package integration

import (
	"context"
	"encoding/hex"
	"fmt"
	"sync"
	"testing"
	"time"

	"github.com/ethereum/go-ethereum/common"
	"github.com/stretchr/testify/assert"

	"github.com/fraktal/mev-beta/internal/logger"
	"github.com/fraktal/mev-beta/internal/monitoring"
	"github.com/fraktal/mev-beta/internal/recovery"
	"github.com/fraktal/mev-beta/internal/utils"
	"github.com/fraktal/mev-beta/internal/validation"
)

// CorruptionSimulator simulates various corruption scenarios for testing
type CorruptionSimulator struct {
	validator        *validation.AddressValidator
	converter        *utils.SafeAddressConverter
	integrityMonitor *monitoring.IntegrityMonitor
	errorHandler     *recovery.ErrorHandler
	retryHandler     *recovery.RetryHandler
	logger           *logger.Logger
}

// NewCorruptionSimulator creates a new corruption simulation test environment
func NewCorruptionSimulator(t *testing.T) *CorruptionSimulator {
	log := logger.New("debug", "text", "")

	validator := validation.NewAddressValidator()
	converter := utils.NewSafeAddressConverter()
	integrityMonitor := monitoring.NewIntegrityMonitor(log)
	errorHandler := recovery.NewErrorHandler(log)
	retryHandler := recovery.NewRetryHandler(log)

	return &CorruptionSimulator{
		validator:        validator,
		converter:        converter,
		integrityMonitor: integrityMonitor,
		errorHandler:     errorHandler,
		retryHandler:     retryHandler,
		logger:           log,
	}
}

// CorruptionScenario represents a specific corruption test case
type CorruptionScenario struct {
	Name               string
	CorruptedAddresses []string
	ValidAddresses     []string
	ExpectedDetections int
	ExpectedRecoveries int
	Severity           recovery.ErrorSeverity
}

func TestCorruption_TOKEN_0x000000_Scenarios(t *testing.T) {
	simulator := NewCorruptionSimulator(t)

	scenarios := []CorruptionScenario{
		{
			Name: "Critical TOKEN_0x000000 Pattern",
			CorruptedAddresses: []string{
				"0x0000000300000000000000000000000000000000", // Exact pattern
				"0x0000000100000000000000000000000000000000", // Similar pattern
				"0x0000000500000000000000000000000000000000", // Variant
			},
			ValidAddresses: []string{
				"0x82aF49447D8a07e3bd95BD0d56f35241523fBab1", // WETH
				"0xaf88d065e77c8cC2239327C5EDb3A432268e5831", // USDC
			},
			ExpectedDetections: 3,
			Severity:           recovery.SeverityCritical,
		},
		{
			Name: "Mixed Corruption Patterns",
			CorruptedAddresses: []string{
				"0x1234000000000000000000000000000000000000", // Partial corruption
				"0x0000000000000000000000000000000000000001", // Almost zero
				"0xabcd567800000000000000000000000000000000", // Trailing zeros
			},
			ValidAddresses: []string{
				"0x912CE59144191C1204E64559FE8253a0e49E6548", // ARB
				"0x2f2a2543B76A4166549F7aaB2e75Bef0aefC5B0f", // WBTC
			},
			ExpectedDetections: 3,
			Severity:           recovery.SeverityHigh,
		},
		{
			Name: "Subtle Corruption",
			CorruptedAddresses: []string{
				"0x82aF49447D8a07e3bd95BD0d56f35241523fBaZ1", // Invalid hex char
				"0x82af49447d8a07e3bd95bd0d56f35241523fbab",  // Truncated address
			},
			ValidAddresses: []string{
				"0xFd086bC7CD5C481DCC9C85ebE478A1C0b69FCbb9", // USDT
			},
			ExpectedDetections: 2,
			Severity:           recovery.SeverityMedium,
		},
	}

	for _, scenario := range scenarios {
		t.Run(scenario.Name, func(t *testing.T) {
			simulator.runCorruptionScenario(t, scenario)
		})
	}
}

func (cs *CorruptionSimulator) runCorruptionScenario(t *testing.T, scenario CorruptionScenario) {
	// Reset monitoring stats
	cs.integrityMonitor = monitoring.NewIntegrityMonitor(cs.logger)

	detectedCorruptions := 0
	successfulRecoveries := 0

	// Process corrupted addresses
	for _, corruptedAddr := range scenario.CorruptedAddresses {
		cs.logger.Debug("Processing corrupted address", "address", corruptedAddr)

