package main

import (
	"context"
	"fmt"
	"net/http"
	"os"
	"os/signal"
	"path/filepath"
	"runtime"
	"syscall"
	"tercul/internal/app"
	"tercul/internal/app/analytics"
	graph "tercul/internal/adapters/graphql"
	dbsql "tercul/internal/data/sql"
	"tercul/internal/jobs/linguistics"
	"tercul/internal/observability"
	"tercul/internal/platform/auth"
	"tercul/internal/platform/config"
	"tercul/internal/platform/db"
	"tercul/internal/platform/log"
	"tercul/internal/platform/search"
	"time"

	"github.com/99designs/gqlgen/graphql/playground"
	"github.com/pressly/goose/v3"
	"github.com/prometheus/client_golang/prometheus"
	"github.com/weaviate/weaviate-go-client/v5/weaviate"
	"gorm.io/gorm"
)

// runMigrations applies database migrations using goose.
func runMigrations(gormDB *gorm.DB) error {
	sqlDB, err := gormDB.DB()
	if err != nil {
		return err
	}

	if err := goose.SetDialect("postgres"); err != nil {
		return err
	}

	// This is brittle. A better approach might be to use an env var or config.
	_, b, _, _ := runtime.Caller(0)
	migrationsDir := filepath.Join(filepath.Dir(b), "../../internal/data/migrations")

	log.Info(fmt.Sprintf("Applying database migrations from %s", migrationsDir))
	if err := goose.Up(sqlDB, migrationsDir); err != nil {
		return err
	}
	log.Info("Database migrations applied successfully")
	return nil
}

// main is the entry point for the Tercul application.
func main() {
	// Load configuration from environment variables
	config.LoadConfig()

	// Initialize logger
	log.Init("tercul-api", config.Cfg.Environment)
	obsLogger := observability.NewLogger("tercul-api", config.Cfg.Environment)

	// Initialize OpenTelemetry Tracer Provider
	tp, err := observability.TracerProvider("tercul-api", config.Cfg.Environment)
	if err != nil {
		log.Fatal(err, "Failed to initialize OpenTelemetry tracer")
	}
	defer func() {
		if err := tp.Shutdown(context.Background()); err != nil {
			log.Error(err, "Error shutting down tracer provider")
		}
	}()

	// Initialize Prometheus metrics
	reg := prometheus.NewRegistry()
	metrics := observability.NewMetrics(reg) // Metrics are registered automatically

	log.Info(fmt.Sprintf("Starting Tercul application in %s environment, version 1.0.0", config.Cfg.Environment))

	// Initialize database connection
	database, err := db.InitDB(metrics)
	if err != nil {
		log.Fatal(err, "Failed to initialize database")
	}
	defer db.Close()

	if err := runMigrations(database); err != nil {
		log.Fatal(err, "Failed to apply database migrations")
	}

	// Initialize Weaviate client
	weaviateCfg := weaviate.Config{
		Host:   config.Cfg.WeaviateHost,
		Scheme: config.Cfg.WeaviateScheme,
	}
	weaviateClient, err := weaviate.NewClient(weaviateCfg)
	if err != nil {
		log.Fatal(err, "Failed to create weaviate client")
	}

	// Create search client
	searchClient := search.NewWeaviateWrapper(weaviateClient)

	// Create repositories
	repos := dbsql.NewRepositories(database)

	// Create linguistics dependencies
	analysisRepo := linguistics.NewGORMAnalysisRepository(database)
	sentimentProvider, err := linguistics.NewGoVADERSentimentProvider()
	if err != nil {
		log.Fatal(err, "Failed to create sentiment provider")
	}

	// Create platform components
	jwtManager := auth.NewJWTManager()

	// Create application services
	analyticsService := analytics.NewService(repos.Analytics, analysisRepo, repos.Translation, repos.Work, sentimentProvider)

	// Create application dependencies
	deps := app.Dependencies{
		WorkRepo:          repos.Work,
		UserRepo:          repos.User,
		AuthorRepo:        repos.Author,
		TranslationRepo:   repos.Translation,
		CommentRepo:       repos.Comment,
		LikeRepo:          repos.Like,
		BookmarkRepo:      repos.Bookmark,
		CollectionRepo:    repos.Collection,
		TagRepo:           repos.Tag,
		CategoryRepo:      repos.Category,
		BookRepo:          repos.Book,
		PublisherRepo:     repos.Publisher,
		SourceRepo:        repos.Source,
		CopyrightRepo:     repos.Copyright,
		MonetizationRepo:  repos.Monetization,
		AnalyticsRepo:     repos.Analytics,
		AuthRepo:          repos.Auth,
		LocalizationRepo:  repos.Localization,
		SearchClient:      searchClient,
		AnalyticsService:  analyticsService,
		JWTManager:        jwtManager,
	}

	// Create application
	application := app.NewApplication(deps)

	// Create GraphQL server
	resolver := &graph.Resolver{
		App: application,
	}

	// Create handlers
	apiHandler := NewServerWithAuth(resolver, jwtManager, metrics, obsLogger)
	playgroundHandler := playground.Handler("GraphQL Playground", "/query")
	metricsHandler := observability.PrometheusHandler(reg)

	// Consolidate handlers into a single mux
	mux := http.NewServeMux()
	mux.Handle("/query", apiHandler)
	mux.Handle("/playground", playgroundHandler)
	mux.Handle("/metrics", metricsHandler)

	// Create a single HTTP server
	mainServer := &http.Server{
		Addr:    config.Cfg.ServerPort,
		Handler: mux,
	}
	log.Info(fmt.Sprintf("API server listening on port %s", config.Cfg.ServerPort))

	// Start the main server in a goroutine
	go func() {
		if err := mainServer.ListenAndServe(); err != nil && err != http.ErrServerClosed {
			log.Fatal(err, "Failed to start server")
		}
	}()

	// Wait for interrupt signal to gracefully shutdown the server
	quit := make(chan os.Signal, 1)
	signal.Notify(quit, syscall.SIGINT, syscall.SIGTERM)
	<-quit
	log.Info("Shutting down server...")

	// Graceful shutdown
	ctx, cancel := context.WithTimeout(context.Background(), 30*time.Second)
	defer cancel()

	if err := mainServer.Shutdown(ctx); err != nil {
		log.Error(err, "Server forced to shutdown")
	}

	log.Info("Server shut down successfully")
}