package yijing

import (
	"testing"
	"time"
)

func TestSeedStableSameInputs(t *testing.T) {
	bt := "10:30"
	now := time.Date(2026, 8, 11, 19, 0, 0, 0, time.FixedZone("CST", 8*3600))
	a := Seed("1990-05-12", &bt, now)
	b := Seed("1990-05-12", &bt, now)
	if a.GuaIndex != b.GuaIndex || a.GuaName != b.GuaName || a.Line != b.Line {
		t.Fatalf("expected stable seed, got %+v vs %+v", a, b)
	}
	if a.GuaIndex < 1 || a.GuaIndex > 64 {
		t.Fatalf("gua out of range: %d", a.GuaIndex)
	}
}

func TestSeedChangesWithDay(t *testing.T) {
	d1 := time.Date(2026, 8, 11, 19, 0, 0, 0, time.FixedZone("CST", 8*3600))
	d2 := time.Date(2026, 8, 12, 19, 0, 0, 0, time.FixedZone("CST", 8*3600))
	a := Seed("1990-05-12", nil, d1)
	b := Seed("1990-05-12", nil, d2)
	if a.GuaIndex == b.GuaIndex && a.Line == b.Line {
		t.Fatalf("expected seed to change across days, both gua=%d line=%d", a.GuaIndex, a.Line)
	}
}