/**
 * Copyright (c) Facebook, Inc. and its affiliates.
 *
 * This source code is licensed under the MIT license found in the
 * LICENSE file in the root directory of this source tree.
 *
 * @format
 * @flow
 * @emails oncall+draft_js
 */
'use strict';

import type ContentState from "./ContentState";
import type { DraftBlockType } from "./DraftBlockType";
import type { DraftEditorCommand } from "./DraftEditorCommand";
import type { DataObjectForLink, RichTextUtils } from "./RichTextUtils";
import type SelectionState from "./SelectionState";
import type URI from "fbjs/lib/URI";

const DraftModifier = require("./DraftModifier");

const EditorState = require("./EditorState");

const adjustBlockDepthForContentState = require("./adjustBlockDepthForContentState");

const nullthrows = require("fbjs/lib/nullthrows");

const RichTextEditorUtil: RichTextUtils = {
  currentBlockContainsLink: function (editorState: EditorState): boolean {
    const selection = editorState.getSelection();
    const contentState = editorState.getCurrentContent();
    const entityMap = contentState.getEntityMap();
    return contentState.getBlockForKey(selection.getAnchorKey()).getCharacterList().slice(selection.getStartOffset(), selection.getEndOffset()).some(v => {
      const entity = v.getEntity();
      return !!entity && entityMap.__get(entity).getType() === 'LINK';
    });
  },
  getCurrentBlockType: function (editorState: EditorState): DraftBlockType {
    const selection = editorState.getSelection();
    return editorState.getCurrentContent().getBlockForKey(selection.getStartKey()).getType();
  },
  getDataObjectForLinkURL: function (uri: URI): DataObjectForLink {
    return {
      url: uri.toString()
    };
  },
  handleKeyCommand: function (editorState: EditorState, command: DraftEditorCommand | string, eventTimeStamp: ?number): ?EditorState {
    switch (command) {
      case 'bold':
        return RichTextEditorUtil.toggleInlineStyle(editorState, 'BOLD');

      case 'italic':
        return RichTextEditorUtil.toggleInlineStyle(editorState, 'ITALIC');

      case 'underline':
        return RichTextEditorUtil.toggleInlineStyle(editorState, 'UNDERLINE');

      case 'code':
        return RichTextEditorUtil.toggleCode(editorState);

      case 'backspace':
      case 'backspace-word':
      case 'backspace-to-start-of-line':
        return RichTextEditorUtil.onBackspace(editorState);

      case 'delete':
      case 'delete-word':
      case 'delete-to-end-of-block':
        return RichTextEditorUtil.onDelete(editorState);

      default:
        // they may have custom editor commands; ignore those
        return null;
    }
  },
  insertSoftNewline: function (editorState: EditorState): EditorState {
    const contentState = DraftModifier.insertText(editorState.getCurrentContent(), editorState.getSelection(), '\n', editorState.getCurrentInlineStyle(), null);
    const newEditorState = EditorState.push(editorState, contentState, 'insert-characters');
    return EditorState.forceSelection(newEditorState, contentState.getSelectionAfter());
  },

  /**
   * For collapsed selections at the start of styled blocks, backspace should
   * just remove the existing style.
   */
  onBackspace: function (editorState: EditorState): ?EditorState {
    const selection = editorState.getSelection();

    if (!selection.isCollapsed() || selection.getAnchorOffset() || selection.getFocusOffset()) {
      return null;
    } // First, try to remove a preceding atomic block.


    const content = editorState.getCurrentContent();
    const startKey = selection.getStartKey();
    const blockBefore = content.getBlockBefore(startKey);

    if (blockBefore && blockBefore.getType() === 'atomic') {
      const blockMap = content.getBlockMap().delete(blockBefore.getKey());
      const withoutAtomicBlock = content.merge({
        blockMap,
        selectionAfter: selection
      });

      if (withoutAtomicBlock !== content) {
        return EditorState.push(editorState, withoutAtomicBlock, 'remove-range');
      }
    } // If that doesn't succeed, try to remove the current block style.


    const withoutBlockStyle = RichTextEditorUtil.tryToRemoveBlockStyle(editorState);

    if (withoutBlockStyle) {
      return EditorState.push(editorState, withoutBlockStyle, 'change-block-type');
    }

    return null;
  },
  onDelete: function (editorState: EditorState): ?EditorState {
    const selection = editorState.getSelection();

    if (!selection.isCollapsed()) {
      return null;
    }

    const content = editorState.getCurrentContent();
    const startKey = selection.getStartKey();
    const block = content.getBlockForKey(startKey);
    const length = block.getLength(); // The cursor is somewhere within the text. Behave normally.

