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

const SCORE_WEIGHTS = {
  proximityMultiplier: 4,   // distance (km, capped at 100) * this = proximity penalty
  proximityMax: 100,        // cap distance at this km value
  loadMultiplier: 30,       // tech.load * this = load penalty
  overloadPenalty: 500,     // added when tech has insufficient capacity
  gpsFreshnessBonus: 20,    // subtracted when GPS is live
}

function todayET () {
  return new Date().toLocaleDateString('en-CA', { timeZone: 'America/Toronto' })
}

function nowHoursET () {
  const parts = new Date().toLocaleString('en-CA', { timeZone: 'America/Toronto', hour12: false }).split(' ')
  const [hh, mm] = parts[1].split(':').map(Number)
  return hh + (mm || 0) / 60
}

function timeToHours (t) {
  if (!t) return 0
  const [h, m] = t.split(':').map(Number)
  return h + (m || 0) / 60
}

function hoursToTime (h) {
  const hh = Math.floor(h)
  const mm = Math.round((h - hh) * 60)
  return String(hh).padStart(2, '0') + ':' + String(mm).padStart(2, '0')
}

function dateAddDays (baseStr, n) {
  const d = new Date(baseStr + 'T12:00:00')
  d.setDate(d.getDate() + n)
  return d.toISOString().slice(0, 10)
}

// Euclidean approximation, km at Montreal latitude
function distKm (a, b) {
  if (!a || !b) return 999
  const dx = (a[0] - b[0]) * 80, dy = (a[1] - b[1]) * 111
  return Math.sqrt(dx * dx + dy * dy)
}

async function getTechsWithLoad (dateStr) {
  const [techRes, jobRes] = await Promise.all([
    erpFetch(`/api/resource/Dispatch Technician?fields=${encodeURIComponent(JSON.stringify(['name', 'technician_id', 'full_name', 'status', 'longitude', 'latitude', 'traccar_device_id', 'phone']))}&limit_page_length=50`),
    erpFetch(`/api/resource/Dispatch Job?filters=${encodeURIComponent(JSON.stringify({ status: ['in', ['open', 'assigned']], scheduled_date: dateStr }))}&fields=${encodeURIComponent(JSON.stringify(['name', 'assigned_tech', 'duration_h', 'longitude', 'latitude', 'status', 'route_order']))}&limit_page_length=200`),
  ])
  if (techRes.status !== 200) throw new Error('Failed to fetch technicians')
  const techs = techRes.data.data || []
  const jobs = jobRes.status === 200 ? (jobRes.data.data || []) : []

  return techs.map(t => {
    const queue = jobs
      .filter(j => j.assigned_tech === t.technician_id)
      .sort((a, b) => (a.route_order || 0) - (b.route_order || 0))
    const load = queue.reduce((s, j) => s + (parseFloat(j.duration_h) || 1), 0)
    return {
      id: t.technician_id, name: t.full_name, status: t.status || 'available',
      coords: [t.longitude || -73.5673, t.latitude || 45.5017],
      traccarDeviceId: t.traccar_device_id, phone: t.phone,
      queue, load, tags: [],
    }
  })
}

async function enrichWithGps (techs) {
  try {
    const { getDevices, getPositions } = require('./traccar')
    const devices = await getDevices()
    const deviceMap = {}
    techs.forEach(t => {
      if (!t.traccarDeviceId) return
      const dev = devices.find(d => d.id === parseInt(t.traccarDeviceId) || d.uniqueId === t.traccarDeviceId)
      if (dev) deviceMap[dev.id] = t
    })
    const deviceIds = Object.keys(deviceMap).map(Number)
    if (!deviceIds.length) return
    const positions = await getPositions(deviceIds)
    positions.forEach(p => {
      const tech = deviceMap[p.deviceId]
      if (tech && p.latitude && p.longitude) {
        tech.gpsCoords = [p.longitude, p.latitude]
        tech.gpsOnline = true
      }
    })
  } catch (e) { log('GPS enrichment error:', e.message) }
}

function rankTechs (techs, jobCoords, jobDuration = 1) {
  const hasCoords = jobCoords && (jobCoords[0] || jobCoords[1])
  const candidates = techs.filter(t => t.status !== 'off' && t.status !== 'unavailable')

  return candidates.map(tech => {
    const pos = tech.gpsOnline ? tech.gpsCoords : tech.coords
    const distance = hasCoords ? distKm(pos, jobCoords) : 999
    const remainingCap = Math.max(0, 8 - tech.load)

