package service

import (
	"strings"
	"testing"
	"unicode/utf8"
)

// TestTruncateCallbackRaw 回调报文截断：短报文原样保留，长报文按上限截断且不产生非法 UTF-8
// （退款流水 callback_raw 为 utf8mb4 列，写入非法字节会直接报错）。
func TestTruncateCallbackRaw(t *testing.T) {
	short := `{"Event":"xpay_refund_notify","MchOrderId":"OD1"}`
	if got := truncateCallbackRaw(short); got != short {
		t.Fatalf("short raw should be kept as-is, got %q", got)
	}

	// 构造跨越截断边界的多字节报文：4KB 边界前后都是中文字符。
	long := strings.Repeat("退", 3000)
	got := truncateCallbackRaw(long)
	if len(got) > 4096 {
		t.Fatalf("truncated length = %d, want <= 4096", len(got))
	}
	if !utf8.ValidString(got) {
		t.Fatal("truncated raw must be valid UTF-8")
	}
	if got == "" || !strings.HasPrefix(long, got) {
		t.Fatalf("truncated raw should be a prefix of the original, got prefix=%q", got[:min(8, len(got))])
	}
}