    if (selection.getStartOffset() < length) {
      return null;
    }

    const blockAfter = content.getBlockAfter(startKey);

    if (!blockAfter || blockAfter.getType() !== 'atomic') {
      return null;
    }

    const atomicBlockTarget = selection.merge({
      focusKey: blockAfter.getKey(),
      focusOffset: blockAfter.getLength()
    });
    const withoutAtomicBlock = DraftModifier.removeRange(content, atomicBlockTarget, 'forward');

    if (withoutAtomicBlock !== content) {
      return EditorState.push(editorState, withoutAtomicBlock, 'remove-range');
    }

    return null;
  },
  onTab: function (event: SyntheticKeyboardEvent<>, editorState: EditorState, maxDepth: number): EditorState {
    const selection = editorState.getSelection();
    const key = selection.getAnchorKey();

    if (key !== selection.getFocusKey()) {
      return editorState;
    }

    const content = editorState.getCurrentContent();
    const block = content.getBlockForKey(key);
    const type = block.getType();

    if (type !== 'unordered-list-item' && type !== 'ordered-list-item') {
      return editorState;
    }

    event.preventDefault();
    const depth = block.getDepth();

    if (!event.shiftKey && depth === maxDepth) {
      return editorState;
    }

    const withAdjustment = adjustBlockDepthForContentState(content, selection, event.shiftKey ? -1 : 1, maxDepth);
    return EditorState.push(editorState, withAdjustment, 'adjust-depth');
  },
  toggleBlockType: function (editorState: EditorState, blockType: DraftBlockType): EditorState {
    const selection = editorState.getSelection();
    const startKey = selection.getStartKey();
    let endKey = selection.getEndKey();
    const content = editorState.getCurrentContent();
    let target = selection; // Triple-click can lead to a selection that includes offset 0 of the
    // following block. The `SelectionState` for this case is accurate, but
    // we should avoid toggling block type for the trailing block because it
    // is a confusing interaction.

    if (startKey !== endKey && selection.getEndOffset() === 0) {
      const blockBefore = nullthrows(content.getBlockBefore(endKey));
      endKey = blockBefore.getKey();
      target = target.merge({
        anchorKey: startKey,
        anchorOffset: selection.getStartOffset(),
        focusKey: endKey,
        focusOffset: blockBefore.getLength(),
        isBackward: false
      });
    }

    const hasAtomicBlock = content.getBlockMap().skipWhile((_, k) => k !== startKey).reverse().skipWhile((_, k) => k !== endKey).some(v => v.getType() === 'atomic');

    if (hasAtomicBlock) {
      return editorState;
    }

    const typeToSet = content.getBlockForKey(startKey).getType() === blockType ? 'unstyled' : blockType;
    return EditorState.push(editorState, DraftModifier.setBlockType(content, target, typeToSet), 'change-block-type');
  },
  toggleCode: function (editorState: EditorState): EditorState {
    const selection = editorState.getSelection();
    const anchorKey = selection.getAnchorKey();
    const focusKey = selection.getFocusKey();

    if (selection.isCollapsed() || anchorKey !== focusKey) {
      return RichTextEditorUtil.toggleBlockType(editorState, 'code-block');
    }

    return RichTextEditorUtil.toggleInlineStyle(editorState, 'CODE');
  },

  /**
   * Toggle the specified inline style for the selection. If the
   * user's selection is collapsed, apply or remove the style for the
   * internal state. If it is not collapsed, apply the change directly
   * to the document state.
   */
  toggleInlineStyle: function (editorState: EditorState, inlineStyle: string): EditorState {
    const selection = editorState.getSelection();
    const currentStyle = editorState.getCurrentInlineStyle(); // If the selection is collapsed, toggle the specified style on or off and
    // set the result as the new inline style override. This will then be
    // used as the inline style for the next character to be inserted.

    if (selection.isCollapsed()) {
      return EditorState.setInlineStyleOverride(editorState, currentStyle.has(inlineStyle) ? currentStyle.remove(inlineStyle) : currentStyle.add(inlineStyle));
    } // If characters are selected, immediately apply or remove the
    // inline style on the document state itself.


    const content = editorState.getCurrentContent();
    let newContent; // If the style is already present for the selection range, remove it.
    // Otherwise, apply it.

    if (currentStyle.has(inlineStyle)) {
      newContent = DraftModifier.removeInlineStyle(content, selection, inlineStyle);
    } else {
      newContent = DraftModifier.applyInlineStyle(content, selection, inlineStyle);
    }

    return EditorState.push(editorState, newContent, 'change-inline-style');
  },
  toggleLink: function (editorState: EditorState, targetSelection: SelectionState, entityKey: ?string): EditorState {
    const withoutLink = DraftModifier.applyEntity(editorState.getCurrentContent(), targetSelection, entityKey);
    return EditorState.push(editorState, withoutLink, 'apply-entity');
  },

  /**
   * When a collapsed cursor is at the start of a styled block, changes block
   * type to 'unstyled'. Returns null if selection does not meet that criteria.
   */
  tryToRemoveBlockStyle: function (editorState: EditorState): ?ContentState {
    const selection = editorState.getSelection();
    const offset = selection.getAnchorOffset();

    if (selection.isCollapsed() && offset === 0) {
      const key = selection.getAnchorKey();
      const content = editorState.getCurrentContent();
      const block = content.getBlockForKey(key);
      const type = block.getType();
      const blockBefore = content.getBlockBefore(key);

      if (type === 'code-block' && blockBefore && blockBefore.getType() === 'code-block' && blockBefore.getLength() !== 0) {
        return null;
      }

      if (type !== 'unstyled') {
        return DraftModifier.setBlockType(content, selection, 'unstyled');
      }
    }

    return null;
  }
};
module.exports = RichTextEditorUtil;