package pdu

import (
	"bytes"
	"encoding/binary"
	"math"
	"sync"
	"testing"
)

// region encode
func TestEncodeReturnsByteSliceOfLength16(t *testing.T) {
	p := &PDU_HEADER{
		command_length:  1,
		command_id:      1,
		command_status:  1,
		sequence_number: 1,
	}
	buf := bytes.NewBuffer(make([]byte, 16))
	buf.Reset()
	err := p.Encode(buf)

	if err != nil {
		t.Errorf("Expected no error, got %v", err)
	}
	if buf.Cap() != 16 {
		t.Errorf("Expected byte slice of length 16, got %d", buf.Cap())
	}
}

func TestEncodeHandlesZeroValues(t *testing.T) {
	p := &PDU_HEADER{
		command_length:  0,
		command_id:      0,
		command_status:  0,
		sequence_number: 0,
	}
	buf := bytes.NewBuffer(make([]byte, 16))
	buf.Reset()
	err := p.Encode(buf)

	if err != nil {
		t.Errorf("Expected no error, got %v", err)
	}
	expected := make([]byte, 16)
	for i, v := range buf.Bytes() {
		if v != expected[i] {
			t.Errorf("Expected byte slice with zero values, got %v", buf.Bytes())
			break
		}
	}
}

func TestEncodeEncodesProperly(t *testing.T) {
	p := &PDU_HEADER{
		command_length:  1,
		command_id:      2,
		command_status:  3,
		sequence_number: 4,
	}
	buf := bytes.NewBuffer(make([]byte, 16))
	buf.Reset()
	err := p.Encode(buf)

	if err != nil {
		t.Errorf("Expected no error, got %v", err)
	}

	expected := []byte{0, 0, 0, 1, 0, 0, 0, 2, 0, 0, 0, 3, 0, 0, 0, 4}
	for i, v := range buf.Bytes() {
		if v != expected[i] {
			t.Errorf("Expected byte slice with values %v, got %v", expected, buf.Bytes())
			break
		}
	}
}

func TestEncodeEncodesProperlyComplex(t *testing.T) {
	p := &PDU_HEADER{
		command_length:  13426724,
		command_id:      254352,
		command_status:  35634264,
		sequence_number: 476543523,
	}
	buf := bytes.NewBuffer(make([]byte, 16))
	buf.Reset()
	err := p.Encode(buf)

	if err != nil {
		t.Errorf("Expected no error, got %v", err)
	}

	expected := []byte{0, 204, 224, 36, 0, 3, 225, 144, 2, 31, 188, 88, 28, 103, 122, 35}
	for i, v := range buf.Bytes() {
		if v != expected[i] {
			t.Errorf("Expected byte slice with values %v, got %v", expected, buf.Bytes())
			break
		}
	}
}

func TestEncodeIntoCorrectlyEncodesFields(t *testing.T) {
	p := &PDU_HEADER{
		command_length:  16,
		command_id:      1,
		command_status:  0,
		sequence_number: 12345,
	}
	buf := bytes.NewBuffer(make([]byte, 16))
	buf.Reset()
	err := p.Encode(buf)

	if err != nil {
		t.Errorf("Expected no error, got %v", err)
	}

	innerbuf := buf.Bytes()
	if binary.BigEndian.Uint32(innerbuf[0:4]) != p.command_length {
		t.Errorf("Expected command_length %d, got %d", p.command_length, binary.BigEndian.Uint32(innerbuf[0:4]))
	}
	if binary.BigEndian.Uint32(innerbuf[4:8]) != p.command_id {
		t.Errorf("Expected command_id %d, got %d", p.command_id, binary.BigEndian.Uint32(innerbuf[4:8]))
	}
	if binary.BigEndian.Uint32(innerbuf[8:12]) != p.command_status {
		t.Errorf("Expected command_status %d, got %d", p.command_status, binary.BigEndian.Uint32(innerbuf[8:12]))
	}
	if binary.BigEndian.Uint32(innerbuf[12:16]) != p.sequence_number {
		t.Errorf("Expected sequence_number %d, got %d", p.sequence_number, binary.BigEndian.Uint32(innerbuf[12:16]))
	}
}

