// 명령 인터페이스
interface Command {
  execute(): boolean;
  undo(): void;
}

// 추상 명령 클래스 (공통 기능 포함)
abstract class EditorCommand implements Command {
  protected app: Application;
  protected editor: Editor;
  protected backup: string = "";

  constructor(app: Application, editor: Editor) {
    this.app = app;
    this.editor = editor;
  }

  // 에디터 상태 백업
  saveBackup(): void {
    this.backup = this.editor.text;
  }

  // 상태 복원
  undo(): void {
    this.editor.text = this.backup;
  }

  abstract execute(): boolean;
}

// 복사 명령 - 상태를 변경하지 않으므로 히스토리에 저장하지 않음
class CopyCommand extends EditorCommand {
  execute(): boolean {
    this.app.clipboard = this.editor.getSelection();
    return false; // 히스토리에 저장하지 않음
  }
}

// 잘라내기 명령 - 상태를 변경하므로 히스토리에 저장
class CutCommand extends EditorCommand {
  execute(): boolean {
    this.saveBackup();
    this.app.clipboard = this.editor.getSelection();
    this.editor.deleteSelection();
    return true; // 히스토리에 저장
  }
}

// 붙여넣기 명령
class PasteCommand extends EditorCommand {
  execute(): boolean {
    this.saveBackup();
    this.editor.replaceSelection(this.app.clipboard);
    return true;
  }
}

// 실행 취소 명령
class UndoCommand extends EditorCommand {
  execute(): boolean {
    this.app.undo();
    return false;
  }
}

// 명령 히스토리 (스택)
class CommandHistory {
  private history: Command[] = [];

  push(command: Command): void {
    this.history.push(command);
  }

  pop(): Command | undefined {
    return this.history.pop();
  }

  isEmpty(): boolean {
    return this.history.length === 0;
  }
}

// 에디터 클래스 (Receiver)
class Editor {
  text: string = "";

  getSelection(): string {
    // 선택된 텍스트 반환
    return "selected text";
  }

  deleteSelection(): void {
    // 선택된 텍스트 삭제
  }

  replaceSelection(text: string): void {
    // 선택 영역을 주어진 텍스트로 교체
  }
}

// 애플리케이션 클래스 (Sender/Invoker)
class Application {
  clipboard: string = "";
  editors: Editor[] = [];
  activeEditor: Editor;
  history: CommandHistory = new CommandHistory();

  constructor() {
    this.activeEditor = new Editor();
    this.editors.push(this.activeEditor);
  }

  // UI 생성 및 명령 바인딩
  createUI(): void {
    // 복사 버튼
    const copyButton = document.getElementById("copy");
    copyButton?.addEventListener("click", () => {
      this.executeCommand(new CopyCommand(this, this.activeEditor));
    });

    // 잘라내기 버튼
    const cutButton = document.getElementById("cut");
    cutButton?.addEventListener("click", () => {
      this.executeCommand(new CutCommand(this, this.activeEditor));
    });

    // 붙여넣기 버튼
    const pasteButton = document.getElementById("paste");
    pasteButton?.addEventListener("click", () => {
      this.executeCommand(new PasteCommand(this, this.activeEditor));
    });

    // 실행 취소 버튼
    const undoButton = document.getElementById("undo");
    undoButton?.addEventListener("click", () => {
      this.executeCommand(new UndoCommand(this, this.activeEditor));
    });

    // 키보드 단축키
    document.addEventListener("keydown", (e) => {
      if (e.ctrlKey && e.key === "c") {
        this.executeCommand(new CopyCommand(this, this.activeEditor));
      }
      if (e.ctrlKey && e.key === "x") {
        this.executeCommand(new CutCommand(this, this.activeEditor));
      }
      if (e.ctrlKey && e.key === "v") {
        this.executeCommand(new PasteCommand(this, this.activeEditor));
      }
      if (e.ctrlKey && e.key === "z") {
        this.executeCommand(new UndoCommand(this, this.activeEditor));
      }
    });
  }

  // 명령 실행
  executeCommand(command: Command): void {
    if (command.execute()) {
      this.history.push(command);
    }
  }

  // 실행 취소
  undo(): void {
    const command = this.history.pop();
    if (command) {
      command.undo();
    }
  }
}