const API_BASE = import.meta.env.VITE_API_URL ?? 'http://localhost:3001';

let authToken: string | null = localStorage.getItem('token-empire-auth-token');

export function setAuthToken(token: string) {
  authToken = token;
  localStorage.setItem('token-empire-auth-token', token);
}

export function getAuthToken() {
  return authToken;
}

export function clearAuthToken() {
  authToken = null;
  localStorage.removeItem('token-empire-auth-token');
}

export interface TokenPayload {
  sub: string;
  email: string | null;
  role: string;
  username: string | null;
  mustResetPassword: boolean;
}

export function decodeTokenPayload(token: string): TokenPayload | null {
  try {
    const parts = token.split('.');
    if (parts.length !== 3) return null;
    const payload = JSON.parse(atob(parts[1].replace(/-/g, '+').replace(/_/g, '/')));
    return {
      sub: payload.sub,
      email: payload.email ?? null,
      role: payload.role ?? 'user',
      username: payload.username ?? null,
      mustResetPassword: payload.mustResetPassword ?? false,
    };
  } catch {
    return null;
  }
}

export function getTokenPayload(): TokenPayload | null {
  const token = getAuthToken();
  if (!token) return null;
  return decodeTokenPayload(token);
}

export function isRegistered(): boolean {
  const payload = getTokenPayload();
  if (!payload) return false;
  return payload.email != null || payload.role === 'admin';
}

export function isAdmin(): boolean {
  const payload = getTokenPayload();
  return payload?.role === 'admin';
}

export function needsPasswordReset(): boolean {
  const payload = getTokenPayload();
  return payload?.mustResetPassword === true;
}

async function request<T>(path: string, options: RequestInit & { timeoutMs?: number } = {}): Promise<T> {
  const { timeoutMs = 10_000, ...fetchOptions } = options;

  const headers: Record<string, string> = {
    'Content-Type': 'application/json',
    ...(fetchOptions.headers as Record<string, string>),
  };

  if (authToken) {
    headers['Authorization'] = `Bearer ${authToken}`;
  }

  const controller = new AbortController();
  const timeout = setTimeout(() => controller.abort(), timeoutMs);

  try {
    const res = await fetch(`${API_BASE}${path}`, {
      ...fetchOptions,
      headers,
      signal: controller.signal,
    });

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

    return res.json();
  } catch (e) {
    if (e instanceof DOMException && e.name === 'AbortError') {
      throw new Error('Request timed out — server may be unreachable');
    }
    if (e instanceof TypeError) {
      throw new Error('Network error — server may be unreachable');
    }
    throw e;
  } finally {
    clearTimeout(timeout);
  }
}

export function validateStoredToken(): void {
  const token = getAuthToken();
  if (token && !decodeTokenPayload(token)) {
    clearAuthToken();
  }
}

export const api = {
  health: () => request<{ status: string }>('/api/health', { timeoutMs: 5_000 }),
  auth: {
    anonymous: () => request<{ userId: string; token: string }>('/api/auth/anonymous', { method: 'POST' }),
    login: (login: string, password: string) =>
      request<{ userId: string; token: string }>('/api/auth/login', {
        method: 'POST',
        body: JSON.stringify({ login, password }),
      }),
    register: (email: string, password: string, inviteCode: string) =>
      request<{ userId: string; token: string }>('/api/auth/register', {
        method: 'POST',
        body: JSON.stringify({ email, password, inviteCode }),
      }),
    changePassword: (newPassword: string, currentPassword?: string) =>
      request<{ success: boolean; token: string }>('/api/auth/change-password', {
        method: 'POST',
        body: JSON.stringify({ newPassword, currentPassword }),
      }),
    changeUsername: (username: string) =>
      request<{ success: boolean; token: string }>('/api/auth/change-username', {
        method: 'POST',
        body: JSON.stringify({ username }),
      }),
    changeEmail: (email: string, currentPassword: string) =>
      request<{ success: boolean; token: string }>('/api/auth/change-email', {
        method: 'POST',
        body: JSON.stringify({ email, currentPassword }),
      }),
  },
  config: {
    get: () => request<{ requireInvite: boolean; userInvitations: number }>('/api/config'),
  },
  invites: {
    create: () => request<{ code: string }>('/api/invites', { method: 'POST' }),
    validate: (code: string) => request<{ valid: boolean }>(`/api/invites/validate/${encodeURIComponent(code)}`),
    list: () => request<{
      invitations: Array<{
        id: string;
        code: string;
        createdBy: { username: string | null; email: string | null };
        usedBy: { username: string | null; email: string | null } | null;
        createdAt: string;
        expiresAt: string | null;
        used: boolean;
      }>;
    }>('/api/invites'),
    remaining: () => request<{ remaining: number }>('/api/invites/remaining'),
    revoke: (id: string) => request<{ deleted: boolean }>(`/api/invites/${id}`, { method: 'DELETE' }),
  },
  saves: {
    list: () => request<{ saves: Array<{ id: string; companyName: string; era: string; tickCount: number; updatedAt: string }> }>('/api/saves'),
    get: (id: string) => request<{ save: { id: string; gameData: unknown } }>(`/api/saves/${id}`),
    put: (data: { companyName: string; saveVersion: number; gameData: unknown; tickCount: number; era: string }) =>
      request<{ id: string }>('/api/saves', { method: 'PUT', body: JSON.stringify(data) }),
    delete: (id: string) => request<{ deleted: boolean }>(`/api/saves/${id}`, { method: 'DELETE' }),
  },
  leaderboard: {
    get: (category: string) => request<{ entries: Array<{ companyName: string; score: number; era: string; tickCount: number }> }>(`/api/leaderboard/${category}`),
    submit: (data: { companyName: string; category: string; score: number; era: string; tickCount: number }) =>
      request<{ entry: unknown }>('/api/leaderboard', { method: 'POST', body: JSON.stringify(data) }),
  },
};