import type { ApiErrorCode, ApiResponse } from "@/api/contracts/common";

export type MockClientOptions = {
  latencyMs?: number;
  errorRate?: number;
};

const defaultOptions: Required<MockClientOptions> = {
  latencyMs: 45,
  errorRate: 0,
};

let options = defaultOptions;

export function configureMockClient(next: MockClientOptions) {
  options = { ...options, ...next };
}

export async function mockResponse<T>(
  data: T,
  overrides?: { errorCode?: ApiErrorCode; message?: string; latencyMs?: number },
): Promise<ApiResponse<T>> {
  const latencyMs = overrides?.latencyMs ?? options.latencyMs;
  await new Promise((resolve) => setTimeout(resolve, latencyMs));
  const requestId = `req_${Math.random().toString(16).slice(2, 10)}`;
  if (overrides?.errorCode || Math.random() < options.errorRate) {
    return {
      data: null,
      meta: { requestId, latencyMs },
      error: {
        code: overrides?.errorCode ?? "NETWORK_ERROR",
        message: overrides?.message ?? "The mock service could not complete the request.",
      },
    };
  }
  return {
    data,
    meta: { requestId, latencyMs },
    error: null,
  };
}