// server/supabase/functions/llm-proxy/index.ts
// Anthropic Claude Messages API 프록시.
// Phase 3.2: 모델별 쿼터 (Haiku/Sonnet/Opus × Free/Pro/Pro+)
// 요청: application/json { messages, system?, max_tokens?, model? }
// 응답: JSON (non-stream) 또는 SSE (stream=true)

import { corsHeaders, handleCorsPreflightRequest } from '../_shared/cors.ts'
import { requireUser, authErrorResponse, type AuthError } from '../_shared/auth.ts'
import {
  checkQuota,
  consumeQuota,
  createServiceRoleClient,
  modelToQuotaKey,
  getQuotaPolicy,
  type Tier,
} from '../_shared/quota.ts'
import {
  hasAssistantText,
  LlmRequestError,
  parseLlmRequest,
} from '../_shared/llm-contract.ts'
import {
  GENERATION_ID_HEADER,
  GENERATION_PURPOSE_HEADER,
  GenerationReceiptError,
  parseGenerationPurpose,
  parseGenerationReceiptId,
  type GenerationPurpose,
} from '../_shared/generation-receipt.ts'
import { buildAnthropicSystemBlocks } from '../_shared/generative-ai-safety.ts'

/** 티어별 허용 모델 — free는 Haiku만, pro는 +Sonnet, pro_plus는 +Opus, team/enterprise는 전 모델 */
const TIER_MODELS: Record<Tier, string[]> = {
  free: ['claude-haiku-4-5-20251001'],
  pro: ['claude-haiku-4-5-20251001', 'claude-sonnet-4-6', 'claude-opus-4-6'],
  pro_plus: ['claude-haiku-4-5-20251001', 'claude-sonnet-4-6', 'claude-opus-4-6'],
  team: ['claude-haiku-4-5-20251001', 'claude-sonnet-4-6', 'claude-opus-4-6'],
  enterprise: ['claude-haiku-4-5-20251001', 'claude-sonnet-4-6', 'claude-opus-4-6'],
}

const DEFAULT_MODEL: Record<Tier, string> = {
  free: 'claude-haiku-4-5-20251001',
  pro: 'claude-sonnet-4-6',
  pro_plus: 'claude-sonnet-4-6',
  team: 'claude-sonnet-4-6',
  enterprise: 'claude-sonnet-4-6',
}

async function issueGenerationReceipt(
  serviceClient: ReturnType<typeof createServiceRoleClient>,
  userId: string,
  purpose: GenerationPurpose | null,
  model: string,
): Promise<string | null> {
  if (purpose === null) return null
  const { data, error } = await serviceClient.rpc('issue_content_generation_receipt_v1', {
    p_actor_id: userId,
    p_purpose: purpose,
    p_model: model,
  })
  if (error) {
    console.error('Generation receipt issuance failed', { code: error.code ?? 'unknown' })
    throw new GenerationReceiptError('generation_receipt_unavailable')
  }
  return parseGenerationReceiptId(data)
}

function generationHeaders(generationId: string | null): Record<string, string> {
  return generationId === null ? {} : { [GENERATION_ID_HEADER]: generationId }
}

Deno.serve(async (req: Request) => {
  const preflight = handleCorsPreflightRequest(req)
  if (preflight) return preflight

  if (req.method !== 'POST') {
    return new Response(JSON.stringify({ error: 'Method not allowed' }), {
      status: 405,
      headers: { ...corsHeaders, 'Content-Type': 'application/json' },
    })
  }

  try {
    const user = await requireUser(req)
    const serviceClient = createServiceRoleClient()

    let rawBody: unknown
    try {
      rawBody = await req.json()
    } catch {
      throw new LlmRequestError('Invalid JSON body')
    }
    const body = parseLlmRequest(rawBody)
    const generationPurpose = parseGenerationPurpose(
      req.headers.get(GENERATION_PURPOSE_HEADER),
    )

    // A deployment without a provider must not consume quota or fabricate an answer.
    const anthropicKey = Deno.env.get('ANTHROPIC_API_KEY')?.trim() ?? ''
    if (!anthropicKey) {
      return new Response(JSON.stringify({ error: 'provider_unavailable' }), {
        status: 503,
        headers: { ...corsHeaders, 'Content-Type': 'application/json', 'Cache-Control': 'no-store' },
      })
    }

    // 1단계: 티어 조회 (어떤 모델이든 한 번만 읽으면 됨 — haiku로 대리 조회)
    const tierCheck = await checkQuota(user.id, 'llm_haiku', serviceClient)
    const tier = tierCheck.tier

    // 모델 선택 + 티어 검증
    const requestedModel = body.model ?? DEFAULT_MODEL[tier]
    if (!TIER_MODELS[tier].includes(requestedModel)) {
      return new Response(
        JSON.stringify({
          error: 'model_not_allowed',
          tier,
          requested: requestedModel,
          allowed: TIER_MODELS[tier],
        }),
        {
          status: 403,
          headers: { ...corsHeaders, 'Content-Type': 'application/json' },
        },
      )
    }