		// Validate address
		result := cs.validator.ValidateAddress(corruptedAddr)
		cs.integrityMonitor.RecordAddressProcessed()

		if !result.IsValid {
			detectedCorruptions++
			addr := common.HexToAddress(corruptedAddr)
			cs.integrityMonitor.RecordCorruptionDetected(addr, result.CorruptionScore, "test_scenario")
			cs.integrityMonitor.RecordValidationResult(false)

			// Simulate recovery attempt
			recoveryAction := cs.errorHandler.HandleError(
				context.Background(),
				recovery.ErrorTypeAddressCorruption,
				scenario.Severity,
				"test_component",
				addr,
				"Simulated corruption",
				map[string]interface{}{"corruption_score": result.CorruptionScore},
			)

			cs.integrityMonitor.RecordRecoveryAction(recoveryAction)

			// Count successful recoveries
			if recoveryAction == recovery.ActionUseFallbackData ||
				recoveryAction == recovery.ActionRetryWithBackoff {
				successfulRecoveries++
			}
		} else {
			cs.integrityMonitor.RecordValidationResult(true)
		}
	}

	// Process valid addresses
	for _, validAddr := range scenario.ValidAddresses {
		cs.logger.Debug("Processing valid address", "address", validAddr)

		result := cs.validator.ValidateAddress(validAddr)
		cs.integrityMonitor.RecordAddressProcessed()

		if result.IsValid {
			cs.integrityMonitor.RecordValidationResult(true)
		} else {
			t.Errorf("Valid address %s was rejected: %v", validAddr, result.ErrorMessages)
		}
	}

	// Verify results
	assert.Equal(t, scenario.ExpectedDetections, detectedCorruptions,
		"Should detect expected number of corruptions")

	metrics := cs.integrityMonitor.GetMetrics()
	assert.Equal(t, int64(detectedCorruptions), metrics.CorruptAddressesDetected,
		"Monitoring should track detected corruptions")

	totalAddresses := len(scenario.CorruptedAddresses) + len(scenario.ValidAddresses)
	assert.Equal(t, int64(totalAddresses), metrics.TotalAddressesProcessed,
		"Should track all processed addresses")

	// Health score should reflect corruption level
	expectedHealthScore := 1.0 - (float64(detectedCorruptions) / float64(totalAddresses))
	assert.InDelta(t, expectedHealthScore, metrics.HealthScore, 0.2,
		"Health score should reflect corruption rate")

	t.Logf("Scenario %s: Detected %d/%d corruptions, Health=%.3f",
		scenario.Name, detectedCorruptions, scenario.ExpectedDetections, metrics.HighScore)
}

func TestCorruption_HighVolumeStressTest(t *testing.T) {
	if testing.Short() {
		t.Skip("Skipping stress test in short mode")
	}

	simulator := NewCorruptionSimulator(t)

	const (
		numWorkers         = 20
		addressesPerWorker = 1000
		corruptionRate     = 0.1 // 10% corruption rate
	)

	var wg sync.WaitGroup
	startTime := time.Now()

	// Launch worker goroutines
	for workerID := 0; workerID < numWorkers; workerID++ {
		wg.Add(1)
		go func(id int) {
			defer wg.Done()

			for i := 0; i < addressesPerWorker; i++ {
				var address string

				// Generate corrupted or valid address based on corruption rate
				if float64(i%100) < corruptionRate*100 {
					// Generate corrupted address
					address = generateCorruptedAddress(id, i)
				} else {
					// Generate valid-looking address
					address = generateValidAddress(id, i)
				}

				// Process address through validation pipeline
				result := simulator.validator.ValidateAddress(address)
				simulator.integrityMonitor.RecordAddressProcessed()

				if result.IsValid {
					simulator.integrityMonitor.RecordValidationResult(true)
				} else {
					addr := common.HexToAddress(address)
					simulator.integrityMonitor.RecordCorruptionDetected(addr, result.CorruptionScore, "stress_test")
					simulator.integrityMonitor.RecordValidationResult(false)

					// Simulate recovery
					recoveryAction := simulator.errorHandler.HandleError(
						context.Background(),
						recovery.ErrorTypeAddressCorruption,
						recovery.SeverityMedium,
						"stress_test",
						addr,
						"Stress test corruption",
						nil,
					)
					simulator.integrityMonitor.RecordRecoveryAction(recoveryAction)
				}
			}
		}(workerID)
	}

	// Wait for completion
	wg.Wait()
	duration := time.Since(startTime)

