'use server'

import prisma from '@/lib/prisma'
import { auth } from '@/auth'
import { SubscriptionTier } from '@prisma/client'
import { VALID_FEATURES, getCurrentPeriodKey } from '@/lib/quota-utils'
import {
  getAllEntitlementsForAdmin,
  invalidateEntitlementCache,
  ENTITLEMENT_UNAVAILABLE,
  type SubscriptionTier as TierType,
} from '@/lib/plan-entitlements'
import { logAuditEventAsync } from '@/lib/audit-log'
import { revalidatePath } from 'next/cache'

const BILLING_CONFIG_KEYS = [
  'BILLING_ENABLED',
  'STRIPE_PRICE_PRO_MONTHLY',
  'STRIPE_PRICE_PRO_ANNUAL',
  'STRIPE_PRICE_BUSINESS_MONTHLY',
  'STRIPE_PRICE_BUSINESS_ANNUAL',
  'STRIPE_PRICE_CREDITS_S',
  'STRIPE_PRICE_CREDITS_M',
  'STRIPE_PRICE_CREDITS_L',
] as const

const TIERS: TierType[] = ['BASIC', 'PRO', 'BUSINESS', 'ENTERPRISE']

async function checkAdmin() {
  const session = await auth()
  if (!session?.user?.id || (session.user as { role?: string }).role !== 'ADMIN') {
    throw new Error('Unauthorized: Admin access required')
  }
  return session
}

function assertValidFeature(feature: string) {
  if (!(VALID_FEATURES as readonly string[]).includes(feature)) {
    throw new Error(`Invalid feature: ${feature}`)
  }
}

function assertValidTier(tier: string): asserts tier is TierType {
  if (!TIERS.includes(tier as TierType)) {
    throw new Error(`Invalid tier: ${tier}`)
  }
}

async function getStripeHealth(billingConfig: Record<string, string>) {
  const secret = process.env.STRIPE_SECRET_KEY ?? ''
  const publishable = process.env.NEXT_PUBLIC_STRIPE_PUBLISHABLE_KEY ?? ''
  const webhook = process.env.STRIPE_WEBHOOK_SECRET ?? ''

  let secretMode: 'test' | 'live' | 'missing' | 'placeholder' = 'missing'
  if (!secret) secretMode = 'missing'
  else if (secret === 'sk_test_placeholder' || secret.includes('placeholder')) secretMode = 'placeholder'
  else if (secret.startsWith('sk_live_')) secretMode = 'live'
  else if (secret.startsWith('sk_test_')) secretMode = 'test'
  else secretMode = 'placeholder'

  const { isBillingEnabled } = await import('@/lib/billing/stripe-prices')
  const { SUBSCRIPTION_TRIAL_DAYS } = await import('@/lib/billing/trial-constants')
  const billingEnabled = await isBillingEnabled()

  const priceKeys = [
    ...BILLING_CONFIG_KEYS.filter((k) => k.startsWith('STRIPE_PRICE_')),
  ] as string[]

  const canCallStripe = secretMode === 'test' || secretMode === 'live'
  let stripe: Awaited<ReturnType<typeof import('@/lib/stripe').getStripe>> | null = null
  if (canCallStripe) {
    try {
      const { getStripe } = await import('@/lib/stripe')
      stripe = getStripe()
    } catch {
      stripe = null
    }
  }

  const prices = await Promise.all(
    priceKeys.map(async (key) => {
      const priceId = (billingConfig[key] || process.env[key] || '').trim()
      const configured = Boolean(priceId) && !priceId.startsWith('price_mock_')
      let stripeAmount: number | null = null
      let stripeCurrency: string | null = null
      let stripeActive: boolean | null = null
      let error: string | null = null

      if (configured && stripe) {
        try {
          const price = await stripe.prices.retrieve(priceId)
          stripeAmount = price.unit_amount != null ? price.unit_amount / 100 : null
          stripeCurrency = price.currency?.toUpperCase() ?? null
          stripeActive = price.active
        } catch (e) {
          error = e instanceof Error ? e.message : 'Stripe price lookup failed'
        }
      }

      return {
        key,
        priceId: configured ? priceId : '',
        configured,
        source: billingConfig[key] ? 'db' : process.env[key] ? 'env' : 'missing',
        stripeAmount,
        stripeCurrency,
        stripeActive,
        error,
      }
    }),
  )

  return {
    secretConfigured: secretMode === 'test' || secretMode === 'live',
    secretMode,
    publishableConfigured: Boolean(publishable) && publishable.startsWith('pk_'),
    webhookSecretConfigured: Boolean(webhook) && webhook.startsWith('whsec_'),
    billingEnabled,
    trialDays: SUBSCRIPTION_TRIAL_DAYS,
    prices,
  }
}

