/**
 * Copyright (c) 2013-present, Facebook, Inc.
 * All rights reserved.
 *
 * This source code is licensed under the BSD-style license found in the
 * LICENSE file in the root directory of this source tree. An additional grant
 * of patent rights can be found in the PATENTS file in the same directory.
 *
 * @providesModule setDraftEditorSelection
 * @format
 * @flow
 */

'use strict';

import type SelectionState from './SelectionState';

const DraftJsDebugLogging = require('./DraftJsDebugLogging');

const containsNode = require('fbjs/lib/containsNode');
const getActiveElement = require('fbjs/lib/getActiveElement');
const invariant = require('fbjs/lib/invariant');

function getAnonymizedDOM(node: Node, getNodeLabels?: (n: Node) => Array<string>): string {
  if (!node) {
    return '[empty]';
  }

  var anonymized = anonymizeTextWithin(node, getNodeLabels);
  if (anonymized.nodeType === Node.TEXT_NODE) {
    return anonymized.textContent;
  }

  invariant(anonymized instanceof Element, 'Node must be an Element if it is not a text node.');
  return anonymized.outerHTML;
}

function anonymizeTextWithin(node: Node, getNodeLabels?: (n: Node) => Array<string>): Node {
  const labels = getNodeLabels !== undefined ? getNodeLabels(node) : [];

  if (node.nodeType === Node.TEXT_NODE) {
    var length = node.textContent.length;
    return document.createTextNode('[text ' + length + (labels.length ? ' | ' + labels.join(', ') : '') + ']');
  }

  var clone = node.cloneNode();
  if (clone.nodeType === 1 && labels.length) {
    ((clone: any): Element).setAttribute('data-labels', labels.join(', '));
  }
  var childNodes = node.childNodes;
  for (var ii = 0; ii < childNodes.length; ii++) {
    clone.appendChild(anonymizeTextWithin(childNodes[ii], getNodeLabels));
  }

  return clone;
}

function getAnonymizedEditorDOM(node: Node, getNodeLabels?: (n: Node) => Array<string>): string {
  // grabbing the DOM content of the Draft editor
  let currentNode = node;
  while (currentNode) {
    if (currentNode instanceof Element && currentNode.hasAttribute('contenteditable')) {
      // found the Draft editor container
      return getAnonymizedDOM(currentNode, getNodeLabels);
    } else {
      currentNode = currentNode.parentNode;
    }
  }
  return 'Could not find contentEditable parent of node';
}

function getNodeLength(node: Node): number {
  return node.nodeValue === null ? node.childNodes.length : node.nodeValue.length;
}

/**
 * In modern non-IE browsers, we can support both forward and backward
 * selections.
 *
 * Note: IE10+ supports the Selection object, but it does not support
 * the `extend` method, which means that even in modern IE, it's not possible
 * to programatically create a backward selection. Thus, for all IE
 * versions, we use the old IE API to create our selections.
 */
function setDraftEditorSelection(selectionState: SelectionState, node: Node, blockKey: string, nodeStart: number, nodeEnd: number): void {
  // It's possible that the editor has been removed from the DOM but
  // our selection code doesn't know it yet. Forcing selection in
  // this case may lead to errors, so just bail now.
  if (!containsNode(document.documentElement, node)) {
    return;
  }

  var selection = global.getSelection();
  var anchorKey = selectionState.getAnchorKey();
  var anchorOffset = selectionState.getAnchorOffset();
  var focusKey = selectionState.getFocusKey();
  var focusOffset = selectionState.getFocusOffset();
  var isBackward = selectionState.getIsBackward();

  // IE doesn't support backward selection. Swap key/offset pairs.
  if (!selection.extend && isBackward) {
    var tempKey = anchorKey;
    var tempOffset = anchorOffset;
    anchorKey = focusKey;
    anchorOffset = focusOffset;
    focusKey = tempKey;
    focusOffset = tempOffset;
    isBackward = false;
  }

  var hasAnchor = anchorKey === blockKey && nodeStart <= anchorOffset && nodeEnd >= anchorOffset;

  var hasFocus = focusKey === blockKey && nodeStart <= focusOffset && nodeEnd >= focusOffset;

  // If the selection is entirely bound within this node, set the selection
  // and be done.
  if (hasAnchor && hasFocus) {
    selection.removeAllRanges();
    addPointToSelection(selection, node, anchorOffset - nodeStart, selectionState);
    addFocusToSelection(selection, node, focusOffset - nodeStart, selectionState);
    return;
  }

  if (!isBackward) {
    // If the anchor is within this node, set the range start.
    if (hasAnchor) {
      selection.removeAllRanges();
      addPointToSelection(selection, node, anchorOffset - nodeStart, selectionState);
    }

