package nnet

import (
	"testing"

	protocolpkg "github.com/noahlann/nnet/pkg/protocol"
	"github.com/stretchr/testify/assert"
	"github.com/stretchr/testify/require"
)

func TestNNetProtocol_DecodeHeader_IncompleteData(t *testing.T) {
	p := NewNNetProtocol("1.0").(*NNetProtocol)

	// 测试数据不完整的情况（只有Magic）
	data := []byte("NNE")
	header, minBytes, err := p.DecodeHeader(data)
	assert.Error(t, err, "Expected error for incomplete data")
	assert.Nil(t, header)
	assert.Equal(t, 9, minBytes, "Expected min bytes to be 9")

	// 测试数据不完整的情况（只有Magic）
	data = []byte("NNET")
	header, minBytes, err = p.DecodeHeader(data)
	assert.NoError(t, err, "Should not error for partial data")
	assert.Nil(t, header, "Should return nil header when data is incomplete")
	assert.Equal(t, 9, minBytes, "Expected min bytes to be 9")

	// 测试数据不完整的情况（Magic + Version）
	data = []byte("NNET\x01")
	header, minBytes, err = p.DecodeHeader(data)
	assert.NoError(t, err, "Should not error for partial data")
	assert.Nil(t, header, "Should return nil header when data is incomplete")
	assert.Equal(t, 9, minBytes, "Expected min bytes to be 9")
}

func TestNNetProtocol_DecodeHeader_CompleteHeader(t *testing.T) {
	p := NewNNetProtocol("1.0").(*NNetProtocol)

	// 创建完整的帧头数据：Magic(4) + Version(1) + Length(4) = 9字节
	data := make([]byte, 9)
	copy(data[0:4], []byte("NNET"))
	data[4] = 1 // Version
	// Length = 5 (数据部分长度)
	data[5] = 0
	data[6] = 0
	data[7] = 0
	data[8] = 5

	header, totalLength, err := p.DecodeHeader(data)
	require.NoError(t, err, "Expected no error")
	require.NotNil(t, header, "Expected header")

	assert.Equal(t, "NNET", header.Get("magic"))
	assert.Equal(t, byte(1), header.Get("version"))
	assert.Equal(t, uint32(5), header.Get("length"))

	// 完整消息长度 = 9(帧头) + 5(数据) + 2(校验和) = 16
	assert.Equal(t, 16, totalLength, "Expected total length to be 16")
}

func TestNNetProtocol_DecodeBody_WithHeader(t *testing.T) {
	p := NewNNetProtocol("1.0").(*NNetProtocol)

	// 创建完整的消息数据
	data := []byte("hello")
	packet, err := p.Encode(data, nil)
	require.NoError(t, err)

	// 先解析帧头
	header, _, err := p.DecodeHeader(packet)
	require.NoError(t, err)
	require.NotNil(t, header)

	// 使用DecodeBody解析数据体（重用已解析的帧头）
	bodyBytes, err := p.DecodeBody(packet, header)
	require.NoError(t, err)
	assert.Equal(t, data, bodyBytes, "Expected body to match original data")
}

func TestNNetProtocol_DecodeBody_WithoutHeader(t *testing.T) {
	p := NewNNetProtocol("1.0").(*NNetProtocol)

	// 创建完整的消息数据
	data := []byte("hello")
	packet, err := p.Encode(data, nil)
	require.NoError(t, err)

	// 使用DecodeBody解析数据体（header为nil，需要从data中解析）
	bodyBytes, err := p.DecodeBody(packet, nil)
	require.NoError(t, err)
	assert.Equal(t, data, bodyBytes, "Expected body to match original data")
}

type incrementalDecoder interface {
	DecodeHeader([]byte) (protocolpkg.FrameHeader, int, error)
	DecodeBody([]byte, protocolpkg.FrameHeader) ([]byte, error)
}

func TestNNetProtocol_IncrementalDecoder_Interface(t *testing.T) {
	p := NewNNetProtocol("1.0")

	// 验证NNetProtocol实现了IncrementalDecoder接口
	var _ incrementalDecoder = p.(*NNetProtocol)

	// 测试增量解码的完整流程
	data := []byte("hello")
	packet, err := p.Encode(data, nil)
	require.NoError(t, err)

	// 转换为IncrementalDecoder类型
	incDecoder := p.(*NNetProtocol)

	// 1. 先解析帧头（增量解析）
	header, totalLength, err := incDecoder.DecodeHeader(packet)
	require.NoError(t, err)
	require.NotNil(t, header)
	assert.Equal(t, len(packet), totalLength, "Expected total length to match packet length")

	// 2. 使用已解析的帧头解析数据体（避免重复解析帧头）
	bodyBytes, err := incDecoder.DecodeBody(packet, header)
	require.NoError(t, err)
	assert.Equal(t, data, bodyBytes, "Expected body to match original data")
}