export abstract class HttpError extends Error {
  abstract readonly status: number;
  abstract readonly code: string;

  constructor(message: string, readonly details?: unknown) {
    super(message);
    this.name = new.target.name;
  }

  toJSON() {
    return {
      error: {
        code: this.code,
        message: this.message,
        details: this.details,
      },
    };
  }
}

export class BadRequestError extends HttpError {
  readonly status = 400;
  readonly code = "BAD_REQUEST";
}

export class UnauthorizedError extends HttpError {
  readonly status = 401;
  readonly code = "UNAUTHORIZED";
}

export class ForbiddenError extends HttpError {
  readonly status = 403;
  readonly code = "FORBIDDEN";
}

export class NotFoundError extends HttpError {
  readonly status = 404;
  readonly code = "NOT_FOUND";
}

export class ConflictError extends HttpError {
  readonly status = 409;
  readonly code = "CONFLICT";
}

export class InternalError extends HttpError {
  readonly status = 500;
  readonly code = "INTERNAL_ERROR";
}

interface ElysiaErrorContext {
  code: string | number;
  error: unknown;
  set: { status?: number | string };
}

/**
 * Drop-in handler for Elysia's `.onError()`. Maps our HttpError hierarchy,
 * Elysia's built-in error codes, and anything unrecognized to a consistent
 * `{ error: { code, message, details? } }` JSON body.
 */
export function toErrorResponse({ code, error, set }: ElysiaErrorContext) {
  if (error instanceof HttpError) {
    set.status = error.status;
    return error.toJSON();
  }

  if (code === "VALIDATION") {
    set.status = 422;
    return {
      error: {
        code: "VALIDATION",
        message: error instanceof Error ? error.message : "validation failed",
      },
    };
  }

  if (code === "NOT_FOUND") {
    set.status = 404;
    return { error: { code: "NOT_FOUND", message: "not found" } };
  }

  set.status = 500;
  return {
    error: {
      code: "INTERNAL_ERROR",
      message: error instanceof Error ? error.message : "internal server error",
    },
  };
}