async function getSubscriptionStats() {
  const [byTierRaw, byStatusRaw, cancelAtPeriodEnd, recent] = await Promise.all([
    prisma.subscription.groupBy({
      by: ['tier'],
      _count: { _all: true },
    }),
    prisma.subscription.groupBy({
      by: ['status'],
      _count: { _all: true },
    }),
    prisma.subscription.count({ where: { cancelAtPeriodEnd: true } }),
    prisma.subscription.findMany({
      where: {
        OR: [
          { tier: { in: ['PRO', 'BUSINESS', 'ENTERPRISE'] } },
          { status: { in: ['TRIALING', 'PAST_DUE', 'ACTIVE'] } },
        ],
      },
      orderBy: { updatedAt: 'desc' },
      take: 15,
      select: {
        tier: true,
        status: true,
        trialEndsAt: true,
        currentPeriodEnd: true,
        cancelAtPeriodEnd: true,
        updatedAt: true,
        stripeSubscriptionId: true,
        user: { select: { email: true, name: true } },
      },
    }),
  ])

  const byTier: Record<string, number> = Object.fromEntries(TIERS.map((t) => [t, 0]))
  for (const row of byTierRaw) {
    byTier[row.tier] = row._count._all
  }

  const byStatus: Record<string, number> = {}
  for (const row of byStatusRaw) {
    byStatus[row.status] = row._count._all
  }

  const usersWithoutSub = await prisma.user.count({
    where: { subscription: null },
  })

  return {
    byTier,
    byStatus,
    cancelAtPeriodEnd,
    usersWithoutSub,
    trialing: byStatus.TRIALING ?? 0,
    pastDue: byStatus.PAST_DUE ?? 0,
    paidActive:
      (byStatus.ACTIVE ?? 0) +
      (byStatus.TRIALING ?? 0),
    recent: recent.map((s) => ({
      email: s.user.email,
      name: s.user.name,
      tier: s.tier,
      status: s.status,
      trialEndsAt: s.trialEndsAt?.toISOString() ?? null,
      currentPeriodEnd: s.currentPeriodEnd?.toISOString() ?? null,
      cancelAtPeriodEnd: s.cancelAtPeriodEnd,
      hasStripeSub: Boolean(s.stripeSubscriptionId),
      updatedAt: s.updatedAt.toISOString(),
    })),
  }
}

export async function getBillingAdminData() {
  await checkAdmin()
  const { getSystemConfig } = await import('@/lib/config')
  const config = await getSystemConfig()
  const entitlements = await getAllEntitlementsForAdmin()
  const usageOverview = await getUsageOverviewInternal()

  const billingConfig = Object.fromEntries(
    BILLING_CONFIG_KEYS.map((key) => [key, config[key] ?? '']),
  )

  const { CREDIT_ALLOCATIONS, CREDIT_COSTS, slideGenerateCreditCost } = await import('@/lib/credits')
  const { CREDIT_PACKS, CREDIT_PACK_IDS } = await import('@/lib/billing/credit-packs')

  const creditAllocations = TIERS.map((tier) => {
    const raw = CREDIT_ALLOCATIONS[tier]
    return {
      tier,
      monthlyCredits: raw === 'unlimited' ? null : raw,
      unlimited: raw === 'unlimited',
    }
  })

  const creditCosts = {
    ...CREDIT_COSTS,
    slide_generate_example: slideGenerateCreditCost(7),
  }

  const creditPacks = CREDIT_PACK_IDS.map((id) => {
    const p = CREDIT_PACKS[id]
    return {
      id: p.id,
      credits: p.credits,
      defaultDisplay: p.defaultDisplay,
    }
  })

  const [stripeHealth, subscriptionStats] = await Promise.all([
    getStripeHealth(billingConfig),
    getSubscriptionStats(),
  ])

  return {
    entitlements,
    billingConfig,
    usageOverview,
    features: [...VALID_FEATURES],
    tiers: TIERS,
    creditAllocations,
    creditCosts,
    creditPacks,
    stripeHealth,
    subscriptionStats,
  }
}

export async function updatePlanEntitlement(
  tier: string,
  feature: string,
  mode: 'unavailable' | 'unlimited' | 'limited',
  limitValue?: number,
) {
  const session = await checkAdmin()
  assertValidTier(tier)
  assertValidFeature(feature)

