import { config } from '../config'
import { prisma } from '../prisma'
import {
  deletePublicFile,
  isR2PublicFilesConfigured,
  publicFileUrl,
  uploadPublicFile,
  userAvatarKey
} from '../storage/r2-public-files'
import { hashPassword, verifyPassword } from '../security/password'
import { redis } from '../redis'
import { randomBytes } from 'crypto'
import { createOpaqueToken, hashToken } from '../security/tokens'
import type { AuthUser } from '../types'

type UserWithAffiliation = {
  id: string
  email: string
  name: string | null
  role: string
  createdAt: Date
  lastLoginAt: Date | null
  appRoles?: Array<{
    appKey: string
    roleCode: string
  }>
  affiliations?: Array<{
    id: string
    organizationId: string
    department: string | null
    position: string | null
    organization: {
      name: string
      type: string
    }
  }>
  userLicenses?: Array<{
    id: string
    startsAt: Date
    expiresAt: Date | null
    license: {
      code: string
      name: string
    }
  }>
}

const activeLicenseWhere = () => {
  const now = new Date()
  return {
    startsAt: { lte: now },
    OR: [{ expiresAt: null }, { expiresAt: { gt: now } }],
    license: { isActive: true }
  }
}

const currentLicenseRelation = () => ({
  where: activeLicenseWhere(),
  orderBy: { startsAt: 'desc' },
  take: 1,
  select: {
    id: true,
    startsAt: true,
    expiresAt: true,
    license: {
      select: {
        code: true,
        name: true
      }
    }
  }
}) as const

const userSelect = () => {
  const now = new Date()
  return {
  id: true,
  email: true,
  name: true,
  role: true,
  createdAt: true,
  lastLoginAt: true,
  affiliations: {
    where: { isPrimary: true, endsAt: null },
    take: 1,
    select: {
      id: true,
      organizationId: true,
      department: true,
      position: true,
      organization: {
        select: {
          name: true,
          type: true
        }
      }
    }
  },
  userLicenses: currentLicenseRelation(),
  appRoles: {
    where: {
      AND: [
        { OR: [{ startsAt: null }, { startsAt: { lte: now } }] },
        { OR: [{ endsAt: null }, { endsAt: { gt: now } }] }
      ]
    },
    select: {
      appKey: true,
      roleCode: true
    }
  }
  }
}

const toAuthUser = (user: UserWithAffiliation): AuthUser => {
  const primaryAffiliation = user.affiliations?.[0]
  const currentLicense = user.userLicenses?.[0]
  return {
    id: user.id,
    email: user.email,
    name: user.name,
    role: user.role,
    appRoles: user.appRoles ?? [],
    createdAt: user.createdAt,
    lastLoginAt: user.lastLoginAt,
    primaryAffiliation: primaryAffiliation
      ? {
        id: primaryAffiliation.id,
        organizationId: primaryAffiliation.organizationId,
        organizationName: primaryAffiliation.organization.name,
        organizationType: primaryAffiliation.organization.type,
        department: primaryAffiliation.department,
        position: primaryAffiliation.position
      }
      : null,
    currentLicense: currentLicense
      ? {
        id: currentLicense.id,
        code: currentLicense.license.code,
        name: currentLicense.license.name,
        startsAt: currentLicense.startsAt,
        expiresAt: currentLicense.expiresAt
      }
      : null
  }
}

export async function findUserByEmail(email: string) {
  return prisma.user.findUnique({
    where: { email: email.toLowerCase() },
    include: {
      affiliations: {
        where: { isPrimary: true, endsAt: null },
        take: 1,
        include: { organization: true }
      },
      userLicenses: {
        where: activeLicenseWhere(),
        orderBy: { startsAt: 'desc' },
        take: 1,
        include: { license: true }
      },
      appRoles: {
        where: {
          AND: [
            { OR: [{ startsAt: null }, { startsAt: { lte: new Date() } }] },
            { OR: [{ endsAt: null }, { endsAt: { gt: new Date() } }] }
          ]
        },
        select: {
          appKey: true,
          roleCode: true
        }
      }
    }
  })
}

