import bcrypt from 'bcrypt'
import * as userRepo from '../repositories/userRepo.js'
import { signToken, generateVerificationToken, hashToken } from '../utils/tokens.js'
import { sendVerificationEmail, sendPasswordResetEmail } from '../utils/email.js'
import { AppError } from '../middleware/error.js'
import * as storageRepo from '../repositories/storageRepo.js'
import type { RegisterInput, LoginInput, UpdateProfileInput, ChangePasswordInput, VerifyEmailInput, ResetPasswordInput } from '../validators/authSchemas.js'

const SALT_ROUNDS = 10
const VERIFY_TOKEN_EXPIRY_MS = 24 * 60 * 60 * 1000
const RESET_TOKEN_EXPIRY_MS = 60 * 60 * 1000

export interface AuthResult {
  token: string
  user: { id: number; email: string; displayName: string; role: string }
}

/** Response for a registration attempt we did not act on (email already exists).
 * Deliberately indistinguishable from success so the endpoint cannot be used
 * to enumerate registered email addresses. */
export interface RegistrationPending {
  message: string
}

function toAuthResult(user: userRepo.DbUser): AuthResult {
  return {
    token: signToken({
      userId: user.id,
      email: user.email,
      displayName: user.display_name,
      role: user.role as 'user' | 'admin',
      tv: user.token_version ?? 0,
    }),
    user: {
      id: user.id,
      email: user.email,
      displayName: user.display_name,
      role: user.role,
    },
  }
}

export async function register(input: RegisterInput): Promise<AuthResult | RegistrationPending> {
  // Hash before the duplicate check so response timing does not reveal whether
  // the email is already registered (user enumeration)
  const passwordHash = await bcrypt.hash(input.password, SALT_ROUNDS)

  const existing = userRepo.getUserByEmail(input.email)
  if (existing) {
    return { message: 'Check your inbox to finish setting up your account.' }
  }

  const rawVerifyToken = generateVerificationToken()
  const verifyTokenHash = hashToken(rawVerifyToken)
  const verifyExpires = Date.now() + VERIFY_TOKEN_EXPIRY_MS

  const { id } = userRepo.createUser({
    email: input.email,
    passwordHash,
    displayName: input.displayName,
    role: 'user',
    emailVerified: 0,
    verifyToken: verifyTokenHash,
    verifyExpires,
  })

  const user = userRepo.getUserById(id)!

  // Don't await — fire and forget so registration isn't blocked by email failures
  sendVerificationEmail(user.email, rawVerifyToken).catch(() => {})

  return toAuthResult(user)
}

export async function login(input: LoginInput): Promise<AuthResult> {
  const user = userRepo.getUserByEmail(input.email)
  if (!user) {
    throw new AppError(401, 'Invalid email or password')
  }

  const valid = await bcrypt.compare(input.password, user.password_hash)
  if (!valid) {
    throw new AppError(401, 'Invalid email or password')
  }

  if (!user.email_verified) {
    throw new AppError(403, 'Please verify your email before logging in')
  }

  return toAuthResult(user)
}

export function getMe(userId: number) {
  const user = userRepo.getUserById(userId)
  if (!user) {
    throw new AppError(404, 'User not found')
  }
  const usage = storageRepo.getUserStorageUsage(userId)
  const usedPercent = user.storage_quota_bytes > 0
    ? Math.round((usage.usedBytes / user.storage_quota_bytes) * 100)
    : 0
  return {
    id: user.id,
    email: user.email,
    displayName: user.display_name,
    role: user.role,
    emailVerified: !!user.email_verified,
    storageQuotaBytes: user.storage_quota_bytes,
    usedBytes: usage.usedBytes,
    usedPercent,
    plan: user.plan,
  }
}

export async function updateProfile(userId: number, input: UpdateProfileInput) {
  userRepo.updateUser(userId, { displayName: input.displayName })
  return getMe(userId)
}

export async function changePassword(userId: number, input: ChangePasswordInput) {
  const user = userRepo.getUserById(userId)
  if (!user) {
    throw new AppError(404, 'User not found')
  }

  const valid = await bcrypt.compare(input.currentPassword, user.password_hash)
  if (!valid) {
    throw new AppError(400, 'Current password is incorrect')
  }

  const passwordHash = await bcrypt.hash(input.newPassword, SALT_ROUNDS)
  // Bump token version so tokens issued before the change stop working
  userRepo.updateUser(userId, {
    passwordHash,
    tokenVersion: (user.token_version ?? 0) + 1,
  })
}

export async function verifyEmail(input: VerifyEmailInput) {
  const tokenHash = hashToken(input.token)
  const user = userRepo.getUserByVerifyTokenHash(tokenHash)
  if (!user || !user.verify_expires || Date.now() > user.verify_expires) {
    throw new AppError(400, 'Invalid or expired verification token')
  }

  userRepo.updateUser(user.id, {
    emailVerified: 1,
    verifyToken: null,
    verifyExpires: null,
  })
}

export async function resendVerification(email: string) {
  const user = userRepo.getUserByEmail(email)
  if (!user || user.email_verified) {
    return
  }

  const rawVerifyToken = generateVerificationToken()
  const verifyTokenHash = hashToken(rawVerifyToken)
  const verifyExpires = Date.now() + VERIFY_TOKEN_EXPIRY_MS

  userRepo.updateUser(user.id, {
    verifyToken: verifyTokenHash,
    verifyExpires,
  })

  sendVerificationEmail(user.email, rawVerifyToken).catch(() => {})
}

export async function forgotPassword(email?: string) {
  if (!email) {
    throw new AppError(400, 'Email is required')
  }

  const user = userRepo.getUserByEmail(email)
  if (!user) {
    // Don't reveal whether email exists
    return
  }

  const rawResetToken = generateVerificationToken()
  const resetTokenHash = hashToken(rawResetToken)
  const resetExpires = Date.now() + RESET_TOKEN_EXPIRY_MS

  userRepo.updateUser(user.id, { resetToken: resetTokenHash, resetExpires })

  // Fire and forget
  sendPasswordResetEmail(user.email, rawResetToken).catch(() => {})
}

export async function resetPassword(input: ResetPasswordInput) {
  const tokenHash = hashToken(input.token)
  const user = userRepo.getUserByResetTokenHash(tokenHash)
  if (!user || !user.reset_expires || Date.now() > user.reset_expires) {
    throw new AppError(400, 'Invalid or expired reset token')
  }

  const passwordHash = await bcrypt.hash(input.newPassword, SALT_ROUNDS)
  // Bump token version so tokens from before the reset stop working
  userRepo.updateUser(user.id, {
    passwordHash,
    resetToken: null,
    resetExpires: null,
    tokenVersion: (user.token_version ?? 0) + 1,
  })
}

export function deleteUserAccount(userId: number) {
  const success = userRepo.deleteUser(userId)
  if (!success) {
    throw new AppError(404, 'User not found')
  }
}