import { describe, expect, it } from "vitest";
import {
  cardPeriods,
  closingOnOrAfter,
  dueDate,
  estimateOverdraftInterest,
  installmentSchedule,
  minimumPayment,
  minimumRateBp,
  nextPeriod,
  periodContaining,
} from "./card-periods";

describe("dönem hesabı", () => {
  it("kesim günü dahil hesap kesim dönemine girer; ertesi gün yeni dönem", () => {
    expect(periodContaining("2026-10-29", 29)).toEqual({ start: "2026-09-30", end: "2026-10-29" });
    expect(periodContaining("2026-10-30", 29)).toEqual({ start: "2026-10-30", end: "2026-11-29" });
  });

  it("kesim günü ayda yoksa ayın son günü (31 → Şubat 28/29)", () => {
    expect(closingOnOrAfter("2026-02-10", 31)).toBe("2026-02-28");
    expect(periodContaining("2028-03-05", 31)).toEqual({ start: "2028-03-01", end: "2028-03-31" });
    expect(periodContaining("2026-03-01", 30)).toEqual({ start: "2026-03-01", end: "2026-03-30" });
    expect(periodContaining("2026-02-28", 30)).toEqual({ start: "2026-01-31", end: "2026-02-28" });
  });

  it("yıl dönümü ve sonraki dönem", () => {
    const p = periodContaining("2026-12-31", 15);
    expect(p).toEqual({ start: "2026-12-16", end: "2027-01-15" });
    expect(nextPeriod(p, 15)).toEqual({ start: "2027-01-16", end: "2027-02-15" });
  });

  it("güncel dönem ve son ekstre; kesim günü bugün iken dönem henüz kapanmamış", () => {
    expect(cardPeriods("2026-11-05", 29)).toEqual({
      current: { start: "2026-10-30", end: "2026-11-29" },
      statement: { start: "2026-09-30", end: "2026-10-29" },
    });
    expect(cardPeriods("2026-11-29", 29).current.end).toBe("2026-11-29");
  });

  it("son ödeme tarihi", () => {
    expect(dueDate("2026-10-29", { kind: "daysAfter", value: 10 })).toBe("2026-11-08");
    expect(dueDate("2026-10-29", { kind: "fixedDay", value: 9 })).toBe("2026-11-09");
    expect(dueDate("2026-10-05", { kind: "fixedDay", value: 20 })).toBe("2026-10-20");
    expect(dueDate("2026-01-29", { kind: "fixedDay", value: 31 })).toBe("2026-01-31");
  });
});

describe("asgari ödeme", () => {
  it("limite göre %20 / %40; kart bazında oran öncelikli; yukarı yuvarlama", () => {
    expect(minimumRateBp(49_999_99, null)).toBe(2000);
    expect(minimumRateBp(50_000_00, null)).toBe(4000);
    expect(minimumRateBp(60_000_00, 2500)).toBe(2500);
    expect(minimumPayment(10_000_01, 2000)).toBe(2_000_01);
    expect(minimumPayment(-5, 2000)).toBe(0);
  });
});

describe("taksit planı", () => {
  it("eşit bölme (kuruş farkı ilk taksitlerde), aylık tarihler, ay sonu", () => {
    const s = installmentSchedule("2026-01-31", 10_000_00, 3);
    expect(s.map((x) => x.amountMinor)).toEqual([3_333_34, 3_333_33, 3_333_33]);
    expect(s.reduce((a, x) => a + x.amountMinor, 0)).toBe(10_000_00);
    expect(s.map((x) => x.date)).toEqual(["2026-01-31", "2026-02-28", "2026-03-31"]);
  });
});

describe("KMH faiz tahmini", () => {
  it("gün sonu eksi bakiyeler üzerinden", () => {
    const period = { start: "2026-11-01", end: "2026-11-30" };
    // 10 gün boyunca -3.000 TL; sonra sıfır.
    const deltas = new Map([
      ["2026-11-01", -3_000_00],
      ["2026-11-11", 3_000_00],
    ]);
    const r = estimateOverdraftInterest(period, 0, deltas, 425);
    // 10 gün × 3.000 TL × %4,25 / 30 = 42,50 TL
    expect(r.interestMinor).toBe(42_50);
    expect(r.days).toBe(30);
    expect(estimateOverdraftInterest(period, 5_000_00, deltas, 425).interestMinor).toBe(0);
  });
});