package domain

import (
	"testing"
	"time"
)

func d(y int, m time.Month, day int) time.Time {
	return time.Date(y, m, day, 0, 0, 0, 0, time.Local)
}

func TestDayDiff(t *testing.T) {
	cases := []struct {
		a, b time.Time
		want int
	}{
		{d(2026, 1, 1), d(2026, 1, 1), 0},
		{d(2026, 1, 1), d(2026, 1, 31), 30},
		{d(2026, 2, 28), d(2026, 3, 1), 1},
		{d(2024, 2, 28), d(2024, 3, 1), 2}, // 闰年
		{d(2026, 12, 31), d(2027, 1, 1), 1},
		{d(2026, 1, 10), d(2026, 1, 1), -9},
	}
	for _, c := range cases {
		if got := DayDiff(c.a, c.b); got != c.want {
			t.Errorf("DayDiff(%s,%s)=%d want %d", Date(c.a), Date(c.b), got, c.want)
		}
	}
}

func TestEvalDay(t *testing.T) {
	today := d(2026, 10, 18)
	cases := []struct {
		name      string
		status    string
		end       string
		wantState string
		wantLevel string
		wantDays  int
	}{
		{"进行中", "active", "2026-11-16", StateActive, LevelOK, 30},
		{"今天到期", "active", "2026-10-18", StateActive, LevelToday, 1},
		{"3天内", "active", "2026-10-20", StateActive, LevelWarn, 3},
		{"已到期", "active", "2026-10-17", StateExpired, LevelExpired, 0},
		{"暂停中", "paused", "2026-11-16", StatePaused, LevelNone, 30},
		{"已结束", "closed", "2026-11-16", StateClosed, LevelNone, 30},
	}
	for _, c := range cases {
		e := EvalSub(c.status, "2026-10-01", c.end, today, 3)
		if e.State != c.wantState {
			t.Errorf("%s: state=%s want %s", c.name, e.State, c.wantState)
		}
		if e.Level != c.wantLevel {
			t.Errorf("%s: level=%s want %s", c.name, e.Level, c.wantLevel)
		}
		if e.RemainingDays != c.wantDays {
			t.Errorf("%s: remaining=%d want %d", c.name, e.RemainingDays, c.wantDays)
		}
	}
}

func TestEvalDayNotStarted(t *testing.T) {
	today := d(2026, 10, 18)
	e := EvalSub("active", "2026-10-20", "2026-11-18", today, 3)
	if e.State != StatePending {
		t.Fatalf("state=%s want pending", e.State)
	}
	if e.RemainingDays != 32 {
		t.Fatalf("remaining=%d want 32", e.RemainingDays)
	}
}

// TestEvalNoEndDate 覆盖历史数据里结束日为空的兜底分支（lite 版没有按次计费）。
func TestEvalNoEndDate(t *testing.T) {
	today := d(2026, 10, 18)

	e := EvalSub("active", "2026-10-01", "", today, 3)
	if e.Level != LevelNone || e.DaysLeft != -1 || e.RemainingDays != 0 {
		t.Fatalf("level=%s daysLeft=%d remain=%d", e.Level, e.DaysLeft, e.RemainingDays)
	}
	if e.State != StateActive {
		t.Fatalf("state=%s want active", e.State)
	}
}

func TestPlanExtend(t *testing.T) {
	today := d(2026, 10, 18)

	// 未到期：从原结束日次日顺延，追加天数 = 新旧结束日之差
	oldEnd := d(2026, 11, 16)
	newEnd := d(2026, 12, 2)
	p := PlanExtend(oldEnd, newEnd, today)
	if Date(p.Base) != "2026-11-17" {
		t.Fatalf("base=%s", Date(p.Base))
	}
	if p.Days != 16 {
		t.Fatalf("days=%d want 16", p.Days)
	}

	// 已到期：从今天起算
	oldEnd = d(2026, 10, 5)
	newEnd = d(2026, 11, 3)
	p = PlanExtend(oldEnd, newEnd, today)
	if Date(p.Base) != "2026-10-18" {
		t.Fatalf("base=%s", Date(p.Base))
	}
	if p.Days != 17 {
		t.Fatalf("days=%d want 17", p.Days)
	}

	// 选的日期早于计算起点 → 无效
	p = PlanExtend(d(2026, 11, 16), d(2026, 11, 10), today)
	if !p.Backwards || p.Days != 0 {
		t.Fatalf("backwards=%v days=%d", p.Backwards, p.Days)
	}
}

func TestMonthHelpers(t *testing.T) {
	if got := Date(MonthEnd(2026, time.February)); got != "2026-02-28" {
		t.Fatalf("MonthEnd=%s", got)
	}
	if got := Date(MonthEnd(2024, time.February)); got != "2024-02-29" {
		t.Fatalf("MonthEnd=%s", got)
	}
	if got := WeekdayIndex(d(2026, 10, 18)); got != 6 { // 周日
		t.Fatalf("WeekdayIndex=%d want 6", got)
	}
	if got := WeekdayIndex(d(2026, 10, 19)); got != 0 { // 周一
		t.Fatalf("WeekdayIndex=%d want 0", got)
	}
}