import Database from 'better-sqlite3'
import { join } from 'path'
import bcrypt from 'bcrypt'
import crypto from 'crypto'

let db: Database.Database | null = null

/**
 * Generate a cryptographically secure random string
 * @param length Length of the string to generate
 * @param charset Character set to use (default: alphanumeric + symbols)
 */
function generateSecurePassword(length: number = 16): string {
  const lowercase = 'abcdefghijklmnopqrstuvwxyz'
  const uppercase = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ'
  const numbers = '0123456789'
  const symbols = '!@#$%^&*-_=+'
  const allChars = lowercase + uppercase + numbers + symbols

  let password = ''

  // Ensure at least one character from each category
  password += lowercase[crypto.randomInt(lowercase.length)]
  password += uppercase[crypto.randomInt(uppercase.length)]
  password += numbers[crypto.randomInt(numbers.length)]
  password += symbols[crypto.randomInt(symbols.length)]

  // Fill the rest randomly
  for (let i = password.length; i < length; i++) {
    password += allChars[crypto.randomInt(allChars.length)]
  }

  // Shuffle the password to avoid predictable patterns
  return password.split('').sort(() => crypto.randomInt(3) - 1).join('')
}

/**
 * Generate a cryptographically secure AUTH_SECRET
 */
function generateAuthSecret(): string {
  return crypto.randomBytes(32).toString('hex')
}

/**
 * Initialize or retrieve AUTH_SECRET from database
 * Falls back to environment variable if provided
 */
function initializeAuthSecret(): string {
  const db = getDatabase()
  const config = useRuntimeConfig()

  // Check if AUTH_SECRET is already in database
  const existingSecret = getSetting('auth_secret')
  if (existingSecret) {
    return existingSecret.value
  }

  // Check if provided via environment (for advanced users)
  const envSecret = config.authSecret
  if (envSecret && envSecret !== 'change-this-secret-in-production' && envSecret !== '') {
    // Store the env-provided secret to database for consistency
    setSetting('auth_secret', envSecret)
    console.log('ℹ️  Using AUTH_SECRET from environment variable')
    return envSecret
  }

  // Generate new secure secret
  const newSecret = generateAuthSecret()
  setSetting('auth_secret', newSecret)

  console.log('\n' + '='.repeat(80))
  console.log('🔐 GENERATED NEW AUTH_SECRET')
  console.log('='.repeat(80))
  console.log('A new authentication secret has been generated and stored in the database.')
  console.log('This secret is used for session management and will persist across restarts.')
  console.log('='.repeat(80) + '\n')

  return newSecret
}

/**
 * Initialize default admin user if no admin exists
 * Generates secure random password and logs it on first creation
 */
function initializeAdminUser(): void {
  const db = getDatabase()
  const config = useRuntimeConfig()

  // Check if ANY admin user exists
  const adminExists = db.prepare('SELECT COUNT(*) as count FROM users WHERE is_admin = 1').get() as { count: number }

  if (adminExists.count > 0) {
    // Admin already exists, nothing to do
    return
  }

  // Determine admin username (allow override via env)
  const adminUsername = config.adminUsername || 'admin'

  // Check if environment provides a password (for backward compatibility or custom setups)
  let adminPassword = config.adminPassword
  let passwordWasGenerated = false

  if (!adminPassword || adminPassword === 'admin123' || adminPassword === 'Admin123!') {
    // Generate secure random password
    adminPassword = generateSecurePassword(20)
    passwordWasGenerated = true
  }

  // Hash the password
  const saltRounds = 10
  const hashedPassword = bcrypt.hashSync(adminPassword, saltRounds)

  // Create admin user
  db.prepare('INSERT INTO users (username, password, is_admin) VALUES (?, ?, 1)')
    .run(adminUsername, hashedPassword)

