'use strict'
const cfg = require('./config')
const { log, json, parseBody, erpFetch } = require('./helpers')
const { signJwt, verifyJwt } = require('./magic-link')

// Résidentiel:
//   - Pénalité = valeur résiduelle des avantages non compensés
//   - Chaque mois d'abonnement "reconnaît" (compense) benefit_value / duration_months
//   - Ex: Installation 288$ gratuite sur 24 mois → 12$/mois compensé
//   - Résiliation au mois 18 → 6 × 12$ = 72$ de pénalité
//
// Commercial:
//   - Pénalité = toutes les mensualités restantes au contrat
//   - Ex: 79.95$/mois × 6 mois restants = 479.70$

function calculateTerminationFee (contract) {
  const now = new Date()
  const start = new Date(contract.start_date)
  const monthsElapsed = Math.max(0, monthsBetween(start, now))
  const monthsRemaining = Math.max(0, (contract.duration_months || 24) - monthsElapsed)

  const benefits = (contract.benefits || []).map(b => {
    const benefitValue = (b.regular_price || 0) - (b.granted_price || 0)
    const monthlyRecognition = benefitValue / (contract.duration_months || 24)
    const recognized = monthlyRecognition * monthsElapsed
    const remaining = Math.max(0, benefitValue - recognized)
    return {
      description: b.description,
      regular_price: b.regular_price,
      granted_price: b.granted_price,
      benefit_value: round2(benefitValue),
      monthly_recognition: round2(monthlyRecognition),
      months_recognized: monthsElapsed,
      remaining_value: round2(remaining),
    }
  })

  const totalBenefitRemaining = round2(benefits.reduce((s, b) => s + b.remaining_value, 0))
  const monthlyRate = contract.monthly_rate || 0

  let fee = 0
  let feeBreakdown = {}

  if (contract.contract_type === 'Commercial') {
    // Commercial: all remaining monthly payments
    fee = round2(monthsRemaining * monthlyRate)
    feeBreakdown = {
      type: 'commercial',
      months_remaining: monthsRemaining,
      monthly_rate: monthlyRate,
      termination_fee_remaining: fee,
      termination_fee_benefits: 0,
      termination_fee_total: fee,
    }
  } else {
    // Résidentiel: only benefit residual value (+ current month max)
    fee = totalBenefitRemaining
    feeBreakdown = {
      type: 'residential',
      months_remaining: monthsRemaining,
      monthly_rate: monthlyRate,
      termination_fee_benefits: totalBenefitRemaining,
      termination_fee_remaining: 0,
      termination_fee_total: totalBenefitRemaining,
    }
  }

  return {
    months_elapsed: monthsElapsed,
    months_remaining: monthsRemaining,
    benefits,
    total_benefit_remaining: totalBenefitRemaining,
    ...feeBreakdown,
  }
}

function generateInvoiceNote (contract) {
  const benefits = contract.benefits || []
  const lines = []
  for (const b of benefits) {
    const benefitValue = (b.regular_price || 0) - (b.granted_price || 0)
    if (benefitValue <= 0) continue
    const monthly = round2(benefitValue / (contract.duration_months || 24))
    lines.push(
      `${b.description} ${b.granted_price || 0}$ sur entente de ${contract.duration_months || 24} mois. ` +
      `(Prix régulier ${b.regular_price}$) Chaque mois d'abonnement reconnaît ${monthly}$ de compensé.`
    )
  }
  return lines.join('\n')
}

function generateContractToken (contractName, customer, phone, ttlHours = 168) {
  return signJwt({
    sub: customer,
    doc: contractName,
    type: 'contract_accept',
    phone: phone || '',
    iat: Math.floor(Date.now() / 1000),
    exp: Math.floor(Date.now() / 1000) + ttlHours * 3600,
  })
}

function generateContractLink (contractName, customer, phone) {
  const token = generateContractToken(contractName, customer, phone)
  return `${cfg.HUB_PUBLIC_URL || 'https://msg.gigafibre.ca'}/contract/accept/${token}`
}

async function handle (req, res, method, path) {
  // GET /contract/list?customer=CUST-001
  if (path === '/contract/list' && method === 'GET') {
    const url = new URL(req.url, `http://localhost:${cfg.PORT}`)
    const customer = url.searchParams.get('customer')
    const filters = customer ? [['customer', '=', customer]] : []
    filters.push(['status', '!=', 'Brouillon'])

    const params = new URLSearchParams({
      fields: JSON.stringify(['name', 'customer', 'customer_name', 'contract_type', 'status',
        'start_date', 'end_date', 'duration_months', 'monthly_rate', 'total_benefit_value',
        'total_remaining_value', 'months_elapsed', 'months_remaining']),
      filters: JSON.stringify(filters),
      limit_page_length: 200,
      order_by: 'start_date desc',
    })
    const r = await erpFetch('/api/resource/Service%20Contract?' + params)
    return json(res, 200, { contracts: r.status === 200 ? (r.data?.data || []) : [] })
  }

