/**
 * Copyright (c) 2018 The xterm.js authors. All rights reserved.
 * @license MIT
 */

import type { Terminal } from '@jsnix/xterm';
import type { LigaturesAddon as ILigaturesApi } from '@xterm/addon-ligatures';
import { enableLigatures } from '.';
import { ILigatureOptions } from './Types';

export interface ITerminalAddon {
  activate(terminal: Terminal): void;
  dispose(): void;
}

export class LigaturesAddon implements ITerminalAddon, ILigaturesApi {
  private readonly _fallbackLigatures: string[];

  private _terminal: Terminal | undefined;
  private _characterJoinerId: number | undefined;

  constructor(options?: Partial<ILigatureOptions>) {
    this._fallbackLigatures = (options?.fallbackLigatures || [
      '<--', '<---', '<<-', '<-', '->', '->>', '-->', '--->',
      '<==', '<===', '<<=', '<=', '=>', '=>>', '==>', '===>', '>=', '>>=',
      '<->', '<-->', '<--->', '<---->', '<=>', '<==>', '<===>', '<====>', '-------->',
      '<~~', '<~', '~>', '~~>', '::', ':::', '==', '!=', '===', '!==',
      ':=', ':-', ':+', '<*', '<*>', '*>', '<|', '<|>', '|>', '+:', '-:', '=:', ':>',
      '++', '+++', '<!--', '<!---', '<***>'
    ]).sort((a, b) => b.length - a.length);
  }

  public activate(terminal: Terminal): void {
    if (!terminal.element) {
      throw new Error('Cannot activate LigaturesAddon before open is called');
    }
    this._terminal = terminal;
    this._characterJoinerId = enableLigatures(terminal, this._fallbackLigatures);
    terminal.element.style.fontFeatureSettings = '"liga" on, "calt" on';
  }

  public dispose(): void {
    if (this._characterJoinerId !== undefined) {
      this._terminal?.deregisterCharacterJoiner(this._characterJoinerId);
      this._characterJoinerId = undefined;
    }
    if (this._terminal?.element) {
      this._terminal.element.style.fontFeatureSettings = '';
    }
  }
}