	// Analyze results
	metrics := simulator.integrityMonitor.GetMetrics()
	totalAddresses := int64(numWorkers * addressesPerWorker)
	actualCorruptionRate := float64(metrics.CorruptAddressesDetected) / float64(totalAddresses)

	t.Logf("Stress Test Results:")
	t.Logf("  Duration: %v", duration)
	t.Logf("  Total Addresses: %d", totalAddresses)
	t.Logf("  Corruptions Detected: %d", metrics.CorruptAddressesDetected)
	t.Logf("  Actual Corruption Rate: %.2f%%", actualCorruptionRate*100)
	t.Logf("  Health Score: %.3f", metrics.HealthScore)
	t.Logf("  Throughput: %.0f addresses/sec", float64(totalAddresses)/duration.Seconds())

	// Verify performance and accuracy
	assert.Equal(t, totalAddresses, metrics.TotalAddressesProcessed)
	assert.InDelta(t, corruptionRate, actualCorruptionRate, 0.05) // Within 5% of expected
	assert.Greater(t, metrics.RetryOperationsTriggered, int64(0)) // Should have triggered recoveries

	// Should process at least 1000 addresses per second
	throughput := float64(totalAddresses) / duration.Seconds()
	assert.Greater(t, throughput, 1000.0, "Should maintain high throughput under stress")
}

func TestCorruption_RecoveryMechanisms(t *testing.T) {
	simulator := NewCorruptionSimulator(t)

	testCases := []struct {
		name           string
		corruptedAddr  string
		errorType      recovery.ErrorType
		severity       recovery.ErrorSeverity
		expectedAction recovery.RecoveryAction
	}{
		{
			name:           "Critical corruption requires fallback",
			corruptedAddr:  "0x0000000300000000000000000000000000000000",
			errorType:      recovery.ErrorTypeAddressCorruption,
			severity:       recovery.SeverityCritical,
			expectedAction: recovery.ActionUseFallbackData,
		},
		{
			name:           "Medium corruption allows retry",
			corruptedAddr:  "0x123400000000000000000000000000000000000",
			errorType:      recovery.ErrorTypeValidationFailed,
			severity:       recovery.SeverityMedium,
			expectedAction: recovery.ActionRetryWithBackoff,
		},
		{
			name:           "Low corruption can be skipped",
			corruptedAddr:  "0x82af49447d8a07e3bd95bd0d56f35241523fbab1", // Wrong checksum
			errorType:      recovery.ErrorTypeValidationFailed,
			severity:       recovery.SeverityLow,
			expectedAction: recovery.ActionSkipAndContinue,
		},
	}

	for _, tc := range testCases {
		t.Run(tc.name, func(t *testing.T) {
			addr := common.HexToAddress(tc.corruptedAddr)

			action := simulator.errorHandler.HandleError(
				context.Background(),
				tc.errorType,
				tc.severity,
				"test_recovery",
				addr,
				"Recovery test",
				nil,
			)

			assert.Equal(t, tc.expectedAction, action,
				"Should select appropriate recovery action for %s", tc.name)

			// Record action and verify it's tracked
			simulator.integrityMonitor.RecordRecoveryAction(action)
			metrics := simulator.integrityMonitor.GetMetrics()
			assert.Greater(t, metrics.RecoveryActions[action], int64(0),
				"Should track recovery action usage")
		})
	}
}

func TestCorruption_RetryMechanisms(t *testing.T) {
	simulator := NewCorruptionSimulator(t)

	// Configure retry for testing
	retryConfig := recovery.RetryConfig{
		MaxAttempts:       3,
		InitialDelay:      1 * time.Millisecond,
		MaxDelay:          10 * time.Millisecond,
		BackoffFactor:     2.0,
		JitterEnabled:     false,
		TimeoutPerAttempt: 100 * time.Millisecond,
	}
	simulator.retryHandler.SetConfig("test_retry", retryConfig)

	t.Run("Successful retry after corruption", func(t *testing.T) {
		attempts := 0
		operation := func(ctx context.Context, attempt int) error {
			attempts++
			if attempt == 1 {
				// Simulate corruption on first attempt
				return fmt.Errorf("address corruption detected")
			}
			// Success on retry
			return nil
		}

		result := simulator.retryHandler.ExecuteWithRetry(context.Background(), "test_retry", operation)

		assert.True(t, result.Success)
		assert.Equal(t, 2, result.Attempts)
		assert.Equal(t, 2, attempts)
	})

	t.Run("Persistent corruption fails after max attempts", func(t *testing.T) {
		attempts := 0
		operation := func(ctx context.Context, attempt int) error {
			attempts++
			return fmt.Errorf("persistent corruption")
		}

		result := simulator.retryHandler.ExecuteWithRetry(context.Background(), "test_retry", operation)

		assert.False(t, result.Success)
		assert.Equal(t, 3, result.Attempts) // Max attempts
		assert.Equal(t, 3, attempts)
	})
}

func TestCorruption_EndToEndPipeline(t *testing.T) {
	simulator := NewCorruptionSimulator(t)