    let score = 0
    const reasons = []

    score += Math.min(distance, SCORE_WEIGHTS.proximityMax) * SCORE_WEIGHTS.proximityMultiplier
    reasons.push(distance < 5 ? `${distance.toFixed(1)} km (très proche)` :
                 distance < 15 ? `${distance.toFixed(1)} km` : `${distance.toFixed(1)} km (loin)`)

    score += tech.load * SCORE_WEIGHTS.loadMultiplier
    if (remainingCap < jobDuration) {
      score += SCORE_WEIGHTS.overloadPenalty
      reasons.push(`Surchargé (${tech.load.toFixed(1)}h/8h)`)
    } else if (tech.load < 4) {
      reasons.push(`Dispo (${tech.load.toFixed(1)}h/8h)`)
    } else {
      reasons.push(`Chargé (${tech.load.toFixed(1)}h/8h)`)
    }

    if (tech.gpsOnline) { score -= SCORE_WEIGHTS.gpsFreshnessBonus; reasons.push('GPS en direct') }

    return { techId: tech.id, techName: tech.name, phone: tech.phone, score, distance, load: tech.load, remainingCap, reasons }
  }).sort((a, b) => a.score - b.score)
}

// ── Slot suggestion ────────────────────────────────────────────────────────
// Finds open time windows across techs for the next N days. Keeps the logic
// simple & predictable: gaps between pinned jobs within a default shift
// window, minus a travel buffer before the new job, minus a "not in the
// past" cutoff. Scores surface the most natural inserts (earliest first,
// then shortest travel), with a 2-slot-per-tech cap to diversify results.
const SLOT_DEFAULT_SHIFT = { start_h: 8, end_h: 17 }
const SLOT_TRAVEL_BUFFER_H = 0.25   // 15 min pre-job slack before proposed start
const SLOT_HORIZON_DAYS = 7
const SLOT_MAX_PER_TECH = 2

async function suggestSlots ({ duration_h = 1, latitude, longitude, after_date, limit = 5 } = {}) {
  const baseDate = after_date || todayET()
  const duration = parseFloat(duration_h) || 1
  const dates = Array.from({ length: SLOT_HORIZON_DAYS }, (_, i) => dateAddDays(baseDate, i))
  const jobCoords = latitude && longitude ? [parseFloat(longitude), parseFloat(latitude)] : null

  const [techRes, jobRes] = await Promise.all([
    erpFetch(`/api/resource/Dispatch Technician?fields=${encodeURIComponent(JSON.stringify([
      'name', 'technician_id', 'full_name', 'status', 'longitude', 'latitude',
      'absence_from', 'absence_until',
    ]))}&limit_page_length=50`),
    erpFetch(`/api/resource/Dispatch Job?filters=${encodeURIComponent(JSON.stringify([
      ['status', 'in', ['open', 'assigned']],
      ['scheduled_date', '>=', dates[0]],
      ['scheduled_date', '<=', dates[dates.length - 1]],
    ]))}&fields=${encodeURIComponent(JSON.stringify([
      'name', 'assigned_tech', 'scheduled_date', 'start_time', 'duration_h',
      'longitude', 'latitude',
    ]))}&limit_page_length=500`),
  ])
  if (techRes.status !== 200) throw new Error('Failed to fetch technicians')
  const techs = (techRes.data.data || []).filter(t => t.status !== 'unavailable')
  const allJobs = jobRes.status === 200 ? (jobRes.data.data || []) : []

  const today = todayET()
  const nowH = nowHoursET()
  const slots = []

  for (const tech of techs) {
    const homeCoords = tech.longitude && tech.latitude
      ? [parseFloat(tech.longitude), parseFloat(tech.latitude)] : null

    for (const dateStr of dates) {
      // Absence window skip.
      if (tech.absence_from && tech.absence_until &&
          dateStr >= tech.absence_from && dateStr <= tech.absence_until) continue

      // Day's pinned jobs (only those with a real start_time — floating jobs
      // without a time are ignored since we don't know when they'll land).
      const dayJobs = allJobs
        .filter(j => j.assigned_tech === tech.technician_id &&
                     j.scheduled_date === dateStr && j.start_time)
        .map(j => {
          const s = timeToHours(j.start_time)
          return {
            start_h: s,
            end_h: s + (parseFloat(j.duration_h) || 1),
            coords: j.latitude && j.longitude ? [parseFloat(j.longitude), parseFloat(j.latitude)] : null,
          }
        })
        .sort((a, b) => a.start_h - b.start_h)