  // Log credentials prominently
  console.log('\n' + '='.repeat(80))
  console.log('🎉 INITIAL ADMIN ACCOUNT CREATED')
  console.log('='.repeat(80))
  console.log(`Username: ${adminUsername}`)
  console.log(`Password: ${adminPassword}`)
  console.log('='.repeat(80))
  console.log('⚠️  IMPORTANT: Save these credentials immediately!')
  console.log('This password will not be shown again.')
  if (passwordWasGenerated) {
    console.log('This password was randomly generated for security.')
  }
  console.log('You can change it after logging in via the Profile page.')
  console.log('='.repeat(80) + '\n')
}

export interface Sermon {
  id?: number
  slug: string
  title: string
  date: string
  dates?: string
  bible_references: string
  personal_appliance: string
  pastors_challenge: string
  worship_songs?: string
  created_by?: string
  created_at?: string
}

export interface User {
  id?: number
  username: string
  password: string
  email?: string
  first_name?: string
  last_name?: string
  is_admin: number
  failed_login_attempts?: number
  locked_until?: string | null
}

export interface PasswordResetCode {
  id?: number
  email: string
  code: string
  expires_at: string
  created_at?: string
}

export interface SermonNote {
  id?: number
  user_id: number
  sermon_id: number
  notes: string
  created_at?: string
  updated_at?: string
}

export interface Session {
  id?: number
  token: string
  username: string
  csrf_token?: string
  expires_at: string
  created_at?: string
}

export interface RateLimit {
  id?: number
  identifier: string
  endpoint: string
  attempts: number
  reset_at: string
}

export interface Setting {
  id?: number
  key: string
  value: string
  updated_at?: string
}

export function getDatabase() {
  if (!db) {
    const dbPath = join(process.cwd(), 'data', 'sermons.db')
    db = new Database(dbPath)
    
    // Create tables if they don't exist
  db.exec(`
    CREATE TABLE IF NOT EXISTS sermons (
      id INTEGER PRIMARY KEY AUTOINCREMENT,
      slug TEXT UNIQUE NOT NULL,
      title TEXT NOT NULL,
      date TEXT NOT NULL,
      dates TEXT,
      bible_references TEXT NOT NULL,
      personal_appliance TEXT NOT NULL,
      pastors_challenge TEXT NOT NULL,
      worship_songs TEXT,
      created_by TEXT,
      archived INTEGER DEFAULT 0,
      created_at DATETIME DEFAULT CURRENT_TIMESTAMP
    )
  `)
  
  // Add created_by column if it doesn't exist (migration)
  try {
    db.exec(`ALTER TABLE sermons ADD COLUMN created_by TEXT`)
  } catch (e) {
    // Column already exists, ignore error
  }
    
    db.exec(`
      CREATE TABLE IF NOT EXISTS users (
        id INTEGER PRIMARY KEY AUTOINCREMENT,
        username TEXT UNIQUE NOT NULL,
        password TEXT NOT NULL,
        email TEXT,
        first_name TEXT,
        last_name TEXT,
        is_admin INTEGER DEFAULT 0,
        failed_login_attempts INTEGER DEFAULT 0,
        locked_until DATETIME
      )
    `)

    // Add account lockout columns if they don't exist (migration)
    try {
      db.exec(`ALTER TABLE users ADD COLUMN failed_login_attempts INTEGER DEFAULT 0`)
    } catch (e) {
      // Column already exists, ignore error
    }

    try {
      db.exec(`ALTER TABLE users ADD COLUMN locked_until DATETIME`)
    } catch (e) {
      // Column already exists, ignore error
    }
    
    db.exec(`
      CREATE TABLE IF NOT EXISTS password_reset_codes (
        id INTEGER PRIMARY KEY AUTOINCREMENT,
        email TEXT NOT NULL,
        code TEXT NOT NULL,
        expires_at DATETIME NOT NULL,
        created_at DATETIME DEFAULT CURRENT_TIMESTAMP
      )
    `)
    
    db.exec(`
      CREATE TABLE IF NOT EXISTS sermon_notes (
        id INTEGER PRIMARY KEY AUTOINCREMENT,
        user_id INTEGER NOT NULL,
        sermon_id INTEGER NOT NULL,
        notes TEXT NOT NULL,
        created_at DATETIME DEFAULT CURRENT_TIMESTAMP,
        updated_at DATETIME DEFAULT CURRENT_TIMESTAMP,
        FOREIGN KEY (user_id) REFERENCES users(id) ON DELETE CASCADE,
        FOREIGN KEY (sermon_id) REFERENCES sermons(id) ON DELETE CASCADE,
        UNIQUE(user_id, sermon_id)
      )
    `)

