import Link from 'next/link'
import { Alert, Box, Button, Chip, Stack, Typography } from '@mui/material'
import { Check } from 'lucide-react'
import type { Subscription, SubscriptionTier } from '@d3ro/api-client'
import type { PaidPlanTier } from '@d3ro/core/plan-catalog'
import { MetalCard, TactileBadge } from '@d3ro/ui/components/ds'
import { d3roFontMono } from '@d3ro/ui/theme'
import { BillingCheckoutOptions } from '@/components/billing/billing-checkout-options'
import { PaypleManageButton } from '@/components/billing/payple-manage-button'
import { PortalButton } from '@/components/billing/portal-button'
import { getSupabaseServerClient } from '@/lib/supabase-server'
import {
  formatPlanCatalogPrice,
  parseBillingCatalog,
  type BillingCatalog,
  type BillingCatalogPrice
} from '@/lib/billing-catalog'

type BillingProvider = Subscription['provider']

interface BillingSubscription {
  tier: SubscriptionTier
  status: string | null
  provider: BillingProvider
  current_period_end: string | null
  cancel_at: string | null
  auto_renewing: boolean | null
}

interface BillingState {
  email: string
  subscription: BillingSubscription
  catalog: BillingCatalog | null
}

interface BillingPageProps {
  searchParams: Promise<Record<string, string | string[] | undefined>>
}

interface Plan {
  tier: SubscriptionTier
  name: string
  features: string[]
  highlight?: boolean
}

const VALID_TIERS = new Set<SubscriptionTier>(['free', 'pro', 'pro_plus'])
const VALID_PROVIDERS = new Set<BillingProvider>([
  'none',
  'stripe',
  'payple',
  'google_play',
  'app_store',
  'admin'
])

const PLANS: Plan[] = [
  {
    tier: 'free',
    name: 'FREE',
    features: ['기본 음성 인식', '로컬 AI 무제한', '무료 클라우드 쿼터']
  },
  {
    tier: 'pro',
    name: 'PRO',
    highlight: true,
    features: [
      'Claude Sonnet / Opus 다듬기',
      '실시간 음성 대화',
      '기기 간 전사 동기화',
      '맞춤형 프롬프트와 자동 서식'
    ]
  },
  {
    tier: 'pro_plus',
    name: 'PRO+',
    features: [
      'PRO 모든 기능',
      '프리미엄 AI 확장 쿼터',
      '고급 회의·요약 기능',
      '우선 지원'
    ]
  }
]

/** 데스크톱·모바일·사이트가 billingUrl({ tier }) 로 넘긴 요금제. 모르는 값은 무시한다. */
function selectedTierFrom(value: string | string[] | undefined): PaidPlanTier | null {
  return value === 'pro' || value === 'pro_plus' ? value : null
}

function tierLabel(tier: SubscriptionTier): string {
  return tier === 'pro_plus' ? 'PRO+' : tier.toUpperCase()
}

function providerLabel(provider: BillingProvider): string {
  const labels: Record<BillingProvider, string> = {
    none: '없음',
    payple: 'Payple',
    stripe: 'Stripe',
    google_play: 'Google Play',
    app_store: 'App Store',
    admin: '관리자 부여'
  }
  return labels[provider]
}

function formatDate(value: string | null): string | null {
  if (!value) return null
  const date = new Date(value)
  if (!Number.isFinite(date.getTime())) return null
  return new Intl.DateTimeFormat('ko-KR', { dateStyle: 'medium' }).format(date)
}

async function loadBillingState(): Promise<BillingState> {
  const supabase = await getSupabaseServerClient()
  const { data: userData, error: userError } = await supabase.auth.getUser()
  if (userError || !userData.user) throw new Error('authenticated_session_required')

  const { data, error } = await supabase
    .from('subscriptions')
    .select('tier, status, provider, payment_provider, current_period_end, cancel_at, auto_renewing')
    .eq('user_id', userData.user.id)
    .maybeSingle()

