const API_BASE = typeof window !== "undefined" ? "" : (process.env.NEXT_PUBLIC_API_URL || "http://localhost:3000");

interface ApiOptions {
  method?: string;
  body?: unknown;
  token?: string;
}

async function apiFetch<T>(path: string, opts: ApiOptions = {}): Promise<T> {
  const headers: Record<string, string> = {
    "Content-Type": "application/json",
  };
  if (opts.token) {
    headers["Authorization"] = `Bearer ${opts.token}`;
  }

  const url = `${API_BASE}${path}`;
  const res = await fetch(url, {
    method: opts.method || "GET",
    headers,
    body: opts.body ? JSON.stringify(opts.body) : undefined,
    cache: "no-store",
  });

  if (!res.ok) {
    const err = await res.json().catch(() => ({ message: res.statusText }));
    throw new Error(err.message || err.error || `HTTP ${res.status}`);
  }

  if (res.status === 204 || res.headers.get("content-length") === "0") {
    return {} as T;
  }

  return res.json();
}

// Auth
export function register(data: { email: string; name: string; phone?: string }) {
  return apiFetch<{ token: string; user: User }>("/api/v1/auth/register", {
    method: "POST",
    body: data,
  });
}

export function login(data: { email: string; password?: string }) {
  return apiFetch<{ token: string; user: User }>("/api/v1/auth/login", {
    method: "POST",
    body: data,
  });
}

export function getMe(token: string) {
  return apiFetch<{ user: User }>("/api/v1/auth/me", { token });
}

// Tasks
export function getTasks(token: string, params?: Record<string, string>) {
  const qs = params ? "?" + new URLSearchParams(params).toString() : "";
  return apiFetch<{ data: Task[]; total: number }>(`/api/v1/tasks${qs}`, { token });
}

export function getTask(token: string, id: string) {
  return apiFetch<Task>(`/api/v1/tasks/${id}`, { token });
}

export function createTask(token: string, data: Partial<Task>) {
  return apiFetch<Task>("/api/v1/tasks", { method: "POST", body: data, token });
}

export function updateTask(token: string, id: string, data: Partial<Task>) {
  return apiFetch<Task>(`/api/v1/tasks/${id}`, { method: "PUT", body: data, token });
}

export function deleteTask(token: string, id: string) {
  return apiFetch<void>(`/api/v1/tasks/${id}`, { method: "DELETE", token });
}

// Groups
export function getGroups(token: string) {
  return apiFetch<{ data: Group[] }>("/api/v1/groups", { token });
}

export function createGroup(token: string, data: Partial<Group>) {
  return apiFetch<Group>("/api/v1/groups", { method: "POST", body: data, token });
}

export function updateGroup(token: string, id: string, data: Partial<Group>) {
  return apiFetch<Group>(`/api/v1/groups/${id}`, { method: "PUT", body: data, token });
}

export function deleteGroup(token: string, id: string) {
  return apiFetch<void>(`/api/v1/groups/${id}`, { method: "DELETE", token });
}

export function reorderGroups(token: string, ids: string[]) {
  return apiFetch<void>("/api/v1/groups/reorder", { method: "PUT", body: { ids }, token });
}

// Connectors
export function getConnectors(token: string) {
  return apiFetch<{ data: Connector[] }>("/api/v1/connectors", { token });
}

export function createConnector(token: string, data: Partial<Connector>) {
  return apiFetch<Connector>("/api/v1/connectors", { method: "POST", body: data, token });
}

// Types
export interface User {
  id: string;
  email: string;
  name: string;
  phone?: string;
}

export interface Task {
  id: string;
  user_id: string | null;
  group_id: string | null;
  title: string;
  description: string;
  status: "pending" | "in_progress" | "done" | "cancelled";
  priority: "low" | "medium" | "high" | "urgent";
  scheduled_at: string | null;
  due_at: string | null;
  completed_at: string | null;
  assigned_to: string[];
  attachments: string[];
  external_id: string | null;
  external_source: string | null;
  created_at: string;
  updated_at: string;
  group_name: string | null;
  group_color: string | null;
  group_icon: string | null;
}

export interface Group {
  id: string;
  name: string;
  color: string;
  icon: string | null;
  sort_order: number;
}

export interface Connector {
  id: string;
  name: string;
  type: string;
  config: Record<string, unknown>;
}