import { getUserByUsername, checkRateLimit, resetRateLimit, createSession, isAccountLocked, incrementFailedAttempts, resetFailedAttempts } from '~/server/utils/database'
import { setAuthCookie, generateSessionToken } from '~/server/utils/auth'
import { generateCsrfToken, setCsrfCookie } from '~/server/utils/csrf'
import bcrypt from 'bcrypt'

export default defineEventHandler(async (event) => {
  // Get real client IP from proxy headers (prioritize x-real-ip for NPM)
  const xRealIp = getHeader(event, 'x-real-ip')
  const xForwardedFor = getHeader(event, 'x-forwarded-for')
  const cfConnectingIp = getHeader(event, 'cf-connecting-ip')
  
  // Use x-real-ip first (set by NPM), then x-forwarded-for, then cf-connecting-ip, then fallback
  const clientIp = xRealIp || 
                   (xForwardedFor ? xForwardedFor.split(',')[0].trim() : null) ||
                   cfConnectingIp ||
                   getRequestIP(event) || 
                   'unknown'
  
  // Log IP for verification
  console.log(`[LOGIN ATTEMPT] IP: ${clientIp}, Headers:`, {
    'x-forwarded-for': xForwardedFor,
    'x-real-ip': xRealIp,
    'cf-connecting-ip': cfConnectingIp,
    'getRequestIP': getRequestIP(event)
  })

  const body = await readBody(event)
  const { username, password } = body

  if (!username || !password) {
    throw createError({
      statusCode: 400,
      message: 'Username and password are required'
    })
  }

  const user = getUserByUsername(username.toLowerCase())

  if (!user) {
    // Check rate limit ONLY on failed attempt
    if (!checkRateLimit(clientIp, 'login', 5, 15)) {
      console.log(`[LOGIN BLOCKED] Rate limited - Username not found: ${username.toLowerCase()}, IP: ${clientIp}`)
      throw createError({
        statusCode: 429,
        message: 'Too many login attempts. Please try again in 15 minutes.'
      })
    }
    console.log(`[LOGIN FAILED] Username not found: ${username.toLowerCase()}, IP: ${clientIp}`)
    throw createError({
      statusCode: 401,
      message: 'Invalid credentials'
    })
  }

  // SECURITY: Check if account is locked due to too many failed attempts
  if (isAccountLocked(username.toLowerCase())) {
    console.log(`[LOGIN BLOCKED] Account locked - User: ${username.toLowerCase()}, IP: ${clientIp}`)
    throw createError({
      statusCode: 403,
      message: 'Account temporarily locked due to too many failed login attempts. Please try again in 30 minutes or contact an administrator.'
    })
  }

  // Compare the provided password with the hashed password in the database
  const passwordMatch = await bcrypt.compare(password, user.password)

  if (!passwordMatch) {
    // SECURITY: Increment failed login attempts for this account
    incrementFailedAttempts(username.toLowerCase())

    // Check rate limit ONLY on failed attempt
    if (!checkRateLimit(clientIp, 'login', 5, 15)) {
      console.log(`[LOGIN BLOCKED] Rate limited - Invalid password for user: ${username.toLowerCase()}, IP: ${clientIp}`)
      throw createError({
        statusCode: 429,
        message: 'Too many login attempts. Please try again in 15 minutes.'
      })
    }
    console.log(`[LOGIN FAILED] Invalid password for user: ${username.toLowerCase()}, IP: ${clientIp}`)
    throw createError({
      statusCode: 401,
      message: 'Invalid credentials'
    })
  }

  // Generate session token and CSRF token
  const sessionToken = generateSessionToken()
  const csrfToken = generateCsrfToken()
  const expiresAt = new Date(Date.now() + 24 * 60 * 60 * 1000).toISOString() // 24 hours

  // Create session with CSRF token
  createSession(sessionToken, user.username, expiresAt, csrfToken)

  // Set session cookie
  setAuthCookie(event, sessionToken)

  // Set CSRF cookie
  setCsrfCookie(event, csrfToken)

  // SECURITY: Reset failed login attempts on successful login
  resetFailedAttempts(username.toLowerCase())

  // Reset rate limit on successful login
  resetRateLimit(clientIp, 'login')

  // Log successful login
  console.log(`[LOGIN SUCCESS] User: ${user.username}, IP: ${clientIp}`)

  return {
    success: true,
    username: user.username
  }
})