func TestEncodeIntoHandlesLargerBuffer(t *testing.T) {
	p := &PDU_HEADER{
		command_length:  16,
		command_id:      1,
		command_status:  0,
		sequence_number: 12345,
	}
	buf := bytes.NewBuffer(make([]byte, 20)) // larger buffer size
	buf.Reset()
	err := p.Encode(buf)

	if err != nil {
		t.Errorf("Expected no error, got %v", err)
	}

	innerbuf := buf.Bytes()
	if binary.BigEndian.Uint32(innerbuf[0:4]) != p.command_length {
		t.Errorf("Expected command_length %d, got %d", p.command_length, binary.BigEndian.Uint32(innerbuf[0:4]))
	}
	if binary.BigEndian.Uint32(innerbuf[4:8]) != p.command_id {
		t.Errorf("Expected command_id %d, got %d", p.command_id, binary.BigEndian.Uint32(innerbuf[4:8]))
	}
	if binary.BigEndian.Uint32(innerbuf[8:12]) != p.command_status {
		t.Errorf("Expected command_status %d, got %d", p.command_status, binary.BigEndian.Uint32(innerbuf[8:12]))
	}
	if binary.BigEndian.Uint32(innerbuf[12:16]) != p.sequence_number {
		t.Errorf("Expected sequence_number %d, got %d", p.sequence_number, binary.BigEndian.Uint32(innerbuf[12:16]))
	}
}

func TestEncodeIntoUsesBigEndianEncoding(t *testing.T) {
	p := &PDU_HEADER{
		command_length:  16,
		command_id:      1,
		command_status:  0,
		sequence_number: 12345,
	}
	buf := bytes.NewBuffer(make([]byte, 16))
	buf.Reset()
	err := p.Encode(buf)

	if err != nil {
		t.Errorf("Expected no error, got %v", err)
	}

	innerbuf := buf.Bytes()
	if binary.BigEndian.Uint32(innerbuf[0:4]) != p.command_length {
		t.Errorf("Expected command_length %d, got %d", p.command_length, binary.BigEndian.Uint32(innerbuf[0:4]))
	}
	if binary.BigEndian.Uint32(innerbuf[4:8]) != p.command_id {
		t.Errorf("Expected command_id %d, got %d", p.command_id, binary.BigEndian.Uint32(innerbuf[4:8]))
	}
	if binary.BigEndian.Uint32(innerbuf[8:12]) != p.command_status {
		t.Errorf("Expected command_status %d, got %d", p.command_status, binary.BigEndian.Uint32(innerbuf[8:12]))
	}
	if binary.BigEndian.Uint32(innerbuf[12:16]) != p.sequence_number {
		t.Errorf("Expected sequence_number %d, got %d", p.sequence_number, binary.BigEndian.Uint32(innerbuf[12:16]))
	}
}

func TestEncodeIntoConcurrencySafety(t *testing.T) {
	p := &PDU_HEADER{
		command_length:  16,
		command_id:      1,
		command_status:  0,
		sequence_number: 12345,
	}
	buf := bytes.NewBuffer(make([]byte, 16))
	buf.Reset()
	var wg sync.WaitGroup
	for i := 0; i < 1000; i++ {
		wg.Add(1)
		go func() {
			defer wg.Done()
			p.Encode(buf)
		}()
	}
	wg.Wait()

	innerbuf := buf.Bytes()
	if binary.BigEndian.Uint32(innerbuf[0:4]) != p.command_length {
		t.Errorf("Expected command_length %d, got %d", p.command_length, binary.BigEndian.Uint32(innerbuf[0:4]))
	}
	if binary.BigEndian.Uint32(innerbuf[4:8]) != p.command_id {
		t.Errorf("Expected command_id %d, got %d", p.command_id, binary.BigEndian.Uint32(innerbuf[4:8]))
	}
	if binary.BigEndian.Uint32(innerbuf[8:12]) != p.command_status {
		t.Errorf("Expected command_status %d, got %d", p.command_status, binary.BigEndian.Uint32(innerbuf[8:12]))
	}
	if binary.BigEndian.Uint32(innerbuf[12:16]) != p.sequence_number {
		t.Errorf("Expected sequence_number %d, got %d", p.sequence_number, binary.BigEndian.Uint32(innerbuf[12:16]))
	}
}

