'use strict'
const { WebSocket } = require('ws')
const cfg = require('./config')
const { log, json, parseBody, lookupCustomerByPhone, createCommunication, erpFetch } = require('./helpers')
const { execTool } = require('./agent')

// Gemini Live API WebSocket endpoint
const GEMINI_WS = 'wss://generativelanguage.googleapis.com/ws/google.ai.generativelanguage.v1beta.GenerativeService.BidiGenerateContent'
const LIVE_MODEL = cfg.VOICE_MODEL || 'models/gemini-2.5-flash-live-preview'

// Active voice sessions: callSid → session
const sessions = new Map()

// ── Audio conversion: Twilio mulaw 8kHz ↔ Gemini PCM16 16kHz/24kHz ──

// mulaw → linear PCM16 lookup table (ITU-T G.711)
const MULAW_TO_LINEAR = new Int16Array(256)
;(() => {
  for (let i = 0; i < 256; i++) {
    let mu = ~i & 0xFF
    const sign = (mu & 0x80) ? -1 : 1
    const exponent = (mu >> 4) & 0x07
    const mantissa = mu & 0x0F
    let magnitude = ((mantissa << 1) + 33) << (exponent + 2)
    magnitude -= 0x84
    MULAW_TO_LINEAR[i] = sign * magnitude
  }
})()

// linear PCM16 → mulaw lookup (bias method)
function linearToMulaw (sample) {
  const BIAS = 0x84, CLIP = 32635
  const sign = (sample >> 8) & 0x80
  if (sign) sample = -sample
  if (sample > CLIP) sample = CLIP
  sample += BIAS
  let exponent = 7
  const expMask = 0x4000
  for (; exponent > 0; exponent--) {
    if (sample & (expMask >> (7 - exponent))) break
  }
  const mantissa = (sample >> (exponent + 3)) & 0x0F
  return ~(sign | (exponent << 4) | mantissa) & 0xFF
}

// Twilio mulaw 8kHz base64 → PCM16 16kHz base64 (for Gemini input)
function mulawToGemini (mulawB64) {
  const mulawBuf = Buffer.from(mulawB64, 'base64')
  // Decode mulaw → PCM16 @ 8kHz
  const pcm8k = Buffer.alloc(mulawBuf.length * 2)
  for (let i = 0; i < mulawBuf.length; i++) {
    pcm8k.writeInt16LE(MULAW_TO_LINEAR[mulawBuf[i]], i * 2)
  }
  // Upsample 8kHz → 16kHz (linear interpolation)
  const pcm16k = Buffer.alloc(pcm8k.length * 2)
  for (let i = 0; i < pcm8k.length / 2; i++) {
    const s0 = pcm8k.readInt16LE(i * 2)
    const s1 = (i + 1 < pcm8k.length / 2) ? pcm8k.readInt16LE((i + 1) * 2) : s0
    pcm16k.writeInt16LE(s0, i * 4)
    pcm16k.writeInt16LE(Math.round((s0 + s1) / 2), i * 4 + 2)
  }
  return pcm16k.toString('base64')
}

// Gemini PCM16 24kHz base64 → Twilio mulaw 8kHz base64
function geminiToMulaw (pcmB64) {
  const pcm24k = Buffer.from(pcmB64, 'base64')
  const samplesIn = pcm24k.length / 2
  // Downsample 24kHz → 8kHz (take every 3rd sample)
  const samplesOut = Math.floor(samplesIn / 3)
  const mulawBuf = Buffer.alloc(samplesOut)
  for (let i = 0; i < samplesOut; i++) {
    const sample = pcm24k.readInt16LE(i * 6)
    mulawBuf[i] = linearToMulaw(sample)
  }
  return mulawBuf.toString('base64')
}

