentElt.getBoundingClientRect().top - scrollElt.getBoundingClientRect().top + scrollElt.scrollTop;
      var minScrollTop = cursorTop - adjustment
      var maxScrollTop = cursorTop + adjustment - scrollEltHeight
      if (scrollElt.scrollTop > minScrollTop) {
        scrollElt.scrollTop = minScrollTop
      } else if (scrollElt.scrollTop < maxScrollTop) {
        scrollElt.scrollTop = maxScrollTop
      }
    }
    adjustScroll = false
  }.cl_bind(this))

  this.updateCursorCoordinates = function (adjustScrollParam) {
    adjustScroll = adjustScroll || adjustScrollParam
    debouncedUpdateCursorCoordinates()
  }

  var oldSelectionRange

  function checkSelection(selectionRange) {
    if (!oldSelectionRange ||
      oldSelectionRange.startContainer !== selectionRange.startContainer ||
      oldSelectionRange.startOffset !== selectionRange.startOffset ||
      oldSelectionRange.endContainer !== selectionRange.endContainer ||
      oldSelectionRange.endOffset !== selectionRange.endOffset
    ) {
      oldSelectionRange = selectionRange
      self.$trigger('selectionChanged', self.selectionStart, self.selectionEnd, selectionRange)
      return true
    }
  }

  this.hasFocus = function() {
    return contentElt === editor.$document.activeElement;
  }

  this.restoreSelection = function () {
    var min = Math.min(this.selectionStart, this.selectionEnd)
    var max = Math.max(this.selectionStart, this.selectionEnd)
    var selectionRange = this.createRange(min, max)
    if (editor.$document.contains(selectionRange.commonAncestorContainer)) {
      var selection = editor.$window.getSelection()
      selection.removeAllRanges()
      var isBackward = this.selectionStart > this.selectionEnd
      if (selection.extend) {
        var beginRange = selectionRange.cloneRange()
        beginRange.collapse(!isBackward)
        selection.addRange(beginRange)
        if (isBackward) {
          selection.extend(selectionRange.startContainer, selectionRange.startOffset)
        } else {
          selection.extend(selectionRange.endContainer, selectionRange.endOffset)
        }
      } else {
        selection.addRange(selectionRange)
      }
      checkSelection(selectionRange)
      return selectionRange
    }
  }

  var saveLastSelection = debounce(function () {
    lastSelectionStart = self.selectionStart
    lastSelectionEnd = self.selectionEnd
  }, 50)

  function setSelection(start, end) {
    if (start === undefined) {
      start = self.selectionStart
    }
    if (start < 0) {
      start = 0
    }
    if (end === undefined) {
      end = this.selectionEnd
    }
    if (end < 0) {
      end = 0
    }
    self.selectionStart = start
    self.selectionEnd = end
    saveLastSelection()
  }

  this.setSelectionStartEnd = function (start, end) {
    setSelection(start, end)
    return this.hasFocus() && this.restoreSelection()
  }

  this.saveSelectionState = (function () {
    // Credit: https://github.com/timdown/rangy
    function arrayContains(arr, val) {
      var i = arr.length
      while (i--) {
        if (arr[i] === val) {
          return true
        }
      }
      return false
    }

    function getClosestAncestorIn(node, ancestor, selfIsAncestor) {
      var p
      var n = selfIsAncestor ? node : node.parentNode
      while (n) {
        p = n.parentNode
        if (p === ancestor) {
          return n
        }
        n = p
      }
      return null
    }

    function getNodeIndex(node) {
      var i = 0
      while ((node = node.previousSibling)) {
        ++i
      }
      return i
    }

    function getCommonAncestor(node1, node2) {
      var ancestors = []
      var n
      for (n = node1; n; n = n.parentNode) {
        ancestors.push(n)
      }

      for (n = node2; n; n = n.parentNode) {
        if (arrayContains(ancestors, n)) {
          return n
        }
      }

      return null
    }

    function comparePoints(nodeA, offsetA, nodeB, offsetB) {
      // See http://www.w3.org/TR/DOM-Level-2-Traversal-Range/ranges.html#Level-2-Range-Comparing
      var nodeC, root, childA, childB, n
      if (nodeA === nodeB) {
        // Case 1: nodes are the same
        return offsetA === offsetB ? 0 : (offsetA < offsetB) ? -1 : 1
      } else if (
        (nodeC = getClosestAncestorIn(nodeB, nodeA, true))
      ) {
        // Case 2: node C (container B or an ancestor) is a child node of A
        return offsetA <= getNodeIndex(nodeC) ? -1 : 1
      } else if (
        (nodeC = getClosestAncestorIn(nodeA, nodeB, true))
      ) {
        // Case 3: node C (container A or an ancestor) is a child node of B
        return getNodeIndex(nodeC) < offsetB ? -1 : 1
      } else {
        root = getCommonAncestor(nodeA, nodeB)
        if (!root) {
          throw new Error('comparePoints error: nodes have no common ancestor')
        }