    // Create indexes for foreign keys to optimize queries
    // SQLite doesn't automatically index foreign keys
    db.exec(`CREATE INDEX IF NOT EXISTS idx_sermon_notes_user_id ON sermon_notes(user_id)`)
    db.exec(`CREATE INDEX IF NOT EXISTS idx_sermon_notes_sermon_id ON sermon_notes(sermon_id)`)
    
    db.exec(`
      CREATE TABLE IF NOT EXISTS sessions (
        id INTEGER PRIMARY KEY AUTOINCREMENT,
        token TEXT UNIQUE NOT NULL,
        username TEXT NOT NULL,
        csrf_token TEXT,
        expires_at DATETIME NOT NULL,
        created_at DATETIME DEFAULT CURRENT_TIMESTAMP
      )
    `)

    // Add csrf_token column if it doesn't exist (migration)
    try {
      db.exec(`ALTER TABLE sessions ADD COLUMN csrf_token TEXT`)
    } catch (e) {
      // Column already exists, ignore error
    }
    
    db.exec(`
      CREATE TABLE IF NOT EXISTS rate_limits (
        id INTEGER PRIMARY KEY AUTOINCREMENT,
        identifier TEXT NOT NULL,
        endpoint TEXT NOT NULL,
        attempts INTEGER DEFAULT 1,
        reset_at DATETIME NOT NULL,
        UNIQUE(identifier, endpoint)
      )
    `)

    db.exec(`
      CREATE TABLE IF NOT EXISTS settings (
        id INTEGER PRIMARY KEY AUTOINCREMENT,
        key TEXT UNIQUE NOT NULL,
        value TEXT NOT NULL,
        updated_at DATETIME DEFAULT CURRENT_TIMESTAMP
      )
    `)

    // Create additional performance indexes for frequently queried columns
    // Sermons: date is used for sorting and filtering
    db.exec(`CREATE INDEX IF NOT EXISTS idx_sermons_date ON sermons(date DESC)`)
    db.exec(`CREATE INDEX IF NOT EXISTS idx_sermons_archived ON sermons(archived, date DESC)`)

    // Users: email lookups for password reset
    db.exec(`CREATE INDEX IF NOT EXISTS idx_users_email ON users(email)`)

    // Sessions: token lookups for authentication
    db.exec(`CREATE INDEX IF NOT EXISTS idx_sessions_token ON sessions(token)`)
    db.exec(`CREATE INDEX IF NOT EXISTS idx_sessions_expires_at ON sessions(expires_at)`)

    // Rate limits: identifier+endpoint lookups
    db.exec(`CREATE INDEX IF NOT EXISTS idx_rate_limits_identifier_endpoint ON rate_limits(identifier, endpoint)`)
    db.exec(`CREATE INDEX IF NOT EXISTS idx_rate_limits_reset_at ON rate_limits(reset_at)`)

    // Password reset codes: email+code lookups
    db.exec(`CREATE INDEX IF NOT EXISTS idx_password_reset_codes_email ON password_reset_codes(email)`)
    db.exec(`CREATE INDEX IF NOT EXISTS idx_password_reset_codes_expires_at ON password_reset_codes(expires_at)`)

    // Initialize AUTH_SECRET (generate if needed)
    initializeAuthSecret()