// ── Gemini Live tool definitions (different format than OpenAI) ──
function buildGeminiTools () {
  const openaiTools = require('./agent-tools.json')
  return [{
    functionDeclarations: openaiTools
      .filter(t => t.function.name !== 'get_chat_link') // voice doesn't need chat link
      .map(t => ({
        name: t.function.name,
        description: t.function.description,
        parameters: t.function.parameters.required?.length
          ? { type: 'OBJECT', properties: Object.fromEntries(Object.entries(t.function.parameters.properties).map(([k, v]) => [k, { type: v.type.toUpperCase(), description: v.description || '' }])), required: t.function.parameters.required }
          : { type: 'OBJECT', properties: {} },
      })),
  }]
}

// ── Voice system prompt ──
const VOICE_SYSTEM_PROMPT = `Tu es l'assistant vocal de Gigafibre, fournisseur Internet fibre optique au Québec.

Règles vocales:
- Parle TOUJOURS en français québécois naturel
- Sois conversationnel et chaleureux, comme un vrai agent au téléphone
- Phrases courtes — max 1-2 phrases avant de laisser le client répondre
- Utilise les outils pour consulter le compte en temps réel
- Pour les problèmes techniques, vérifie l'état du modem (check_device_status) avant de suggérer quoi que ce soit
- Signal optique < -25 dBm = problème fibre physique → crée un ticket
- Modem hors ligne > 10 min → suggère un redémarrage
- Ne partage JAMAIS d'infos techniques internes (OLT port, network ID, IP de gestion)
- Si tu ne peux pas résoudre, crée un ticket
- Quand tu obtiens des données d'un outil, résume en langage simple (pas de jargon technique)`

// ── Inbound call handler: lookup caller, build dynamic IVR ──
async function handleInboundCall (req, res) {
  const body = await parseBody(req)
  const from = body.From || ''
  const callSid = body.CallSid || ''
  log(`Voice IN: ${from} (CallSid: ${callSid})`)

  const customer = await lookupCustomerByPhone(from)
  if (!customer) {
    // Unknown caller — polite redirect
    const twiml = `<?xml version="1.0" encoding="UTF-8"?>
<Response>
  <Say language="fr-CA" voice="Google.fr-CA-Neural2-A">Bonjour, bienvenue chez Gigafibre. Nous n'avons pas trouvé votre numéro dans notre système. Veuillez nous joindre au 4 5 0, 6 5 5, 3 2 3 5.</Say>
  <Hangup/>
</Response>`
    res.writeHead(200, { 'Content-Type': 'text/xml' })
    return res.end(twiml)
  }

  // Fetch locations that have active subscriptions (not just any Service Location)
  let locations = []
  try {
    const subFields = JSON.stringify(['service_location', 'item_code', 'custom_description'])
    const subFilters = JSON.stringify({ party_type: 'Customer', party: customer.name, status: 'Active' })
    const r = await erpFetch(`/api/resource/Subscription?filters=${encodeURIComponent(subFilters)}&fields=${encodeURIComponent(subFields)}&limit_page_length=50`)
    const subs = (r.status === 200 && r.data?.data) || []
    // Deduplicate by service_location, keep the service description
    const locMap = new Map()
    for (const s of subs) {
      if (!s.service_location) continue
      if (!locMap.has(s.service_location)) locMap.set(s.service_location, { name: s.service_location, service: s.custom_description || s.item_code })
    }
    // Resolve addresses for each unique location
    for (const [locId, loc] of locMap) {
      try {
        const lr = await erpFetch(`/api/resource/Service Location/${encodeURIComponent(locId)}?fields=["address_line","city"]`)
        if (lr.status === 200 && lr.data?.data) {
          loc.address_line = lr.data.data.address_line || locId
          loc.city = lr.data.data.city || ''
        }
      } catch { loc.address_line = locId; loc.city = '' }
    }
    locations = [...locMap.values()]
  } catch {}

  const firstName = (customer.customer_name || '').split(' ')[0] || 'client'

  if (locations.length === 0) {
    // No active locations — go straight to voice agent
    const twiml = buildStreamTwiml(callSid, customer, null, firstName)
    res.writeHead(200, { 'Content-Type': 'text/xml' })
    return res.end(twiml)
  }

  if (locations.length === 1) {
    // Single location — go straight to voice agent with context
    const twiml = buildStreamTwiml(callSid, customer, locations[0], firstName)
    res.writeHead(200, { 'Content-Type': 'text/xml' })
    return res.end(twiml)
  }

