'use client'

import { useState, useEffect } from 'react'

export interface FpAnnualKPIs {
  revenue: number
  ebit: number
  personal: number
  netIncome: number
  steuern: number
  liquiditaet: number
  customers: number
  headcount: number
  mrr: number
  arr: number
  arpu: number
  revPerEmp: number
  ebitMargin: number
  grossMargin: number
  nrr: number           // Net Revenue Retention %
  paybackMonths: number  // CAC Payback Period in months
}

interface SheetRow {
  row_label?: string
  values?: Record<string, number>
  values_total?: Record<string, number>
}

/**
 * Loads annual KPIs directly from fp_* tables (source of truth).
 * Returns a map of year keys (y2026-y2030) to KPI objects.
 */
export function useFpKPIs(isWandeldarlehen?: boolean) {
  const [kpis, setKpis] = useState<Record<string, FpAnnualKPIs>>({})
  const [loading, setLoading] = useState(true)

  useEffect(() => {
    async function load() {
      try {
        const param = isWandeldarlehen ? '?scenarioId=c0000000-0000-0000-0000-000000000200' : ''
        const [guvRes, liqRes, persRes, kundenRes] = await Promise.all([
          fetch(`/api/finanzplan/guv${param}`, { cache: 'no-store' }),
          fetch(`/api/finanzplan/liquiditaet${param}`, { cache: 'no-store' }),
          fetch(`/api/finanzplan/personalkosten${param}`, { cache: 'no-store' }),
          fetch(`/api/finanzplan/kunden${param}`, { cache: 'no-store' }),
        ])
        const [guv, liq, pers, kunden] = await Promise.all([guvRes.json(), liqRes.json(), persRes.json(), kundenRes.json()])

        const guvRows: SheetRow[] = guv.rows || []
        const liqRows: SheetRow[] = liq.rows || []
        const persRows: SheetRow[] = pers.rows || []
        const kundenRows: SheetRow[] = kunden.rows || []

        const findGuv = (label: string) => guvRows.find(r => (r.row_label || '').includes(label))
        const findLiq = (label: string) => liqRows.find(r => (r.row_label || '').includes(label))
        const kundenGesamt = kundenRows.find(r => r.row_label === 'Bestandskunden gesamt')

        const result: Record<string, FpAnnualKPIs> = {}

        for (const y of [2026, 2027, 2028, 2029, 2030]) {
          const yk = `y${y}`
          const mk = `m${(y - 2026) * 12 + 12}` // December

          const revenue = findGuv('Umsatzerlöse')?.values?.[yk] || 0
          const ebit = findGuv('EBIT')?.values?.[yk] || 0
          const personal = findGuv('Summe Personalaufwand')?.values?.[yk] || 0
          const netIncome = findGuv('Jahresüberschuss')?.values?.[yk] || findGuv('Jahresueber')?.values?.[yk] || 0
          const steuern = findGuv('Steuern gesamt')?.values?.[yk] || 0
          const liquiditaet = findLiq('LIQUIDIT')?.values?.[mk] || findLiq('LIQUIDITAET')?.values?.[mk] || 0
          const customers = kundenGesamt?.values?.[mk] || 0
          const headcount = persRows.filter(r => ((r.values_total || r.values)?.[mk] || 0) > 0).length
          const mrr = revenue > 0 ? Math.round(revenue / 12) : 0
          const arr = mrr * 12
          const arpu = customers > 0 ? Math.round(mrr / customers) : 0
          const revPerEmp = headcount > 0 ? Math.round(revenue / headcount) : 0
          const ebitMargin = revenue > 0 ? Math.round((ebit / revenue) * 100) : 0
          const grossMargin = revenue > 0 ? Math.round(((revenue - (findGuv('Summe Materialaufwand')?.values?.[yk] || 0)) / revenue) * 100) : 0

          // NRR: compare Dec revenue of this year vs Dec revenue of prior year
          // NRR = (MRR_Dec_thisYear / MRR_Dec_lastYear) * 100
          const prevMk = `m${(y - 2026) * 12}` // December of prior year (m0 for 2026 = no prior)
          const prevRevenue = y > 2026 ? (findGuv('Umsatzerlöse')?.values?.[`y${y - 1}`] || 0) : 0
          const nrr = prevRevenue > 0 ? Math.round((revenue / prevRevenue) * 100) : 0

          // Payback: Marketing costs / monthly gross profit per new customer
          // Simplified: annual marketing spend / (new customers * monthly ARPU)
          const sonstAufw = findGuv('Sonst. betriebl. Aufwend')?.values?.[yk] || 0
          // Marketing ~ 10% of sonstige (rough estimate from our formula)
          const marketingSpend = Math.round(revenue * 0.10)
          const prevCustomers = y > 2026 ? (kundenGesamt?.values?.[`m${(y - 2026) * 12}`] || 0) : 0
          const newCustomers = Math.max(customers - prevCustomers, 1)
          const cac = newCustomers > 0 ? Math.round(marketingSpend / newCustomers) : 0
          const monthlyGrossProfit = arpu > 0 ? arpu * (grossMargin / 100) : 0
          const paybackMonths = monthlyGrossProfit > 0 ? Math.round(cac / monthlyGrossProfit) : 0

          result[yk] = { revenue, ebit, personal, netIncome, steuern, liquiditaet, customers, headcount, mrr, arr, arpu, revPerEmp, ebitMargin, grossMargin, nrr, paybackMonths }
        }

        setKpis(result)
      } catch { /* ignore */ }
      setLoading(false)
    }
    load()
  }, [isWandeldarlehen])

  const last = kpis.y2030
  return { kpis, loading, last }
}