    // Initialize admin user (create if no admin exists)
    initializeAdminUser()
  }
  
  return db
}

export function getAllSermons(limit?: number, includeArchived: boolean = false) {
  const db = getDatabase()
  const whereClause = includeArchived ? '' : 'WHERE archived = 0'
  
  if (limit) {
    return db.prepare(`SELECT * FROM sermons ${whereClause} ORDER BY date DESC LIMIT ?`).all(limit) as Sermon[]
  }
  return db.prepare(`SELECT * FROM sermons ${whereClause} ORDER BY date DESC`).all() as Sermon[]
}

export function getArchivedSermons() {
  const db = getDatabase()
  return db.prepare('SELECT * FROM sermons WHERE archived = 1 ORDER BY date DESC').all() as Sermon[]
}

export function archiveSermon(id: number) {
  const db = getDatabase()
  return db.prepare('UPDATE sermons SET archived = 1 WHERE id = ?').run(id)
}

export function getSermonBySlug(slug: string) {
  const db = getDatabase()
  return db.prepare('SELECT * FROM sermons WHERE slug = ?').get(slug) as Sermon | undefined
}

export function createSermon(sermon: Sermon) {
  const db = getDatabase()
  const stmt = db.prepare(`
    INSERT INTO sermons (slug, title, date, dates, bible_references, personal_appliance, pastors_challenge, worship_songs, created_by)
    VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?)
  `)
  return stmt.run(
    sermon.slug,
    sermon.title,
    sermon.date,
    sermon.dates || null,
    sermon.bible_references,
    sermon.personal_appliance,
    sermon.pastors_challenge,
    sermon.worship_songs || null,
    sermon.created_by || null
  )
}

export function getUserByUsername(username: string) {
  const db = getDatabase()
  return db.prepare('SELECT * FROM users WHERE username = ?').get(username) as User | undefined
}

export function createUser(username: string, password: string, email?: string, firstName?: string, lastName?: string) {
  const db = getDatabase()
  const saltRounds = 10
  const hashedPassword = bcrypt.hashSync(password, saltRounds)
  return db.prepare('INSERT INTO users (username, password, email, first_name, last_name, is_admin) VALUES (?, ?, ?, ?, ?, 0)')
    .run(username, hashedPassword, email || null, firstName || null, lastName || null)
}

export function getUserByEmail(email: string) {
  const db = getDatabase()
  return db.prepare('SELECT * FROM users WHERE email = ?').get(email) as User | undefined
}

export function createPasswordResetCode(email: string, code: string, expiresAt: string) {
  const db = getDatabase()
  // Delete any existing codes for this email
  db.prepare('DELETE FROM password_reset_codes WHERE email = ?').run(email)
  return db.prepare('INSERT INTO password_reset_codes (email, code, expires_at) VALUES (?, ?, ?)')
    .run(email, code, expiresAt)
}

export function getPasswordResetCode(email: string, code: string) {
  const db = getDatabase()
  return db.prepare("SELECT * FROM password_reset_codes WHERE email = ? AND code = ? AND expires_at > datetime('now')")
    .get(email, code) as PasswordResetCode | undefined
}

export function deletePasswordResetCode(email: string) {
  const db = getDatabase()
  return db.prepare('DELETE FROM password_reset_codes WHERE email = ?').run(email)
}

export function resetPasswordByEmail(email: string, newPassword: string) {
  const db = getDatabase()
  const saltRounds = 10
  const hashedPassword = bcrypt.hashSync(newPassword, saltRounds)
  const result = db.prepare('UPDATE users SET password = ? WHERE LOWER(email) = LOWER(?)').run(hashedPassword, email)
  return result
}

export function getAllUsers() {
  const db = getDatabase()
  return db.prepare('SELECT id, username, email, first_name, last_name, is_admin, failed_login_attempts, locked_until FROM users ORDER BY username').all() as Omit<User, 'password'>[]
}

export function deleteUser(id: number) {
  const db = getDatabase()
  return db.prepare('DELETE FROM users WHERE id = ?').run(id)
}

export function updateUserRole(id: number, isAdmin: number) {
  const db = getDatabase()
  return db.prepare('UPDATE users SET is_admin = ? WHERE id = ?').run(isAdmin, id)
}

export function resetUserPassword(id: number, newPassword: string) {
  const db = getDatabase()
  const saltRounds = 10
  const hashedPassword = bcrypt.hashSync(newPassword, saltRounds)
  return db.prepare('UPDATE users SET password = ? WHERE id = ?').run(hashedPassword, id)
}