  if (error) throw new Error('subscription_lookup_failed')
  if (!data) throw new Error('subscription_not_initialized')
  if (!VALID_TIERS.has(data.tier)) throw new Error('subscription_tier_invalid')

  const providerCandidate = data.provider === 'none' && data.payment_provider !== 'none'
    ? data.payment_provider
    : data.provider
  if (!VALID_PROVIDERS.has(providerCandidate)) throw new Error('subscription_provider_invalid')

  const { data: catalogData, error: catalogError } = await supabase.functions.invoke('billing-catalog', {
    body: {}
  })
  const catalog = catalogError ? null : parseBillingCatalog(catalogData)

  return {
    email: userData.user.email ?? '이메일 없음',
    subscription: {
      tier: data.tier,
      status: data.status,
      provider: providerCandidate,
      current_period_end: data.current_period_end,
      cancel_at: data.cancel_at,
      auto_renewing: data.auto_renewing
    },
    catalog
  }
}

export default async function BillingPage({ searchParams }: BillingPageProps): Promise<React.ReactElement> {
  const params = await searchParams
  let state: BillingState
  try {
    state = await loadBillingState()
  } catch {
    return <BillingLoadError />
  }

  const { subscription } = state
  const isPaid = subscription.tier !== 'free'
  const canPurchase = !isPaid && subscription.provider === 'none'
  const cancellationDate = formatDate(subscription.cancel_at)
  const periodEnd = formatDate(subscription.current_period_end)
  const stripeCanceled = params['canceled'] === '1'
  const stripeReturned = params['success'] === '1'
  const selectedTier = selectedTierFrom(params['tier'])

  return (
    <Box sx={{ maxWidth: 1120, mx: 'auto', p: { xs: 2.5, md: 4 }, pt: 4, pb: 10 }}>
      <Box sx={{ textAlign: 'center', mb: 4 }}>
        <Box sx={{ display: 'inline-flex', alignItems: 'center', gap: 1, mb: 1.5 }}>
          <TactileBadge ledColor="amber" tone="accent">D3RO VOICE PRO</TactileBadge>
        </Box>
        <Typography component="h1" sx={{ fontSize: 28, fontWeight: 500, color: 'var(--d3-text-inverse)', letterSpacing: '-0.02em', mb: 1 }}>
          구독 및 결제
        </Typography>
        <Typography sx={{ fontSize: 14, color: 'var(--d3-text-label)' }}>
          결제 계정과 provider를 확인한 뒤 필요한 플랜을 선택해 주세요.
        </Typography>
      </Box>

      {stripeCanceled && (
        <Alert severity="info" sx={{ mb: 2 }} data-testid="stripe-canceled-message">
          Stripe Checkout을 취소했습니다. 결제나 구독 변경은 발생하지 않았습니다.
        </Alert>
      )}
      {stripeReturned && (
        <Alert severity={isPaid ? 'success' : 'warning'} sx={{ mb: 2 }} data-testid="stripe-return-message">
          {isPaid
            ? 'Stripe 결제가 확인되어 구독 정보가 갱신되었습니다.'
            : 'Stripe 결제 결과를 확인 중입니다. 잠시 후 이 페이지를 새로고침해 주세요.'}
        </Alert>
      )}

