// server/supabase/functions/stt-proxy/index.ts
// D3RO Voice — Multi-Provider Cloud Speech-to-Text Proxy
// Supports dynamic routing via D3RO API Backend or Direct Providers (Groq, OpenAI, Deepgram, Google)

import { corsHeaders, handleCorsPreflightRequest } from '../_shared/cors.ts'
import { requireUser, authErrorResponse, type AuthError } from '../_shared/auth.ts'
import { createServiceRoleClient, finalizeSttQuota, reserveSttQuota } from '../_shared/quota.ts'
import {
  buildDictionaryHints,
  createInternalSttGatewayUrl,
  createDeepgramSttUrl,
  normalizeSttResult,
  type NormalizedSttResult,
  SttInputError,
  STT_PROVIDER_TIMEOUT_MS,
  validateSttAudio,
} from '../_shared/stt-contract.ts'

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' }
    })
  }

  let quotaReservation: {
    id: string
    client: ReturnType<typeof createServiceRoleClient>
  } | null = null

  try {
    // 1) 인증
    let user: Awaited<ReturnType<typeof requireUser>>
    try {
      user = await requireUser(req)
    } catch (err) {
      if (
        err &&
        typeof err === 'object' &&
        'status' in err &&
        (err.status === 401 || err.status === 403) &&
        'message' in err &&
        typeof err.message === 'string'
      ) {
        return authErrorResponse(err as AuthError, corsHeaders)
      }

      return new Response(JSON.stringify({ error: 'internal_error' }), {
        status: 500,
        headers: { ...corsHeaders, 'Content-Type': 'application/json' }
      })
    }

    // 2) service client
    const serviceClient = createServiceRoleClient()

    // 3) 입력 파싱
    const formData = await req.formData()
    const audio = formData.get('audio') ?? formData.get('file')
    const languageCode = String(formData.get('language_code') ?? 'ko')

    if (!(audio instanceof Blob)) {
      return new Response(JSON.stringify({ error: 'Missing audio field' }), {
        status: 400,
        headers: { ...corsHeaders, 'Content-Type': 'application/json' }
      })
    }

    let audioInput: ReturnType<typeof validateSttAudio>
    try {
      audioInput = validateSttAudio(audio, languageCode)
    } catch (error) {
      if (error instanceof SttInputError) {
        return new Response(JSON.stringify({ error: error.code }), {
          status: error.status,
          headers: { ...corsHeaders, 'Content-Type': 'application/json' },
        })
      }
      throw error
    }

    // Reserve before provider work. The DB advisory lock closes concurrent
    // quota races; failed or crashed provider work is refunded/reclaimed.
    const quota = await reserveSttQuota(user.id, crypto.randomUUID(), serviceClient)
    if (!quota.allowed || !quota.reservationId || quota.status !== 'reserved') {
      return new Response(
        JSON.stringify({
          error: 'quota_exceeded',
          current: quota.current,
          limit: quota.limit,
          period: quota.period,
          tier: quota.tier,
          overage_credits: quota.overageCredits,
        }),
        {
          status: 429,
          headers: { ...corsHeaders, 'Content-Type': 'application/json' },
        },
      )
    }
    quotaReservation = { id: quota.reservationId, client: serviceClient }

    const dictionaryQuery = await serviceClient
      .from('dictionary')
      .select('word,pronunciation')
      .eq('user_id', user.id)
      .order('usage_count', { ascending: false })
      .limit(50)
    const dictionaryHints = buildDictionaryHints(
      dictionaryQuery.error ? [] : (dictionaryQuery.data ?? []),
    )

    const apiServerUrl = Deno.env.get('D3RO_API_URL') ?? Deno.env.get('BACKEND_ORIGIN') ?? ''
    // Supabase user JWTs are not valid D3RO API JWTs. Configure a dedicated backend token.
    const apiServerToken = Deno.env.get('D3RO_API_TOKEN') ?? ''
    const groqKey = Deno.env.get('GROQ_API_KEY') ?? ''
    const openaiKey = Deno.env.get('OPENAI_API_KEY') ?? ''
    const deepgramKey = Deno.env.get('DEEPGRAM_API_KEY') ?? ''

    let result: NormalizedSttResult | null = null
    let attemptedProvider = false
    let sawBadGatewayFailure = false
    let sawServiceUnavailable = false