export async function createUser(input: { email: string; password: string; name?: string | null }): Promise<AuthUser> {
  const freeLicense = await prisma.license.findUnique({
    where: { code: 'FREE' },
    select: { defaultDurationDays: true }
  })
  const licenseStartsAt = new Date()
  const licenseExpiresAt = calculateLicenseExpiresAt(licenseStartsAt, freeLicense?.defaultDurationDays)

  const user = await prisma.user.create({
    data: {
      email: input.email.toLowerCase(),
      passwordHash: await hashPassword(input.password),
      name: input.name?.trim() || null,
      userLicenses: {
        create: {
          startsAt: licenseStartsAt,
          expiresAt: licenseExpiresAt,
          license: {
            connect: { code: 'FREE' }
          }
        }
      }
    },
    select: userSelect()
  })

  return toAuthUser(user)
}

export async function createInstructorUser(input: {
  email: string
  password: string
  name?: string | null
  instructorInviteCode: string
}): Promise<AuthUser | null> {
  return prisma.$transaction(async (tx) => {
    const organization = await tx.organization.findFirst({
      where: {
        isActive: true,
        instructorInviteCode: input.instructorInviteCode.trim().toUpperCase()
      },
      select: { id: true, defaultLicenseCode: true }
    })
    if (!organization) return null

    const requestedLicenseCode = organization.defaultLicenseCode ?? 'FREE'
    const license = await tx.license.findFirst({
      where: { code: requestedLicenseCode as 'FREE' | 'EDU' | 'PRO', isActive: true },
      select: { code: true }
    })

    const user = await tx.user.create({
      data: {
        email: input.email.toLowerCase(),
        passwordHash: await hashPassword(input.password),
        name: input.name?.trim() || null,
        affiliations: {
          create: { organizationId: organization.id, isPrimary: true }
        },
        appRoles: {
          create: { appKey: 'LMS', roleCode: 'INSTRUCTOR' }
        },
        userLicenses: {
          create: {
            license: { connect: { code: license?.code ?? 'FREE' } }
          }
        }
      },
      select: userSelect()
    })

    return toAuthUser(user)
  })
}

export async function findOrCreateOAuthUser(input: {
  provider: string
  providerUserId: string
  email: string
  name?: string | null
}): Promise<AuthUser> {
  const provider = input.provider.toLowerCase()
  const email = input.email.toLowerCase()

  const oauthAccount = await prisma.userOauthAccount.findUnique({
    where: {
      provider_providerUserId: {
        provider,
        providerUserId: input.providerUserId
      }
    },
    include: {
      user: {
        select: userSelect()
      }
    }
  })

  if (oauthAccount?.user) return toAuthUserEnsuringFreeLicense(oauthAccount.user)

  const existingUser = await prisma.user.findUnique({
    where: { email },
    select: { id: true }
  })

  if (existingUser) {
    const user = await prisma.user.update({
      where: { id: existingUser.id },
      data: {
        oauthAccounts: {
          create: {
            provider,
            providerUserId: input.providerUserId,
            email
          }
        }
      },
      select: userSelect()
    })

    return toAuthUserEnsuringFreeLicense(user)
  }

  const freeLicense = await prisma.license.findUnique({
    where: { code: 'FREE' },
    select: { defaultDurationDays: true }
  })
  const licenseStartsAt = new Date()
  const licenseExpiresAt = calculateLicenseExpiresAt(licenseStartsAt, freeLicense?.defaultDurationDays)