      <MetalCard sx={{ p: { xs: 2.5, md: 3.5 }, mb: 4 }}>
        <Stack direction={{ xs: 'column', md: 'row' }} justifyContent="space-between" gap={3}>
          <Box>
            <Typography sx={{ fontFamily: d3roFontMono, fontSize: 11, letterSpacing: 1.5, color: 'var(--d3-text-label)', mb: 1 }}>
              CURRENT SUBSCRIPTION
            </Typography>
            <Box sx={{ display: 'flex', alignItems: 'center', gap: 1.5, flexWrap: 'wrap' }}>
              <Typography data-testid="billing-current-tier" sx={{ fontSize: 28, fontWeight: 600, color: 'var(--d3-text-inverse)' }}>
                {tierLabel(subscription.tier)}
              </Typography>
              <Chip
                data-testid="billing-current-provider"
                size="small"
                label={providerLabel(subscription.provider)}
                color={subscription.provider === 'none' ? 'default' : 'primary'}
              />
              {subscription.status && <Chip size="small" variant="outlined" label={subscription.status} />}
            </Box>
            <Typography data-testid="billing-account" sx={{ mt: 1.5, color: 'var(--d3-text-label)', fontSize: 13 }}>
              결제 계정: {state.email}
            </Typography>
            {cancellationDate ? (
              <Typography data-testid="billing-cancel-at" sx={{ mt: 1, color: 'var(--d3-status-warning)', fontSize: 12 }}>
                {cancellationDate}에 구독이 종료됩니다.
              </Typography>
            ) : periodEnd && isPaid ? (
              <Typography sx={{ mt: 1, color: 'var(--d3-text-label)', fontSize: 12 }}>
                현재 결제 기간: {periodEnd}까지
              </Typography>
            ) : null}
          </Box>

          <SubscriptionManagement subscription={subscription} />
        </Stack>
      </MetalCard>

      {!canPurchase && !isPaid && (
        <Alert severity="warning" sx={{ mb: 3 }}>
          기존 결제 provider 상태가 정리되지 않아 새 결제를 시작할 수 없습니다. 고객센터에 문의해 주세요.
        </Alert>
      )}

      {!state.catalog && (
        <Alert severity="error" sx={{ mb: 3 }} data-testid="billing-catalog-unavailable">
          검증된 결제 가격을 불러오지 못했습니다. 가격이 확인될 때까지 새 결제를 시작할 수 없습니다.
        </Alert>
      )}

      <Box sx={{ display: 'grid', gridTemplateColumns: { xs: '1fr', md: 'repeat(3, 1fr)' }, gap: 2.5 }}>
        {PLANS.map((plan) => (
          <PlanCard
            key={plan.tier}
            plan={plan}
            currentTier={subscription.tier}
            canPurchase={canPurchase}
            catalog={state.catalog}
            selectedTier={selectedTier}
          />
        ))}
      </Box>

      <Typography sx={{ mt: 4, textAlign: 'center', color: 'var(--d3-text-label)', fontSize: 11 }}>
        국내 카드는 Payple, 해외 카드는 Stripe가 처리합니다. 활성 구독이 있으면 같은 provider에서만 관리할 수 있습니다.
      </Typography>
    </Box>
  )
}

function PlanCard({
  plan,
  currentTier,
  canPurchase,
  catalog,
  selectedTier
}: {
  plan: Plan
  currentTier: SubscriptionTier
  canPurchase: boolean
  catalog: BillingCatalog | null
  selectedTier: PaidPlanTier | null
}): React.ReactElement {
  const active = plan.tier === currentTier
  // 외부에서 고른 요금제가 있으면 그 카드만, 없으면 기본 추천 카드를 강조한다.
  const selected = !active && selectedTier === plan.tier
  const recommended = !active && !selectedTier && Boolean(plan.highlight)
  const catalogPrices: BillingCatalogPrice[] = plan.tier === 'free' || !catalog
    ? []
    : catalog.plans[plan.tier]
  const priceLabel = formatPlanCatalogPrice(plan.tier, catalog) ?? '가격 정보 이용 불가'
  return (
    <MetalCard
      data-testid={`billing-plan-${plan.tier}`}
      data-selected={selected ? 'true' : undefined}
      aria-current={selected ? 'true' : undefined}
      sx={{
        p: 3,
        display: 'flex',
        flexDirection: 'column',
        minHeight: 390,
        border: active || selected
          ? '2px solid var(--d3-accent-main)'
          : recommended
            ? '1px solid var(--d3-accent-glow)'
            : undefined
      }}
    >
      <Box sx={{ flex: 1 }}>
        <Typography sx={{ fontFamily: d3roFontMono, fontSize: 11, color: active || selected ? 'var(--d3-accent-main)' : 'var(--d3-text-label)', mb: 0.75 }}>
          {active ? 'CURRENT PLAN' : selected ? 'SELECTED PLAN' : recommended ? 'RECOMMENDED' : 'PLAN'}
        </Typography>
        <Typography component="h2" sx={{ fontSize: 24, fontWeight: 600, color: 'var(--d3-text-inverse)' }}>{plan.name}</Typography>
        <Typography sx={{ mt: 0.5, mb: 3, color: plan.tier === 'free' ? 'var(--d3-text-label)' : 'var(--d3-accent-main)', fontFamily: d3roFontMono, fontSize: 16 }}>
          {priceLabel}
        </Typography>
        <Stack spacing={1.5} sx={{ mb: 3 }}>
          {plan.features.map((feature) => (
            <Box key={feature} sx={{ display: 'flex', alignItems: 'flex-start', gap: 1.25 }}>
              <Check size={15} color="var(--d3-accent-main)" style={{ marginTop: 2, flexShrink: 0 }} />
              <Typography sx={{ color: 'var(--d3-text-secondary)', fontSize: 13 }}>{feature}</Typography>
            </Box>
          ))}
        </Stack>
      </Box>

