package timeutil

import (
	"testing"
	"time"
)

func TestFormatAPITimeUsesBusinessTimezone(t *testing.T) {
	value := time.Date(2026, 7, 30, 9, 53, 58, 147355000, time.UTC)
	if got := FormatAPITime(value); got != "2026-07-30T17:53:58+08:00" {
		t.Fatalf("unexpected api time: %s", got)
	}
}

func TestStartOfDayUsesBusinessTimezone(t *testing.T) {
	value := time.Date(2026, 7, 30, 18, 30, 0, 0, time.UTC)
	got := StartOfDay(value)
	if got.Format(APITimeLayout) != "2026-07-31T00:00:00+08:00" {
		t.Fatalf("unexpected day start: %s", got.Format(APITimeLayout))
	}
}

// TestLocalZoneNotice 锁住启动体检：进程时区偏移不等于 +08:00 时必须给出提示，
// 否则 pgx 把 timestamptz 解码到 time.Local 会让接口返回的时间偏移悄悄变化。
func TestLocalZoneNotice(t *testing.T) {
	original := time.Local
	t.Cleanup(func() { time.Local = original })

	time.Local = time.FixedZone("CST", BusinessZoneOffsetSeconds)
	if got := LocalZoneNotice(); got != "" {
		t.Fatalf("业务时区不应告警，实际 %q", got)
	}

	time.Local = time.UTC
	if got := LocalZoneNotice(); got == "" {
		t.Fatal("UTC 进程时区必须告警")
	}

	time.Local = time.FixedZone("EST", -5*60*60)
	if got := LocalZoneNotice(); got == "" {
		t.Fatal("负偏移进程时区必须告警")
	}
}