    // 2단계: 해당 모델의 쿼터 확인 (모델별 일간/주간)
    const quotaKey = modelToQuotaKey(requestedModel)
    const modelQuota = await checkQuota(user.id, quotaKey, serviceClient)
    if (!modelQuota.allowed) {
      return new Response(
        JSON.stringify({
          error: 'quota_exceeded',
          model: requestedModel,
          current: modelQuota.current,
          limit: modelQuota.limit,
          period: modelQuota.period,
          tier,
          overage_credits: modelQuota.overageCredits,
        }),
        {
          status: 429,
          headers: { ...corsHeaders, 'Content-Type': 'application/json' },
        },
      )
    }

    // 3단계: 쿼터 소비 (원자적 base → overage fallback)
    const policy = getQuotaPolicy(tier, quotaKey)
    const consume = await consumeQuota(user.id, quotaKey, serviceClient, policy.limit)
    if (!consume.allowed) {
      return new Response(
        JSON.stringify({
          error: 'quota_exceeded',
          model: requestedModel,
          current: consume.current,
          limit: consume.limit,
          tier,
          overage_credits: consume.overageCredits,
        }),
        {
          status: 429,
          headers: { ...corsHeaders, 'Content-Type': 'application/json' },
        },
      )
    }

    // 실제 Anthropic API 호출 (Prompt Caching 2024-07-31 활성화)
    const systemPayload = buildAnthropicSystemBlocks(body.system)

    const anthropicResp = await fetch('https://api.anthropic.com/v1/messages', {
      method: 'POST',
      headers: {
        'Content-Type': 'application/json',
        'x-api-key': anthropicKey,
        'anthropic-version': '2023-06-01',
        'anthropic-beta': 'prompt-caching-2024-07-31',
      },
      body: JSON.stringify({
        model: requestedModel,
        max_tokens: body.max_tokens,
        system: systemPayload,
        messages: body.messages,
        stream: body.stream,
      }),
      signal: AbortSignal.timeout(45_000),
    })

    if (!anthropicResp.ok) {
      console.error('Anthropic request failed', { status: anthropicResp.status })
      return new Response(JSON.stringify({ error: 'provider_request_failed' }), {
        status: 502,
        headers: { ...corsHeaders, 'Content-Type': 'application/json', 'Cache-Control': 'no-store' },
      })
    }

    if (body.stream && anthropicResp.body) {
      const generationId = await issueGenerationReceipt(
        serviceClient,
        user.id,
        generationPurpose,
        requestedModel,
      )
      return new Response(anthropicResp.body, {
        status: 200,
        headers: {
          ...corsHeaders,
          ...generationHeaders(generationId),
          'Content-Type': 'text/event-stream',
          'Cache-Control': 'no-store',
          Connection: 'keep-alive',
        },
      })
    }

    const data: unknown = await anthropicResp.json()
    if (!hasAssistantText(data)) {
      console.error('Anthropic returned an invalid response shape')
      return new Response(JSON.stringify({ error: 'provider_invalid_response' }), {
        status: 502,
        headers: { ...corsHeaders, 'Content-Type': 'application/json', 'Cache-Control': 'no-store' },
      })
    }
    const generationId = await issueGenerationReceipt(
      serviceClient,
      user.id,
      generationPurpose,
      requestedModel,
    )
    return new Response(JSON.stringify(data), {
      status: 200,
      headers: {
        ...corsHeaders,
        ...generationHeaders(generationId),
        'Content-Type': 'application/json',
        'Cache-Control': 'no-store',
      },
    })
  } catch (err) {
    if (err instanceof GenerationReceiptError) {
      const invalidPurpose = err.code === 'invalid_generation_purpose'
      return new Response(JSON.stringify({
        error: invalidPurpose ? 'invalid_request' : 'generation_receipt_unavailable',
      }), {
        status: invalidPurpose ? 400 : 503,
        headers: { ...corsHeaders, 'Content-Type': 'application/json', 'Cache-Control': 'no-store' },
      })
    }
    if (err instanceof LlmRequestError) {
      return new Response(JSON.stringify({ error: 'invalid_request', message: err.message }), {
        status: err.status,
        headers: { ...corsHeaders, 'Content-Type': 'application/json', 'Cache-Control': 'no-store' },
      })
    }
    if (err && typeof err === 'object' && 'status' in err && 'message' in err) {
      return authErrorResponse(err as AuthError, corsHeaders)
    }
    const timedOut = err instanceof DOMException && err.name === 'TimeoutError'
    console.error('llm-proxy failed', { kind: timedOut ? 'provider_timeout' : 'internal_error' })
    return new Response(JSON.stringify({ error: timedOut ? 'provider_timeout' : 'internal_error' }), {
      status: timedOut ? 504 : 500,
      headers: { ...corsHeaders, 'Content-Type': 'application/json', 'Cache-Control': 'no-store' },
    })
  }
})