package arbitrum

import (
	"context"
	"os"
	"testing"
	"time"

	"github.com/fraktal/mev-beta/internal/config"
	"github.com/stretchr/testify/assert"
)

func TestConnectionManager_GetPrimaryEndpoint(t *testing.T) {
	tests := []struct {
		name           string
		envValue       string
		configValue    string
		expectedResult string
	}{
		{
			name:           "Environment variable takes precedence",
			envValue:       "wss://env-endpoint.com",
			configValue:    "wss://config-endpoint.com",
			expectedResult: "wss://env-endpoint.com",
		},
		{
			name:           "Config value used when env not set",
			envValue:       "",
			configValue:    "wss://config-endpoint.com",
			expectedResult: "wss://config-endpoint.com",
		},
		{
			name:           "Default fallback when neither set",
			envValue:       "",
			configValue:    "",
			expectedResult: "wss://arbitrum-mainnet.core.chainstack.com/f69d14406bc00700da9b936504e1a870",
		},
	}

	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			// Set up environment
			if tt.envValue != "" {
				os.Setenv("ARBITRUM_RPC_ENDPOINT", tt.envValue)
			} else {
				os.Unsetenv("ARBITRUM_RPC_ENDPOINT")
			}
			defer os.Unsetenv("ARBITRUM_RPC_ENDPOINT")

			// Create connection manager with config
			cfg := &config.ArbitrumConfig{
				RPCEndpoint: tt.configValue,
			}
			cm := NewConnectionManager(cfg)

			// Test
			result := cm.getPrimaryEndpoint()
			assert.Equal(t, tt.expectedResult, result)
		})
	}
}

func TestConnectionManager_GetFallbackEndpoints(t *testing.T) {
	tests := []struct {
		name             string
		envValue         string
		configEndpoints  []config.EndpointConfig
		expectedContains []string
	}{
		{
			name:     "Environment variable endpoints",
			envValue: "https://endpoint1.com,https://endpoint2.com, https://endpoint3.com ",
			expectedContains: []string{
				"https://endpoint1.com",
				"https://endpoint2.com",
				"https://endpoint3.com",
			},
		},
		{
			name:     "Config endpoints used when env not set",
			envValue: "",
			configEndpoints: []config.EndpointConfig{
				{URL: "https://config1.com"},
				{URL: "https://config2.com"},
			},
			expectedContains: []string{
				"https://config1.com",
				"https://config2.com",
			},
		},
		{
			name:     "Default endpoints when nothing configured",
			envValue: "",
			expectedContains: []string{
				"https://arb1.arbitrum.io/rpc",
				"https://arbitrum.llamarpc.com",
				"https://arbitrum-one.publicnode.com",
				"https://arbitrum-one.public.blastapi.io",
			},
		},
	}

	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			// Set up environment
			if tt.envValue != "" {
				os.Setenv("ARBITRUM_FALLBACK_ENDPOINTS", tt.envValue)
			} else {
				os.Unsetenv("ARBITRUM_FALLBACK_ENDPOINTS")
			}
			defer os.Unsetenv("ARBITRUM_FALLBACK_ENDPOINTS")

			// Create connection manager with config
			cfg := &config.ArbitrumConfig{
				FallbackEndpoints: tt.configEndpoints,
			}
			cm := NewConnectionManager(cfg)

			// Test
			result := cm.getFallbackEndpoints()

			// Check that all expected endpoints are present
			for _, expected := range tt.expectedContains {
				assert.Contains(t, result, expected, "Expected endpoint %s not found in results", expected)
			}
		})
	}
}

func TestConnectionManager_ConnectWithTimeout(t *testing.T) {
	cm := NewConnectionManager(&config.ArbitrumConfig{})
	ctx := context.Background()

	t.Run("Invalid endpoint fails quickly", func(t *testing.T) {
		start := time.Now()
		_, err := cm.connectWithTimeout(ctx, "wss://invalid-endpoint-that-does-not-exist.com")
		duration := time.Since(start)

		assert.Error(t, err)
		assert.Less(t, duration, 15*time.Second, "Should fail within timeout period")
	})

	t.Run("Connection respects context cancellation", func(t *testing.T) {
		ctx, cancel := context.WithTimeout(context.Background(), 100*time.Millisecond)
		defer cancel()

		start := time.Now()
		_, err := cm.connectWithTimeout(ctx, "wss://very-slow-endpoint.com")
		duration := time.Since(start)

		assert.Error(t, err)
		assert.Less(t, duration, 2*time.Second, "Should respect context timeout")
	})
}

func TestConnectionManager_GetClientWithRetry(t *testing.T) {
	cm := NewConnectionManager(&config.ArbitrumConfig{})
	ctx := context.Background()

	t.Run("Retry logic with exponential backoff", func(t *testing.T) {
		start := time.Now()

