import { Database } from "bun:sqlite";

const DB_PATH = "./musicroom.db";
const SESSION_EXPIRY_DAYS = 7;

const db = new Database(DB_PATH);

// Initialize tables
db.run(`
  CREATE TABLE IF NOT EXISTS users (
    id INTEGER PRIMARY KEY AUTOINCREMENT,
    username TEXT UNIQUE NOT NULL,
    password_hash TEXT NOT NULL,
    is_admin INTEGER DEFAULT 0,
    created_at INTEGER DEFAULT (unixepoch())
  )
`);

db.run(`
  CREATE TABLE IF NOT EXISTS sessions (
    token TEXT PRIMARY KEY,
    user_id INTEGER NOT NULL,
    expires_at INTEGER NOT NULL,
    created_at INTEGER DEFAULT (unixepoch()),
    user_agent TEXT,
    ip_address TEXT,
    FOREIGN KEY (user_id) REFERENCES users(id) ON DELETE CASCADE
  )
`);

// Migration: add columns if they don't exist
try {
  db.run(`ALTER TABLE sessions ADD COLUMN user_agent TEXT`);
} catch {}
try {
  db.run(`ALTER TABLE sessions ADD COLUMN ip_address TEXT`);
} catch {}

db.run(`
  CREATE TABLE IF NOT EXISTS permissions (
    id INTEGER PRIMARY KEY AUTOINCREMENT,
    user_id INTEGER NOT NULL,
    resource_type TEXT NOT NULL,
    resource_id TEXT,
    permission TEXT NOT NULL,
    FOREIGN KEY (user_id) REFERENCES users(id) ON DELETE CASCADE,
    UNIQUE(user_id, resource_type, resource_id, permission)
  )
`);

// Types
export interface User {
  id: number;
  username: string;
  password_hash: string;
  is_admin: boolean;
  created_at: number;
}

export interface Session {
  token: string;
  user_id: number;
  expires_at: number;
  created_at: number;
  user_agent: string | null;
  ip_address: string | null;
}

export interface Permission {
  id: number;
  user_id: number;
  resource_type: string;
  resource_id: string | null;
  permission: string;
}

// User functions
export async function createUser(username: string, password: string): Promise<User> {
  const password_hash = await Bun.password.hash(password);
  
  // First user becomes admin
  const userCount = db.query("SELECT COUNT(*) as count FROM users").get() as { count: number };
  const is_admin = userCount.count === 0 ? 1 : 0;
  
  const result = db.query(
    "INSERT INTO users (username, password_hash, is_admin) VALUES (?, ?, ?) RETURNING *"
  ).get(username, password_hash, is_admin) as any;
  
  return { ...result, is_admin: !!result.is_admin };
}

export function findUserById(id: number): User | null {
  const result = db.query("SELECT * FROM users WHERE id = ?").get(id) as any;
  if (!result) return null;
  return { ...result, is_admin: !!result.is_admin };
}

export function findUserByUsername(username: string): User | null {
  const result = db.query("SELECT * FROM users WHERE username = ?").get(username) as any;
  if (!result) return null;
  return { ...result, is_admin: !!result.is_admin };
}

export async function validatePassword(user: User, password: string): Promise<boolean> {
  return Bun.password.verify(password, user.password_hash);
}

// Session functions
export function createSession(userId: number, userAgent?: string, ipAddress?: string): string {
  const token = crypto.randomUUID();
  const expires_at = Math.floor(Date.now() / 1000) + (SESSION_EXPIRY_DAYS * 24 * 60 * 60);
  
  db.query("INSERT INTO sessions (token, user_id, expires_at, user_agent, ip_address) VALUES (?, ?, ?, ?, ?)")
    .run(token, userId, expires_at, userAgent ?? null, ipAddress ?? null);
  
  return token;
}

export function validateSession(token: string, currentUserAgent?: string, currentIpAddress?: string): User | null {
  const now = Math.floor(Date.now() / 1000);
  const session = db.query(
    "SELECT * FROM sessions WHERE token = ? AND expires_at > ?"
  ).get(token, now) as Session | null;
  
  if (!session) return null;
  
  // Invalidate if BOTH ip and user agent changed (potential session hijack)
  if (currentUserAgent && currentIpAddress && session.user_agent && session.ip_address) {
    const ipChanged = session.ip_address !== currentIpAddress;
    const uaChanged = session.user_agent !== currentUserAgent;
    if (ipChanged && uaChanged) {
      console.log(`[AUTH] Session invalidated (ip+ua changed): session=${token} old_ip=${session.ip_address} new_ip=${currentIpAddress}`);
      deleteSession(token);
      return null;
    }
  }
  
  // Sliding expiration - extend on each use
  const newExpiry = now + (SESSION_EXPIRY_DAYS * 24 * 60 * 60);
  db.query("UPDATE sessions SET expires_at = ? WHERE token = ?").run(newExpiry, token);
  
  return findUserById(session.user_id);
}

export function deleteSession(token: string): void {
  db.query("DELETE FROM sessions WHERE token = ?").run(token);
}

export function deleteExpiredSessions(): void {
  const now = Math.floor(Date.now() / 1000);
  db.query("DELETE FROM sessions WHERE expires_at <= ?").run(now);
}

// Permission functions
export function hasPermission(
  userId: number,
  resourceType: string,
  resourceId: string | null,
  permission: string
): boolean {
  const user = findUserById(userId);
  if (!user) return false;
  if (user.is_admin) return true;
  
  const result = db.query(`
    SELECT 1 FROM permissions 
    WHERE user_id = ? 
      AND resource_type = ? 
      AND (resource_id = ? OR resource_id IS NULL)
      AND permission = ?
    LIMIT 1
  `).get(userId, resourceType, resourceId, permission);
  
  return !!result;
}

export function grantPermission(
  userId: number,
  resourceType: string,
  resourceId: string | null,
  permission: string
): void {
  db.query(`
    INSERT OR IGNORE INTO permissions (user_id, resource_type, resource_id, permission)
    VALUES (?, ?, ?, ?)
  `).run(userId, resourceType, resourceId, permission);
}

export function revokePermission(
  userId: number,
  resourceType: string,
  resourceId: string | null,
  permission: string
): void {
  db.query(`
    DELETE FROM permissions 
    WHERE user_id = ? AND resource_type = ? AND resource_id IS ? AND permission = ?
  `).run(userId, resourceType, resourceId, permission);
}

export function getUserPermissions(userId: number): Permission[] {
  return db.query("SELECT * FROM permissions WHERE user_id = ?").all(userId) as Permission[];
}

export function getAllUsers(): Omit<User, 'password_hash'>[] {
  const users = db.query("SELECT id, username, is_admin, created_at FROM users").all() as any[];
  return users.map(u => ({ ...u, is_admin: !!u.is_admin }));
}

export function getUserSessions(userId: number): Omit<Session, 'token'>[] {
  return db.query(
    "SELECT user_id, expires_at, created_at, user_agent, ip_address FROM sessions WHERE user_id = ? AND expires_at > ?"
  ).all(userId, Math.floor(Date.now() / 1000)) as Omit<Session, 'token'>[];
}

// Cleanup expired sessions periodically
setInterval(() => deleteExpiredSessions(), 60 * 60 * 1000); // Every hour