package di

import (
	"context"
	"fmt"
	"net/http"
	"os"
	"time"

	"git.dcentral.systems/toolz/goplt/internal/client"
	configimpl "git.dcentral.systems/toolz/goplt/internal/config"
	errorbusimpl "git.dcentral.systems/toolz/goplt/internal/errorbus"
	"git.dcentral.systems/toolz/goplt/internal/health"
	"git.dcentral.systems/toolz/goplt/internal/infra/database"
	loggerimpl "git.dcentral.systems/toolz/goplt/internal/logger"
	"git.dcentral.systems/toolz/goplt/internal/metrics"
	"git.dcentral.systems/toolz/goplt/internal/observability"
	"git.dcentral.systems/toolz/goplt/internal/registry/consul"
	"git.dcentral.systems/toolz/goplt/internal/server"
	"git.dcentral.systems/toolz/goplt/pkg/config"
	"git.dcentral.systems/toolz/goplt/pkg/errorbus"
	"git.dcentral.systems/toolz/goplt/pkg/logger"
	"git.dcentral.systems/toolz/goplt/pkg/registry"
	"go.opentelemetry.io/otel/trace"
	"go.opentelemetry.io/otel/trace/noop"
	"go.uber.org/fx"
)

// ProvideConfig creates an FX option that provides ConfigProvider.
func ProvideConfig() fx.Option {
	return fx.Provide(func() (config.ConfigProvider, error) {
		// Determine environment from environment variable or default to "development"
		env := os.Getenv("ENVIRONMENT")
		if env == "" {
			env = "development"
		}

		cfg, err := configimpl.LoadConfig(env)
		if err != nil {
			return nil, fmt.Errorf("failed to load config: %w", err)
		}

		return cfg, nil
	})
}

// ProvideLogger creates an FX option that provides Logger.
func ProvideLogger() fx.Option {
	return fx.Provide(func(cfg config.ConfigProvider) (logger.Logger, error) {
		level := cfg.GetString("logging.level")
		if level == "" {
			level = "info"
		}

		format := cfg.GetString("logging.format")
		if format == "" {
			format = "json"
		}

		log, err := loggerimpl.NewZapLogger(level, format)
		if err != nil {
			return nil, fmt.Errorf("failed to create logger: %w", err)
		}

		// Set as global logger
		logger.SetGlobalLogger(log)

		return log, nil
	})
}

// ProvideDatabase creates an FX option that provides the database client.
func ProvideDatabase() fx.Option {
	return fx.Provide(func(cfg config.ConfigProvider, log logger.Logger, lc fx.Lifecycle) (*database.Client, error) {
		dsn := cfg.GetString("database.dsn")
		if dsn == "" {
			log.Error("ProvideDatabase: DSN is empty")
			return nil, fmt.Errorf("database DSN is not configured")
		}

		maxConns := cfg.GetInt("database.max_connections")
		if maxConns == 0 {
			maxConns = 25
		}

		maxIdleConns := cfg.GetInt("database.max_idle_connections")
		if maxIdleConns == 0 {
			maxIdleConns = 5
		}

		connMaxLifetime := cfg.GetDuration("database.conn_max_lifetime")
		if connMaxLifetime == 0 {
			connMaxLifetime = 5 * time.Minute
		}

		connMaxIdleTime := cfg.GetDuration("database.conn_max_idle_time")
		if connMaxIdleTime == 0 {
			connMaxIdleTime = 10 * time.Minute
		}

		log.Info("Preparing database connection",
			logger.String("dsn_mask", maskDSN(dsn)),
			logger.Int("max_connections", maxConns),
		)

		log.Info("Connecting to database...")
		dbClient, err := database.NewClient(database.Config{
			DSN:             dsn,
			MaxConnections:  maxConns,
			MaxIdleConns:    maxIdleConns,
			ConnMaxLifetime: connMaxLifetime,
			ConnMaxIdleTime: connMaxIdleTime,
		})
		if err != nil {
			log.Error("Failed to create database client",
				logger.Error(err),
			)
			return nil, fmt.Errorf("failed to create database client: %w", err)
		}

		log.Info("Database client created successfully")

		// Register lifecycle hooks
		lc.Append(fx.Hook{
			OnStart: func(ctx context.Context) error {
				log.Info("Running database migrations...")
				// Run migrations on startup
				if err := dbClient.Migrate(ctx); err != nil {
					log.Error("Database migrations failed",
						logger.Error(err),
					)
					return fmt.Errorf("failed to run database migrations: %w", err)
				}
				log.Info("Database migrations completed successfully")
				return nil
			},
			OnStop: func(_ context.Context) error {
				return dbClient.Close()
			},
		})

		return dbClient, nil
	})
}

// ProvideErrorBus creates an FX option that provides the error bus.
func ProvideErrorBus() fx.Option {
	return fx.Provide(func(log logger.Logger, lc fx.Lifecycle) (errorbus.ErrorPublisher, error) {
		bufferSize := 100 // Can be made configurable
		bus := errorbusimpl.NewChannelBus(log, bufferSize)