  // Multiple locations — dynamic IVR
  let gatherOptions = ''
  locations.forEach((loc, i) => {
    const addr = (loc.address_line || '').replace(/&/g, 'et')
    gatherOptions += `Pour le ${addr}, appuyez ${i + 1}. `
  })
  gatherOptions += `Pour autre chose, appuyez 0.`

  // Store locations in session for the gather callback
  sessions.set(`gather:${callSid}`, { customer, locations })

  const twiml = `<?xml version="1.0" encoding="UTF-8"?>
<Response>
  <Gather numDigits="1" action="${cfg.HUB_PUBLIC_URL}/voice/gather" method="POST" timeout="8">
    <Say language="fr-CA" voice="Google.fr-CA-Neural2-A">Bonjour ${firstName}! ${gatherOptions}</Say>
  </Gather>
  <Say language="fr-CA" voice="Google.fr-CA-Neural2-A">Je n'ai pas reçu de réponse. Je vous transfère à un assistant.</Say>
  <Redirect method="POST">${cfg.HUB_PUBLIC_URL}/voice/connect-agent?callSid=${callSid}&amp;customer=${encodeURIComponent(customer.name)}</Redirect>
</Response>`
  res.writeHead(200, { 'Content-Type': 'text/xml' })
  res.end(twiml)
}

// ── Gather callback: customer pressed a digit ──
async function handleGather (req, res) {
  const body = await parseBody(req)
  const digit = body.Digits || '0'
  const callSid = body.CallSid || ''

  const session = sessions.get(`gather:${callSid}`)
  sessions.delete(`gather:${callSid}`)

  if (!session) {
    res.writeHead(200, { 'Content-Type': 'text/xml' })
    return res.end('<Response><Say language="fr-CA">Erreur de session. Veuillez rappeler.</Say><Hangup/></Response>')
  }

  const { customer, locations } = session
  const idx = parseInt(digit, 10)
  const selectedLoc = (idx >= 1 && idx <= locations.length) ? locations[idx - 1] : null
  const firstName = (customer.customer_name || '').split(' ')[0] || 'client'

  const twiml = buildStreamTwiml(callSid, customer, selectedLoc, firstName)
  res.writeHead(200, { 'Content-Type': 'text/xml' })
  res.end(twiml)
}

// ── Build TwiML that opens a Media Stream to our WebSocket ──
function buildStreamTwiml (callSid, customer, location, firstName) {
  const wsUrl = cfg.HUB_PUBLIC_URL.replace('https://', 'wss://').replace('http://', 'ws://') + '/voice/ws'
  const meta = JSON.stringify({
    callSid, customerId: customer.name, customerName: customer.customer_name,
    location: location ? { name: location.name, address: location.address_line, city: location.city } : null,
  })

  const locContext = location
    ? ` pour votre adresse au ${(location.address_line || '').replace(/&/g, 'et')}`
    : ''

  return `<?xml version="1.0" encoding="UTF-8"?>
<Response>
  <Say language="fr-CA" voice="Google.fr-CA-Neural2-A">Parfait ${firstName}, je vous mets en ligne avec notre assistant${locContext}. Un moment.</Say>
  <Connect>
    <Stream url="${wsUrl}" statusCallbackMethod="POST">
      <Parameter name="meta" value="${Buffer.from(meta).toString('base64')}" />
    </Stream>
  </Connect>
</Response>`
}

