/**
 * Copyright (c) 2020 The xterm.js authors. All rights reserved.
 * @license MIT
 */

import { ImageStorage, CELL_SIZE_DEFAULT } from './ImageStorage';
import { IImageAddonOptions, ITerminalExt, IAddImageOpts } from './Types';
import { ImageRenderer } from './ImageRenderer';

/**
 * Sixel-specific image storage controller.
 *
 * Wraps the shared ImageStorage with sixel protocol semantics:
 * - Cursor behavior governed by DECSET 80 (sixelScrolling option)
 * - advanceCursor for empty sixels carrying only height
 */
export class SixelImageStorage {
  private _addImageOpts: IAddImageOpts = { scrolling: true, layer: 'top', zIndex: 0, cursorPos: 'vt340' };
  constructor(
    private readonly _storage: ImageStorage,
    private readonly _opts: IImageAddonOptions,
    private readonly _renderer: ImageRenderer,
    private readonly _terminal: ITerminalExt
  ) {}

  /**
   * Add a sixel image to storage.
   * Cursor behavior depends on the sixelScrolling option (DECSET 80).
   */
  public addImage(img: HTMLCanvasElement | ImageBitmap): void {
    this._addImageOpts.scrolling = this._opts.sixelScrolling;
    this._storage.addImage(img, this._addImageOpts);
  }

  /**
   * Only advance text cursor.
   * This is an edge case from empty sixels carrying only a height but no pixels.
   * Partially fixes https://github.com/jerch/xterm-addon-image/issues/37.
   */
  public advanceCursor(height: number): void {
    if (this._opts.sixelScrolling) {
      let cellSize = this._renderer.cellSize;
      if (cellSize.width === -1 || cellSize.height === -1) {
        cellSize = CELL_SIZE_DEFAULT;
      }
      const rows = Math.ceil(height / cellSize.height);
      for (let i = 1; i < rows; ++i) {
        this._terminal._core._inputHandler.lineFeed();
      }
    }
  }
}