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

const ROUND_LABELS = ['30-day', '60-day', '90-day'] as const
const NEXT_INTERVAL_DAYS: (number | null)[] = [60, 90, null]

export function getRoundLabel(round: number): string {
  return ROUND_LABELS[round] ?? '90-day'
}

export function getNextRecheckDate(verifiedAt: string, currentRound: number): string | null {
  const days = NEXT_INTERVAL_DAYS[currentRound]
  if (days === null || days === undefined) return null
  const base = new Date(verifiedAt)
  base.setDate(base.getDate() + days)
  return base.toISOString().split('T')[0]
}

export function shouldSendRecheck(
  recheckDate: string | null,
  round: number,
  today: string = new Date().toISOString().split('T')[0],
): boolean {
  if (!recheckDate || round >= 3) return false
  return recheckDate <= today
}

export async function sendEffectivenessRecheckNotifications(
  supabase: SupabaseClient,
): Promise<{ notified: number }> {
  const today = new Date().toISOString().split('T')[0]

  const { data: capas } = await supabase
    .from('capa_actions')
    .select(`
      id, description, effectiveness_recheck_date, effectiveness_recheck_round,
      verified_at, incident_id,
      incidents (reference_no),
      verifier:users!verified_by (email, name, phone)
    `)
    .in('status', ['verified', 'closed'])
    .not('effectiveness_recheck_date', 'is', null)
    .lt('effectiveness_recheck_round', 3)

  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 whatsappPhoneId: string | null = null
  let whatsappToken: string | null = null
  try {
    whatsappPhoneId = await getApiKey(supabase, 'META_WHATSAPP_PHONE_NUMBER_ID')
    whatsappToken = await getApiKey(supabase, 'META_WHATSAPP_ACCESS_TOKEN')
  } catch {
    // WhatsApp not configured — email only
  }

  let notified = 0

  for (const capa of capas) {
    const recheckDate = (capa as { effectiveness_recheck_date: string | null }).effectiveness_recheck_date
    const round = (capa as { effectiveness_recheck_round: number }).effectiveness_recheck_round

    if (!shouldSendRecheck(recheckDate, round, today)) continue

    const verifierEmail = (capa.verifier as unknown as { email: string } | null)?.email
    const verifierName = (capa.verifier as unknown as { name: string } | null)?.name ?? 'HSE Officer'
    const verifierPhone = (capa.verifier as unknown as { phone: string | null } | null)?.phone ?? ''
    if (!verifierEmail) continue

    const incidentRef = (capa.incidents as unknown as { reference_no: string | null } | null)?.reference_no
      ?? (capa as { incident_id: string }).incident_id
    const roundLabel = getRoundLabel(round)
    const capaDesc = (capa as { description: string }).description
    const capaUrl = `${siteUrl}/ims/hse/capa/${(capa as { id: string }).id}`

    const subject = `[IMS] ${roundLabel} effectiveness check — ${incidentRef}`
    const html = `
      <p>Hi ${verifierName},</p>
      <p>This is the <strong>${roundLabel} effectiveness check</strong> for a corrective action you verified on incident <strong>${incidentRef}</strong>.</p>
      <p><strong>Action:</strong> ${capaDesc}</p>
      <p>Please confirm the corrective action is still in place and effective.</p>
      <p><a href="${capaUrl}">View CAPA</a></p>
    `
    const text = `${roundLabel} effectiveness check for ${incidentRef}\nAction: ${capaDesc}\n${capaUrl}`

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

    // WhatsApp (non-blocking, best-effort)
    if (whatsappPhoneId && whatsappToken && verifierPhone) {
      sendWhatsAppMessage(
        verifierPhone,
        'ims_effectiveness_recheck',
        [roundLabel, incidentRef, capaDesc],
        whatsappPhoneId,
        whatsappToken,
      ).catch(err => console.error('WhatsApp recheck error:', err))
    }

    // Advance round
    const verifiedAt = (capa as { verified_at: string }).verified_at
    const nextDate = getNextRecheckDate(verifiedAt, round)
    await supabase
      .from('capa_actions')
      .update({
        effectiveness_recheck_round: round + 1,
        effectiveness_recheck_date: nextDate ?? null,
      })
      .eq('id', (capa as { id: string }).id)

    notified++
  }

  return { notified }
}