  // GET /contract/detail/CTR-00001
  if (path.startsWith('/contract/detail/') && method === 'GET') {
    const name = decodeURIComponent(path.replace('/contract/detail/', ''))
    const r = await erpFetch(`/api/resource/Service%20Contract/${encodeURIComponent(name)}`)
    if (r.status !== 200) return json(res, 404, { error: 'Contract not found' })
    return json(res, 200, { contract: r.data.data })
  }

  // POST /contract/create — create a new contract
  if (path === '/contract/create' && method === 'POST') {
    const body = await parseBody(req)
    if (!body.customer || !body.duration_months) {
      return json(res, 400, { error: 'customer and duration_months required' })
    }

    // Build benefits with calculated fields
    const duration = body.duration_months || 24
    const benefits = (body.benefits || []).map(b => ({
      description: b.description || '',
      regular_price: b.regular_price || 0,
      granted_price: b.granted_price || 0,
      benefit_value: round2((b.regular_price || 0) - (b.granted_price || 0)),
      monthly_recognition: round2(((b.regular_price || 0) - (b.granted_price || 0)) / duration),
      months_recognized: 0,
      remaining_value: round2((b.regular_price || 0) - (b.granted_price || 0)),
    }))

    const totalBenefitValue = round2(benefits.reduce((s, b) => s + b.benefit_value, 0))

    const startDate = body.start_date || new Date().toISOString().slice(0, 10)
    const endDate = addMonths(startDate, duration)

    // Generate invoice note
    const invoiceNote = generateInvoiceNote({
      benefits: body.benefits || [],
      duration_months: duration,
    })

    const payload = {
      customer: body.customer,
      contract_type: body.contract_type || 'Résidentiel',
      status: 'Brouillon',
      start_date: startDate,
      end_date: endDate,
      duration_months: duration,
      monthly_rate: body.monthly_rate || 0,
      service_location: body.service_location || '',
      quotation: body.quotation || '',
      subscription: body.subscription || '',
      benefits,
      total_benefit_value: totalBenefitValue,
      total_remaining_value: totalBenefitValue,
      months_elapsed: 0,
      months_remaining: duration,
      invoice_note: invoiceNote,
      acceptance_method: body.acceptance_method || '',
      docuseal_template_id: body.docuseal_template_id || 0,
    }

    const r = await erpFetch('/api/resource/Service%20Contract', {
      method: 'POST',
      body: JSON.stringify(payload),
    })

    if (r.status !== 200) {
      return json(res, 500, { error: 'Failed to create contract', detail: r.data })
    }

    log(`Contract created: ${r.data.data.name} for ${body.customer}`)
    return json(res, 200, { ok: true, contract: r.data.data })
  }

  // POST /contract/calculate-termination — preview termination fee without saving
  if (path === '/contract/calculate-termination' && method === 'POST') {
    const body = await parseBody(req)
    if (!body.name) return json(res, 400, { error: 'contract name required' })

    const r = await erpFetch(`/api/resource/Service%20Contract/${encodeURIComponent(body.name)}`)
    if (r.status !== 200) return json(res, 404, { error: 'Contract not found' })

    const contract = r.data.data
    const calc = calculateTerminationFee(contract)
    return json(res, 200, { contract_name: body.name, ...calc })
  }

  // POST /contract/terminate — execute termination + create invoice
  if (path === '/contract/terminate' && method === 'POST') {
    const body = await parseBody(req)
    if (!body.name) return json(res, 400, { error: 'contract name required' })

    const r = await erpFetch(`/api/resource/Service%20Contract/${encodeURIComponent(body.name)}`)
    if (r.status !== 200) return json(res, 404, { error: 'Contract not found' })

    const contract = r.data.data
    if (contract.status === 'Résilié' || contract.status === 'Complété') {
      return json(res, 400, { error: 'Contract already terminated' })
    }

    const calc = calculateTerminationFee(contract)
    const today = new Date().toISOString().slice(0, 10)

