package application

import (
	"bytes"
	"context"
	"encoding/json"
	"errors"
	"testing"

	"hash-of-wisdom/internal/application/mocks"
	"hash-of-wisdom/internal/pow/challenge"
	"hash-of-wisdom/internal/protocol"
	"hash-of-wisdom/internal/quotes"
	"hash-of-wisdom/internal/service"

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

func TestNewWisdomApplication(t *testing.T) {
	mockService := mocks.NewMockWisdomService(t)
	app := NewWisdomApplication(mockService)

	assert.NotNil(t, app)
	assert.Equal(t, mockService, app.wisdomService)
}

func TestWisdomApplication_HandleMessage_UnsupportedType(t *testing.T) {
	mockService := mocks.NewMockWisdomService(t)
	app := NewWisdomApplication(mockService)

	ctx := context.Background()
	msg := &protocol.Message{
		Type:           protocol.MessageType(0xFF), // Invalid type
		PayloadLength:  0,
		PayloadStream:  nil,
	}

	response, err := app.HandleMessage(ctx, msg)
	require.NoError(t, err)

	// Type assert to ErrorResponse
	errorResponse, ok := response.(*protocol.ErrorResponse)
	require.True(t, ok, "Expected ErrorResponse")
	assert.Equal(t, protocol.ErrMalformedMessage, errorResponse.Code)
	assert.Contains(t, errorResponse.Message, "unsupported message type: 0xff")
}

func TestWisdomApplication_HandleChallengeRequest_Success(t *testing.T) {
	mockService := mocks.NewMockWisdomService(t)
	app := NewWisdomApplication(mockService)

	// Mock successful challenge generation
	testChallenge := &challenge.Challenge{
		Resource:   "quotes",
		Timestamp:  12345,
		Difficulty: 4,
		Random:     []byte("test"),
		HMAC:       []byte("signature"),
	}

	mockService.On("GenerateChallenge", mock.Anything, "quotes").Return(testChallenge, nil)

	ctx := context.Background()
	msg := &protocol.Message{
		Type:           protocol.ChallengeRequestType,
		PayloadLength:  0,
		PayloadStream:  nil,
	}

	response, err := app.HandleMessage(ctx, msg)
	require.NoError(t, err)

	// Type assert to ChallengeResponse
	challengeResponse, ok := response.(*protocol.ChallengeResponse)
	require.True(t, ok, "Expected ChallengeResponse")
	assert.Equal(t, testChallenge, challengeResponse.Challenge)

	mockService.AssertExpectations(t)
}

func TestWisdomApplication_HandleChallengeRequest_ServiceError(t *testing.T) {
	mockService := mocks.NewMockWisdomService(t)
	app := NewWisdomApplication(mockService)

	// Mock service error
	mockService.On("GenerateChallenge", mock.Anything, "quotes").Return(nil, errors.New("service error"))

	ctx := context.Background()
	msg := &protocol.Message{
		Type:           protocol.ChallengeRequestType,
		PayloadLength:  0,
		PayloadStream:  nil,
	}

	response, err := app.HandleMessage(ctx, msg)
	require.NoError(t, err)

	// Type assert to ErrorResponse
	errorResponse, ok := response.(*protocol.ErrorResponse)
	require.True(t, ok, "Expected ErrorResponse")
	assert.Equal(t, protocol.ErrServerError, errorResponse.Code)
	assert.Equal(t, "Contact administrator", errorResponse.Message)

	mockService.AssertExpectations(t)
}

func TestWisdomApplication_HandleSolutionRequest_Success(t *testing.T) {
	mockService := mocks.NewMockWisdomService(t)
	app := NewWisdomApplication(mockService)

	// Create test solution request
	testChallenge := challenge.Challenge{
		Resource:   "quotes",
		Timestamp:  12345,
		Difficulty: 4,
		Random:     []byte("test"),
		HMAC:       []byte("signature"),
	}

	solutionPayload := protocol.SolutionRequest{
		Challenge: testChallenge,
		Nonce:     12345,
	}

	payloadJSON, err := json.Marshal(solutionPayload)
	require.NoError(t, err)

	testQuote := &quotes.Quote{
		Text:   "Test quote",
		Author: "Test Author",
	}

	// Mock successful verification and quote retrieval
	mockService.On("VerifySolution", mock.Anything, mock.AnythingOfType("*challenge.Solution")).Return(nil)
	mockService.On("GetQuote", mock.Anything).Return(testQuote, nil)

	ctx := context.Background()
	msg := &protocol.Message{
		Type:           protocol.SolutionRequestType,
		PayloadLength:  uint32(len(payloadJSON)),
		PayloadStream:  bytes.NewReader(payloadJSON),
	}

	response, err := app.HandleMessage(ctx, msg)
	require.NoError(t, err)

	// Type assert to SolutionResponse
	solutionResponse, ok := response.(*protocol.SolutionResponse)
	require.True(t, ok, "Expected SolutionResponse")
	assert.Equal(t, testQuote, solutionResponse.Quote)

	mockService.AssertExpectations(t)
}

func TestWisdomApplication_HandleSolutionRequest_InvalidJSON(t *testing.T) {
	mockService := mocks.NewMockWisdomService(t)
	app := NewWisdomApplication(mockService)

	invalidJSON := []byte("invalid json")
	ctx := context.Background()
	msg := &protocol.Message{
		Type:           protocol.SolutionRequestType,
		PayloadLength:  uint32(len(invalidJSON)),
		PayloadStream:  bytes.NewReader(invalidJSON),
	}

	response, err := app.HandleMessage(ctx, msg)
	require.NoError(t, err)

