// Copyright 2022 The Ip2Region Authors. All rights reserved.
// Use of this source code is governed by a Apache2.0-style
// license that can be found in the LICENSE file.

package xdb

import (
	"testing"
)

func TestNewHeaderShortInput(t *testing.T) {
	// input shorter than 20 bytes should be rejected
	short := make([]byte, 16)
	_, err := NewHeader(short)
	if err == nil {
		t.Fatal("NewHeader with 16 bytes should fail")
	}

	// 20 bytes should be accepted
	valid := make([]byte, 20)
	_, err = NewHeader(valid)
	if err != nil {
		t.Fatalf("NewHeader with 20 bytes should succeed: %s", err)
	}
}

func TestNewHeaderParsing(t *testing.T) {
	// construct a known 20-byte header
	input := []byte{
		0x03, 0x00, // Version = 3 (LE)
		0x01, 0x00, // IndexPolicy = 1 (LE)
		0x00, 0x00, 0x00, 0x00, // CreatedAt = 0
		0x00, 0x00, 0x00, 0x00, // StartIndexPtr = 0
		0x00, 0x00, 0x00, 0x00, // EndIndexPtr = 0
		0x04, 0x00, // IPVersion = 4
		0x04, 0x00, // RuntimePtrBytes = 4
	}

	h, err := NewHeader(input)
	if err != nil {
		t.Fatalf("NewHeader failed: %s", err)
	}

	if h.Version != 3 {
		t.Errorf("Version = %d, want 3", h.Version)
	}
	if h.IndexPolicy != 1 {
		t.Errorf("IndexPolicy = %d, want 1", h.IndexPolicy)
	}
	if h.IPVersion != 4 {
		t.Errorf("IPVersion = %d, want 4", h.IPVersion)
	}
	if h.RuntimePtrBytes != 4 {
		t.Errorf("RuntimePtrBytes = %d, want 4", h.RuntimePtrBytes)
	}
}