import { CallHandler, ExecutionContext, Injectable, NestInterceptor } from '@nestjs/common';
import { Observable } from 'rxjs';
import { map } from 'rxjs/operators';

/** 递归将 Date 转为 Unix 毫秒 number（API 时间契约：统一毫秒时间戳）。 */
function toUnixMs(value: unknown): unknown {
  if (value instanceof Date) return value.getTime();
  if (Array.isArray(value)) return value.map(toUnixMs);
  if (value && typeof value === 'object') {
    const out: Record<string, unknown> = {};
    for (const [k, v] of Object.entries(value as Record<string, unknown>)) out[k] = toUnixMs(v);
    return out;
  }
  return value;
}

/**
 * 统一响应封装：{ code, message, data }，成功 code = 0；时间统一 Unix 毫秒。
 */
@Injectable()
export class TransformInterceptor<T> implements NestInterceptor<T, unknown> {
  intercept(_context: ExecutionContext, next: CallHandler<T>): Observable<unknown> {
    return next.handle().pipe(map((data) => ({ code: 0, message: 'ok', data: toUnixMs(data ?? null) })));
  }
}