/*---------------------------------------------------------------------------------------------
 *  Copyright (c) Microsoft Corporation. All rights reserved.
 *  Licensed under the MIT License. See License.txt in the project root for license information.
 *--------------------------------------------------------------------------------------------*/

import {
  SelectionRangeProvider,
  SelectionRange,
} from '../../../../vs/editor/common/modes';
import { ITextModel } from '../../../../vs/editor/common/model';
import { Position } from '../../../../vs/editor/common/core/position';
import { Range } from '../../../../vs/editor/common/core/range';
import { CharCode } from '../../../../vs/base/common/charCode';
import {
  isUpperAsciiLetter,
  isLowerAsciiLetter,
} from '../../../../vs/base/common/strings';

export class WordSelectionRangeProvider implements SelectionRangeProvider {
  provideSelectionRanges(
    model: ITextModel,
    positions: Position[]
  ): SelectionRange[][] {
    const result: SelectionRange[][] = [];
    for (const position of positions) {
      const bucket: SelectionRange[] = [];
      result.push(bucket);
      this._addInWordRanges(bucket, model, position);
      this._addWordRanges(bucket, model, position);
      this._addWhitespaceLine(bucket, model, position);
      bucket.push({ range: model.getFullModelRange() });
    }
    return result;
  }

  private _addInWordRanges(
    bucket: SelectionRange[],
    model: ITextModel,
    pos: Position
  ): void {
    const obj = model.getWordAtPosition(pos);
    if (!obj) {
      return;
    }

    let { word, startColumn } = obj;
    let offset = pos.column - startColumn;
    let start = offset;
    let end = offset;
    let lastCh: number = 0;

    // LEFT anchor (start)
    for (; start >= 0; start--) {
      let ch = word.charCodeAt(start);
      if (
        start !== offset &&
        (ch === CharCode.Underline || ch === CharCode.Dash)
      ) {
        // foo-bar OR foo_bar
        break;
      } else if (isLowerAsciiLetter(ch) && isUpperAsciiLetter(lastCh)) {
        // fooBar
        break;
      }
      lastCh = ch;
    }
    start += 1;

    // RIGHT anchor (end)
    for (; end < word.length; end++) {
      let ch = word.charCodeAt(end);
      if (isUpperAsciiLetter(ch) && isLowerAsciiLetter(lastCh)) {
        // fooBar
        break;
      } else if (ch === CharCode.Underline || ch === CharCode.Dash) {
        // foo-bar OR foo_bar
        break;
      }
      lastCh = ch;
    }

    if (start < end) {
      bucket.push({
        range: new Range(
          pos.lineNumber,
          startColumn + start,
          pos.lineNumber,
          startColumn + end
        ),
      });
    }
  }

  private _addWordRanges(
    bucket: SelectionRange[],
    model: ITextModel,
    pos: Position
  ): void {
    const word = model.getWordAtPosition(pos);
    if (word) {
      bucket.push({
        range: new Range(
          pos.lineNumber,
          word.startColumn,
          pos.lineNumber,
          word.endColumn
        ),
      });
    }
  }

  private _addWhitespaceLine(
    bucket: SelectionRange[],
    model: ITextModel,
    pos: Position
  ): void {
    if (
      model.getLineLength(pos.lineNumber) > 0 &&
      model.getLineFirstNonWhitespaceColumn(pos.lineNumber) === 0 &&
      model.getLineLastNonWhitespaceColumn(pos.lineNumber) === 0
    ) {
      bucket.push({
        range: new Range(
          pos.lineNumber,
          1,
          pos.lineNumber,
          model.getLineMaxColumn(pos.lineNumber)
        ),
      });
    }
  }
}