export type DevelopmentRuntimeSignal =
  | Readonly<{ kind: "buildStarted"; buildVersion?: string }>
  | Readonly<{ kind: "buildCompleted"; buildVersion?: string }>
  | Readonly<{ kind: "buildFailed"; message: string }>;

export class DevelopmentRuntimeRouteGuard {
  static isAuthorized(request: Request): boolean {
    if (this.isLoopbackRequest(request)) {
      return true;
    }
    const expectedToken = process.env.CODEMATION_DEV_SERVER_TOKEN;
    if (!expectedToken) {
      return true;
    }
    return request.headers.get("x-codemation-dev-token") === expectedToken;
  }

  private static isLoopbackRequest(request: Request): boolean {
    const requestUrl = new URL(request.url);
    return requestUrl.hostname === "127.0.0.1" || requestUrl.hostname === "localhost" || requestUrl.hostname === "::1";
  }

  static async parseSignal(request: Request): Promise<DevelopmentRuntimeSignal> {
    const payload = (await request.json()) as Readonly<{
      kind?: unknown;
      buildVersion?: unknown;
      message?: unknown;
    }>;
    return DevelopmentRuntimeRouteGuard.parseSignalFromPayload(payload);
  }

  static parseSignalFromPayload(
    payload: Readonly<{
      kind?: unknown;
      buildVersion?: unknown;
      message?: unknown;
    }>,
  ): DevelopmentRuntimeSignal {
    if (payload.kind === "buildStarted") {
      return {
        kind: payload.kind,
        buildVersion: typeof payload.buildVersion === "string" ? payload.buildVersion : undefined,
      };
    }
    if (payload.kind === "buildCompleted") {
      return {
        kind: payload.kind,
        buildVersion: typeof payload.buildVersion === "string" ? payload.buildVersion : undefined,
      };
    }
    if (payload.kind === "buildFailed" && typeof payload.message === "string" && payload.message.length > 0) {
      return {
        kind: payload.kind,
        message: payload.message,
      };
    }
    throw new Error("Unsupported development runtime signal.");
  }
}