  const user = await prisma.user.create({
    data: {
      email,
      passwordHash: await hashPassword(createOpaqueToken()),
      name: input.name?.trim() || null,
      oauthAccounts: {
        create: {
          provider,
          providerUserId: input.providerUserId,
          email
        }
      },
      userLicenses: {
        create: {
          startsAt: licenseStartsAt,
          expiresAt: licenseExpiresAt,
          license: {
            connect: { code: 'FREE' }
          }
        }
      }
    },
    select: userSelect()
  })

  return toAuthUser(user)
}

async function toAuthUserEnsuringFreeLicense(user: UserWithAffiliation): Promise<AuthUser> {
  if (user.userLicenses?.[0]) return toAuthUser(user)

  await ensureFreeLicense(user.id)
  return (await findUserById(user.id)) ?? toAuthUser(user)
}

async function ensureFreeLicense(userId: string): Promise<void> {
  const activeLicense = await prisma.userLicense.findFirst({
    where: {
      userId,
      ...activeLicenseWhere()
    },
    select: { id: true }
  })

  if (activeLicense) return

  const freeLicense = await prisma.license.findUnique({
    where: { code: 'FREE' },
    select: { id: true, defaultDurationDays: true }
  })
  if (!freeLicense) throw new Error('FREE license is not configured')

  const licenseStartsAt = new Date()
  const licenseExpiresAt = calculateLicenseExpiresAt(licenseStartsAt, freeLicense.defaultDurationDays)

  await prisma.userLicense.create({
    data: {
      userId,
      licenseId: freeLicense.id,
      startsAt: licenseStartsAt,
      expiresAt: licenseExpiresAt
    }
  })
}

function calculateLicenseExpiresAt(startsAt: Date, durationDays: number | null | undefined): Date | null {
  if (!durationDays) return null

  const expiresAt = new Date(startsAt)
  expiresAt.setDate(expiresAt.getDate() + durationDays)
  return expiresAt
}

export async function createManagedUser(input: {
  email: string
  password: string
  name?: string | null
  organizationId: string
  department?: string | null
  position?: string | null
  licenseCode?: 'FREE' | 'EDU' | 'PRO'
}): Promise<AuthUser> {
  const user = await prisma.user.create({
    data: {
      email: input.email.toLowerCase(),
      passwordHash: await hashPassword(input.password),
      name: input.name?.trim() || null,
      role: 'USER',
      affiliations: {
        create: {
          organizationId: input.organizationId,
          department: input.department?.trim() || null,
          position: input.position?.trim() || null,
          isPrimary: true
        }
      },
      userLicenses: {
        create: {
          license: {
            connect: { code: input.licenseCode ?? 'EDU' }
          }
        }
      }
    },
    select: userSelect()
  })

  return toAuthUser(user)
}

export async function updateUserPassword(userId: string, password: string): Promise<void> {
  await prisma.user.update({
    where: { id: userId },
    data: { passwordHash: await hashPassword(password) }
  })
}

export async function changeUserPassword(userId: string, currentPassword: string, newPassword: string): Promise<boolean> {
  const user = await prisma.user.findFirst({
    where: { id: userId, isActive: true },
    select: { passwordHash: true }
  })

  if (!user) return false

  const passwordOk = await verifyPassword(currentPassword, user.passwordHash)
  if (!passwordOk) return false

  await updateUserPassword(userId, newPassword)
  return true
}

export async function updateUserProfileImage(userId: string, imageData: Uint8Array, mimeType: string): Promise<void> {
  if (isR2PublicFilesConfigured()) {
    await uploadPublicFile({
      key: userAvatarKey(userId),
      body: imageData,
      contentType: mimeType
    })

    await prisma.user.update({
      where: { id: userId },
      data: {
        profileImageData: null,
        profileImageMime: mimeType,
        profileImageUpdatedAt: new Date()
      }
    })
    return
  }

  await prisma.user.update({
    where: { id: userId },
    data: {
      profileImageData: Buffer.from(imageData),
      profileImageMime: mimeType,
      profileImageUpdatedAt: new Date()
    }
  })
}

