import type { ZodType } from 'zod';
import {
  botStatsSchema,
  controlResponseSchema,
  timersSchema,
  type BotStats,
  type ControlResponse,
  type Timers,
} from './contracts.js';
import { createDashboardRequest } from './request.js';

export class ApiError extends Error {
  constructor(
    message: string,
    readonly status: number,
  ) {
    super(message);
    this.name = 'ApiError';
  }
}

interface ErrorPayload {
  error?: unknown;
}

async function parseResponse<T>(response: Response, schema: ZodType<T>): Promise<T> {
  const payload: unknown = await response.json();
  if (!response.ok) {
    const errorPayload = payload as ErrorPayload;
    const message = typeof errorPayload.error === 'string' ? errorPayload.error : `Request failed (${response.status})`;
    throw new ApiError(message, response.status);
  }
  return schema.parse(payload);
}

export interface DashboardApi {
  getStats(): Promise<BotStats>;
  getTimers(): Promise<Timers>;
  setRunning(isRunning: boolean): Promise<ControlResponse>;
}

export function createDashboardApi(fetchImplementation?: typeof fetch): DashboardApi {
  const request = createDashboardRequest(fetchImplementation);

  return {
    async getStats() {
      return parseResponse(await request('/api/stats'), botStatsSchema);
    },
    async getTimers() {
      return parseResponse(await request('/api/timers'), timersSchema);
    },
    async setRunning(isRunning) {
      const endpoint = isRunning ? '/api/start' : '/api/stop';
      return parseResponse(await request(endpoint, { method: 'POST' }), controlResponseSchema);
    },
  };
}

export const dashboardApi = createDashboardApi();