/**
 * Account Lockout Functions
 * Provides protection against distributed brute force attacks
 */

/**
 * Check if account is currently locked
 * Returns true if account is locked, false if unlocked or lock has expired
 */
export function isAccountLocked(username: string): boolean {
  const db = getDatabase()
  const user = db.prepare("SELECT locked_until FROM users WHERE username = ? AND locked_until > datetime('now')")
    .get(username) as { locked_until: string } | undefined

  return !!user
}

/**
 * Increment failed login attempts for an account
 * Locks account if threshold (10 attempts) is reached
 */
export function incrementFailedAttempts(username: string): void {
  const db = getDatabase()

  // Get current attempt count
  const user = db.prepare('SELECT failed_login_attempts FROM users WHERE username = ?')
    .get(username) as { failed_login_attempts: number } | undefined

  if (!user) return

  const newAttempts = (user.failed_login_attempts || 0) + 1
  const maxAttempts = 5 // Aligned with IP rate limiting

  if (newAttempts >= maxAttempts) {
    // Lock account for 15 minutes (aligned with IP rate limiting)
    const lockUntil = new Date(Date.now() + 15 * 60 * 1000).toISOString()
    db.prepare('UPDATE users SET failed_login_attempts = ?, locked_until = ? WHERE username = ?')
      .run(newAttempts, lockUntil, username)
    console.log(`[ACCOUNT LOCKED] User ${username} locked after ${newAttempts} failed attempts until ${lockUntil}`)
  } else {
    // Just increment counter
    db.prepare('UPDATE users SET failed_login_attempts = ? WHERE username = ?')
      .run(newAttempts, username)
    console.log(`[ACCOUNT SECURITY] Failed login attempt #${newAttempts} for user: ${username}`)
  }
}

/**
 * Reset failed login attempts on successful login
 */
export function resetFailedAttempts(username: string): void {
  const db = getDatabase()
  db.prepare('UPDATE users SET failed_login_attempts = 0, locked_until = NULL WHERE username = ?')
    .run(username)
}

/**
 * Admin function to manually unlock an account
 */
export function unlockAccount(userId: number): void {
  const db = getDatabase()
  db.prepare('UPDATE users SET failed_login_attempts = 0, locked_until = NULL WHERE id = ?')
    .run(userId)
}

export function getSermonNote(userId: number, sermonId: number) {
  const db = getDatabase()
  return db.prepare('SELECT * FROM sermon_notes WHERE user_id = ? AND sermon_id = ?').get(userId, sermonId) as SermonNote | undefined
}

export function saveSermonNote(userId: number, sermonId: number, notes: string) {
  const db = getDatabase()
  const existing = getSermonNote(userId, sermonId)
  
  if (existing) {
    return db.prepare('UPDATE sermon_notes SET notes = ?, updated_at = CURRENT_TIMESTAMP WHERE user_id = ? AND sermon_id = ?').run(notes, userId, sermonId)
  } else {
    return db.prepare('INSERT INTO sermon_notes (user_id, sermon_id, notes) VALUES (?, ?, ?)').run(userId, sermonId, notes)
  }
}

export function deleteSermonNote(userId: number, sermonId: number) {
  const db = getDatabase()
  return db.prepare('DELETE FROM sermon_notes WHERE user_id = ? AND sermon_id = ?').run(userId, sermonId)
}

// Session management functions
export function createSession(token: string, username: string, expiresAt: string, csrfToken?: string) {
  const db = getDatabase()
  return db.prepare('INSERT INTO sessions (token, username, csrf_token, expires_at) VALUES (?, ?, ?, ?)')
    .run(token, username, csrfToken || null, expiresAt)
}

export function getSessionByToken(token: string) {
  const db = getDatabase()
  return db.prepare("SELECT * FROM sessions WHERE token = ? AND expires_at > datetime('now')")
    .get(token) as Session | undefined
}

export function deleteSession(token: string) {
  const db = getDatabase()
  return db.prepare('DELETE FROM sessions WHERE token = ?').run(token)
}

export function deleteExpiredSessions() {
  const db = getDatabase()
  return db.prepare("DELETE FROM sessions WHERE expires_at <= datetime('now')").run()
}

