import { NextRequest, NextResponse } from 'next/server'
import jwt from 'jsonwebtoken'
import bcrypt from 'bcryptjs'
import crypto from 'crypto'
import connectToDatabase from './mongodb'
import { User } from './models'
import type { AuthUser, SessionPayload } from '@/types/user'

// ─── Password Hashing ────────────────────────────────────────────

export async function hashPassword(password: string): Promise<string> {
  return bcrypt.hash(password, 12)
}

export async function verifyPassword(password: string, hashedPassword: string): Promise<boolean> {
  return bcrypt.compare(password, hashedPassword)
}

// ─── JWT Tokens ──────────────────────────────────────────────────

export function generateAccessToken(payload: SessionPayload): string {
  return jwt.sign(payload, process.env.JWT_ACCESS_SECRET!, { expiresIn: '1h' })
}

export function generateRefreshToken(payload: SessionPayload): string {
  return jwt.sign(payload, process.env.JWT_REFRESH_SECRET!, { expiresIn: '7d' })
}

export function verifyAccessToken(token: string): SessionPayload | null {
  try {
    return jwt.verify(token, process.env.JWT_ACCESS_SECRET!) as SessionPayload
  } catch {
    return null
  }
}

export function verifyRefreshToken(token: string): SessionPayload | null {
  try {
    return jwt.verify(token, process.env.JWT_REFRESH_SECRET!) as SessionPayload
  } catch {
    return null
  }
}

// ─── 2FA Code ────────────────────────────────────────────────────

export function generate2FACode(): string {
  return crypto.randomInt(100000, 999999).toString()
}

export function hash2FACode(code: string): string {
  const hmac = crypto.createHmac('sha256', process.env.TWO_FACTOR_SECRET!)
  hmac.update(code)
  return hmac.digest('hex')
}

export function verify2FACode(inputCode: string, hashedCode: string): boolean {
  const inputHash = hash2FACode(inputCode.trim())

  try {
    return crypto.timingSafeEqual(
      Buffer.from(inputHash, 'hex'),
      Buffer.from(hashedCode, 'hex')
    )
  } catch {
    return false
  }
}

// ─── Session Validation ──────────────────────────────────────────

export async function validateSession(request: NextRequest): Promise<AuthUser | null> {
  const token = request.cookies.get('session-token')?.value

  if (!token) return null

  const payload = verifyAccessToken(token)
  if (!payload) return null

  try {
    await connectToDatabase()

    const user = await User.findById(payload.userId)
      .populate('roles')
      .lean()

    if (!user || user.status !== 'active') return null

    const permissions = new Set<string>()
    const roleNames: string[] = []

    if (Array.isArray(user.roles)) {
      for (const role of user.roles) {
        if (typeof role === 'object' && role !== null) {
          const r = role as unknown as { name: string; permissions: { resource: string; actions: string[] }[] }
          roleNames.push(r.name)
          for (const perm of r.permissions) {
            for (const action of perm.actions) {
              permissions.add(`${perm.resource}:${action}`)
            }
          }
        }
      }
    }

    return {
      _id: user._id.toString(),
      id: user._id.toString(),
      username: user.username,
      email: user.email,
      permissions: Array.from(permissions),
      roles: roleNames,
    }
  } catch {
    return null
  }
}

// ─── Cookie Helpers ──────────────────────────────────────────────

export function setAuthCookies(response: NextResponse, accessToken: string, refreshToken: string): void {
  const isProduction = process.env.NODE_ENV === 'production'

  response.cookies.set('session-token', accessToken, {
    httpOnly: true,
    secure: isProduction,
    sameSite: 'strict',
    maxAge: 3600, // 1 hour
    path: '/',
  })

  response.cookies.set('refresh-token', refreshToken, {
    httpOnly: true,
    secure: isProduction,
    sameSite: 'strict',
    maxAge: 7 * 24 * 3600, // 7 days
    path: '/',
  })
}

export function clearAuthCookies(response: NextResponse): void {
  response.cookies.set('session-token', '', { maxAge: 0, path: '/' })
  response.cookies.set('refresh-token', '', { maxAge: 0, path: '/' })
}

// ─── Permission Check ────────────────────────────────────────────

export function hasPermission(user: AuthUser, permission: string): boolean {
  if (user.permissions.includes('*:*')) return true
  return user.permissions.includes(permission)
}