  if (mode === 'limited') {
    if (limitValue === undefined || !Number.isFinite(limitValue) || limitValue < 0) {
      throw new Error('Limit must be a non-negative number')
    }
  }

  if (mode === 'unavailable') {
    await prisma.planEntitlement.upsert({
      where: {
        tier_feature: {
          tier: tier as SubscriptionTier,
          feature,
        },
      },
      update: { limitValue: ENTITLEMENT_UNAVAILABLE },
      create: {
        tier: tier as SubscriptionTier,
        feature,
        limitValue: ENTITLEMENT_UNAVAILABLE,
      },
    });
  } else {
    await prisma.planEntitlement.upsert({
      where: {
        tier_feature: {
          tier: tier as SubscriptionTier,
          feature,
        },
      },
      update: {
        limitValue: mode === 'unlimited' ? null : Math.round(limitValue!),
      },
      create: {
        tier: tier as SubscriptionTier,
        feature,
        limitValue: mode === 'unlimited' ? null : Math.round(limitValue!),
      },
    })
  }

  invalidateEntitlementCache()

  await logAuditEventAsync({
    userId: session.user?.id,
    action: 'PLAN_ENTITLEMENT_UPDATED',
    resource: `${tier}:${feature}`,
    metadata: { tier, feature, mode, limitValue: mode === 'limited' ? limitValue : mode },
  })

  revalidatePath('/admin/billing')
  return { success: true }
}

export async function updateBillingConfig(data: Record<string, string>) {
  const session = await checkAdmin()

  const filtered = Object.fromEntries(
    Object.entries(data).filter(([key, value]) =>
      (BILLING_CONFIG_KEYS as readonly string[]).includes(key)
      && value !== ''
      && !value.includes('sk_')
      && !value.includes('whsec_'),
    ),
  )

  if (filtered.BILLING_ENABLED === 'true') {
    const required = [
      'STRIPE_PRICE_PRO_MONTHLY',
      'STRIPE_PRICE_PRO_ANNUAL',
      'STRIPE_PRICE_BUSINESS_MONTHLY',
      'STRIPE_PRICE_BUSINESS_ANNUAL',
    ] as const
    for (const key of required) {
      if (!filtered[key] && !process.env[key]) {
        throw new Error(`Missing ${key} when billing is enabled`)
      }
    }
  }

  const operations = Object.entries(filtered).map(([key, value]) =>
    prisma.systemConfig.upsert({
      where: { key },
      update: { value },
      create: { key, value },
    }),
  )

  await prisma.$transaction(operations)

  await logAuditEventAsync({
    userId: session.user?.id,
    action: 'BILLING_CONFIG_UPDATED',
    resource: 'billing',
    metadata: { keys: Object.keys(filtered) },
  })

  revalidatePath('/admin/billing')
  revalidatePath('/settings/billing')
  return { success: true }
}

async function getUsageOverviewInternal() {
  const period = getCurrentPeriodKey()
  const periodStart = new Date(`${period}-01T00:00:00.000Z`)

  const aggregated = await prisma.usageLog.groupBy({
    by: ['feature'],
    where: { periodStart },
    _sum: { requestsCount: true, tokensUsed: true },
    _count: { userId: true },
  })

  const lastSync = await prisma.usageLog.findFirst({
    where: { periodStart },
    orderBy: { syncedAt: 'desc' },
    select: { syncedAt: true },
  })

  const topUsers = await prisma.usageLog.groupBy({
    by: ['userId'],
    where: { periodStart },
    _sum: { requestsCount: true },
    orderBy: { _sum: { requestsCount: 'desc' } },
    take: 10,
  })

  const userIds = topUsers.map((u) => u.userId)
  const users = userIds.length
    ? await prisma.user.findMany({
        where: { id: { in: userIds } },
        select: { id: true, email: true, name: true },
      })
    : []

  const userMap = Object.fromEntries(users.map((u) => [u.id, u]))

  return {
    period,
    lastSyncedAt: lastSync?.syncedAt?.toISOString() ?? null,
    byFeature: aggregated.map((row) => ({
      feature: row.feature,
      requests: row._sum.requestsCount ?? 0,
      tokens: row._sum.tokensUsed ?? 0,
      users: row._count.userId,
    })),
    topUsers: topUsers.map((row) => ({
      userId: row.userId,
      email: userMap[row.userId]?.email ?? row.userId,
      name: userMap[row.userId]?.name ?? null,
      requests: row._sum.requestsCount ?? 0,
    })),
  }
}

export async function getUsageOverview() {
  await checkAdmin()
  return getUsageOverviewInternal()
}