import type { ApiSettings } from "../types";

const STORAGE_KEY = "multimailer.apiSettings";

export function loadApiSettings(): ApiSettings {
  const storedBaseUrl = localStorage.getItem(`${STORAGE_KEY}.baseUrl`);

  return {
    // Empty base URL means "same origin". In Vite dev, /api is proxied to FastAPI.
    apiBaseUrl:
      storedBaseUrl !== null
        ? storedBaseUrl
        : import.meta.env.VITE_API_BASE_URL ?? "",
    apiKey: localStorage.getItem(`${STORAGE_KEY}.apiKey`) || "",
    accessToken: localStorage.getItem(`${STORAGE_KEY}.accessToken`) || ""
  };
}

export function saveApiSettings(settings: ApiSettings): void {
  localStorage.setItem(`${STORAGE_KEY}.baseUrl`, settings.apiBaseUrl);
  localStorage.setItem(`${STORAGE_KEY}.apiKey`, settings.apiKey);
  localStorage.setItem(`${STORAGE_KEY}.accessToken`, settings.accessToken);
}

export function clearAccessToken(): void {
  localStorage.removeItem(`${STORAGE_KEY}.accessToken`);
}

export async function apiFetch<T>(settings: ApiSettings, path: string, init?: RequestInit): Promise<T> {
  const baseUrl = settings.apiBaseUrl.trim().replace(/\/$/, "");
  const url = baseUrl ? `${baseUrl}${path}` : path;

  const headers = new Headers(init?.headers || {});

  if (!(init?.body instanceof FormData) && !headers.has("Content-Type")) {
    headers.set("Content-Type", "application/json");
  }

  if (settings.accessToken) {
    headers.set("Authorization", `Bearer ${settings.accessToken}`);
  } else if (settings.apiKey) {
    headers.set("X-API-Key", settings.apiKey);
  }

  const response = await fetch(url, { ...init, headers });

  if (!response.ok) {
    const text = await response.text();
    throw new Error(`${response.status} ${response.statusText}: ${text}`);
  }

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

  const contentType = response.headers.get("content-type") || "";
  if (!contentType.includes("application/json")) {
    return (await response.text()) as T;
  }

  return (await response.json()) as T;
}