export async function deleteUserProfileImage(userId: string): Promise<void> {
  await deletePublicFile(userAvatarKey(userId)).catch(() => undefined)

  await prisma.user.update({
    where: { id: userId },
    data: {
      profileImageData: null,
      profileImageMime: null,
      profileImageUpdatedAt: null
    }
  })
}

export async function findUserProfileImage(userId: string): Promise<{ data?: Buffer; url?: string; mimeType: string; updatedAt: Date | null } | null> {
  const user = await prisma.user.findFirst({
    where: { id: userId, isActive: true },
    select: {
      profileImageData: true,
      profileImageMime: true,
      profileImageUpdatedAt: true
    }
  })

  if (!user?.profileImageMime) return null

  const storedUrl = publicFileUrl(userAvatarKey(userId))
  if (!user.profileImageData && storedUrl) {
    return {
      url: storedUrl,
      mimeType: user.profileImageMime,
      updatedAt: user.profileImageUpdatedAt
    }
  }

  if (!user.profileImageData) return null

  return {
    data: Buffer.from(user.profileImageData),
    mimeType: user.profileImageMime,
    updatedAt: user.profileImageUpdatedAt
  }
}

export async function findUserById(id: string): Promise<AuthUser | null> {
  const user = await prisma.user.findFirst({
    where: { id, isActive: true },
    select: userSelect()
  })

  return user ? toAuthUser(user) : null
}

export async function listOrganizations() {
  return prisma.organization.findMany({
    where: { isActive: true },
    orderBy: [{ type: 'asc' }, { name: 'asc' }],
    select: {
      id: true,
      name: true,
      type: true,
      domain: true,
      createdAt: true
    }
  })
}

export async function createOrganization(input: { name: string; type: 'COMPANY' | 'SCHOOL' | 'GOVERNMENT' | 'LAB' | 'OTHER'; domain?: string | null }) {
  const instructorInviteCode = await createInstructorInviteCode()
  return prisma.organization.create({
    data: {
      name: input.name.trim(),
      type: input.type,
      domain: input.domain?.trim() || null,
      instructorInviteCode
    },
    select: {
      id: true,
      name: true,
      type: true,
      domain: true,
      createdAt: true
    }
  })
}

async function createInstructorInviteCode(): Promise<string> {
  const alphabet = 'ABCDEFGHJKLMNPQRSTUVWXYZ23456789'
  for (let attempt = 0; attempt < 10; attempt += 1) {
    const code = Array.from(randomBytes(6), (byte) => alphabet[byte % alphabet.length]).join('')
    const existing = await prisma.organization.findUnique({
      where: { instructorInviteCode: code },
      select: { id: true }
    })
    if (!existing) return code
  }

  throw new Error('failed_to_generate_instructor_invite_code')
}

export async function assignUserAffiliation(input: {
  userId: string
  organizationId: string
  department?: string | null
  position?: string | null
  isPrimary?: boolean
}) {
  return prisma.$transaction(async (tx) => {
    if (input.isPrimary) {
      await tx.userAffiliation.updateMany({
        where: { userId: input.userId, endsAt: null },
        data: { isPrimary: false }
      })
    }

    return tx.userAffiliation.create({
      data: {
        userId: input.userId,
        organizationId: input.organizationId,
        department: input.department?.trim() || null,
        position: input.position?.trim() || null,
        isPrimary: input.isPrimary ?? true
      },
      select: {
        id: true,
        userId: true,
        organizationId: true,
        department: true,
        position: true,
        isPrimary: true,
        organization: {
          select: {
            name: true,
            type: true
          }
        }
      }
    })
  })
}

export async function markLastLogin(userId: string, loggedInAt = new Date()): Promise<void> {
  await prisma.user.update({
    where: { id: userId },
    data: { lastLoginAt: loggedInAt }
  })
}