    // 4) Forward to D3RO API Gateway Orchestrator if available
    if (apiServerUrl && apiServerToken) {
      attemptedProvider = true
      try {
        const forwardForm = new FormData()
        forwardForm.append('file', audio, audioInput.fileName)
        forwardForm.append('language', audioInput.languageCode)
        if (dictionaryHints.prompt) forwardForm.append('prompt', dictionaryHints.prompt)

        const apiResp = await fetch(createInternalSttGatewayUrl(apiServerUrl), {
          method: 'POST',
          headers: { 'X-D3RO-STT-Gateway-Token': apiServerToken },
          body: forwardForm,
          signal: AbortSignal.timeout(STT_PROVIDER_TIMEOUT_MS),
        })

        if (apiResp.ok) {
          const apiData = await apiResp.json()
          if (typeof apiData?.text !== 'string') {
            throw new Error('Invalid STT gateway response')
          }
          result = normalizeSttResult({
            transcript: apiData.text,
            confidence: apiData.confidence ?? 0.98,
            language_code: apiData.language
              ?? (audioInput.languageCode === 'auto' || audioInput.languageCode === 'multi' ? 'und' : audioInput.languageCode),
            duration_seconds: apiData.durationSeconds ?? (audio.size / 4000),
            provider: apiData.provider ?? 'd3ro-gateway',
          })
        } else if (apiResp.status === 503) {
          sawServiceUnavailable = true
        } else {
          sawBadGatewayFailure = true
        }
      } catch {
        sawBadGatewayFailure = true
      }
    }

    // 5) Direct Groq Whisper LPU Fallback (Sub-200ms)
    if (!result && groqKey) {
      attemptedProvider = true
      try {
        const groqForm = new FormData()
        groqForm.append('file', audio, audioInput.fileName)
        groqForm.append('model', 'whisper-large-v3-turbo')
        if (audioInput.languageCode !== 'auto' && audioInput.languageCode !== 'multi') {
          groqForm.append('language', audioInput.languageCode)
        }
        if (dictionaryHints.prompt) groqForm.append('prompt', dictionaryHints.prompt)
        groqForm.append('response_format', 'verbose_json')

        const groqResp = await fetch('https://api.groq.com/openai/v1/audio/transcriptions', {
          method: 'POST',
          headers: {
            Authorization: `Bearer ${groqKey}`,
          },
          body: groqForm,
          signal: AbortSignal.timeout(STT_PROVIDER_TIMEOUT_MS),
        })

        if (groqResp.ok) {
          const groqData = await groqResp.json()
          if (typeof groqData?.text !== 'string') {
            throw new Error('Invalid Groq STT response')
          }
          result = normalizeSttResult({
            transcript: groqData.text,
            confidence: 0.98,
            language_code: groqData.language
              ?? (audioInput.languageCode === 'auto' || audioInput.languageCode === 'multi' ? 'und' : audioInput.languageCode),
            duration_seconds: groqData.duration ?? (audio.size / 4000),
            provider: 'groq',
          })
        } else {
          sawBadGatewayFailure = true
        }
      } catch {
        sawBadGatewayFailure = true
      }
    }