// ── Connect to agent directly (no location selection) ──
async function handleConnectAgent (req, res) {
  const body = await parseBody(req)
  const callSid = body.CallSid || req.url?.searchParams?.get('callSid') || ''
  const customerName = req.url?.searchParams?.get('customer') || ''

  let customer = null
  if (customerName) {
    try {
      const r = await erpFetch(`/api/resource/Customer/${encodeURIComponent(customerName)}`)
      if (r.status === 200) customer = r.data.data
    } catch {}
  }

  const firstName = customer ? (customer.customer_name || '').split(' ')[0] : ''
  const twiml = buildStreamTwiml(callSid, customer || { name: customerName, customer_name: customerName }, null, firstName || 'client')
  res.writeHead(200, { 'Content-Type': 'text/xml' })
  res.end(twiml)
}

// ── WebSocket handler: Twilio Media Stream ↔ Gemini Live ──
function handleMediaStream (ws, req) {
  let geminiWs = null
  let streamSid = null
  let meta = null
  let callSid = null

  ws.on('message', async (data) => {
    let msg
    try { msg = JSON.parse(data) } catch { return }

    switch (msg.event) {
      case 'connected':
        log('Twilio Media Stream connected')
        break

      case 'start':
        streamSid = msg.start?.streamSid
        callSid = msg.start?.callSid
        // Decode metadata passed from TwiML
        const metaB64 = msg.start?.customParameters?.meta
        if (metaB64) {
          try { meta = JSON.parse(Buffer.from(metaB64, 'base64').toString()) } catch {}
        }
        log(`Voice session started: ${callSid} customer=${meta?.customerId}`)

        // Open Gemini Live session
        geminiWs = await openGeminiSession(ws, streamSid, meta)
        if (geminiWs) {
          sessions.set(callSid, { ws, geminiWs, streamSid, meta, startedAt: Date.now() })
        }
        break

      case 'media':
        // Forward audio to Gemini (convert mulaw → PCM16)
        if (geminiWs?.readyState === WebSocket.OPEN && msg.media?.payload) {
          try {
            const pcmB64 = mulawToGemini(msg.media.payload)
            geminiWs.send(JSON.stringify({
              realtimeInput: { audio: { data: pcmB64, mimeType: 'audio/pcm;rate=16000' } },
            }))
          } catch {}
        }
        break

      case 'stop':
        log(`Voice session ended: ${callSid}`)
        if (geminiWs) { try { geminiWs.close() } catch {} }
        if (callSid) {
          const session = sessions.get(callSid)
          if (session) {
            const duration = Math.floor((Date.now() - session.startedAt) / 1000)
            logVoiceSession(meta, duration)
            sessions.delete(callSid)
          }
        }
        break
    }
  })

  ws.on('close', () => {
    if (geminiWs) try { geminiWs.close() } catch {}
  })
}

// ── Open Gemini Live WebSocket session ──
async function openGeminiSession (twilioWs, streamSid, meta) {
  if (!cfg.AI_API_KEY) {
    log('Voice agent: no AI_API_KEY configured')
    return null
  }

  return new Promise((resolve) => {
    const url = `${GEMINI_WS}?key=${cfg.AI_API_KEY}`
    const ws = new WebSocket(url)
    let setupDone = false

    const timeout = setTimeout(() => {
      if (!setupDone) { log('Gemini Live: setup timeout'); ws.close(); resolve(null) }
    }, 10000)

    ws.on('open', () => {
      // Build context from customer data
      const locContext = meta?.location
        ? `\nAdresse sélectionnée: ${meta.location.address}, ${meta.location.city} (${meta.location.name})`
        : ''

