import axios, {
  type AxiosError,
  type AxiosInstance,
  type AxiosRequestConfig,
  type InternalAxiosRequestConfig,
} from "axios";

import type { ApiEnvelope, ApiErrorEnvelope, AuthTokens } from "@geo/shared-types";

export interface AuthBindings {
  getAccessToken: () => string | null;
  getRefreshToken: () => string | null;
  setTokens: (tokens: AuthTokens) => void;
  clearTokens: () => void;
  refresh: (refreshToken: string) => Promise<AuthTokens>;
}

export interface CreateApiClientOptions {
  baseURL?: string;
  timeoutMs?: number;
  auth?: AuthBindings;
}

export class ApiClientError extends Error {
  status?: number;
  code: number;
  detail?: string;
  requestId?: string;

  constructor(input: {
    message: string;
    code?: number;
    status?: number;
    detail?: string;
    requestId?: string;
  }) {
    super(input.message);
    this.name = "ApiClientError";
    this.code = input.code ?? 50000;
    this.status = input.status;
    this.detail = input.detail;
    this.requestId = input.requestId;
  }
}

export interface ApiClient {
  raw: AxiosInstance;
  get: <T>(url: string, config?: AxiosRequestConfig) => Promise<T>;
  post: <T, B = unknown>(url: string, body?: B, config?: AxiosRequestConfig) => Promise<T>;
  put: <T, B = unknown>(url: string, body?: B, config?: AxiosRequestConfig) => Promise<T>;
  remove: <T>(url: string, config?: AxiosRequestConfig) => Promise<T>;
}

function normalizeError(error: unknown): ApiClientError {
  if (error instanceof ApiClientError) {
    return error;
  }

  if (axios.isAxiosError(error)) {
    const payload = error.response?.data as Partial<ApiErrorEnvelope> | undefined;
    return new ApiClientError({
      message: payload?.message ?? error.message ?? "network_error",
      code: payload?.code ?? 50000,
      status: error.response?.status,
      detail: payload?.detail,
      requestId: payload?.request_id,
    });
  }

  if (error instanceof Error) {
    return new ApiClientError({ message: error.message });
  }

  return new ApiClientError({ message: "unknown_error" });
}

function unwrapEnvelope<T>(response: { data: ApiEnvelope<T> }): T {
  return response.data.data;
}

export function createApiClient(options: CreateApiClientOptions = {}): ApiClient {
  const client = axios.create({
    baseURL: options.baseURL ?? "",
    timeout: options.timeoutMs ?? 15000,
    withCredentials: false,
  });

  const auth = options.auth;
  let refreshPromise: Promise<AuthTokens> | null = null;

  client.interceptors.request.use((config) => {
    if (!auth) {
      return config;
    }

    const accessToken = auth.getAccessToken();
    if (accessToken) {
      config.headers = config.headers ?? {};
      (config.headers as Record<string, string>).Authorization = `Bearer ${accessToken}`;
    }

    return config;
  });

  client.interceptors.response.use(
    (response) => response,
    async (error: AxiosError<ApiErrorEnvelope>) => {
      if (auth && error.response?.status === 401 && error.config) {
        const originalRequest = error.config as InternalAxiosRequestConfig & {
          _retry?: boolean;
        };
        const refreshToken = auth.getRefreshToken();

        if (refreshToken && !originalRequest._retry) {
          originalRequest._retry = true;

          try {
            if (!refreshPromise) {
              refreshPromise = auth
                .refresh(refreshToken)
                .then((tokens) => {
                  auth.setTokens(tokens);
                  return tokens;
                })
                .finally(() => {
                  refreshPromise = null;
                });
            }

            const nextTokens = await refreshPromise;
            originalRequest.headers = originalRequest.headers ?? {};
            (originalRequest.headers as Record<string, string>).Authorization =
              `Bearer ${nextTokens.accessToken}`;
            return client.request(originalRequest);
          } catch (refreshError) {
            auth.clearTokens();
            throw normalizeError(refreshError);
          }
        }

        auth.clearTokens();
      }

      throw normalizeError(error);
    },
  );

  return {
    raw: client,
    async get<T>(url: string, config?: AxiosRequestConfig) {
      return unwrapEnvelope(await client.get<ApiEnvelope<T>>(url, config));
    },
    async post<T, B = unknown>(url: string, body?: B, config?: AxiosRequestConfig) {
      return unwrapEnvelope(await client.post<ApiEnvelope<T>>(url, body, config));
    },
    async put<T, B = unknown>(url: string, body?: B, config?: AxiosRequestConfig) {
      return unwrapEnvelope(await client.put<ApiEnvelope<T>>(url, body, config));
    },
    async remove<T>(url: string, config?: AxiosRequestConfig) {
      return unwrapEnvelope(await client.delete<ApiEnvelope<T>>(url, config));
    },
  };
}