import "server-only";
import { budgetFor, settingsOf } from "@/features/budgets/service";
import { incomeByDay, incomePlan, monthDailyPlan } from "@/features/budgets/plan";
import { loadContext } from "@/features/transactions/service";
import { budgetPeriod, periodOfDate } from "@/shared/budget";
import { todayIstanbul } from "@/shared/dates";
import {
  overviewRange,
  type OverviewPeriod,
  type OverviewPoint,
  type OverviewRange,
} from "@/shared/overview";

/**
 * Dashboard ana grafiği (Bölüm 6.13). Bütçe ve gelir planı motorlarıyla aynı kurallar: bütçe ayı,
 * taksit modu ve gizli hesap ayarı.
 *
 * Aylık noktalar: beklenen gelir (gerçekleşen + planlı + elle), bütçe toplamı (bütçe yoksa boş),
 * gerçekleşen gider. Günlük noktalar: o günün gelirleri (elle eklenen beklenen gelir dönemin ilk
 * gününe), günlük plan payı, o günün gerçekleşen gideri; gelecek günlerde gerçekleşen boş.
 */
export type OverviewData = {
  period: OverviewPeriod;
  range: OverviewRange;
  points: OverviewPoint[];
  today: string;
};

export async function getOverview(
  userId: string,
  householdId: string,
  period: OverviewPeriod,
): Promise<OverviewData | null> {
  const ctx = await loadContext(userId, householdId, "viewer");
  if (!ctx) return null;
  const s = await settingsOf(ctx.m.householdId);
  const today = todayIstanbul();
  const range = overviewRange(period, today, s.startDay);

  if (range.granularity === "month") {
    const points = await Promise.all(
      range.buckets.map(async (month) => {
        const [budget, income] = await Promise.all([
          budgetFor(ctx, s, month),
          incomePlan(ctx, s, month),
        ]);
        return {
          key: month,
          plannedIncome: income.expectedMinor,
          budget: budget.hasBudget ? budget.totals.limitMinor : null,
          actual: budget.totals.actualMinor,
        };
      }),
    );
    return { period, range, points, today };
  }

  // Günlük: aralığın dokunduğu bütçe ayları (hafta iki aya yayılabilir).
  const months = [...new Set([range.from, range.to].map((d) => periodOfDate(d, s.startDay)))];
  const planned = new Map<string, number | null>();
  const actual = new Map<string, number>();
  const income = new Map<string, number>();
  for (const month of months) {
    const [budget, plan] = await Promise.all([budgetFor(ctx, s, month), incomePlan(ctx, s, month)]);
    const dp = await monthDailyPlan(ctx, s, month, budget.totals.limitMinor, today);
    for (const d of dp.days) {
      planned.set(d.date, budget.hasBudget ? d.plannedMinor : null);
      actual.set(d.date, d.actualMinor);
    }
    const first = budgetPeriod(month, s.startDay).from;
    if (plan.manualMinor) income.set(first, (income.get(first) ?? 0) + plan.manualMinor);
  }
  for (const [d, v] of await incomeByDay(ctx, s, range.from, range.to))
    income.set(d, (income.get(d) ?? 0) + v);

  const points = range.buckets.map((d) => ({
    key: d,
    plannedIncome: income.get(d) ?? 0,
    budget: planned.get(d) ?? null,
    actual: d <= today ? (actual.get(d) ?? 0) : null,
  }));
  return { period, range, points, today };
}