func TestEncodeIntoWithMaximumValues(t *testing.T) {
	p := &PDU_HEADER{
		command_length:  math.MaxUint32,
		command_id:      math.MaxUint32,
		command_status:  math.MaxUint32,
		sequence_number: math.MaxUint32,
	}
	buf := bytes.NewBuffer(make([]byte, 16))
	buf.Reset()
	err := p.Encode(buf)

	if err != nil {
		t.Errorf("Expected no error, got %v", err)
	}

	innerbuf := buf.Bytes()
	if binary.BigEndian.Uint32(innerbuf[0:4]) != p.command_length {
		t.Errorf("Expected command_length %d, got %d", p.command_length, binary.BigEndian.Uint32(innerbuf[0:4]))
	}
	if binary.BigEndian.Uint32(innerbuf[4:8]) != p.command_id {
		t.Errorf("Expected command_id %d, got %d", p.command_id, binary.BigEndian.Uint32(innerbuf[4:8]))
	}
	if binary.BigEndian.Uint32(innerbuf[8:12]) != p.command_status {
		t.Errorf("Expected command_status %d, got %d", p.command_status, binary.BigEndian.Uint32(innerbuf[8:12]))
	}
	if binary.BigEndian.Uint32(innerbuf[12:16]) != p.sequence_number {
		t.Errorf("Expected sequence_number %d, got %d", p.sequence_number, binary.BigEndian.Uint32(innerbuf[12:16]))
	}
}

func TestEncodeIntoWithBoundaryValues(t *testing.T) {
	p := &PDU_HEADER{
		command_length:  0,
		command_id:      0,
		command_status:  0,
		sequence_number: 0,
	}
	buf := bytes.NewBuffer(make([]byte, 16))
	buf.Reset()
	err := p.Encode(buf)

	if err != nil {
		t.Errorf("Expected no error, got %v", err)
	}

	innerbuf := buf.Bytes()
	if binary.BigEndian.Uint32(innerbuf[0:4]) != p.command_length {
		t.Errorf("Expected command_length %d, got %d", p.command_length, binary.BigEndian.Uint32(innerbuf[0:4]))
	}
	if binary.BigEndian.Uint32(innerbuf[4:8]) != p.command_id {
		t.Errorf("Expected command_id %d, got %d", p.command_id, binary.BigEndian.Uint32(innerbuf[4:8]))
	}
	if binary.BigEndian.Uint32(innerbuf[8:12]) != p.command_status {
		t.Errorf("Expected command_status %d, got %d", p.command_status, binary.BigEndian.Uint32(innerbuf[8:12]))
	}
	if binary.BigEndian.Uint32(innerbuf[12:16]) != p.sequence_number {
		t.Errorf("Expected sequence_number %d, got %d", p.sequence_number, binary.BigEndian.Uint32(innerbuf[12:16]))
	}
}

