import { Resend } from 'resend'
import type { SupabaseClient } from '@supabase/supabase-js'
import { sendWhatsAppMessage } from '@/lib/notifications/whatsapp'
import { createInAppNotifications } from '@/lib/notifications/in-app'
import { getApiKey } from '@/lib/settings'

export type EscalationThreshold = 'warning_3d' | 'due_today' | 'overdue_3d' | 'overdue_7d'

export function getEscalationThreshold(dueDateIso: string): EscalationThreshold | null {
  const today = new Date()
  today.setUTCHours(0, 0, 0, 0)
  const due = new Date(dueDateIso)
  // date-only ISO strings are parsed as UTC midnight — keep due in UTC too
  const diffDays = Math.round((due.getTime() - today.getTime()) / 86_400_000)

  if (diffDays === 3) return 'warning_3d'
  if (diffDays === 0) return 'due_today'
  if (diffDays === -3) return 'overdue_3d'
  if (diffDays === -7) return 'overdue_7d'
  return null
}

const THRESHOLD_SUBJECT: Record<EscalationThreshold, string> = {
  warning_3d: '[IMS] CAPA action due in 3 days',
  due_today: '[IMS] CAPA action due TODAY',
  overdue_3d: '[IMS] CAPA action 3 days OVERDUE',
  overdue_7d: '[IMS] URGENT: CAPA action 7 days OVERDUE',
}

export async function escalateOverdueCapa(
  supabase: SupabaseClient
): Promise<{ notified: number }> {
  const { data: capas } = await supabase
    .from('capa_actions')
    .select(`
      id, description, due_date, incident_id, owner_user_id,
      incidents (reference_no, site_id),
      owner:users!owner_user_id (email, name, phone)
    `)
    .not('status', 'in', '(verified,closed)')

  if (!capas || capas.length === 0) return { notified: 0 }

  const resend = new Resend(process.env.RESEND_API_KEY)
  const from = process.env.RESEND_FROM_EMAIL ?? 'onboarding@resend.dev'
  const siteUrl = process.env.NEXT_PUBLIC_SITE_URL ?? 'http://localhost:3000'
  let notified = 0

  const whatsappPhoneNumberId = await getApiKey(supabase, 'META_WHATSAPP_PHONE_NUMBER_ID')
  const whatsappAccessToken = await getApiKey(supabase, 'META_WHATSAPP_ACCESS_TOKEN')

  for (const capa of capas) {
    const threshold = getEscalationThreshold((capa as { due_date: string }).due_date)
    if (!threshold) continue

    const { data: alreadySent } = await supabase
      .from('notifications_log')
      .select('id')
      .eq('capa_id', capa.id)
      .eq('channel', 'email')
      .eq('status', threshold)
      .limit(1)
      .maybeSingle()

    if (alreadySent) continue

    const ownerEmail = (capa.owner as unknown as { email: string } | null)?.email
    const ownerName = (capa.owner as unknown as { name: string } | null)?.name ?? 'Owner'
    if (!ownerEmail) continue

    const incidentRef = (capa.incidents as unknown as { reference_no: string | null } | null)?.reference_no ?? capa.incident_id
    const capaUrl = `${siteUrl}/ims/hse/capa/${capa.id}`
    const subject = THRESHOLD_SUBJECT[threshold]
    const html = `
      <p>Hi ${ownerName},</p>
      <p>CAPA action for incident <strong>${incidentRef}</strong> requires attention.</p>
      <p><strong>Action:</strong> ${(capa as { description: string }).description}</p>
      <p><strong>Due date:</strong> ${(capa as { due_date: string }).due_date}</p>
      <p><a href="${capaUrl}">View CAPA</a></p>
    `
    const text = `CAPA ${incidentRef}: ${(capa as { description: string }).description}\nDue: ${(capa as { due_date: string }).due_date}\n${capaUrl}`

    const to = [ownerEmail]
    const siteId = (capa.incidents as unknown as { site_id: string } | null)?.site_id
    if (siteId && ['due_today', 'overdue_3d', 'overdue_7d'].includes(threshold)) {
      const { data: hseUsers } = await supabase
        .from('users')
        .select('email')
        .eq('site_id', siteId)
        .in('role', ['hse', 'supervisor', 'management'])
      if (hseUsers) to.push(...hseUsers.map((u: { email: string }) => u.email))
    }

    const { error } = await resend.emails.send({ from, to: [...new Set(to)], subject, html, text })
    if (error) {
      console.error('Escalation email error:', error)
      continue
    }

    // WhatsApp for urgent thresholds only (owner must have a phone number)
    if (['overdue_3d', 'overdue_7d'].includes(threshold)) {
      const ownerPhone = (capa.owner as unknown as { phone: string | null } | null)?.phone ?? ''
      if (ownerPhone) {
        try {
          await sendWhatsAppMessage(
            ownerPhone,
            'ims_capa_overdue',
            [incidentRef, (capa as { description: string }).description, (capa as { due_date: string }).due_date],
            whatsappPhoneNumberId,
            whatsappAccessToken,
          )
        } catch (waErr) {
          console.error('WhatsApp escalation error:', waErr)
        }
      }
    }

    await supabase.from('notifications_log').insert({
      capa_id: capa.id,
      channel: 'email',
      recipient: to.join(','),
      status: threshold,
    })

    const ownerUserId = (capa as { owner_user_id: string | null }).owner_user_id
    if (ownerUserId) {
      await createInAppNotifications(supabase, [{
        userId: ownerUserId,
        title: `${THRESHOLD_SUBJECT[threshold].replace('[IMS] ', '')} — ${incidentRef}`,
        link: `/hse/capa/${capa.id}`,
        incidentId: capa.incident_id as string,
        capaId: capa.id as string,
      }])
    }

    notified++
  }

  return { notified }
}