package decoder

import (
	"bytes"
	"testing"

	"github.com/AFASystems/presence/internal/pkg/common/appcontext"
	"github.com/AFASystems/presence/internal/pkg/model"
	"github.com/segmentio/kafka-go"
)

func TestDecodeBeacon_EmptyData(t *testing.T) {
	// Setup
	appState := appcontext.NewAppState()
	mockWriter := &MockKafkaWriter{Messages: []kafka.Message{}}
	parserRegistry := &model.ParserRegistry{}

	adv := model.BeaconAdvertisement{
		ID:   "test-beacon",
		Data: "", // Empty data
	}

	// Execute
	err := decodeBeacon(adv, appState, mockWriter, parserRegistry)

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

	if len(mockWriter.Messages) != 0 {
		t.Errorf("Expected no messages for empty data, got %d", len(mockWriter.Messages))
	}
}

func TestDecodeBeacon_WhitespaceOnly(t *testing.T) {
	// Setup
	appState := appcontext.NewAppState()
	mockWriter := &MockKafkaWriter{Messages: []kafka.Message{}}
	parserRegistry := &model.ParserRegistry{}

	adv := model.BeaconAdvertisement{
		ID:   "test-beacon",
		Data: "   ", // Whitespace only
	}

	// Execute
	err := decodeBeacon(adv, appState, mockWriter, parserRegistry)

	// Assert
	if err != nil {
		t.Errorf("Expected no error for whitespace-only data, got %v", err)
	}

	if len(mockWriter.Messages) != 0 {
		t.Errorf("Expected no messages for whitespace-only data, got %d", len(mockWriter.Messages))
	}
}

func TestDecodeBeacon_InvalidHex(t *testing.T) {
	// Setup
	appState := appcontext.NewAppState()
	mockWriter := &MockKafkaWriter{Messages: []kafka.Message{}}
	parserRegistry := &model.ParserRegistry{}

	adv := model.BeaconAdvertisement{
		ID:   "test-beacon",
		Data: "INVALID_HEX_DATA!!!",
	}

	// Execute
	err := decodeBeacon(adv, appState, mockWriter, parserRegistry)

	// Assert
	if err == nil {
		t.Error("Expected error for invalid hex data, got nil")
	}

	if len(mockWriter.Messages) != 0 {
		t.Errorf("Expected no messages for invalid hex, got %d", len(mockWriter.Messages))
	}
}

func TestDecodeBeacon_ValidHexNoParser(t *testing.T) {
	// Setup
	appState := appcontext.NewAppState()
	mockWriter := &MockKafkaWriter{Messages: []kafka.Message{}}
	parserRegistry := &model.ParserRegistry{} // No parsers registered

	// Valid hex but no matching parser
	adv := model.BeaconAdvertisement{
		ID:   "test-beacon",
		Data: "0201060302A0", // Valid AD structure
	}

	// Execute
	err := decodeBeacon(adv, appState, mockWriter, parserRegistry)

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

	if len(mockWriter.Messages) != 0 {
		t.Errorf("Expected no messages when no parser matches, got %d", len(mockWriter.Messages))
	}
}

func TestDecodeBeacon_Deduplication(t *testing.T) {
	// Setup
	appState := appcontext.NewAppState()
	mockWriter := &MockKafkaWriter{Messages: []kafka.Message{}}
	parserRegistry := &model.ParserRegistry{}

	// Register a test parser
	config := model.Config{
		Name:   "test-parser",
		Prefix: "02",
		Length: 2,
	}
	parserRegistry.Register("test-parser", config)

	// Create an event that will be parsed
	adv := model.BeaconAdvertisement{
		ID:   "test-beacon",
		Data: "020106", // Simple AD structure
	}

	// First processing - should publish
	err := decodeBeacon(adv, appState, mockWriter, parserRegistry)
	if err != nil {
		t.Fatalf("First processing failed: %v", err)
	}

	firstMessageCount := len(mockWriter.Messages)

	// Second processing with identical data - should deduplicate
	err = decodeBeacon(adv, appState, mockWriter, parserRegistry)
	if err != nil {
		t.Fatalf("Second processing failed: %v", err)
	}

	// Assert - message count should not have changed
	if len(mockWriter.Messages) != firstMessageCount {
		t.Errorf("Expected deduplication, got %d messages (should be %d)", len(mockWriter.Messages), firstMessageCount)
	}
}

func TestDecodeBeacon_DifferentDataPublishes(t *testing.T) {
	// Setup
	appState := appcontext.NewAppState()
	mockWriter := &MockKafkaWriter{Messages: []kafka.Message{}}
	parserRegistry := &model.ParserRegistry{}

	// Register a test parser
	config := model.Config{
		Name:   "test-parser",
		Prefix: "02",
		Length: 2,
	}
	parserRegistry.Register("test-parser", config)

	// First processing
	adv1 := model.BeaconAdvertisement{
		ID:   "test-beacon",
		Data: "020106",
	}

	err := decodeBeacon(adv1, appState, mockWriter, parserRegistry)
	if err != nil {
		t.Fatalf("First processing failed: %v", err)
	}

	firstMessageCount := len(mockWriter.Messages)

	// Second processing with different data - should publish again
	adv2 := model.BeaconAdvertisement{
		ID:   "test-beacon",
		Data: "020107", // Different data
	}

	err = decodeBeacon(adv2, appState, mockWriter, parserRegistry)
	if err != nil {
		t.Fatalf("Second processing failed: %v", err)
	}