      {active ? (
        <Box sx={{ py: 1.5, textAlign: 'center', border: '1px solid var(--d3-border-default)', borderRadius: 2, color: 'var(--d3-text-label)', fontSize: 12 }}>
          현재 이용 중
        </Box>
      ) : plan.tier === 'free' ? (
        <Typography sx={{ py: 1.5, textAlign: 'center', color: 'var(--d3-text-label)', fontSize: 12 }}>
          유료 구독 종료 후 적용됩니다.
        </Typography>
      ) : canPurchase && catalogPrices.length > 0 ? (
        <BillingCheckoutOptions tier={plan.tier} prices={catalogPrices} />
      ) : canPurchase ? (
        <Typography data-testid={`billing-price-unavailable-${plan.tier}`} sx={{ py: 1.5, textAlign: 'center', color: 'var(--d3-status-warning)', fontSize: 12 }}>
          검증된 가격을 불러온 뒤 결제할 수 있습니다.
        </Typography>
      ) : (
        <Typography sx={{ py: 1.5, textAlign: 'center', color: 'var(--d3-text-label)', fontSize: 12 }}>
          현재 구독을 먼저 관리해 주세요.
        </Typography>
      )}
    </MetalCard>
  )
}

function SubscriptionManagement({ subscription }: { subscription: BillingSubscription }): React.ReactElement {
  if (subscription.tier === 'free') {
    return <Typography sx={{ color: 'var(--d3-text-label)', fontSize: 12 }}>활성 유료 구독이 없습니다.</Typography>
  }
  if (subscription.cancel_at || subscription.auto_renewing === false) {
    return <Typography sx={{ color: 'var(--d3-status-warning)', fontSize: 12 }}>자동 갱신이 해지되었습니다.</Typography>
  }
  if (subscription.provider === 'payple') return <PaypleManageButton />
  if (subscription.provider === 'stripe') return <PortalButton />
  if (subscription.provider === 'google_play') {
    return <Alert severity="info">Google Play 앱에서 구독을 관리해 주세요.</Alert>
  }
  if (subscription.provider === 'app_store') {
    return <Alert severity="info">App Store 구독 설정에서 관리해 주세요.</Alert>
  }
  if (subscription.provider === 'admin') {
    return <Alert severity="info">관리자가 부여한 구독입니다.</Alert>
  }
  return <Alert severity="warning">구독 provider를 확인할 수 없습니다.</Alert>
}

function BillingLoadError(): React.ReactElement {
  return (
    <Box sx={{ maxWidth: 720, mx: 'auto', p: 4 }}>
      <Alert severity="error" data-testid="billing-load-error" sx={{ mb: 2 }}>
        구독 정보를 불러오지 못했습니다. 결제를 시작하지 않았습니다.
      </Alert>
      <Link href="/billing" style={{ textDecoration: 'none' }}>
        <Button variant="outlined">다시 시도</Button>
      </Link>
    </Box>
  )
}