// func TestRealScenario(t *testing.T) {
// 	expected := []byte{0, 0, 0, 54, 0, 0, 0, 4, 0, 0, 0, 0, 0, 0, 0, 1, 67, 77, 84, 0, 1, 1, 49, 50, 51, 52, 53, 0, 1, 1, 54, 55, 56, 57, 48, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 12, 72, 101, 108, 108, 111, 44, 32, 83, 77, 80, 80, 33}
// 	p := &SUBMIT_SM{
// 		header: PDU_HEADER{
// 			command_length:  0,
// 			command_id:      4,
// 			command_status:  0,
// 			sequence_number: 1,
// 		},
// 		service_type:           "CMT",
// 		source_addr_ton:        1,
// 		source_addr_npi:        1,
// 		source_addr:            "12345",
// 		dest_addr_ton:          1,
// 		dest_addr_npi:          1,
// 		destination_addr:       "67890",
// 		esm_class:              0,
// 		protocol_id:            0,
// 		priority_flag:          0,
// 		schedule_delivery_time: "",
// 		validity_period:        "",
// 		registered_delivery:    1,
// 		data_coding:            0,
// 		sm_default_msg_id:      0,
// 		short_message:          "Hello, SMPP!",
// 	}
// 	p.header.command_length = uint32(p.Size())
// 	p.sm_length = byte(len(p.short_message))
// 	buf := make([]byte, p.Size())
// 	err := p.EncodeInto(&buf)
// 	if err != nil {
// 		t.Errorf("Expected no error, got %v", err)
// 	}
// 	if len(buf) != len(expected) {
// 		t.Errorf("Expected byte slice of length %d, got %d", len(expected), len(buf))
// 	}
// 	for i, v := range buf {
// 		if v != expected[i] {
// 			t.Errorf("Expected byte slice with values %v, got %v", expected, buf)
// 			break
// 		}
// 	}
// }

// // region decode
// func TestDecodeHandlesShortByteSlice(t *testing.T) {
// 	var p PDU_HEADER
// 	data := []byte{0, 0, 0, 10}
// 	defer func() {
// 		if r := recover(); r != nil {
// 			t.Errorf("Decode panicked with short byte slice")
// 		}
// 	}()
// 	err := p.Decode(data)
// 	if err != nil {
// 		t.Errorf("Expected no error, got %v", err)
// 	}
// }

// func TestDecodeParsesValidByteSlice(t *testing.T) {
// 	var p PDU_HEADER
// 	data := []byte{0, 0, 0, 16, 0, 0, 0, 1, 0, 0, 0, 2, 0, 0, 0, 3}
// 	err := p.Decode(data)

// 	if err != nil {
// 		t.Errorf("Expected no error, got %v", err)
// 	}

// 	if p.command_length != 16 {
// 		t.Errorf("Expected command_length to be 16, got %d", p.command_length)
// 	}
// 	if p.command_id != 1 {
// 		t.Errorf("Expected command_id to be 1, got %d", p.command_id)
// 	}
// 	if p.command_status != 2 {
// 		t.Errorf("Expected command_status to be 2, got %d", p.command_status)
// 	}
// 	if p.sequence_number != 3 {
// 		t.Errorf("Expected sequence_number to be 3, got %d", p.sequence_number)
// 	}
// }

// func TestDecodeHandlesLongerByteSliceWithoutCrashing(t *testing.T) {
// 	var p PDU_HEADER
// 	data := make([]byte, 20)
// 	defer func() {
// 		if r := recover(); r != nil {
// 			t.Errorf("Decode panicked with long byte slice")
// 		}
// 	}()
// 	err := p.Decode(data)
// 	if err != nil {
// 		t.Errorf("Expected no error, got %v", err)
// 	}
// }

// func TestDecodeHandlesNilDataInput(t *testing.T) {
// 	var p PDU_HEADER
// 	err := p.Decode(nil)

// 	if err != nil {
// 		t.Errorf("Expected no error, got %v", err)
// 	}

// 	if p.command_length != 0 {
// 		t.Errorf("Expected command_length to be 0, got %d", p.command_length)
// 	}
// 	if p.command_id != 0 {
// 		t.Errorf("Expected command_id to be 0, got %d", p.command_id)
// 	}
// 	if p.command_status != 0 {
// 		t.Errorf("Expected command_status to be 0, got %d", p.command_status)
// 	}
// 	if p.sequence_number != 0 {
// 		t.Errorf("Expected sequence_number to be 0, got %d", p.sequence_number)
// 	}
// }

// func TestDecodeHandlesEmptyByteSliceGracefully(t *testing.T) {
// 	var p PDU_HEADER
// 	data := []byte{}
// 	err := p.Decode(data)