	// Assert - message count should have increased
	if len(mockWriter.Messages) != firstMessageCount+1 {
		t.Errorf("Expected new message for different data, got %d messages (expected %d)", len(mockWriter.Messages), firstMessageCount+1)
	}
}

func TestDecodeBeacon_WithFlagBytes(t *testing.T) {
	// Setup
	appState := appcontext.NewAppState()
	mockWriter := &MockKafkaWriter{Messages: []kafka.Message{}}
	parserRegistry := &model.ParserRegistry{}

	// Register a test parser
	config := model.Config{
		Name:   "test-parser",
		Prefix: "02",
		Length: 2,
	}
	parserRegistry.Register("test-parser", config)

	// Data with flag bytes (0x01 at position 1)
	adv := model.BeaconAdvertisement{
		ID:   "test-beacon",
		Data: "0201060302A0", // Will have flags removed
	}

	// Execute
	err := decodeBeacon(adv, appState, mockWriter, parserRegistry)

	// Assert - should process successfully after flag removal
	if err != nil {
		t.Errorf("Expected no error with flag bytes, got %v", err)
	}
}

func TestDecodeBeacon_MultipleBeacons(t *testing.T) {
	// Setup
	appState := appcontext.NewAppState()
	mockWriter := &MockKafkaWriter{Messages: []kafka.Message{}}
	parserRegistry := &model.ParserRegistry{}

	// Register a test parser
	config := model.Config{
		Name:   "test-parser",
		Prefix: "02",
		Length: 2,
	}
	parserRegistry.Register("test-parser", config)

	// Process multiple different beacons
	beacons := []model.BeaconAdvertisement{
		{ID: "beacon-1", Data: "020106"},
		{ID: "beacon-2", Data: "020107"},
		{ID: "beacon-3", Data: "020108"},
	}

	for _, adv := range beacons {
		err := decodeBeacon(adv, appState, mockWriter, parserRegistry)
		if err != nil {
			t.Errorf("Failed to process beacon %s: %v", adv.ID, err)
		}
	}

	// Each unique beacon should produce a message
	if len(mockWriter.Messages) != len(beacons) {
		t.Errorf("Expected %d messages, got %d", len(beacons), len(mockWriter.Messages))
	}
}

func TestProcessIncoming_ErrorHandling(t *testing.T) {
	// Setup
	appState := appcontext.NewAppState()
	mockWriter := &MockKafkaWriter{Messages: []kafka.Message{}}
	parserRegistry := &model.ParserRegistry{}

	// Invalid data that will cause an error
	adv := model.BeaconAdvertisement{
		ID:   "test-beacon",
		Data: "INVALID_HEX",
	}

	// Execute - should not panic, just handle error
	processIncoming(adv, appState, mockWriter, parserRegistry)

	// Assert - no messages should be written
	if len(mockWriter.Messages) != 0 {
		t.Errorf("Expected no messages on error, got %d", len(mockWriter.Messages))
	}
}

func TestDecodeBeacon_EventHashing(t *testing.T) {
	// Setup
	appState := appcontext.NewAppState()
	mockWriter := &MockKafkaWriter{Messages: []kafka.Message{}}
	parserRegistry := &model.ParserRegistry{}

	// Register a test parser that creates consistent events
	config := model.Config{
		Name:   "test-parser",
		Prefix: "02",
		Length: 2,
	}
	parserRegistry.Register("test-parser", config)

	adv := model.BeaconAdvertisement{
		ID:   "test-beacon",
		Data: "020106",
	}

	// First processing
	err := decodeBeacon(adv, appState, mockWriter, parserRegistry)
	if err != nil {
		t.Fatalf("First processing failed: %v", err)
	}

	// Get the event from appState
	event, exists := appState.GetBeaconEvent("test-beacon")
	if !exists {
		t.Fatal("Event should exist in appState")
	}

	// Verify hash is created
	hash := event.Hash()
	if hash == nil || len(hash) == 0 {
		t.Error("Expected non-empty hash")
	}

	// Second processing should be deduplicated based on hash
	err = decodeBeacon(adv, appState, mockWriter, parserRegistry)
	if err != nil {
		t.Fatalf("Second processing failed: %v", err)
	}

	// Should still have only one message
	if len(mockWriter.Messages) != 1 {
		t.Errorf("Expected 1 message after deduplication, got %d", len(mockWriter.Messages))
	}
}

func TestDecodeBeacon_VariousHexFormats(t *testing.T) {
	// Setup
	appState := appcontext.NewAppState()
	mockWriter := &MockKafkaWriter{Messages: []kafka.Message{}}
	parserRegistry := &model.ParserRegistry{}

	testCases := []struct {
		name        string
		hexData     string
		shouldError bool
	}{
		{"lowercase hex", "020106aa", false},
		{"uppercase hex", "020106AA", false},
		{"mixed case", "020106AaFf", false},
		{"with spaces", " 020106 ", false},
		{"odd length", "02016", true},
		{"invalid chars", "020106ZZ", true},
	}

	for _, tc := range testCases {
		t.Run(tc.name, func(t *testing.T) {
			adv := model.BeaconAdvertisement{
				ID:   "test-beacon",
				Data: tc.hexData,
			}

			err := decodeBeacon(adv, appState, mockWriter, parserRegistry)

			if tc.shouldError && err == nil {
				t.Errorf("Expected error for %s, got nil", tc.name)
			}

			if !tc.shouldError && err != nil && !bytes.Contains(err.Error(), []byte("no parser")) {
				// Error is OK if it's "no parser", but not for hex decoding
				t.Logf("Got expected error for %s: %v", tc.name, err)
			}
		})
	}
}