    // Update contract with termination data
    const updateData = {
      status: 'Résilié',
      terminated_at: today,
      termination_reason: body.reason || '',
      termination_fee_benefits: calc.termination_fee_benefits,
      termination_fee_remaining: calc.termination_fee_remaining,
      termination_fee_total: calc.termination_fee_total,
      months_elapsed: calc.months_elapsed,
      months_remaining: calc.months_remaining,
    }

    // Update benefits rows with current recognition
    if (contract.benefits && contract.benefits.length) {
      updateData.benefits = calc.benefits.map((b, i) => ({
        ...contract.benefits[i],
        months_recognized: b.months_recognized,
        remaining_value: b.remaining_value,
        benefit_value: b.benefit_value,
        monthly_recognition: b.monthly_recognition,
      }))
      updateData.total_remaining_value = calc.total_benefit_remaining
    }

    await erpFetch(`/api/resource/Service%20Contract/${encodeURIComponent(body.name)}`, {
      method: 'PUT',
      body: JSON.stringify(updateData),
    })

    // Create termination invoice if fee > 0
    let invoiceName = null
    if (calc.termination_fee_total > 0 && body.create_invoice !== false) {
      invoiceName = await createTerminationInvoice(contract, calc, body.reason)
      if (invoiceName) {
        await erpFetch(`/api/resource/Service%20Contract/${encodeURIComponent(body.name)}`, {
          method: 'PUT',
          body: JSON.stringify({ termination_invoice: invoiceName }),
        })
      }
    }

    log(`Contract ${body.name} terminated. Fee: ${calc.termination_fee_total}$. Invoice: ${invoiceName || 'none'}`)
    return json(res, 200, {
      ok: true,
      ...calc,
      termination_invoice: invoiceName,
    })
  }

  // POST /contract/send — send contract for acceptance (DocuSeal or JWT SMS)
  if (path === '/contract/send' && method === 'POST') {
    const body = await parseBody(req)
    if (!body.name) return json(res, 400, { error: 'contract name required' })

    const r = await erpFetch(`/api/resource/Service%20Contract/${encodeURIComponent(body.name)}`)
    if (r.status !== 200) return json(res, 404, { error: 'Contract not found' })

    const contract = r.data.data
    const phone = body.phone
    const email = body.email

    let result = {}

    // Try DocuSeal first if configured
    if (body.use_docuseal && cfg.DOCUSEAL_URL && cfg.DOCUSEAL_API_KEY) {
      const { createDocuSealSubmission } = require('./acceptance')
      const acceptLink = generateContractLink(body.name, contract.customer, phone)
      const ds = await createDocuSealSubmission({
        templateId: contract.docuseal_template_id || body.docuseal_template_id || 1,
        email: email || '',
        name: contract.customer_name || contract.customer,
        phone: phone || '',
        values: {
          'Nom': contract.customer_name || '',
          'Contrat': body.name,
          'Mensualité': `${contract.monthly_rate}$`,
          'Durée': `${contract.duration_months} mois`,
          'Avantages': (contract.benefits || []).map(b => b.description).join(', '),
        },
        completedRedirectUrl: acceptLink + '?signed=1',
      })

      if (ds) {
        await erpFetch(`/api/resource/Service%20Contract/${encodeURIComponent(body.name)}`, {
          method: 'PUT',
          body: JSON.stringify({
            status: 'Envoyé',
            acceptance_method: 'DocuSeal',
            docuseal_submission_id: ds.submissionId,
          }),
        })
        result = { method: 'docuseal', sign_url: ds.signUrl, submission_id: ds.submissionId }
      }
    }

    // Fallback: JWT SMS acceptance
    if (!result.method && phone) {
      const link = generateContractLink(body.name, contract.customer, phone)
      const { sendSmsInternal } = require('./twilio')
      const note = (contract.benefits || []).map(b =>
        `${b.description}: ${b.granted_price || 0}$ (rég. ${b.regular_price}$)`
      ).join('\n')

      const msg = `Gigafibre — Entente de service\n` +
        `${contract.monthly_rate}$/mois × ${contract.duration_months} mois\n` +
        (note ? note + '\n' : '') +
        `Accepter: ${link}`

      const sid = await sendSmsInternal(phone, msg)

      await erpFetch(`/api/resource/Service%20Contract/${encodeURIComponent(body.name)}`, {
        method: 'PUT',
        body: JSON.stringify({ status: 'Envoyé', acceptance_method: 'JWT SMS' }),
      })
      result = { method: 'sms', sent_to: phone, sms_sid: sid, accept_link: link }
    }

    if (!result.method) {
      return json(res, 400, { error: 'No phone or DocuSeal configured for sending' })
    }

    log(`Contract ${body.name} sent via ${result.method}`)
    return json(res, 200, { ok: true, ...result })
  }