	// Type assert to ErrorResponse
	errorResponse, ok := response.(*protocol.ErrorResponse)
	require.True(t, ok, "Expected ErrorResponse")
	assert.Equal(t, protocol.ErrMalformedMessage, errorResponse.Code)
	assert.Equal(t, "invalid solution format", errorResponse.Message)

	mockService.AssertNotCalled(t, "VerifySolution")
	mockService.AssertNotCalled(t, "GetQuote")
}

func TestWisdomApplication_HandleSolutionRequest_VerificationFailed(t *testing.T) {
	mockService := mocks.NewMockWisdomService(t)
	app := NewWisdomApplication(mockService)

	// Create test solution request
	testChallenge := challenge.Challenge{
		Resource:   "quotes",
		Timestamp:  12345,
		Difficulty: 4,
		Random:     []byte("test"),
		HMAC:       []byte("signature"),
	}

	solutionPayload := protocol.SolutionRequest{
		Challenge: testChallenge,
		Nonce:     12345,
	}

	payloadJSON, err := json.Marshal(solutionPayload)
	require.NoError(t, err)

	// Mock verification failure
	mockService.On("VerifySolution", mock.Anything, mock.AnythingOfType("*challenge.Solution")).Return(service.ErrInvalidSolution)

	ctx := context.Background()
	msg := &protocol.Message{
		Type:           protocol.SolutionRequestType,
		PayloadLength:  uint32(len(payloadJSON)),
		PayloadStream:  bytes.NewReader(payloadJSON),
	}

	response, err := app.HandleMessage(ctx, msg)
	require.NoError(t, err)

	// Type assert to ErrorResponse
	errorResponse, ok := response.(*protocol.ErrorResponse)
	require.True(t, ok, "Expected ErrorResponse")
	assert.Equal(t, protocol.ErrInvalidSolution, errorResponse.Code)
	assert.Equal(t, "solution verification failed", errorResponse.Message)

	mockService.AssertExpectations(t)
	mockService.AssertNotCalled(t, "GetQuote")
}

func TestWisdomApplication_HandleSolutionRequest_QuoteServiceError(t *testing.T) {
	mockService := mocks.NewMockWisdomService(t)
	app := NewWisdomApplication(mockService)

	// Create test solution request
	testChallenge := challenge.Challenge{
		Resource:   "quotes",
		Timestamp:  12345,
		Difficulty: 4,
		Random:     []byte("test"),
		HMAC:       []byte("signature"),
	}

	solutionPayload := protocol.SolutionRequest{
		Challenge: testChallenge,
		Nonce:     12345,
	}

	payloadJSON, err := json.Marshal(solutionPayload)
	require.NoError(t, err)

	// Mock successful verification but quote service error
	mockService.On("VerifySolution", mock.Anything, mock.AnythingOfType("*challenge.Solution")).Return(nil)
	mockService.On("GetQuote", mock.Anything).Return(nil, errors.New("quote service error"))

	ctx := context.Background()
	msg := &protocol.Message{
		Type:           protocol.SolutionRequestType,
		PayloadLength:  uint32(len(payloadJSON)),
		PayloadStream:  bytes.NewReader(payloadJSON),
	}

	response, err := app.HandleMessage(ctx, msg)
	require.NoError(t, err)

	// Type assert to ErrorResponse
	errorResponse, ok := response.(*protocol.ErrorResponse)
	require.True(t, ok, "Expected ErrorResponse")
	assert.Equal(t, protocol.ErrServerError, errorResponse.Code)
	assert.Equal(t, "Contact administrator", errorResponse.Message)

	mockService.AssertExpectations(t)
}

func TestWisdomApplication_HandleMessage_ContextCancellation(t *testing.T) {
	mockService := mocks.NewMockWisdomService(t)
	app := NewWisdomApplication(mockService)

	// Create cancelled context
	ctx, cancel := context.WithCancel(context.Background())
	cancel()

	// Mock service to respect context cancellation
	mockService.On("GenerateChallenge", mock.Anything, "quotes").Return(nil, context.Canceled)

	msg := &protocol.Message{
		Type:           protocol.ChallengeRequestType,
		PayloadLength:  0,
		PayloadStream:  nil,
	}

	response, err := app.HandleMessage(ctx, msg)
	require.NoError(t, err)

	// Type assert to ErrorResponse
	errorResponse, ok := response.(*protocol.ErrorResponse)
	require.True(t, ok, "Expected ErrorResponse")
	assert.Equal(t, protocol.ErrServerError, errorResponse.Code)

	mockService.AssertExpectations(t)
}

func TestResponseEncoding(t *testing.T) {
	// Test ChallengeResponse encoding produces valid binary format
	testChallenge := &challenge.Challenge{
		Resource:   "quotes",
		Timestamp:  12345,
		Difficulty: 4,
		Random:     []byte("test"),
		HMAC:       []byte("signature"),
	}

	challengeResponse := &protocol.ChallengeResponse{Challenge: testChallenge}
	var buf bytes.Buffer
	err := challengeResponse.Encode(&buf)
	require.NoError(t, err)

	// Verify binary format
	data := buf.Bytes()
	assert.GreaterOrEqual(t, len(data), 5) // At least header size

	// Check message type
	assert.Equal(t, byte(protocol.ChallengeResponseType), data[0])

	// Check payload contains expected data
	payload := string(data[5:]) // Skip header
	assert.Contains(t, payload, "quotes")
	assert.Contains(t, payload, "12345")
}