export async function isLoginBlocked(email: string): Promise<boolean> {
  const attempts = Number(await redis.get(loginAttemptKey(email)))
  return Number.isFinite(attempts) && attempts >= config.maxFailedLoginAttempts
}

export async function recordFailedLogin(email: string): Promise<void> {
  const attempts = await redis.incr(loginAttemptKey(email))
  if (attempts === 1) {
    await redis.expire(loginAttemptKey(email), config.loginAttemptWindowSeconds)
  }
}

export async function clearLoginAttempts(email: string): Promise<void> {
  await redis.del(loginAttemptKey(email))
}

export async function storeEmailVerificationCode(email: string, code: string): Promise<void> {
  await redis.set(
    emailVerificationKey(email),
    JSON.stringify({ code, email: email.toLowerCase() }),
    'EX',
    config.emailVerificationTtlSeconds
  )
}

export async function verifyEmailVerificationCode(email: string, code: string): Promise<boolean> {
  const key = emailVerificationKey(email)
  const tokenJson = await redis.get(key)
  if (typeof tokenJson !== 'string') return false

  const token = parseStoredEmailVerification(tokenJson)
  if (!token || token.email !== email.toLowerCase() || token.code !== code) return false

  await redis.del(key)
  return true
}

export async function storePasswordResetCode(email: string, code: string): Promise<void> {
  await redis.set(
    passwordResetKey(email),
    JSON.stringify({ code, email: email.toLowerCase() }),
    'EX',
    config.emailVerificationTtlSeconds
  )
}

export async function verifyPasswordResetCode(email: string, code: string): Promise<boolean> {
  const key = passwordResetKey(email)
  const tokenJson = await redis.get(key)
  if (typeof tokenJson !== 'string') return false

  const token = parseStoredEmailVerification(tokenJson)
  if (!token || token.email !== email.toLowerCase() || token.code !== code) return false

  await redis.del(key)
  return true
}

export async function createRefreshToken(userId: string): Promise<string> {
  const token = createOpaqueToken()
  const expiresAt = new Date(Date.now() + config.refreshTokenTtlSeconds * 1000)

  await redis.set(refreshTokenKey(token), JSON.stringify({ userId }), 'EX', config.refreshTokenTtlSeconds)

  await prisma.$transaction([
    prisma.refreshToken.updateMany({
      where: {
        userId,
        revokedAt: null,
        expiresAt: { gt: new Date() }
      },
      data: { revokedAt: new Date() }
    }),
    prisma.refreshToken.create({
      data: {
        userId,
        tokenHash: hashToken(token),
        expiresAt
      }
    })
  ])

  return token
}

export async function rotateRefreshToken(refreshToken: string): Promise<AuthUser | null> {
  const tokenHash = hashToken(refreshToken)
  const tokenJson = await redis.send('GETDEL', [refreshTokenKey(refreshToken)])
  if (typeof tokenJson !== 'string') return null

  const token = parseStoredRefreshToken(tokenJson)
  if (!token) return null

  const storedToken = await prisma.refreshToken.findUnique({
    where: { tokenHash },
    select: { id: true, userId: true, revokedAt: true, expiresAt: true }
  })

  if (!storedToken || storedToken.userId !== token.userId || storedToken.revokedAt || storedToken.expiresAt <= new Date()) {
    return null
  }

  await prisma.refreshToken.update({
    where: { id: storedToken.id },
    data: { revokedAt: new Date() }
  })

  return findUserById(token.userId)
}

export async function createOAuthState(redirectUri: string): Promise<string> {
  const state = createOpaqueToken()
  await redis.set(oauthStateKey(state), JSON.stringify({ redirectUri }), 'EX', 10 * 60)
  return state
}

export async function consumeOAuthState(state: string): Promise<{ redirectUri: string } | null> {
  const tokenJson = await redis.send('GETDEL', [oauthStateKey(state)])
  if (!tokenJson) return null