      ws.send(JSON.stringify({
        setup: {
          model: LIVE_MODEL,
          generationConfig: {
            responseModalities: ['AUDIO'],
            speechConfig: {
              voiceConfig: { prebuiltVoiceConfig: { voiceName: 'Aoede' } },
            },
          },
          systemInstruction: {
            parts: [{ text: `${VOICE_SYSTEM_PROMPT}\n\nContexte: Client ${meta?.customerName || 'inconnu'} (${meta?.customerId || '?'})${locContext}` }],
          },
          tools: buildGeminiTools(),
          realtimeInputConfig: {
            automaticActivityDetection: {
              disabled: false,
              startOfSpeechSensitivity: 'HIGH',
              endOfSpeechSensitivity: 'MEDIUM',
              silenceDurationMs: 1200,
            },
            activityHandling: 'START_OF_ACTIVITY_INTERRUPTS',
          },
          inputAudioTranscription: {},
          outputAudioTranscription: {},
        },
      }))
    })

    ws.on('message', async (data) => {
      let msg
      try { msg = JSON.parse(data.toString()) } catch { return }

      // Setup confirmation
      if (msg.setupComplete) {
        setupDone = true
        clearTimeout(timeout)
        log(`Gemini Live session ready (model: ${LIVE_MODEL})`)
        resolve(ws)
        return
      }

      // Audio response from Gemini → convert and send to Twilio
      if (msg.serverContent?.modelTurn?.parts) {
        for (const part of msg.serverContent.modelTurn.parts) {
          if (part.inlineData?.data) {
            try {
              const mulawB64 = geminiToMulaw(part.inlineData.data)
              if (twilioWs.readyState === WebSocket.OPEN) {
                twilioWs.send(JSON.stringify({
                  event: 'media',
                  streamSid,
                  media: { payload: mulawB64 },
                }))
              }
            } catch {}
          }
        }
      }

      // Transcription (for logging)
      if (msg.serverContent?.outputTranscription?.text) {
        log(`Voice AI: ${msg.serverContent.outputTranscription.text.substring(0, 100)}`)
      }
      if (msg.serverContent?.inputTranscription?.text) {
        log(`Voice Customer: ${msg.serverContent.inputTranscription.text.substring(0, 100)}`)
      }

      // Tool call from Gemini
      if (msg.toolCall?.functionCalls) {
        const responses = []
        for (const fc of msg.toolCall.functionCalls) {
          log(`Voice tool call: ${fc.name}(${JSON.stringify(fc.args)})`)
          const result = await execTool(fc.name, fc.args || {})
          log(`Voice tool result: ${fc.name} →`, JSON.stringify(result).substring(0, 200))
          responses.push({ id: fc.id, name: fc.name, response: { result } })
        }
        ws.send(JSON.stringify({ toolResponse: { functionResponses: responses } }))
      }
    })

    ws.on('error', (e) => {
      log('Gemini Live WS error:', e.message)
      if (!setupDone) { clearTimeout(timeout); resolve(null) }
    })

    ws.on('close', () => {
      log('Gemini Live session closed')
    })
  })
}

// ── Log voice session to ERPNext ──
async function logVoiceSession (meta, duration) {
  if (!meta?.customerId) return
  try {
    const dMin = Math.floor(duration / 60), dSec = duration % 60
    const durStr = `${dMin}m${dSec.toString().padStart(2, '0')}s`
    await createCommunication({
      communication_type: 'Communication', communication_medium: 'Phone',
      sent_or_received: 'Received', sender: 'voice-ai@gigafibre.ca',
      sender_full_name: 'Gigafibre Voice AI', phone_no: meta.phone || '',
      content: `Appel vocal IA — Client: ${meta.customerName}, Durée: ${durStr}${meta.location ? ', Adresse: ' + meta.location.address : ''}`,
      subject: `Appel vocal IA: ${meta.customerName}`,
      reference_doctype: 'Customer', reference_name: meta.customerId, status: 'Linked',
    })
    log(`Voice session logged: ${meta.customerId} (${durStr})`)
  } catch (e) { log('Voice session log error:', e.message) }
}

module.exports = { handleInboundCall, handleGather, handleConnectAgent, handleMediaStream }