package proto

import (
	"bufio"
	"bytes"
	"net"
	"testing"
)

func TestEncodeDecode(t *testing.T) {
	client, server := net.Pipe()
	defer client.Close()
	defer server.Close()

	want := []byte("hello proto")
	go func() {
		data, err := Encode(want)
		if err != nil {
			t.Errorf("Encode: %v", err)
			server.Close()
			return
		}
		server.Write(data)
	}()

	got, err := Decode(bufio.NewReader(client))
	if err != nil {
		t.Fatalf("Decode: %v", err)
	}
	if !bytes.Equal(got, want) {
		t.Errorf("Decode = %q, want %q", got, want)
	}
}

func TestEncodeDecodeCrc32(t *testing.T) {
	client, server := net.Pipe()
	defer client.Close()
	defer server.Close()

	want := []byte("hello crc32")
	go func() {
		data, err := EncodeCrc32(want)
		if err != nil {
			t.Errorf("EncodeCrc32: %v", err)
			server.Close()
			return
		}
		server.Write(data)
	}()

	got, err := DecodeCrc32(bufio.NewReader(client))
	if err != nil {
		t.Fatalf("DecodeCrc32: %v", err)
	}
	if !bytes.Equal(got, want) {
		t.Errorf("DecodeCrc32 = %q, want %q", got, want)
	}
}

func TestDecodeCrc32Corrupted(t *testing.T) {
	client, server := net.Pipe()
	defer client.Close()
	defer server.Close()

	go func() {
		data, _ := EncodeCrc32([]byte("payload"))
		data[len(data)-1] ^= 0xFF // 篡改数据
		server.Write(data)
	}()

	_, err := DecodeCrc32(bufio.NewReader(client))
	if err == nil {
		t.Error("篡改数据后 DecodeCrc32 应返回错误")
	}
}

func TestEncodeHeaderFormat(t *testing.T) {
	// 头 8 字节：[0:4] 为 CRC/ID，[4:8] 为小端长度
	data, err := EncodeCrc32([]byte("abcd"))
	if err != nil {
		t.Fatalf("EncodeCrc32: %v", err)
	}
	length := int(data[4]) | int(data[5])<<8 | int(data[6])<<16 | int(data[7])<<24
	if length != 4 {
		t.Errorf("长度字段 = %d, want 4", length)
	}
	if len(data) != int(PakHeadLen)+4 {
		t.Errorf("报文总长 = %d, want %d", len(data), PakHeadLen+4)
	}
}