		// Register lifecycle hook to close the bus on shutdown
		lc.Append(fx.Hook{
			OnStop: func(_ context.Context) error {
				return bus.Close()
			},
		})

		return bus, nil
	})
}

// ProvideHealthRegistry creates an FX option that provides the health check registry.
// Note: Database health checkers are registered by services that create their own database clients.
func ProvideHealthRegistry() fx.Option {
	return fx.Provide(func() (*health.Registry, error) {
		registry := health.NewRegistry()
		// Services will register their own health checkers (e.g., database, external dependencies)
		return registry, nil
	})
}

// ProvideMetrics creates an FX option that provides the Prometheus metrics registry.
func ProvideMetrics() fx.Option {
	return fx.Provide(func() *metrics.Metrics {
		return metrics.NewMetrics()
	})
}

// ProvideServiceRegistry creates an FX option that provides the service registry.
func ProvideServiceRegistry() fx.Option {
	return fx.Provide(func(cfg config.ConfigProvider) (registry.ServiceRegistry, error) {
		registryType := cfg.GetString("registry.type")
		if registryType == "" {
			registryType = "consul"
		}

		switch registryType {
		case "consul":
			consulCfg := consul.Config{
				Address:    cfg.GetString("registry.consul.address"),
				Datacenter: cfg.GetString("registry.consul.datacenter"),
				Scheme:     cfg.GetString("registry.consul.scheme"),
			}

			// Set defaults
			if consulCfg.Address == "" {
				consulCfg.Address = "localhost:8500"
			}
			if consulCfg.Datacenter == "" {
				consulCfg.Datacenter = "dc1"
			}
			if consulCfg.Scheme == "" {
				consulCfg.Scheme = "http"
			}

			// Parse health check configuration
			healthCheckInterval := cfg.GetDuration("registry.consul.health_check.interval")
			if healthCheckInterval == 0 {
				healthCheckInterval = 10 * time.Second
			}
			healthCheckTimeout := cfg.GetDuration("registry.consul.health_check.timeout")
			if healthCheckTimeout == 0 {
				healthCheckTimeout = 3 * time.Second
			}
			healthCheckDeregisterAfter := cfg.GetDuration("registry.consul.health_check.deregister_after")
			if healthCheckDeregisterAfter == 0 {
				healthCheckDeregisterAfter = 30 * time.Second
			}
			healthCheckHTTP := cfg.GetString("registry.consul.health_check.http")
			healthCheckGRPC := cfg.GetString("registry.consul.health_check.grpc")
			useGRPC := cfg.GetBool("registry.consul.health_check.use_grpc")
			// Default to gRPC if not explicitly set (services are gRPC by default)
			if !cfg.IsSet("registry.consul.health_check.use_grpc") {
				useGRPC = true
			}
			if healthCheckGRPC == "" {
				healthCheckGRPC = "grpc.health.v1.Health"
			}

			consulCfg.HealthCheck = consul.HealthCheckConfig{
				Interval:        healthCheckInterval,
				Timeout:         healthCheckTimeout,
				DeregisterAfter: healthCheckDeregisterAfter,
				HTTP:            healthCheckHTTP,
				GRPC:            healthCheckGRPC,
				UseGRPC:         useGRPC,
			}

			return consul.NewRegistry(consulCfg)
		default:
			return nil, fmt.Errorf("unsupported registry type: %s", registryType)
		}
	})
}

// ProvideServiceClientFactory creates an FX option that provides the service client factory.
func ProvideServiceClientFactory() fx.Option {
	return fx.Provide(func(reg registry.ServiceRegistry) (*client.ServiceClientFactory, error) {
		return client.NewServiceClientFactory(reg), nil
	})
}

// ProvideTracer creates an FX option that provides the OpenTelemetry tracer.
func ProvideTracer() fx.Option {
	return fx.Provide(func(cfg config.ConfigProvider, lc fx.Lifecycle) (trace.TracerProvider, error) {
		enabled := cfg.GetBool("tracing.enabled")
		if !enabled {
			// Return no-op tracer
			return noop.NewTracerProvider(), nil
		}

		serviceName := cfg.GetString("tracing.service_name")
		if serviceName == "" {
			serviceName = "platform"
		}

		serviceVersion := cfg.GetString("tracing.service_version")
		if serviceVersion == "" {
			serviceVersion = "1.0.0"
		}

		env := cfg.GetString("environment")
		if env == "" {
			env = "development"
		}

		otlpEndpoint := cfg.GetString("tracing.otlp_endpoint")

		tp, err := observability.InitTracer(context.Background(), observability.Config{
			Enabled:        enabled,
			ServiceName:    serviceName,
			ServiceVersion: serviceVersion,
			Environment:    env,
			OTLPEndpoint:   otlpEndpoint,
		})
		if err != nil {
			return nil, fmt.Errorf("failed to initialize tracer: %w", err)
		}

