/**
 * 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 SelectionState
 * @format
 * @flow
 */

'use strict';

var Immutable = require('immutable');

var { Record } = Immutable;

var defaultRecord: {
  anchorKey: string;
  anchorOffset: number;
  focusKey: string;
  focusOffset: number;
  isBackward: boolean;
  hasFocus: boolean;
} = {
  anchorKey: '',
  anchorOffset: 0,
  focusKey: '',
  focusOffset: 0,
  isBackward: false,
  hasFocus: false
};

var SelectionStateRecord = Record(defaultRecord);

class SelectionState extends SelectionStateRecord {
  serialize(): string {
    return 'Anchor: ' + this.getAnchorKey() + ':' + this.getAnchorOffset() + ', ' + 'Focus: ' + this.getFocusKey() + ':' + this.getFocusOffset() + ', ' + 'Is Backward: ' + String(this.getIsBackward()) + ', ' + 'Has Focus: ' + String(this.getHasFocus());
  }

  getAnchorKey(): string {
    return this.get('anchorKey');
  }

  getAnchorOffset(): number {
    return this.get('anchorOffset');
  }

  getFocusKey(): string {
    return this.get('focusKey');
  }

  getFocusOffset(): number {
    return this.get('focusOffset');
  }

  getIsBackward(): boolean {
    return this.get('isBackward');
  }

  getHasFocus(): boolean {
    return this.get('hasFocus');
  }

  /**
   * Return whether the specified range overlaps with an edge of the
   * SelectionState.
   */
  hasEdgeWithin(blockKey: string, start: number, end: number): boolean {
    var anchorKey = this.getAnchorKey();
    var focusKey = this.getFocusKey();

    if (anchorKey === focusKey && anchorKey === blockKey) {
      var selectionStart = this.getStartOffset();
      var selectionEnd = this.getEndOffset();
      return start <= selectionEnd && selectionStart <= end;
    }

    if (blockKey !== anchorKey && blockKey !== focusKey) {
      return false;
    }

    var offsetToCheck = blockKey === anchorKey ? this.getAnchorOffset() : this.getFocusOffset();

    return start <= offsetToCheck && end >= offsetToCheck;
  }

  isCollapsed(): boolean {
    return this.getAnchorKey() === this.getFocusKey() && this.getAnchorOffset() === this.getFocusOffset();
  }

  getStartKey(): string {
    return this.getIsBackward() ? this.getFocusKey() : this.getAnchorKey();
  }

  getStartOffset(): number {
    return this.getIsBackward() ? this.getFocusOffset() : this.getAnchorOffset();
  }

  getEndKey(): string {
    return this.getIsBackward() ? this.getAnchorKey() : this.getFocusKey();
  }

  getEndOffset(): number {
    return this.getIsBackward() ? this.getAnchorOffset() : this.getFocusOffset();
  }

  static createEmpty(key: string): SelectionState {
    return new SelectionState({
      anchorKey: key,
      anchorOffset: 0,
      focusKey: key,
      focusOffset: 0,
      isBackward: false,
      hasFocus: false
    });
  }
}

module.exports = SelectionState;