package pdu

import (
	"testing"
)

// region encode
func TestEncodeReturnsByteSliceOfLength16(t *testing.T) {
	p := &PDU_HEADER{
		command_length:  1,
		command_id:      1,
		command_status:  1,
		sequence_number: 1,
	}
	result := p.Encode()
	if len(result) != 16 {
		t.Errorf("Expected byte slice of length 16, got %d", len(result))
	}
}

func TestEncodeHandlesZeroValues(t *testing.T) {
	p := &PDU_HEADER{
		command_length:  0,
		command_id:      0,
		command_status:  0,
		sequence_number: 0,
	}
	result := p.Encode()
	expected := make([]uint8, 16)
	for i, v := range result {
		if v != expected[i] {
			t.Errorf("Expected byte slice with zero values, got %v", result)
			break
		}
	}
}

func TestEncodeEncodesProperly(t *testing.T) {
	p := &PDU_HEADER{
		command_length:  1,
		command_id:      2,
		command_status:  3,
		sequence_number: 4,
	}
	result := p.Encode()
	expected := []uint8{0, 0, 0, 1, 0, 0, 0, 2, 0, 0, 0, 3, 0, 0, 0, 4}
	for i, v := range result {
		if v != expected[i] {
			t.Errorf("Expected byte slice with values %v, got %v", expected, result)
			break
		}
	}
}

func TestEncodeEncodesProperlyComplex(t *testing.T) {
	p := &PDU_HEADER{
		command_length:  13426724,
		command_id:      254352,
		command_status:  35634264,
		sequence_number: 476543523,
	}
	result := p.Encode()
	expected := []uint8{0, 204, 224, 36, 0, 3, 225, 144, 2, 31, 188, 88, 28, 103, 122, 35}
	for i, v := range result {
		if v != expected[i] {
			t.Errorf("Expected byte slice with values %v, got %v", expected, result)
			break
		}
	}
}

// region decode
func TestDecodeHandlesShortByteSlice(t *testing.T) {
	var p PDU_HEADER
	data := []uint8{0, 0, 0, 10}
	defer func() {
		if r := recover(); r != nil {
			t.Errorf("Decode panicked with short byte slice")
		}
	}()
	p.Decode(data)
}

func TestDecodeParsesValidByteSlice(t *testing.T) {
	var p PDU_HEADER
	data := []uint8{0, 0, 0, 16, 0, 0, 0, 1, 0, 0, 0, 2, 0, 0, 0, 3}
	p.Decode(data)
	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([]uint8, 20)
	defer func() {
		if r := recover(); r != nil {
			t.Errorf("Decode panicked with long byte slice")
		}
	}()
	p.Decode(data)
}

func TestDecodeHandlesNilDataInput(t *testing.T) {
	var p PDU_HEADER
	p.Decode(nil)
	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 := []uint8{}
	p.Decode(data)
	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 := []uint8{0, 0, 0, 16, 0, 0, 0, 1, 0, 0, 0, 2, 0, 0, 0, 3}
	originalData := make([]uint8, len(data))
	copy(originalData, data)

	p.Decode(data)

	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 := []uint8{255, 255, 255, 255, 255, 255, 255, 255}
	p.Decode(data)
	if p.command_length != 4294967295 {
		t.Errorf("Expected command_length to be 4294967295, got %d", p.command_length)
	}
	if p.command_id != 4294967295 {
		t.Errorf("Expected command_id to be 4294967295, got %d", p.command_id)
	}
}

func TestDecodeHandlesByteSlicesWithMinimumUint32Values(t *testing.T) {
	var p PDU_HEADER
	data := []uint8{0, 0, 0, 0, 0, 0, 0, 0}
	p.Decode(data)
	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)
	}
}