/**
 * Borç takibi (docs/BORC_TAKIBI.md): sorgu kancaları ve saf hesaplar.
 * Hesaplar backend `services/debt.rs` ile aynı tutulmalı (form önizlemesi, grafik).
 */
import { useMutation, useQuery, useQueryClient } from '@tanstack/react-query'
import type { DebtImportReport } from '@/types/DebtImportReport'
import type { DebtSnapshot } from '@/types/DebtSnapshot'
import type { DebtSnapshotRequest } from '@/types/DebtSnapshotRequest'
import type { DebtSummary } from '@/types/DebtSummary'
import type { DebtTarget } from '@/types/DebtTarget'
import type { InstallmentPlan } from '@/types/InstallmentPlan'
import type { InstallmentRequest } from '@/types/InstallmentRequest'
import type { PeriodDebt } from '@/types/PeriodDebt'
import { api } from './api'
import { queryKeys } from './query'

// ---------- Saf hesaplar ----------

/** KMH + kart + kalan taksit − artı bakiye */
export function debtTotal(x: {
  kmh: number
  card_balance: number
  remaining_installments: number
  positive_balance: number
}): number {
  return x.kmh + x.card_balance + x.remaining_installments - x.positive_balance
}

/** `"2026-11"` → ay sırası; geçersizse `null` */
export function monthIndex(m: string): number | null {
  const r = /^(\d{4})-(\d{2})$/.exec(m)
  if (!r) return null
  const mo = Number(r[2])
  return mo >= 1 && mo <= 12 ? Number(r[1]) * 12 + mo - 1 : null
}

export function monthName(i: number): string {
  return `${Math.floor(i / 12)}-${String((i % 12) + 1).padStart(2, '0')}`
}

type PlanShape = Pick<InstallmentPlan, 'monthly_amount' | 'total_count' | 'first_month'>

/** `month`'tan sonra ekstreye gelecek taksitler (ölçümdeki "kalan taksit" önerisi) */
export function remainingAfter(plans: readonly PlanShape[], month: number): number {
  return plans.reduce((sum, p) => {
    const first = monthIndex(p.first_month)
    if (first === null) return sum
    const paid = Math.min(Math.max(month - first + 1, 0), p.total_count)
    return sum + (p.total_count - paid) * p.monthly_amount
  }, 0)
}

/** Ayın taksit yükü */
export function installmentLoad(plans: readonly PlanShape[], month: number): number {
  return plans.reduce((sum, p) => {
    const first = monthIndex(p.first_month)
    if (first === null) return sum
    return month >= first && month <= first + p.total_count - 1 ? sum + p.monthly_amount : sum
  }, 0)
}

/** Ayın son günü `"YYYY-MM-DD"` (hedef noktaları grafikte ay sonuna konur) */
export function monthEnd(ym: string): string {
  const i = monthIndex(ym)
  if (i === null) return ym
  const d = new Date(Date.UTC(Math.floor(i / 12), (i % 12) + 1, 0))
  return d.toISOString().slice(0, 10)
}

export type DebtPoint = { t: number; date: string; actual?: number; target?: number }

/**
 * Grafik: ölçümler (gerçek) + yol haritası (hedef, ay sonları). Hedef çizgisi ilk ölçümden
 * başlar ki başlangıçla bağlansın. Zaman ekseni gün (ms).
 */
export function debtSeries(
  snapshots: readonly Pick<DebtSnapshot, 'date' | 'total'>[],
  targets: readonly DebtTarget[],
): DebtPoint[] {
  const map = new Map<string, DebtPoint>()
  const at = (date: string) => {
    let p = map.get(date)
    if (!p) map.set(date, (p = { t: Date.parse(`${date}T00:00:00Z`), date }))
    return p
  }
  const sorted = [...snapshots].sort((a, b) => a.date.localeCompare(b.date))
  for (const s of sorted) at(s.date).actual = s.total
  if (sorted.length > 0 && targets.length > 0) at(sorted[0].date).target = sorted[0].total
  for (const tg of targets) at(monthEnd(tg.month)).target = tg.closing_target
  return [...map.values()].sort((a, b) => a.t - b.t)
}

// ---------- Sorgular ----------

export function useDebt() {
  return useQuery({ queryKey: queryKeys.debt, queryFn: () => api.get<DebtSummary>('/debt') })
}

export function usePeriodDebt(periodId: string) {
  return useQuery({
    queryKey: queryKeys.periodDebt(periodId),
    queryFn: () => api.get<PeriodDebt>(`/periods/${periodId}/debt`),
  })
}

/** Borç verisi değişince özet ve dönem borçları yenilenir */
function useInvalidateDebt() {
  const qc = useQueryClient()
  return () =>
    Promise.all([
      qc.invalidateQueries({ queryKey: queryKeys.debt }),
      qc.invalidateQueries({ queryKey: ['period'] }),
    ])
}

export function useSaveSnapshot() {
  const invalidate = useInvalidateDebt()
  return useMutation({
    mutationFn: ({ id, ...body }: DebtSnapshotRequest & { id?: string }) =>
      id
        ? api.patch<DebtSnapshot>(`/debt/snapshots/${id}`, body)
        : api.post<DebtSnapshot>('/debt/snapshots', body),
    onSuccess: invalidate,
  })
}

export function useDeleteSnapshot() {
  const invalidate = useInvalidateDebt()
  return useMutation({
    mutationFn: (id: string) => api.delete(`/debt/snapshots/${id}`),
    onSettled: invalidate,
  })
}

export function useSaveInstallment() {
  const invalidate = useInvalidateDebt()
  return useMutation({
    mutationFn: ({ id, ...body }: InstallmentRequest & { id?: string }) =>
      id
        ? api.patch<InstallmentPlan>(`/debt/installments/${id}`, body)
        : api.post<InstallmentPlan>('/debt/installments', body),
    onSuccess: invalidate,
  })
}

export function useDeleteInstallment() {
  const invalidate = useInvalidateDebt()
  return useMutation({
    mutationFn: (id: string) => api.delete(`/debt/installments/${id}`),
    onSettled: invalidate,
  })
}

export function useSetTargets() {
  const invalidate = useInvalidateDebt()
  return useMutation({
    mutationFn: (targets: DebtTarget[]) => api.put<void>('/debt/targets', { targets }),
    onSuccess: invalidate,
  })
}

export function useSetOpeningDebt(periodId: string) {
  const invalidate = useInvalidateDebt()
  return useMutation({
    mutationFn: (amount: number | null) =>
      api.put<void>(`/periods/${periodId}/opening-debt`, { amount }),
    onSuccess: invalidate,
  })
}

/** Plan kalemlerinde "Taksit(ler)" adlı sabit gider (büyük/küçük harf ve Türkçe harf duyarsız) */
export function findInstallmentItem<T extends { kind: string; name: string }>(
  items: readonly T[],
): T | undefined {
  return items.find(
    (i) => i.kind === 'expense' && /^taks[iı]t(ler|lar)?$/.test(i.name.trim().toLocaleLowerCase('tr')),
  )
}

export function useDebtImport() {
  const invalidate = useInvalidateDebt()
  return useMutation({
    mutationFn: ({ json, commit }: { json: unknown; commit: boolean }) =>
      api.post<DebtImportReport>(`/debt/import?commit=${commit}`, json),
    onSuccess: (_, v) => {
      if (v.commit) void invalidate()
    },
  })
}