        // Case 4: containers are siblings or descendants of siblings
        childA = (nodeA === root) ? root : getClosestAncestorIn(nodeA, root, true)
        childB = (nodeB === root) ? root : getClosestAncestorIn(nodeB, root, true)

        if (childA === childB) {
          // This shouldn't be possible
          throw module.createError('comparePoints got to case 4 and childA and childB are the same!')
        } else {
          n = root.firstChild
          while (n) {
            if (n === childA) {
              return -1
            } else if (n === childB) {
              return 1
            }
            n = n.nextSibling
          }
        }
      }
    }

    function save() {
      var result
      if (self.hasFocus()) {
        var selectionStart = self.selectionStart
        var selectionEnd = self.selectionEnd
        var selection = editor.$window.getSelection()
        if (selection.rangeCount > 0) {
          var selectionRange = selection.getRangeAt(0)
          var node = selectionRange.startContainer
          if ((contentElt.compareDocumentPosition(node) & window.Node.DOCUMENT_POSITION_CONTAINED_BY) || contentElt === node) {
            var offset = selectionRange.startOffset
            if (node.firstChild && offset > 0) {
              node = node.childNodes[offset - 1]
              offset = node.textContent.length
            }
            var container = node
            while (node !== contentElt) {
              while ((node = node.previousSibling)) {
                offset += (node.textContent || '').length
              }
              node = container = container.parentNode
            }
            var selectionText = selectionRange + ''
            // Fix end of line when only br is selected
            var brElt = selectionRange.endContainer.firstChild
            if (brElt && brElt.tagName === 'BR' && selectionRange.endOffset === 1) {
              selectionText += '\n'
            }
            if (comparePoints(selection.anchorNode, selection.anchorOffset, selection.focusNode, selection.focusOffset) === 1) {
              selectionStart = offset + selectionText.length
              selectionEnd = offset
            } else {
              selectionStart = offset
              selectionEnd = offset + selectionText.length
            }

            if (selectionStart === selectionEnd && selectionStart === editor.getContent().length) {
              // If cursor is after the trailingNode
              selectionStart = --selectionEnd
              result = self.setSelectionStartEnd(selectionStart, selectionEnd)
            } else {
              setSelection(selectionStart, selectionEnd)
              result = checkSelection(selectionRange)
              result = result || lastSelectionStart !== self.selectionStart // selectionRange doesn't change when selection is at the start of a section
            }
          }
        }
      }
      return result
    }

    function saveCheckChange() {
      return save() && (lastSelectionStart !== self.selectionStart || lastSelectionEnd !== self.selectionEnd)
    }

    var nextTickAdjustScroll = false
    var debouncedSave = debounce(function () {
      self.updateCursorCoordinates(saveCheckChange() && nextTickAdjustScroll)
      // In some cases we have to wait a little longer to see the selection change (Cmd+A on Chrome OSX)
      longerDebouncedSave()
    })
    var longerDebouncedSave = debounce(function () {
      self.updateCursorCoordinates(saveCheckChange() && nextTickAdjustScroll)
      nextTickAdjustScroll = false
    }, 10)

    return function (debounced, adjustScroll, forceAdjustScroll) {
      if (forceAdjustScroll) {
        lastSelectionStart = undefined
        lastSelectionEnd = undefined
      }
      if (debounced) {
        nextTickAdjustScroll = nextTickAdjustScroll || adjustScroll
        return debouncedSave()
      } else {
        save()
      }
    }
  })()

  this.getSelectedText = function () {
    var min = Math.min(this.selectionStart, this.selectionEnd)
    var max = Math.max(this.selectionStart, this.selectionEnd)
    return editor.getContent().substring(min, max)
  }

  this.getCoordinates = function (inputOffset, container, offsetInContainer) {
    if (!container) {
      var offset = this.findContainer(inputOffset)
      container = offset.container
      offsetInContainer = offset.offsetInContainer
    }
    var containerElt = container
    if (!containerElt.hasChildNodes()) {
      containerElt = container.parentNode
    }
    var isInvisible = false
    var index = editor.$allElements.indexOf(containerElt)
    while (containerElt.offsetHeight === 0 && index > 0) {
      isInvisible = true
      containerElt = editor.$allElements[--index]
    }
    var rect
    var contentRect
    var left = 'left'
    if (isInvisible || container.textContent === '\n') {
      rect = containerElt.getBoundingClientRect()
    } else {
      var selectedChar = editor.getContent()[inputOffset]
      var startOffset = {
        container: container,
        offsetInContainer: offsetInContainer
      }
      var endOffset = {
        container: container,
        offsetInContainer: offsetInContainer
      }
      if (inputOffset > 0 && (selectedChar === undefined || selectedChar === '\n')) {
        left = 'right'
        if (startOffset.offsetInContainer === 0) {
          // Need to calculate offset-1
          startOffset = inputOffset - 1
        } else {
          startOffset.offsetInContainer -= 1
        }
      } else {
        if (endOffset.offsetInContainer === container.textContent.length) {
          // Need to calculate offset+1
          endOffset = inputOffset + 1
        } else {
          endOffset.offsetInContainer += 1
        }
      }
      var range = this.createRange(startOffset, endOffset)
      rect = range.getBoundingClientRect()
    }
    contentRect = contentElt.getBoundingClientRect()
    return {
      top: Math.round(rect.top - contentRect.top + contentElt.scrollTop),
      height: Math.round(rect.height),
      left: Math.round(rect[left] - contentRect.left + contentElt.scrollLeft)
    }
  }

  this.getClosestWordOffset = function (offset) {
    var offsetStart = 0
    var offsetEnd = 0
    var nextOffset = 0
    editor.getContent().split(/\s/).cl_some(function (word) {
      if (word) {
        offsetStart = nextOffset
        offsetEnd = nextOffset + word.length
        if (offsetEnd > offset) {
          return true
        }
      }
      nextOffset += word.length + 1
    })
    return {
      start: offsetStart,
      end: offsetEnd
    }
  }
}

cledit.SelectionMgr = SelectionMgr