// 	if err != nil {
// 		t.Errorf("Expected no error, got %v", err)
// 	}

// 	if p.command_length != 0 {
// 		t.Errorf("Expected command_length to be 0, got %d", p.command_length)
// 	}
// 	if p.command_id != 0 {
// 		t.Errorf("Expected command_id to be 0, got %d", p.command_id)
// 	}
// 	if p.command_status != 0 {
// 		t.Errorf("Expected command_status to be 0, got %d", p.command_status)
// 	}
// 	if p.sequence_number != 0 {
// 		t.Errorf("Expected sequence_number to be 0, got %d", p.sequence_number)
// 	}
// }

// func TestDecodeDoesNotModifyInputByteSlice(t *testing.T) {
// 	var p PDU_HEADER
// 	data := []byte{0, 0, 0, 16, 0, 0, 0, 1, 0, 0, 0, 2, 0, 0, 0, 3}
// 	originalData := make([]byte, len(data))
// 	copy(originalData, data)

// 	err := p.Decode(data)

// 	if err != nil {
// 		t.Errorf("Expected no error, got %v", err)
// 	}

// 	for i := range data {
// 		if data[i] != originalData[i] {
// 			t.Errorf("Expected data at index %d to be %d, got %d", i, originalData[i], data[i])
// 		}
// 	}
// }

// func TestDecodeHandlesByteSlicesWithMaxUint32Values(t *testing.T) {
// 	var p PDU_HEADER
// 	data := []byte{255, 255, 255, 255, 255, 255, 255, 255}
// 	err := p.Decode(data)

// 	if err != nil {
// 		t.Errorf("Expected no error, got %v", err)
// 	}

// 	if p.command_length != math.MaxUint32 {
// 		t.Errorf("Expected command_length to be %d, got %d", math.MaxUint32, p.command_length)
// 	}
// 	if p.command_id != math.MaxUint32 {
// 		t.Errorf("Expected command_id to be %d, got %d", math.MaxUint32, p.command_id)
// 	}
// }

// func TestDecodeHandlesByteSlicesWithMinimumUint32Values(t *testing.T) {
// 	var p PDU_HEADER
// 	data := []byte{0, 0, 0, 0, 0, 0, 0, 0}
// 	err := p.Decode(data)

// 	if err != nil {
// 		t.Errorf("Expected no error, got %v", err)
// 	}

// 	if p.command_length != 0 {
// 		t.Errorf("Expected command_length to be 0, got %d", p.command_length)
// 	}
// 	if p.command_id != 0 {
// 		t.Errorf("Expected command_id to be 0, got %d", p.command_id)
// 	}
// }

// // region size
// func TestSizeReturns16(t *testing.T) {
// 	var p PDU_HEADER
// 	if p.Size() != 16 {
// 		t.Errorf("Expected size to be 16, got %d", p.Size())
// 	}
// }

// // region benchmarks

// With buffer pool
func BenchmarkEncodeWithBufferPool(b *testing.B) {
	p := &PDU_HEADER{
		command_length:  16,
		command_id:      1,
		command_status:  0,
		sequence_number: 12345,
	}
	b.ResetTimer()
	for i := 0; i < b.N; i++ {
		buf := ByteBufferPool.Get(p.Size())
		p.Encode(buf)
		ByteBufferPool.Put(buf)
	}
}

// Without buffer pool
func BenchmarkEncodeWithoutBufferPool(b *testing.B) {
	p := &PDU_HEADER{
		command_length:  16,
		command_id:      1,
		command_status:  0,
		sequence_number: 12345,
	}
	b.ResetTimer()
	for i := 0; i < b.N; i++ {
		buf := bytes.Buffer{}
		p.Encode(&buf)
	}
}

func BenchmarkDecodeBufferPool(b *testing.B) {
	p := &PDU_HEADER{}
	b.ResetTimer()
	for i := 0; i < b.N; i++ {
		data := []byte{0, 0, 0, 16, 0, 0, 0, 1, 0, 0, 0, 2, 0, 0, 0, 3}
		buf := ByteBufferPool.Get(len(data))
		buf.Write(data)
		p.Decode(buf)
		ByteBufferPool.Put(buf)
	}
}