		// This should fail but test the retry mechanism
		_, err := cm.GetClientWithRetry(ctx, 3)
		duration := time.Since(start)

		// Should have attempted 3 times with exponential backoff
		// First attempt: immediate
		// Second attempt: 1 second wait
		// Third attempt: 2 second wait
		// Total minimum time should be around 3 seconds
		assert.Error(t, err)
		assert.GreaterOrEqual(t, duration, 3*time.Second, "Should include retry delays")
		assert.Contains(t, err.Error(), "failed to connect after 3 attempts")
	})
}

func TestConnectionManager_HealthyClient(t *testing.T) {
	t.Run("GetHealthyClient returns error when no endpoints work", func(t *testing.T) {
		// Set invalid endpoints to test failure case
		os.Setenv("ARBITRUM_RPC_ENDPOINT", "wss://invalid-endpoint.com")
		os.Setenv("ARBITRUM_FALLBACK_ENDPOINTS", "https://invalid1.com,https://invalid2.com")
		defer func() {
			os.Unsetenv("ARBITRUM_RPC_ENDPOINT")
			os.Unsetenv("ARBITRUM_FALLBACK_ENDPOINTS")
		}()

		ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
		defer cancel()

		_, err := GetHealthyClient(ctx)
		assert.Error(t, err, "Should fail when all endpoints are invalid")
	})
}

func TestConnectionManager_Configuration(t *testing.T) {
	t.Run("Environment variables override config file", func(t *testing.T) {
		// Set environment variables
		os.Setenv("ARBITRUM_RPC_ENDPOINT", "wss://env-primary.com")
		os.Setenv("ARBITRUM_FALLBACK_ENDPOINTS", "https://env-fallback1.com,https://env-fallback2.com")
		defer func() {
			os.Unsetenv("ARBITRUM_RPC_ENDPOINT")
			os.Unsetenv("ARBITRUM_FALLBACK_ENDPOINTS")
		}()

		// Create config with different values
		cfg := &config.ArbitrumConfig{
			RPCEndpoint: "wss://config-primary.com",
			FallbackEndpoints: []config.EndpointConfig{
				{URL: "https://config-fallback1.com"},
				{URL: "https://config-fallback2.com"},
			},
		}

		cm := NewConnectionManager(cfg)

		// Test that environment variables take precedence
		primary := cm.getPrimaryEndpoint()
		assert.Equal(t, "wss://env-primary.com", primary)

		fallbacks := cm.getFallbackEndpoints()
		assert.Contains(t, fallbacks, "https://env-fallback1.com")
		assert.Contains(t, fallbacks, "https://env-fallback2.com")
		assert.NotContains(t, fallbacks, "https://config-fallback1.com")
		assert.NotContains(t, fallbacks, "https://config-fallback2.com")
	})
}

func TestConnectionManager_Lifecycle(t *testing.T) {
	cm := NewConnectionManager(&config.ArbitrumConfig{})

	t.Run("Close handles nil clients gracefully", func(t *testing.T) {
		// Should not panic
		assert.NotPanics(t, func() {
			cm.Close()
		})
	})

	t.Run("Multiple close calls are safe", func(t *testing.T) {
		assert.NotPanics(t, func() {
			cm.Close()
			cm.Close()
			cm.Close()
		})
	})
}

// Integration test that requires real network access
func TestConnectionManager_RealEndpoints(t *testing.T) {
	if testing.Short() {
		t.Skip("Skipping integration test in short mode")
	}

	t.Run("Public Arbitrum RPC endpoints should be reachable", func(t *testing.T) {
		publicEndpoints := []string{
			"https://arb1.arbitrum.io/rpc",
			"https://arbitrum.llamarpc.com",
			"https://arbitrum-one.publicnode.com",
		}

		cm := NewConnectionManager(&config.ArbitrumConfig{})
		ctx, cancel := context.WithTimeout(context.Background(), 30*time.Second)
		defer cancel()

		successCount := 0
		for _, endpoint := range publicEndpoints {
			client, err := cm.connectWithTimeout(ctx, endpoint)
			if err == nil {
				client.Close()
				successCount++
				t.Logf("Successfully connected to %s", endpoint)
			} else {
				t.Logf("Failed to connect to %s: %v", endpoint, err)
			}
		}

		// At least one public endpoint should be working
		assert.Greater(t, successCount, 0, "At least one public Arbitrum RPC should be reachable")
	})
}

// Benchmark connection establishment
func BenchmarkConnectionManager_GetClient(b *testing.B) {
	cm := NewConnectionManager(&config.ArbitrumConfig{})
	ctx := context.Background()

	b.ResetTimer()

	for i := 0; i < b.N; i++ {
		// This will fail but tests the connection attempt performance
		_, _ = cm.GetClient(ctx)
	}
}