	// Simulate complete transaction processing pipeline
	testTransactions := []struct {
		txHash     string
		inputData  string
		addresses  []string
		shouldFail bool
	}{
		{
			txHash:    "0x1234567890abcdef1234567890abcdef1234567890abcdef1234567890abcdef",
			inputData: "0x022c0d9f000000000000000000000000000000000000000000000000000000000000000300000000000000000000000000000000000000000000000000000000",
			addresses: []string{
				"0x0000000300000000000000000000000000000000", // Corrupted
				"0x82aF49447D8a07e3bd95BD0d56f35241523fBab1", // Valid WETH
			},
			shouldFail: true, // Should fail due to corruption
		},
		{
			txHash:    "0xabcdef1234567890abcdef1234567890abcdef1234567890abcdef1234567890",
			inputData: "0x128acb08000000000000000000000000af88d065e77c8cc2239327c5edb3a432268e583100000000000000000000000082af49447d8a07e3bd95bd0d56f35241523fbab1",
			addresses: []string{
				"0xaf88d065e77c8cC2239327C5EDb3A432268e5831", // Valid USDC
				"0x82aF49447D8a07e3bd95BD0d56f35241523fBab1", // Valid WETH
			},
			shouldFail: false, // Should succeed
		},
	}

	for _, tx := range testTransactions {
		t.Run(fmt.Sprintf("Transaction_%s", tx.txHash[:10]), func(t *testing.T) {
			success := simulator.processTransaction(tx.txHash, tx.inputData, tx.addresses)

			if tx.shouldFail {
				assert.False(t, success, "Transaction with corruption should fail")
			} else {
				assert.True(t, success, "Transaction with valid addresses should succeed")
			}
		})
	}

	// Verify overall system health
	metrics := simulator.integrityMonitor.GetMetrics()
	assert.Greater(t, metrics.TotalAddressesProcessed, int64(0))

	if metrics.CorruptAddressesDetected > 0 {
		assert.Greater(t, metrics.RetryOperationsTriggered+metrics.FallbackOperationsUsed, int64(0),
			"Should have triggered recovery mechanisms for corruption")
	}
}

// processTransaction simulates processing a transaction through the full pipeline
func (cs *CorruptionSimulator) processTransaction(txHash, inputData string, addresses []string) bool {
	allValid := true

	for _, addr := range addresses {
		cs.integrityMonitor.RecordAddressProcessed()

		// Validate address
		result := cs.validator.ValidateAddress(addr)
		if !result.IsValid {
			allValid = false

			// Record corruption
			address := common.HexToAddress(addr)
			cs.integrityMonitor.RecordCorruptionDetected(address, result.CorruptionScore, "pipeline_test")
			cs.integrityMonitor.RecordValidationResult(false)

			// Attempt recovery
			recoveryAction := cs.errorHandler.HandleError(
				context.Background(),
				recovery.ErrorTypeAddressCorruption,
				recovery.SeverityCritical,
				"transaction_processor",
				address,
				"Address corruption in transaction",
				map[string]interface{}{
					"tx_hash":    txHash,
					"input_data": inputData,
				},
			)

			cs.integrityMonitor.RecordRecoveryAction(recoveryAction)

			// Only continue if recovery suggests it's safe
			if recoveryAction == recovery.ActionEmergencyStop || recoveryAction == recovery.ActionCircuitBreaker {
				return false
			}
		} else {
			cs.integrityMonitor.RecordValidationResult(true)
		}

		// Simulate contract call
		if result.IsValid || result.CorruptionScore < 50 { // Allow low corruption with retry
			cs.integrityMonitor.RecordContractCallResult(true)
		} else {
			cs.integrityMonitor.RecordContractCallResult(false)
			allValid = false
		}
	}

	return allValid
}

// Helper functions for generating test addresses
func generateCorruptedAddress(workerID, index int) string {
	patterns := []string{
		"0x000000%02d00000000000000000000000000000000", // TOKEN_0x000000 style
		"0x%04x000000000000000000000000000000000000",   // Partial corruption
		"0x000000000000000000000000000000000000%04x",   // Trailing corruption
	}

	pattern := patterns[index%len(patterns)]
	return fmt.Sprintf(pattern, workerID*1000+index)
}

func generateValidAddress(workerID, index int) string {
	bytes := make([]byte, common.AddressLength)
	seed := workerID*97 + index*31
	for i := 0; i < len(bytes); i++ {
		seed = (seed*131 + i*17) & 0xff
		bytes[i] = byte(seed)
	}
	return "0x" + hex.EncodeToString(bytes)
}