import { ApiError } from "@/types";

const API_BASE_URL = process.env.NEXT_PUBLIC_API_URL || "http://localhost:8000";

class ApiClient {
  private baseUrl: string;

  constructor(baseUrl: string) {
    this.baseUrl = baseUrl;
  }

  private async request<T>(
    method: string,
    path: string,
    options?: {
      body?: unknown;
      params?: Record<string, string | number | boolean | undefined | null>;
    }
  ): Promise<T> {
    const url = new URL(`${this.baseUrl}${path}`);

    if (options?.params) {
      Object.entries(options.params).forEach(([key, value]) => {
        if (value !== undefined && value !== null) {
          url.searchParams.set(key, String(value));
        }
      });
    }

    const res = await fetch(url.toString(), {
      method,
      headers: {
        "Content-Type": "application/json",
      },
      body: options?.body ? JSON.stringify(options.body) : undefined,
    });

    if (res.status === 204) {
      return undefined as T;
    }

    if (!res.ok) {
      const error = await res
        .json()
        .catch(() => ({ detail: "알 수 없는 오류가 발생했습니다" }));
      throw {
        detail: error.detail || `HTTP ${res.status} Error`,
        status: res.status,
      } as ApiError;
    }

    return res.json();
  }

  get<T>(
    path: string,
    params?: Record<string, string | number | boolean | undefined | null>
  ) {
    return this.request<T>("GET", path, { params });
  }

  post<T>(path: string, body?: unknown) {
    return this.request<T>("POST", path, { body });
  }

  put<T>(path: string, body?: unknown) {
    return this.request<T>("PUT", path, { body });
  }

  patch<T>(path: string, body?: unknown) {
    return this.request<T>("PATCH", path, { body });
  }

  delete<T>(path: string) {
    return this.request<T>("DELETE", path);
  }

  async uploadFiles<T>(path: string, files: File[]): Promise<T> {
    const url = new URL(`${this.baseUrl}${path}`);
    const formData = new FormData();
    files.forEach((file) => formData.append("files", file));

    const res = await fetch(url.toString(), {
      method: "POST",
      body: formData,
    });

    if (!res.ok) {
      const error = await res
        .json()
        .catch(() => ({ detail: "파일 업로드에 실패했습니다" }));
      throw {
        detail: error.detail || `HTTP ${res.status} Error`,
        status: res.status,
      } as ApiError;
    }

    return res.json();
  }

  async downloadFile(path: string, filename: string): Promise<void> {
    const url = new URL(`${this.baseUrl}${path}`);
    const res = await fetch(url.toString());

    if (!res.ok) {
      throw new Error("다운로드에 실패했습니다");
    }

    const blob = await res.blob();
    const downloadUrl = window.URL.createObjectURL(blob);
    const link = document.createElement("a");
    link.href = downloadUrl;
    link.download = filename;
    document.body.appendChild(link);
    link.click();
    link.remove();
    window.URL.revokeObjectURL(downloadUrl);
  }
}

export const apiClient = new ApiClient(API_BASE_URL);