  // GET /contract/accept/:token — accept contract via JWT
  if (path.startsWith('/contract/accept/') && method === 'GET') {
    const token = path.replace('/contract/accept/', '')
    const payload = verifyJwt(token)
    if (!payload || payload.type !== 'contract_accept') {
      return json(res, 401, { error: 'Lien expiré ou invalide.' })
    }

    // Render simple acceptance page
    const contractName = payload.doc
    const r = await erpFetch(`/api/resource/Service%20Contract/${encodeURIComponent(contractName)}`)
    if (r.status !== 200) return json(res, 404, { error: 'Contrat introuvable' })
    const contract = r.data.data

    const html = renderAcceptancePage(contract, token)
    res.writeHead(200, { 'Content-Type': 'text/html; charset=utf-8' })
    return res.end(html)
  }

  // POST /contract/confirm — confirm acceptance
  if (path === '/contract/confirm' && method === 'POST') {
    const body = await parseBody(req)
    if (!body.token) return json(res, 400, { error: 'token required' })

    const payload = verifyJwt(body.token)
    if (!payload || payload.type !== 'contract_accept') {
      return json(res, 401, { error: 'Lien expiré' })
    }

    const contractName = payload.doc
    const ip = req.headers['x-forwarded-for'] || req.socket?.remoteAddress || ''
    const ua = req.headers['user-agent'] || ''
    const now = new Date().toISOString()

    await erpFetch(`/api/resource/Service%20Contract/${encodeURIComponent(contractName)}`, {
      method: 'PUT',
      body: JSON.stringify({
        status: 'Actif',
        signed_at: now,
        signed_by: payload.sub,
        signature_proof: `IP: ${ip}\nUser-Agent: ${ua}\nDate: ${now}\nPhone: ${payload.phone || ''}`,
      }),
    })

    log(`Contract ${contractName} accepted by ${payload.sub}`)
    return json(res, 200, { ok: true, contract: contractName })
  }

  return json(res, 404, { error: 'Contract endpoint not found' })
}

async function createTerminationInvoice (contract, calc, reason) {
  const items = []
  const today = new Date().toISOString().slice(0, 10)

  if (contract.contract_type === 'Commercial') {
    items.push({
      item_name: 'Frais de résiliation anticipée',
      description: `Résiliation anticipée du contrat ${contract.name}. ` +
        `${calc.months_remaining} mois restants × ${contract.monthly_rate}$/mois.` +
        (reason ? ` Raison: ${reason}` : ''),
      qty: calc.months_remaining,
      rate: contract.monthly_rate,
      income_account: '', // will use default
    })
  } else {
    // Residential: charge benefit residual
    for (const b of calc.benefits) {
      if (b.remaining_value <= 0) continue
      items.push({
        item_name: `Résiliation — ${b.description}`,
        description: `Valeur résiduelle: ${b.benefit_value}$ - ${b.months_recognized} mois reconnus ` +
          `(${b.monthly_recognition}$/mois). Restant: ${b.remaining_value}$`,
        qty: 1,
        rate: b.remaining_value,
      })
    }
  }

  if (!items.length) return null

  const payload = {
    customer: contract.customer,
    posting_date: today,
    due_date: today,
    items,
    remarks: `Facture de résiliation anticipée — Contrat ${contract.name}`,
  }

  try {
    const r = await erpFetch('/api/resource/Sales%20Invoice', {
      method: 'POST',
      body: JSON.stringify(payload),
    })
    if (r.status === 200 && r.data?.data) {
      return r.data.data.name
    }
  } catch (e) {
    log('Termination invoice creation failed:', e.message)
  }
  return null
}

function renderAcceptancePage (contract, token) {
  const benefits = (contract.benefits || []).map(b => {
    const val = (b.regular_price || 0) - (b.granted_price || 0)
    const monthly = round2(val / (contract.duration_months || 24))
    return `<tr>
      <td>${b.description}</td>
      <td style="text-align:right">${b.regular_price || 0}$</td>
      <td style="text-align:right">${b.granted_price || 0}$</td>
      <td style="text-align:right">${monthly}$/mois compensé</td>
    </tr>`
  }).join('')

