package unpacker

import (
	"testing"

	"github.com/stretchr/testify/assert"
	"github.com/stretchr/testify/require"
)

func TestDelimiterUnpacker(t *testing.T) {
	u := NewDelimiterUnpacker([]byte("\n"))

	// 测试单个消息
	data := []byte("hello\n")
	messages, remaining, consumed, err := u.Unpack(data)
	require.NoError(t, err, "Expected no error")
	assert.Equal(t, 1, len(messages), "Expected 1 message")
	assert.Equal(t, "hello\n", string(messages[0]), "Expected 'hello\\n'")
	assert.Equal(t, 0, len(remaining), "Expected no remaining data")
	assert.Equal(t, len(data), consumed, "Expected consumed equals input data length")
}

func TestDelimiterUnpackerMultipleMessages(t *testing.T) {
	u := NewDelimiterUnpacker([]byte("\n"))

	// 测试多个消息
	data := []byte("hello\nworld\ntest\n")
	messages, remaining, consumed, err := u.Unpack(data)
	require.NoError(t, err, "Expected no error")
	assert.Equal(t, 3, len(messages), "Expected 3 messages")
	assert.Equal(t, "hello\n", string(messages[0]), "Expected 'hello\\n'")
	assert.Equal(t, "world\n", string(messages[1]), "Expected 'world\\n'")
	assert.Equal(t, "test\n", string(messages[2]), "Expected 'test\\n'")
	assert.Equal(t, 0, len(remaining), "Expected no remaining data")
	assert.Equal(t, len(data), consumed, "Expected consumed equals input data length")
}

func TestDelimiterUnpackerIncompleteMessage(t *testing.T) {
	u := NewDelimiterUnpacker([]byte("\n"))

	// 测试不完整的消息
	data := []byte("hello")
	messages, remaining, consumed, err := u.Unpack(data)
	require.NoError(t, err, "Expected no error")
	assert.Equal(t, 0, len(messages), "Expected 0 messages")
	assert.Equal(t, "hello", string(remaining), "Expected 'hello' as remaining")
	assert.Equal(t, len(data), consumed, "Expected all data consumed when no complete message")

	// 添加分隔符，应该完成消息
	data2 := []byte("\n")
	messages, remaining, consumed, err = u.Unpack(data2)
	require.NoError(t, err, "Expected no error")
	assert.Equal(t, 1, len(messages), "Expected 1 message")
	assert.Equal(t, "hello\n", string(messages[0]), "Expected 'hello\\n'")
	assert.Equal(t, len(data2), consumed, "Expected consumed equals input data length")
}

func TestDelimiterUnpackerPack(t *testing.T) {
	u := NewDelimiterUnpacker([]byte("\n"))

	// 测试打包
	data := []byte("hello")
	packed, err := u.Pack(data)
	require.NoError(t, err, "Expected no error")
	assert.Equal(t, "hello\n", string(packed), "Expected 'hello\\n'")

	// 测试已包含分隔符的数据
	data2 := []byte("world\n")
	packed2, err := u.Pack(data2)
	require.NoError(t, err, "Expected no error")
	assert.Equal(t, "world\n", string(packed2), "Expected 'world\\n'")
}

func TestDelimiterUnpackerEmptyDelimiter(t *testing.T) {
	// 测试空分隔符（应该使用默认换行符）
	u := NewDelimiterUnpacker(nil)
	data := []byte("hello\n")
	messages, _, consumed, err := u.Unpack(data)
	require.NoError(t, err)
	assert.Equal(t, 1, len(messages))
	assert.Equal(t, len(data), consumed, "Expected consumed equals input data length")
}

func TestDelimiterUnpackerBufferSizeLimit(t *testing.T) {
	// 测试缓冲区大小限制
	u := NewDelimiterUnpackerWithMaxBuffer([]byte("\n"), 10)

	// 创建超过缓冲区大小的数据
	data := make([]byte, 20)
	for i := range data {
		data[i] = 'a'
	}

	_, _, _, err := u.Unpack(data)
	assert.Error(t, err, "Expected error for buffer size exceeded")
}