/**
 * Delete all sessions for a specific user
 * Used when password changes or security events require session invalidation
 */
export function deleteAllUserSessions(username: string) {
  const db = getDatabase()
  return db.prepare('DELETE FROM sessions WHERE username = ?').run(username)
}

/**
 * Delete all sessions except the current one
 * Used when user wants to logout other devices but keep current session
 */
export function deleteOtherUserSessions(username: string, currentToken: string) {
  const db = getDatabase()
  return db.prepare('DELETE FROM sessions WHERE username = ? AND token != ?').run(username, currentToken)
}

// Rate limiting functions
export function checkRateLimit(identifier: string, endpoint: string, maxAttempts: number, windowMinutes: number): boolean {
  const db = getDatabase()
  
  // Clean up expired rate limit records
  db.prepare("DELETE FROM rate_limits WHERE reset_at <= datetime('now')").run()
  
  const existing = db.prepare('SELECT * FROM rate_limits WHERE identifier = ? AND endpoint = ?')
    .get(identifier, endpoint) as RateLimit | undefined
  
  if (!existing) {
    // First attempt - create new record
    const resetAt = new Date(Date.now() + windowMinutes * 60 * 1000).toISOString()
    db.prepare('INSERT INTO rate_limits (identifier, endpoint, attempts, reset_at) VALUES (?, ?, 1, ?)')
      .run(identifier, endpoint, resetAt)
    return true
  }
  
  if (existing.attempts >= maxAttempts) {
    // Rate limit exceeded
    return false
  }
  
  // Increment attempts
  db.prepare('UPDATE rate_limits SET attempts = attempts + 1 WHERE identifier = ? AND endpoint = ?')
    .run(identifier, endpoint)
  return true
}

export function resetRateLimit(identifier: string, endpoint: string) {
  const db = getDatabase()
  return db.prepare('DELETE FROM rate_limits WHERE identifier = ? AND endpoint = ?')
    .run(identifier, endpoint)
}

/**
 * Clear all rate limits for a specific endpoint
 * Used when admin performs actions that should clear all rate limiting (e.g., unlocking accounts)
 */
export function clearAllRateLimitsForEndpoint(endpoint: string) {
  const db = getDatabase()
  const result = db.prepare('DELETE FROM rate_limits WHERE endpoint = ?').run(endpoint)
  console.log(`[RATE LIMIT CLEARED] Cleared ${result.changes} rate limit entries for endpoint: ${endpoint}`)
  return result
}

// Settings management functions
export function getSetting(key: string) {
  const db = getDatabase()
  return db.prepare('SELECT * FROM settings WHERE key = ?').get(key) as Setting | undefined
}

export function setSetting(key: string, value: string) {
  const db = getDatabase()
  const existing = getSetting(key)

  if (existing) {
    return db.prepare('UPDATE settings SET value = ?, updated_at = CURRENT_TIMESTAMP WHERE key = ?').run(value, key)
  } else {
    return db.prepare('INSERT INTO settings (key, value) VALUES (?, ?)').run(key, value)
  }
}

/**
 * Get the AUTH_SECRET from database
 * This should always exist after database initialization
 */
export function getAuthSecret(): string {
  const secret = getSetting('auth_secret')
  if (!secret) {
    throw new Error('AUTH_SECRET not found in database. Database may not be properly initialized.')
  }
  return secret.value
}

// Sermon retention policy functions
export function deleteOldSermons(retentionDays: number) {
  const db = getDatabase()
  // Calculate the cutoff date based on retention days
  const cutoffDate = new Date()
  cutoffDate.setDate(cutoffDate.getDate() - retentionDays)
  const cutoffDateStr = cutoffDate.toISOString().split('T')[0] // Format as YYYY-MM-DD

  // Delete sermons older than the cutoff date
  return db.prepare('DELETE FROM sermons WHERE date < ?').run(cutoffDateStr)
}