  return `<!DOCTYPE html><html lang="fr"><head>
<meta charset="utf-8"><meta name="viewport" content="width=device-width,initial-scale=1">
<title>Entente de service — Gigafibre</title>
<style>
*{box-sizing:border-box;margin:0;padding:0}
body{font-family:-apple-system,system-ui,sans-serif;background:#f8fafc;color:#1e293b;padding:16px}
.card{background:#fff;border-radius:12px;padding:24px;max-width:500px;margin:0 auto;box-shadow:0 2px 8px rgba(0,0,0,.08)}
h1{font-size:20px;margin-bottom:4px}
.sub{color:#64748b;font-size:14px;margin-bottom:20px}
.field{display:flex;justify-content:space-between;padding:8px 0;border-bottom:1px solid #f1f5f9}
.field .label{color:#64748b;font-size:14px}
.field .value{font-weight:600}
table{width:100%;border-collapse:collapse;margin:12px 0;font-size:13px}
th{text-align:left;padding:6px 8px;background:#f1f5f9;font-weight:600}
td{padding:6px 8px;border-bottom:1px solid #f1f5f9}
.note{background:#fffbeb;border:1px solid #fde68a;border-radius:8px;padding:12px;margin:16px 0;font-size:13px;line-height:1.5}
.btn{display:block;width:100%;padding:14px;background:#10b981;color:#fff;border:none;border-radius:10px;font-size:16px;font-weight:600;cursor:pointer;margin-top:20px}
.btn:active{background:#059669}
.ok{text-align:center;padding:40px 20px}
.ok h2{color:#10b981;margin-bottom:8px}
#result{display:none}
</style></head><body>
<div class="card" id="contract">
  <h1>Entente de service</h1>
  <div class="sub">Gigafibre — TARGO Communications Inc.</div>

  <div class="field"><span class="label">Client</span><span class="value">${contract.customer_name || contract.customer}</span></div>
  <div class="field"><span class="label">Type</span><span class="value">${contract.contract_type}</span></div>
  <div class="field"><span class="label">Mensualité</span><span class="value">${contract.monthly_rate}$/mois</span></div>
  <div class="field"><span class="label">Durée</span><span class="value">${contract.duration_months} mois</span></div>
  <div class="field"><span class="label">Début</span><span class="value">${contract.start_date || 'À déterminer'}</span></div>

  ${benefits ? `
  <h3 style="margin-top:16px;font-size:15px">Avantages accordés</h3>
  <table><thead><tr><th>Description</th><th>Rég.</th><th>Accordé</th><th>Reconnaissance</th></tr></thead>
  <tbody>${benefits}</tbody></table>` : ''}

  ${contract.invoice_note ? `<div class="note">${contract.invoice_note.replace(/\n/g, '<br>')}</div>` : ''}

  <div style="font-size:12px;color:#94a3b8;margin-top:16px;line-height:1.6">
    En acceptant, vous confirmez avoir lu et compris les termes de cette entente de service.
    ${contract.contract_type === 'Résidentiel'
      ? 'En cas de résiliation anticipée, les avantages non compensés au pro-rata des mois écoulés seront facturés.'
      : 'En cas de résiliation anticipée, la totalité des mensualités restantes au contrat sera facturée.'}
  </div>

  <button class="btn" onclick="accept()">✓ J'accepte cette entente</button>
</div>

<div class="card ok" id="result">
  <h2>✓ Entente acceptée</h2>
  <p>Merci ! Votre acceptation a été enregistrée.</p>
</div>

<script>
async function accept(){
  const btn=document.querySelector('.btn');btn.disabled=true;btn.textContent='En cours...';
  try{
    const r=await fetch('/contract/confirm',{method:'POST',headers:{'Content-Type':'application/json'},body:JSON.stringify({token:'${token}'})});
    const d=await r.json();
    if(d.ok){document.getElementById('contract').style.display='none';document.getElementById('result').style.display='block';}
    else{btn.textContent='Erreur: '+(d.error||'Réessayez');btn.disabled=false;}
  }catch(e){btn.textContent='Erreur réseau';btn.disabled=false;}
}
</script></body></html>`
}

function monthsBetween (d1, d2) {
  return (d2.getFullYear() - d1.getFullYear()) * 12 + (d2.getMonth() - d1.getMonth())
}

function addMonths (dateStr, months) {
  const d = new Date(dateStr)
  d.setMonth(d.getMonth() + months)
  return d.toISOString().slice(0, 10)
}

function round2 (v) { return Math.round(v * 100) / 100 }

module.exports = { handle, calculateTerminationFee, generateInvoiceNote, generateContractLink }