const API_URL = process.env.NEXT_PUBLIC_API_URL ?? "http://localhost:8000";

export type Song = {
  id: string;
  user_id: string;
  owner_display_name: string | null;
  title: string;
  prompt: string;
  lyrics: string | null;
  mode: "instrumental" | "vocals";
  status: "pending" | "processing" | "completed" | "failed";
  error_message: string | null;
  duration_seconds: number | null;
  cover_seed: number;
  is_public: boolean;
  like_count: number;
  liked_by_me: boolean;
  audio_url: string | null;
  created_at: string;
};

export type User = {
  id: string;
  email: string;
  display_name: string;
  created_at: string;
};

class ApiError extends Error {
  status: number;
  constructor(status: number, message: string) {
    super(message);
    this.status = status;
  }
}

function getToken(): string | null {
  if (typeof window === "undefined") return null;
  return window.localStorage.getItem("aurora_token");
}

export function setToken(token: string | null) {
  if (typeof window === "undefined") return;
  if (token) window.localStorage.setItem("aurora_token", token);
  else window.localStorage.removeItem("aurora_token");
}

async function request<T>(path: string, options: RequestInit = {}): Promise<T> {
  const token = getToken();
  const headers: Record<string, string> = {
    "Content-Type": "application/json",
    ...(options.headers as Record<string, string> | undefined),
  };
  if (token) headers["Authorization"] = `Bearer ${token}`;

  const res = await fetch(`${API_URL}${path}`, { ...options, headers });

  if (!res.ok) {
    let detail = res.statusText;
    try {
      const body = await res.json();
      detail = body.detail ?? detail;
    } catch {
      // ignore
    }
    throw new ApiError(res.status, typeof detail === "string" ? detail : JSON.stringify(detail));
  }

  if (res.status === 204) return undefined as T;
  return res.json() as Promise<T>;
}

export function mediaUrl(audioUrl: string | null): string | null {
  if (!audioUrl) return null;
  return `${API_URL}${audioUrl}`;
}

export const api = {
  signup: (email: string, password: string, display_name: string) =>
    request<{ access_token: string }>("/auth/signup", {
      method: "POST",
      body: JSON.stringify({ email, password, display_name }),
    }),
  login: (email: string, password: string) =>
    request<{ access_token: string }>("/auth/login", {
      method: "POST",
      body: JSON.stringify({ email, password }),
    }),
  me: () => request<User>("/auth/me"),
  createSong: (payload: {
    title: string;
    prompt: string;
    mode: "instrumental" | "vocals";
    lyrics?: string | null;
    is_public: boolean;
  }) => request<Song>("/songs", { method: "POST", body: JSON.stringify(payload) }),
  mySongs: () => request<{ items: Song[]; total: number }>("/songs/mine"),
  feed: () => request<{ items: Song[]; total: number }>("/songs/feed"),
  getSong: (id: string) => request<Song>(`/songs/${id}`),
  updateSong: (id: string, payload: { title?: string; is_public?: boolean }) =>
    request<Song>(`/songs/${id}`, { method: "PATCH", body: JSON.stringify(payload) }),
  deleteSong: (id: string) => request<void>(`/songs/${id}`, { method: "DELETE" }),
  likeSong: (id: string) => request<Song>(`/songs/${id}/like`, { method: "POST" }),
  unlikeSong: (id: string) => request<Song>(`/songs/${id}/like`, { method: "DELETE" }),
};

export { ApiError };