export abstract class FrontCommand {
  protected request: Request;

  constructor(request: Request) {
    this.request = request;
  }

  abstract process(): Promise<Response>;

  /**
   * Helper to build a response by forwarding to a static file (the "view").
   */
  protected async forward(pathname: string): Promise<Response> {
    // Use Bun.file for optimized file serving.
    const file = Bun.file(`${import.meta.dir}/../${pathname}`);
    if (await file.exists()) {
      return new Response(file);
    }
    return new Response("Not Found", { status: 404 });
  }
}

export class ArtistCommand extends FrontCommand {
  async process(): Promise<Response> {
    const url = new URL(this.request.url);
    const artistName = url.searchParams.get("name");

    console.log(`Fetching data for artist: ${artistName}`);

    // The path is relative to the project root.
    return this.forward("views/artist.html");
  }
}

export class UnknownCommand extends FrontCommand {
  async process(): Promise<Response> {
    return new Response("Command not found.", { status: 404 });
  }
}

type CommandConstructor = new (request: Request) => FrontCommand;

export class FrontController {
  public async handle(request: Request): Promise<Response> {
    const Command = await this.getCommandClass(request);
    const commandInstance = new Command(request);
    return commandInstance.process();
  }

  private async getCommandClass(request: Request): Promise<CommandConstructor> {
    const url = new URL(request.url);
    const commandName = url.searchParams.get("command");

    switch (commandName?.toLowerCase()) {
      case "artist":
        return ArtistCommand;
      default:
        return UnknownCommand;
    }
  }
}

const controller = new FrontController();
const port = 3000;

Bun.serve({
  port,
  fetch: (request) => controller.handle(request)
});

console.log(`Server running with Bun at http://localhost:${port}`);