  try {
    const payload = JSON.parse(String(tokenJson)) as { redirectUri?: unknown }
    return typeof payload.redirectUri === 'string' ? { redirectUri: payload.redirectUri } : null
  } catch {
    return null
  }
}

export async function createOAuthLoginToken(userId: string): Promise<string> {
  const token = createOpaqueToken()
  await redis.set(oauthLoginTokenKey(token), JSON.stringify({ userId }), 'EX', config.oauthLoginTokenTtlSeconds)
  return token
}

export async function exchangeOAuthLoginToken(loginToken: string): Promise<AuthUser | null> {
  const tokenJson = await redis.send('GETDEL', [oauthLoginTokenKey(loginToken)])
  if (!tokenJson) return null

  try {
    const payload = JSON.parse(String(tokenJson)) as { userId?: unknown }
    return typeof payload.userId === 'string' ? findUserById(payload.userId) : null
  } catch {
    return null
  }
}

export async function revokeRefreshToken(refreshToken: string): Promise<void> {
  await Promise.all([
    redis.del(refreshTokenKey(refreshToken)),
    prisma.refreshToken.updateMany({
      where: {
        tokenHash: hashToken(refreshToken),
        revokedAt: null
      },
      data: { revokedAt: new Date() }
    })
  ])
}

export async function revokeRefreshTokensForUser(userId: string): Promise<void> {
  await prisma.refreshToken.updateMany({
    where: {
      userId,
      revokedAt: null,
      expiresAt: { gt: new Date() }
    },
    data: { revokedAt: new Date() }
  })
}

export async function createHandoffToken(userId: string, audienceApp: string): Promise<string> {
  const token = createOpaqueToken()
  await redis.set(
    handoffTokenKey(token),
    JSON.stringify({ userId, audienceApp }),
    'EX',
    config.handoffTokenTtlSeconds
  )
  return token
}

export async function exchangeHandoffToken(handoffToken: string, audienceApp?: string): Promise<AuthUser | null> {
  const tokenJson = await redis.send('GETDEL', [handoffTokenKey(handoffToken)])
  if (typeof tokenJson !== 'string') return null

  const token = parseStoredHandoffToken(tokenJson)
  if (!token || (audienceApp && token.audienceApp !== audienceApp)) return null

  return findUserById(token.userId)
}

const refreshTokenKey = (token: string): string => `auth:refresh:${hashToken(token)}`
const oauthStateKey = (state: string): string => `auth:oauth:state:${hashToken(state)}`
const oauthLoginTokenKey = (token: string): string => `auth:oauth:login:${hashToken(token)}`

const handoffTokenKey = (token: string): string => `auth:handoff:${hashToken(token)}`

const loginAttemptKey = (email: string): string => `auth:login_attempt:${hashToken(email.toLowerCase())}`

const emailVerificationKey = (email: string): string => `auth:email_verify:${hashToken(email.toLowerCase())}`

const passwordResetKey = (email: string): string => `auth:password_reset:${hashToken(email.toLowerCase())}`

const parseStoredRefreshToken = (value: string): { userId: string } | null => {
  try {
    const parsed = JSON.parse(value)
    return typeof parsed.userId === 'string' ? { userId: parsed.userId } : null
  } catch {
    return null
  }
}

const parseStoredHandoffToken = (value: string): { userId: string; audienceApp: string } | null => {
  try {
    const parsed = JSON.parse(value)
    return typeof parsed.userId === 'string' && typeof parsed.audienceApp === 'string'
      ? { userId: parsed.userId, audienceApp: parsed.audienceApp }
      : null
  } catch {
    return null
  }
}

const parseStoredEmailVerification = (value: string): { email: string; code: string } | null => {
  try {
    const parsed = JSON.parse(value)
    return typeof parsed.email === 'string' && typeof parsed.code === 'string'
      ? { email: parsed.email, code: parsed.code }
      : null
  } catch {
    return null
  }
}