import type { AxiosInstance, AxiosResponse } from 'axios';
import { type Fetcher, type Method, createApiClient } from '../generated/api-client/api-client';
import { TanstackQueryApiClient } from '../generated/api-client/tanstack-client';

const API_BASE_URL: string | undefined = import.meta.env.VITE_API_BASE_URL;

const get_fetch: (axios: AxiosInstance) => Fetcher['fetch'] =
  (axios) =>
  async ({ method, url: incomingUrl, parameters: params }) => {
    // Use a plain object for Axios headers
    const headers: Record<string, string> = {};

    // Replace path parameters (supports both {param} and :param formats)
    const actualUrl = replacePathParams(incomingUrl.toString(), (params?.path ?? {}) as Record<string, string>);
    const url = new URL(actualUrl);

    // Handle query parameters
    if (params?.query) {
      const searchParams = new URLSearchParams();
      Object.entries(params.query).forEach(([key, value]) => {
        if (value != null) {
          // Skip null/undefined values
          if (Array.isArray(value)) {
            value.forEach((val) => val != null && searchParams.append(key, String(val)));
          } else {
            searchParams.append(key, String(value));
          }
        }
      });
      url.search = searchParams.toString();
    }

    // Handle request body for mutation methods (use Axios `data`)
    const data = (['post', 'put', 'patch', 'delete'] satisfies Method[] as string[]).includes(method.toLowerCase()) ? params?.body : undefined;

    if (data != null) {
      headers['Content-Type'] = 'application/json';
    }

    // Add custom headers
    if (params?.header) {
      Object.entries(params.header).forEach(([key, value]) => {
        if (value != null) {
          headers[key] = String(value);
        }
      });
    }

    const response = await axios(url.toString(), {
      method: method.toUpperCase(),
      ...(data !== undefined && { data }),
      headers: headers,
    });

    return axiosResponseToFetchResponse(response);
  };

function axiosResponseToFetchResponse(response: AxiosResponse): Response {
  const headers = new Headers();
  Object.entries(response.headers).forEach(([key, value]) => {
    if (Array.isArray(value)) {
      value.forEach((val) => headers.append(key, val));
    } else {
      headers.append(key, value);
    }
  });

  return new Response(response.data, {
    status: response.status,
    statusText: response.statusText,
    headers: headers,
  });
}

/**
 * Replace path parameters in URL
 * Supports both OpenAPI format {param} and Express format :param
 */
function replacePathParams(url: string, params: Record<string, string>): string {
  return url.replace(/{(\w+)}/g, (_, key: string) => params[key] || `{${key}}`).replace(/:([a-zA-Z0-9_]+)/g, (_, key: string) => params[key] || `:${key}`);
}

export function createApi(axios: AxiosInstance) {
  return createApiClient(
    {
      fetch: get_fetch(axios),
    },
    API_BASE_URL ?? window.location.origin
  );
}

export function createTanstackApi(axios: AxiosInstance) {
  return new TanstackQueryApiClient(createApi(axios));
}