		// Register lifecycle hook to shutdown tracer
		lc.Append(fx.Hook{
			OnStop: func(ctx context.Context) error {
				return observability.ShutdownTracer(ctx, tp)
			},
		})

		return tp, nil
	})
}

// ProvideHTTPServer creates an FX option that provides the HTTP server.
func ProvideHTTPServer() fx.Option {
	return fx.Provide(func(
		cfg config.ConfigProvider,
		log logger.Logger,
		healthRegistry *health.Registry,
		metricsRegistry *metrics.Metrics,
		errorBus errorbus.ErrorPublisher,
		tracer trace.TracerProvider,
		lc fx.Lifecycle,
	) (*server.Server, error) {
		log.Info("Creating HTTP server...")

		srv, err := server.NewServer(cfg, log, healthRegistry, metricsRegistry, errorBus, tracer)
		if err != nil {
			log.Error("Failed to create HTTP server",
				logger.Error(err),
			)
			return nil, fmt.Errorf("failed to create HTTP server: %w", err)
		}

		log.Info("HTTP server created, registering lifecycle hooks...")

		// Register lifecycle hooks
		lc.Append(fx.Hook{
			OnStart: func(_ context.Context) error {
				// Get server address from config
				port := cfg.GetInt("server.port")
				if port == 0 {
					port = 8080
				}
				host := cfg.GetString("server.host")
				if host == "" {
					host = "0.0.0.0"
				}
				addr := fmt.Sprintf("%s:%d", host, port)

				log.Info("HTTP server starting",
					logger.String("addr", addr),
				)

				// Start server in a goroutine
				// ListenAndServe blocks, so we need to start it async
				// If there's an immediate error (like port in use), it will return quickly
				errChan := make(chan error, 1)
				go func() {
					if err := srv.Start(); err != nil && err != http.ErrServerClosed {
						log.Error("HTTP server failed",
							logger.String("error", err.Error()),
						)
						select {
						case errChan <- err:
						default:
						}
					}
				}()

				// Wait a short time to detect immediate binding errors
				// If ListenAndServe fails immediately (e.g., port in use), it will return quickly
				select {
				case err := <-errChan:
					return fmt.Errorf("HTTP server failed to start: %w", err)
				case <-time.After(500 * time.Millisecond):
					// If no error after 500ms, verify server is actually listening
					// by attempting a connection
					client := &http.Client{Timeout: 1 * time.Second}
					checkURL := fmt.Sprintf("http://localhost:%d/healthz", port)
					resp, err := client.Get(checkURL)
					if err != nil {
						// Server might still be starting, but log the attempt
						log.Warn("Could not verify HTTP server is listening (may still be starting)",
							logger.String("url", checkURL),
							logger.String("error", err.Error()),
						)
						// Continue anyway - server might still be starting
					} else {
						_ = resp.Body.Close()
					}

					log.Info("HTTP server started successfully",
						logger.String("addr", addr),
					)
					return nil
				}
			},
			OnStop: func(ctx context.Context) error {
				return srv.Shutdown(ctx)
			},
		})

		return srv, nil
	})
}

// CoreModule returns an FX option that provides all core kernel infrastructure services.
// This includes configuration, logging, error bus, health checks, metrics, tracing, service registry, and service client factory.
// Note: Database and HTTP server are NOT included - services will create their own instances.
// HTTP server foundation is available via server.NewServer() for services to use.
func CoreModule() fx.Option {
	return fx.Options(
		ProvideConfig(),
		ProvideLogger(),
		ProvideErrorBus(),
		ProvideHealthRegistry(),
		ProvideMetrics(),
		ProvideTracer(),
		ProvideServiceRegistry(),
		ProvideServiceClientFactory(),
		// Note: ProvideDatabase() and ProvideHTTPServer() are removed - services create their own
	)
}

// maskDSN masks sensitive information in DSN for logging.
func maskDSN(dsn string) string {
	// Simple masking: replace password with ***
	// Format: postgres://user:password@host:port/db
	if len(dsn) < 20 {
		return "***"
	}
	// Find @ symbol and replace password part
	if idx := indexOf(dsn, '@'); idx > 0 {
		if colonIdx := indexOf(dsn[:idx], ':'); colonIdx > 0 {
			return dsn[:colonIdx+1] + "***" + dsn[idx:]
		}
	}
	return "***"
}

// indexOf finds the index of a character in a string.
func indexOf(s string, c byte) int {
	for i := 0; i < len(s); i++ {
		if s[i] == c {
			return i
		}
	}
	return -1
}

// RegisterLifecycleHooks registers lifecycle hooks for logging.
func RegisterLifecycleHooks(lc fx.Lifecycle, l logger.Logger) {
	lc.Append(fx.Hook{
		OnStart: func(_ context.Context) error {
			l.Info("Application starting",
				logger.String("component", "bootstrap"),
			)
			return nil
		},
		OnStop: func(_ context.Context) error {
			l.Info("Application shutting down",
				logger.String("component", "bootstrap"),
			)
			return nil
		},
	})
}