      // Build gaps bounded by shift_start/end.
      const shift = SLOT_DEFAULT_SHIFT
      const gaps = []
      let cursor = shift.start_h, prevCoords = homeCoords
      for (const j of dayJobs) {
        gaps.push({
          start_h: cursor, end_h: j.start_h, prev_coords: prevCoords,
          position: gaps.length === 0 ? 'first' : 'between',
        })
        cursor = j.end_h
        prevCoords = j.coords
      }
      gaps.push({
        start_h: cursor, end_h: shift.end_h, prev_coords: prevCoords,
        position: dayJobs.length === 0 ? 'free_day' : 'last',
      })

      for (const g of gaps) {
        const gapLen = g.end_h - g.start_h
        if (gapLen < duration + SLOT_TRAVEL_BUFFER_H) continue

        const startH = g.start_h + SLOT_TRAVEL_BUFFER_H
        const endH = startH + duration
        if (endH > g.end_h) continue

        // Skip slots already in the past (or within 30 min).
        if (dateStr === today && startH < nowH + 0.5) continue

        const distanceKm = jobCoords && g.prev_coords ? distKm(g.prev_coords, jobCoords) : null
        const travelMin = distanceKm != null
          ? Math.max(5, Math.min(90, Math.round(distanceKm * 1.5)))
          : Math.round(SLOT_TRAVEL_BUFFER_H * 60)

        const reasons = []
        if (g.position === 'free_day') reasons.push('Journée libre')
        else if (g.position === 'first') reasons.push('Début de journée')
        else if (g.position === 'last') reasons.push('Fin de journée')
        else reasons.push('Entre 2 rendez-vous')
        if (distanceKm != null) reasons.push(`${distanceKm.toFixed(1)} km du précédent`)

        slots.push({
          tech_id: tech.technician_id,
          tech_name: tech.full_name,
          date: dateStr,
          start_time: hoursToTime(startH),
          end_time: hoursToTime(endH),
          travel_min: travelMin,
          distance_km: distanceKm != null ? +distanceKm.toFixed(1) : null,
          gap_h: +gapLen.toFixed(1),
          reasons,
          position: g.position,
        })
      }
    }
  }

  // Sort: earliest first, then shortest travel.
  slots.sort((a, b) => {
    if (a.date !== b.date) return a.date < b.date ? -1 : 1
    if (a.start_time !== b.start_time) return a.start_time < b.start_time ? -1 : 1
    return (a.travel_min || 0) - (b.travel_min || 0)
  })

  // Diversify: cap slots-per-tech so we don't return 5 options from the
  // same person. Dispatchers want to compare across resources.
  const byTech = {}
  const picked = []
  for (const s of slots) {
    byTech[s.tech_id] = byTech[s.tech_id] || 0
    if (byTech[s.tech_id] >= SLOT_MAX_PER_TECH) continue
    picked.push(s)
    byTech[s.tech_id]++
    if (picked.length >= limit) break
  }

  return picked
}

async function createDispatchJob ({ subject, address, priority, duration_h, job_type, customer, service_location, source_issue, notes, latitude, longitude, assigned_tech, scheduled_date }) {
  const ticketId = 'DJ-' + Date.now().toString(36).toUpperCase()
  const payload = {
    ticket_id: ticketId,
    subject: subject || 'Travail urgent',
    address: address || '',
    duration_h: parseFloat(duration_h) || 1,
    priority: priority || 'high',
    status: assigned_tech ? 'assigned' : 'open',
    job_type: job_type || 'Dépannage',
    customer: customer || '',
    service_location: service_location || '',
    source_issue: source_issue || '',
    notes: notes || '',
    latitude: latitude || '',
    longitude: longitude || '',
    assigned_tech: assigned_tech || '',
    scheduled_date: scheduled_date || todayET(),
  }
  const r = await erpFetch('/api/resource/Dispatch Job', { method: 'POST', body: JSON.stringify(payload) })
  if (r.status < 200 || r.status >= 300) throw new Error('Failed to create dispatch job')
  return { success: true, job_id: r.data?.data?.name || ticketId, ...payload }
}

async function handle (req, res, method, path) {
  const sub = path.replace('/dispatch/', '')