    // 6) Direct OpenAI Whisper Fallback
    if (!result && openaiKey) {
      attemptedProvider = true
      try {
        const openAiForm = new FormData()
        openAiForm.append('file', audio, audioInput.fileName)
        openAiForm.append('model', 'whisper-1')
        if (audioInput.languageCode !== 'auto' && audioInput.languageCode !== 'multi') {
          openAiForm.append('language', audioInput.languageCode)
        }
        if (dictionaryHints.prompt) openAiForm.append('prompt', dictionaryHints.prompt)
        openAiForm.append('response_format', 'verbose_json')

        const openAiResp = await fetch('https://api.openai.com/v1/audio/transcriptions', {
          method: 'POST',
          headers: {
            Authorization: `Bearer ${openaiKey}`,
          },
          body: openAiForm,
          signal: AbortSignal.timeout(STT_PROVIDER_TIMEOUT_MS),
        })

        if (openAiResp.ok) {
          const openAiData = await openAiResp.json()
          if (typeof openAiData?.text !== 'string') {
            throw new Error('Invalid OpenAI STT response')
          }
          result = normalizeSttResult({
            transcript: openAiData.text,
            confidence: 0.98,
            language_code: openAiData.language
              ?? (audioInput.languageCode === 'auto' || audioInput.languageCode === 'multi' ? 'und' : audioInput.languageCode),
            duration_seconds: openAiData.duration ?? (audio.size / 4000),
            provider: 'openai',
          })
        } else {
          sawBadGatewayFailure = true
        }
      } catch {
        sawBadGatewayFailure = true
      }
    }

    // 7) Direct Deepgram Nova-3 Fallback
    if (!result && deepgramKey) {
      attemptedProvider = true
      try {
        const audioBuffer = await audio.arrayBuffer()
        const dgResp = await fetch(createDeepgramSttUrl(
          audioInput.languageCode,
          dictionaryHints.keyterms,
        ), {
          method: 'POST',
          headers: {
            Authorization: `Token ${deepgramKey}`,
            'Content-Type': audioInput.contentType,
          },
          body: audioBuffer,
          signal: AbortSignal.timeout(STT_PROVIDER_TIMEOUT_MS),
        })

        if (dgResp.ok) {
          const dgData = await dgResp.json()
          const transcript = dgData.results?.channels?.[0]?.alternatives?.[0]?.transcript
          if (typeof transcript !== 'string') {
            throw new Error('Invalid Deepgram STT response')
          }
          const confidence = dgData.results?.channels?.[0]?.alternatives?.[0]?.confidence ?? 0.95
          result = normalizeSttResult({
            transcript,
            confidence,
            language_code: dgData.results?.channels?.[0]?.detected_language
              ?? (audioInput.languageCode === 'auto' || audioInput.languageCode === 'multi' ? 'und' : audioInput.languageCode),
            duration_seconds: dgData.metadata?.duration ?? (audio.size / 4000),
            provider: 'deepgram',
          })
        } else {
          sawBadGatewayFailure = true
        }
      } catch {
        sawBadGatewayFailure = true
      }
    }

    // 8) Fail closed if no provider produced a real transcription.
    if (!result) {
      await finalizeSttQuota(quotaReservation.id, false, quotaReservation.client).catch(() => undefined)
      quotaReservation = null
      const status = !attemptedProvider || (!sawBadGatewayFailure && sawServiceUnavailable) ? 503 : 502
      const error = status === 503 ? 'stt_provider_unavailable' : 'stt_upstream_failed'
      return new Response(JSON.stringify({ error }), {
        status,
        headers: { ...corsHeaders, 'Content-Type': 'application/json' }
      })
    }

    // 9) Mark the exact pre-provider reservation as consumed.
    const finalStatus = await finalizeSttQuota(quotaReservation.id, true, quotaReservation.client)
    if (finalStatus !== 'completed') {
      throw new Error('STT quota reservation was reclaimed before completion.')
    }
    quotaReservation = null

    return new Response(JSON.stringify(result), {
      status: 200,
      headers: { ...corsHeaders, 'Content-Type': 'application/json' }
    })
  } catch {
    if (quotaReservation) {
      await finalizeSttQuota(quotaReservation.id, false, quotaReservation.client).catch(() => undefined)
    }
    return new Response(JSON.stringify({ error: 'internal_error' }), {
      status: 500,
      headers: { ...corsHeaders, 'Content-Type': 'application/json' }
    })
  }
})