package quota

import (
	"errors"
	"testing"

	"hunjing/shenshi/internal/store"
)

func TestReserveRejectsWhenBudgetExhausted(t *testing.T) {
	st := store.NewMem()
	l := New(st, 1000)
	if _, err := l.Reserve("u1", 600); err != nil {
		t.Fatal(err)
	}
	if _, err := l.Reserve("u1", 600); err == nil {
		t.Fatal("累计超预算应拒绝（HJ-2004）")
	} else if !errors.Is(err, ErrInsufficient) {
		t.Fatalf("错误类型错误: %v", err)
	}
}

func TestSettleReleasesAndAllowsReuse(t *testing.T) {
	st := store.NewMem()
	l := New(st, 1000)
	r, _ := l.Reserve("u1", 600)
	if err := l.Settle("u1", r, 100); err != nil {
		t.Fatal(err)
	}
	// 已用 100，剩 900 可用
	if _, err := l.Reserve("u1", 900); err != nil {
		t.Fatalf("结算释放差值后应可继续使用: %v", err)
	}
}

func TestRefundIdempotent(t *testing.T) {
	st := store.NewMem()
	l := New(st, 1000)
	r, _ := l.Reserve("u1", 500)
	_ = l.Refund("u1", r)
	_ = l.Refund("u1", r) // 幂等重放
	budget, used, reserved, _ := l.Budget("u1")
	if reserved != 0 || used != 0 || budget != 1000 {
		t.Fatalf("重复退款后账目异常: budget=%d used=%d reserved=%d", budget, used, reserved)
	}
}

func TestClampCeiling(t *testing.T) {
	if got := clamp(1 << 30); got != 1<<20 {
		t.Fatalf("超大预扣应钳位到 1M，实际 %d", got)
	}
	if got := clamp(-5); got != 0 {
		t.Fatalf("负值应截断为 0，实际 %d", got)
	}
}

func TestZeroBudgetMeansUnlimited(t *testing.T) {
	st := store.NewMem()
	l := New(st, 0)
	for i := 0; i < 3; i++ {
		if _, err := l.Reserve("u1", 1<<20); err != nil {
			t.Fatalf("budget=0 不应裁决: %v", err)
		}
	}
}