  // POST /dispatch/best-tech — find optimal tech for a job location
  if (sub === 'best-tech' && method === 'POST') {
    try {
      const body = await parseBody(req)
      const dateStr = body.date || todayET()
      const jobCoords = body.latitude && body.longitude ? [parseFloat(body.longitude), parseFloat(body.latitude)] : null
      const techs = await getTechsWithLoad(dateStr)
      await enrichWithGps(techs)
      const ranked = rankTechs(techs, jobCoords, parseFloat(body.duration_h) || 1)
      return json(res, 200, { ranking: ranked })
    } catch (e) {
      log('best-tech error:', e.message)
      return json(res, 500, { error: e.message })
    }
  }

  // POST /dispatch/suggest-slots — return 5 best available time windows
  if (sub === 'suggest-slots' && method === 'POST') {
    try {
      const body = await parseBody(req)
      const slots = await suggestSlots(body)
      return json(res, 200, { slots })
    } catch (e) {
      log('suggest-slots error:', e.message)
      return json(res, 500, { error: e.message })
    }
  }

  // POST /dispatch/create-job — create + optionally auto-assign to best tech
  if (sub === 'create-job' && method === 'POST') {
    try {
      const body = await parseBody(req)
      let assignedTech = body.assigned_tech

      if (body.auto_assign) {
        const dateStr = body.scheduled_date || todayET()
        const jobCoords = body.latitude && body.longitude ? [parseFloat(body.longitude), parseFloat(body.latitude)] : null
        const techs = await getTechsWithLoad(dateStr)
        await enrichWithGps(techs)
        const ranked = rankTechs(techs, jobCoords, parseFloat(body.duration_h) || 1)
        if (ranked.length) {
          assignedTech = ranked[0].techId
          log(`Auto-assigned to ${ranked[0].techName} (score: ${ranked[0].score.toFixed(0)}, ${ranked[0].reasons.join(', ')})`)
        }
      }

      const result = await createDispatchJob({ ...body, assigned_tech: assignedTech })
      return json(res, 200, result)
    } catch (e) {
      log('create-job error:', e.message)
      return json(res, 500, { error: e.message })
    }
  }

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

async function agentCreateDispatchJob ({ customer_id, service_location, subject, priority, job_type, notes, auto_assign }) {
  let address = '', latitude = null, longitude = null
  if (service_location) {
    const locRes = await erpFetch(`/api/resource/Service Location/${encodeURIComponent(service_location)}`)
    if (locRes.status === 200) {
      const loc = locRes.data.data
      address = [loc.address_line, loc.city, loc.postal_code].filter(Boolean).join(', ')
      latitude = loc.latitude || null
      longitude = loc.longitude || null
    }
  }

  const dateStr = todayET()
  let assignedTech = null, techInfo = null

  if (auto_assign !== false) {
    try {
      const jobCoords = latitude && longitude ? [parseFloat(longitude), parseFloat(latitude)] : null
      const techs = await getTechsWithLoad(dateStr)
      await enrichWithGps(techs)
      const ranked = rankTechs(techs, jobCoords, 1)
      if (ranked.length) {
        assignedTech = ranked[0].techId
        techInfo = { name: ranked[0].techName, phone: ranked[0].phone, distance: ranked[0].distance, reasons: ranked[0].reasons }
        log(`Agent auto-assigned to ${ranked[0].techName}`)
      }
    } catch (e) { log('Agent auto-assign error:', e.message) }
  }

  const result = await createDispatchJob({
    subject: subject || 'Intervention urgente',
    address, latitude, longitude,
    priority: priority || 'high',
    duration_h: 1,
    job_type: job_type || 'Dépannage',
    customer: customer_id || '',
    service_location: service_location || '',
    notes: notes || '',
    assigned_tech: assignedTech,
    scheduled_date: dateStr,
  })

  return {
    success: true,
    job_id: result.job_id,
    assigned_tech: techInfo ? `${techInfo.name} (${techInfo.reasons.join(', ')})` : 'Aucun tech disponible — job créé en attente',
    address: result.address,
    message: techInfo ? `Travail créé et assigné à ${techInfo.name}` : 'Travail créé, en attente d\'assignation',
  }
}

module.exports = { handle, agentCreateDispatchJob, rankTechs, getTechsWithLoad, enrichWithGps, suggestSlots }