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

import {
  IPosition,
  Position,
} from '../../../../vs/editor/common/core/position';
import { Range } from '../../../../vs/editor/common/core/range';

/**
 * A selection in the editor.
 * The selection is a range that has an orientation.
 */
export interface ISelection {
  /**
   * The line number on which the selection has started.
   */
  readonly selectionStartLineNumber: number;
  /**
   * The column on `selectionStartLineNumber` where the selection has started.
   */
  readonly selectionStartColumn: number;
  /**
   * The line number on which the selection has ended.
   */
  readonly positionLineNumber: number;
  /**
   * The column on `positionLineNumber` where the selection has ended.
   */
  readonly positionColumn: number;
}

/**
 * The direction of a selection.
 */
export const enum SelectionDirection {
  /**
   * The selection starts above where it ends.
   */
  LTR,
  /**
   * The selection starts below where it ends.
   */
  RTL,
}

/**
 * A selection in the editor.
 * The selection is a range that has an orientation.
 */
export class Selection extends Range {
  /**
   * The line number on which the selection has started.
   */
  public readonly selectionStartLineNumber: number;
  /**
   * The column on `selectionStartLineNumber` where the selection has started.
   */
  public readonly selectionStartColumn: number;
  /**
   * The line number on which the selection has ended.
   */
  public readonly positionLineNumber: number;
  /**
   * The column on `positionLineNumber` where the selection has ended.
   */
  public readonly positionColumn: number;

  constructor(
    selectionStartLineNumber: number,
    selectionStartColumn: number,
    positionLineNumber: number,
    positionColumn: number
  ) {
    super(
      selectionStartLineNumber,
      selectionStartColumn,
      positionLineNumber,
      positionColumn
    );
    this.selectionStartLineNumber = selectionStartLineNumber;
    this.selectionStartColumn = selectionStartColumn;
    this.positionLineNumber = positionLineNumber;
    this.positionColumn = positionColumn;
  }

  /**
   * Transform to a human-readable representation.
   */
  public override toString(): string {
    return (
      '[' +
      this.selectionStartLineNumber +
      ',' +
      this.selectionStartColumn +
      ' -> ' +
      this.positionLineNumber +
      ',' +
      this.positionColumn +
      ']'
    );
  }

  /**
   * Test if equals other selection.
   */
  public equalsSelection(other: ISelection): boolean {
    return Selection.selectionsEqual(this, other);
  }

  /**
   * Test if the two selections are equal.
   */
  public static selectionsEqual(a: ISelection, b: ISelection): boolean {
    return (
      a.selectionStartLineNumber === b.selectionStartLineNumber &&
      a.selectionStartColumn === b.selectionStartColumn &&
      a.positionLineNumber === b.positionLineNumber &&
      a.positionColumn === b.positionColumn
    );
  }

  /**
   * Get directions (LTR or RTL).
   */
  public getDirection(): SelectionDirection {
    if (
      this.selectionStartLineNumber === this.startLineNumber &&
      this.selectionStartColumn === this.startColumn
    ) {
      return SelectionDirection.LTR;
    }
    return SelectionDirection.RTL;
  }

  /**
   * Create a new selection with a different `positionLineNumber` and `positionColumn`.
   */
  public override setEndPosition(
    endLineNumber: number,
    endColumn: number
  ): Selection {
    if (this.getDirection() === SelectionDirection.LTR) {
      return new Selection(
        this.startLineNumber,
        this.startColumn,
        endLineNumber,
        endColumn
      );
    }
    return new Selection(
      endLineNumber,
      endColumn,
      this.startLineNumber,
      this.startColumn
    );
  }

  /**
   * Get the position at `positionLineNumber` and `positionColumn`.
   */
  public getPosition(): Position {
    return new Position(this.positionLineNumber, this.positionColumn);
  }

  /**
   * Create a new selection with a different `selectionStartLineNumber` and `selectionStartColumn`.
   */
  public override setStartPosition(
    startLineNumber: number,
    startColumn: number
  ): Selection {
    if (this.getDirection() === SelectionDirection.LTR) {
      return new Selection(
        startLineNumber,
        startColumn,
        this.endLineNumber,
        this.endColumn
      );
    }
    return new Selection(
      this.endLineNumber,
      this.endColumn,
      startLineNumber,
      startColumn
    );
  }

  // ----

  /**
   * Create a `Selection` from one or two positions
   */
  public static override fromPositions(
    start: IPosition,
    end: IPosition = start
  ): Selection {
    return new Selection(
      start.lineNumber,
      start.column,
      end.lineNumber,
      end.column
    );
  }

  /**
   * Create a `Selection` from an `ISelection`.
   */
  public static liftSelection(sel: ISelection): Selection {
    return new Selection(
      sel.selectionStartLineNumber,
      sel.selectionStartColumn,
      sel.positionLineNumber,
      sel.positionColumn
    );
  }

  /**
   * `a` equals `b`.
   */
  public static selectionsArrEqual(a: ISelection[], b: ISelection[]): boolean {
    if ((a && !b) || (!a && b)) {
      return false;
    }
    if (!a && !b) {
      return true;
    }
    if (a.length !== b.length) {
      return false;
    }
    for (let i = 0, len = a.length; i < len; i++) {
      if (!this.selectionsEqual(a[i], b[i])) {
        return false;
      }
    }
    return true;
  }

  /**
   * Test if `obj` is an `ISelection`.
   */
  public static isISelection(obj: any): obj is ISelection {
    return (
      obj &&
      typeof obj.selectionStartLineNumber === 'number' &&
      typeof obj.selectionStartColumn === 'number' &&
      typeof obj.positionLineNumber === 'number' &&
      typeof obj.positionColumn === 'number'
    );
  }

  /**
   * Create with a direction.
   */
  public static createWithDirection(
    startLineNumber: number,
    startColumn: number,
    endLineNumber: number,
    endColumn: number,
    direction: SelectionDirection
  ): Selection {
    if (direction === SelectionDirection.LTR) {
      return new Selection(
        startLineNumber,
        startColumn,
        endLineNumber,
        endColumn
      );
    }

    return new Selection(
      endLineNumber,
      endColumn,
      startLineNumber,
      startColumn
    );
  }
}