    // If the focus is within this node, we can assume that we have
    // already set the appropriate start range on the selection, and
    // can simply extend the selection.
    if (hasFocus) {
      addFocusToSelection(selection, node, focusOffset - nodeStart, selectionState);
    }
  } else {
    // If this node has the focus, set the selection range to be a
    // collapsed range beginning here. Later, when we encounter the anchor,
    // we'll use this information to extend the selection.
    if (hasFocus) {
      selection.removeAllRanges();
      addPointToSelection(selection, node, focusOffset - nodeStart, selectionState);
    }

    // If this node has the anchor, we may assume that the correct
    // focus information is already stored on the selection object.
    // We keep track of it, reset the selection range, and extend it
    // back to the focus point.
    if (hasAnchor) {
      var storedFocusNode = selection.focusNode;
      var storedFocusOffset = selection.focusOffset;

      selection.removeAllRanges();
      addPointToSelection(selection, node, anchorOffset - nodeStart, selectionState);
      addFocusToSelection(selection, storedFocusNode, storedFocusOffset, selectionState);
    }
  }
}

/**
 * Extend selection towards focus point.
 */
function addFocusToSelection(selection: Object, node: Node, offset: number, selectionState: SelectionState): void {
  const activeElement = getActiveElement();
  if (selection.extend && containsNode(activeElement, node)) {
    // If `extend` is called while another element has focus, an error is
    // thrown. We therefore disable `extend` if the active element is somewhere
    // other than the node we are selecting. This should only occur in Firefox,
    // since it is the only browser to support multiple selections.
    // See https://bugzilla.mozilla.org/show_bug.cgi?id=921444.

    // logging to catch bug that is being reported in t16250795
    if (offset > getNodeLength(node)) {
      // the call to 'selection.extend' is about to throw
      DraftJsDebugLogging.logSelectionStateFailure({
        anonymizedDom: getAnonymizedEditorDOM(node),
        extraParams: JSON.stringify({ offset: offset }),
        selectionState: JSON.stringify(selectionState.toJS())
      });
    }

    // logging to catch bug that is being reported in t18110632
    const nodeWasFocus = node === selection.focusNode;
    try {
      selection.extend(node, offset);
    } catch (e) {
      DraftJsDebugLogging.logSelectionStateFailure({
        anonymizedDom: getAnonymizedEditorDOM(node, function (n) {
          const labels = [];
          if (n === activeElement) {
            labels.push('active element');
          }
          if (n === selection.anchorNode) {
            labels.push('selection anchor node');
          }
          if (n === selection.focusNode) {
            labels.push('selection focus node');
          }
          return labels;
        }),
        extraParams: JSON.stringify({
          activeElementName: activeElement ? activeElement.nodeName : null,
          nodeIsFocus: node === selection.focusNode,
          nodeWasFocus: nodeWasFocus,
          selectionRangeCount: selection.rangeCount,
          selectionAnchorNodeName: selection.anchorNode ? selection.anchorNode.nodeName : null,
          selectionAnchorOffset: selection.anchorOffset,
          selectionFocusNodeName: selection.focusNode ? selection.focusNode.nodeName : null,
          selectionFocusOffset: selection.focusOffset,
          message: e ? '' + e : null,
          offset: offset
        }, null, 2),
        selectionState: JSON.stringify(selectionState.toJS(), null, 2)
      });
      // allow the error to be thrown -
      // better than continuing in a broken state
      throw e;
    }
  } else {
    // IE doesn't support extend. This will mean no backward selection.
    // Extract the existing selection range and add focus to it.
    // Additionally, clone the selection range. IE11 throws an
    // InvalidStateError when attempting to access selection properties
    // after the range is detached.
    var range = selection.getRangeAt(0);
    range.setEnd(node, offset);
    selection.addRange(range.cloneRange());
  }
}

function addPointToSelection(selection: Object, node: Node, offset: number, selectionState: SelectionState): void {
  var range = document.createRange();
  // logging to catch bug that is being reported in t16250795
  if (offset > getNodeLength(node)) {
    // in this case we know that the call to 'range.setStart' is about to throw
    DraftJsDebugLogging.logSelectionStateFailure({
      anonymizedDom: getAnonymizedEditorDOM(node),
      extraParams: JSON.stringify({ offset: offset }),
      selectionState: JSON.stringify(selectionState.toJS())
    });
  }
  range.setStart(node, offset);
  selection.addRange(range);
}

module.exports = setDraftEditorSelection;