package main

import (
	"context"
	"flag"
	"fmt"
	"log/slog"
	"net"
	"net/http"
	"os"
	"os/exec"
	"os/signal"
	"path/filepath"
	"runtime"
	"syscall"
	"time"

	qfassets "git.mchus.pro/mchus/priceforge"
	"git.mchus.pro/mchus/priceforge/internal/appmeta"
	"git.mchus.pro/mchus/priceforge/internal/appstate"
	"git.mchus.pro/mchus/priceforge/internal/config"
	"git.mchus.pro/mchus/priceforge/internal/db"
	"git.mchus.pro/mchus/priceforge/internal/handlers"
	"git.mchus.pro/mchus/priceforge/internal/middleware"
	"git.mchus.pro/mchus/priceforge/internal/models"
	"git.mchus.pro/mchus/priceforge/internal/repository"
	"git.mchus.pro/mchus/priceforge/internal/services"
	"git.mchus.pro/mchus/priceforge/internal/services/alerts"
	"git.mchus.pro/mchus/priceforge/internal/services/pricelist"
	"git.mchus.pro/mchus/priceforge/internal/services/pricing"
	"github.com/gin-gonic/gin"
	"gorm.io/driver/mysql"
	"gorm.io/gorm"
	"gorm.io/gorm/logger"
)

// Version is set via ldflags during build
var Version = "dev"

const backgroundSyncInterval = 5 * time.Minute

func main() {
	configPath := flag.String("config", "", "path to config file (default: user state dir or QFS_CONFIG_PATH)")
	migrate := flag.Bool("migrate", false, "run database migrations")
	version := flag.Bool("version", false, "show version information")
	flag.Parse()

	// Show version if requested
	if *version {
		fmt.Printf("pfs version %s\n", Version)
		os.Exit(0)
	}

	exePath, _ := os.Executable()
	slog.Info("starting pfs", "version", Version, "executable", exePath)
	appmeta.SetVersion(Version)

	resolvedConfigPath, err := appstate.ResolveConfigPath(*configPath)
	if err != nil {
		slog.Error("failed to resolve config path", "error", err)
		os.Exit(1)
	}

	// Migrate legacy project-local config path to the user state directory when using defaults.
	if *configPath == "" && os.Getenv("QFS_CONFIG_PATH") == "" {
		migratedFrom, migrateErr := appstate.MigrateLegacyFile(resolvedConfigPath, []string{"config.yaml"})
		if migrateErr != nil {
			slog.Warn("failed to migrate legacy config file", "error", migrateErr)
		} else if migratedFrom != "" {
			slog.Info("migrated legacy config file", "from", migratedFrom, "to", resolvedConfigPath)
		}
	}

	// Load config for server settings
	cfg, err := config.Load(resolvedConfigPath)
	if err != nil {
		slog.Error("failed to load config", "path", resolvedConfigPath, "error", err)
		os.Exit(1)
	}
	setConfigDefaults(cfg)
	slog.Info("resolved runtime files", "config_path", resolvedConfigPath)

	setupLogger(cfg.Logging)

	dsn := cfg.Database.DSN()
	dsnHost := net.JoinHostPort(cfg.Database.Host, fmt.Sprintf("%d", cfg.Database.Port))
	connMgr := db.NewConnectionManager(dsn, dsnHost)
	dbUser := cfg.Database.User

	// Fail-fast mode: MariaDB must be available on startup.
	mariaDB, err := connMgr.GetDB()
	if err != nil {
		slog.Error("failed to connect to MariaDB on startup", "error", err)
		os.Exit(1)
	}
	slog.Info("successfully connected to MariaDB on startup")

	slog.Info("starting PriceForge server",
		"version", Version,
		"host", cfg.Server.Host,
		"port", cfg.Server.Port,
		"db_user", dbUser,
		"online", true,
	)

	if *migrate {
		slog.Info("running database migrations...")
		if err := models.Migrate(mariaDB); err != nil {
			slog.Error("migration failed", "error", err)
			os.Exit(1)
		}
		if err := models.SeedCategories(mariaDB); err != nil {
			slog.Error("seeding categories failed", "error", err)
			os.Exit(1)
		}
		slog.Info("migrations completed")
	}

	// Always apply SQL migrations on startup when database is available.
	// This keeps schema in sync for long-running installations without manual steps.
	// If current DB user does not have enough privileges, continue startup in normal mode.
	sqlMigrationsPath := filepath.Join("migrations")
	needsMigrations, err := models.NeedsSQLMigrations(mariaDB, sqlMigrationsPath)
	if err != nil {
		if models.IsMigrationPermissionError(err) {
			slog.Info("startup SQL migrations skipped: insufficient database privileges", "path", sqlMigrationsPath, "error", err)
		} else if needsMigrations {
			slog.Error("startup SQL migrations check failed", "path", sqlMigrationsPath, "error", err)
			os.Exit(1)
		}
	} else if needsMigrations {
		if err := models.RunSQLMigrations(mariaDB, sqlMigrationsPath); err != nil {
			if models.IsMigrationPermissionError(err) {
				slog.Info("startup SQL migrations skipped: insufficient database privileges", "path", sqlMigrationsPath, "error", err)
			} else {
				slog.Error("startup SQL migrations failed", "path", sqlMigrationsPath, "error", err)
				os.Exit(1)
			}
		} else {
			slog.Info("startup SQL migrations applied", "path", sqlMigrationsPath)
		}
	} else {
		slog.Debug("startup SQL migrations not needed", "path", sqlMigrationsPath)
	}

	gin.SetMode(cfg.Server.Mode)
	router, err := setupRouter(cfg, connMgr, mariaDB, dbUser)
	if err != nil {
		slog.Error("failed to setup router", "error", err)
		os.Exit(1)
	}

	srv := &http.Server{
		Addr:         cfg.Address(),
		Handler:      router,
		ReadTimeout:  cfg.Server.ReadTimeout,
		WriteTimeout: cfg.Server.WriteTimeout,
	}

	go func() {
		slog.Info("server listening", "address", cfg.Address())
		if err := srv.ListenAndServe(); err != nil && err != http.ErrServerClosed {
			slog.Error("server error", "error", err)
			os.Exit(1)
		}
	}()

	// Automatically open browser after server starts (with a small delay)
	go func() {
		time.Sleep(1 * time.Second)
		// Always use localhost for browser, even if server binds to 0.0.0.0
		browserURL := fmt.Sprintf("http://127.0.0.1:%d", cfg.Server.Port)
		slog.Info("Opening browser to", "url", browserURL)
		err := openBrowser(browserURL)
		if err != nil {
			slog.Warn("Failed to open browser", "error", err)
		}
	}()

	quit := make(chan os.Signal, 1)
	signal.Notify(quit, syscall.SIGINT, syscall.SIGTERM)

	<-quit
	slog.Info("shutting down server...")

	// Shutdown HTTP server
	ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
	defer cancel()

	if err := srv.Shutdown(ctx); err != nil {
		slog.Error("server forced to shutdown", "error", err)
	}

	slog.Info("server stopped")

}

func setConfigDefaults(cfg *config.Config) {
	if cfg.Server.Host == "" {
		cfg.Server.Host = "127.0.0.1"
	}
	if cfg.Server.Port == 0 {
		cfg.Server.Port = 8084
	}
	if cfg.Server.Mode == "" {
		cfg.Server.Mode = "release"
	}
	if cfg.Server.ReadTimeout == 0 {
		cfg.Server.ReadTimeout = 30 * time.Second
	}
	if cfg.Server.WriteTimeout == 0 {
		cfg.Server.WriteTimeout = 30 * time.Second
	}
	if cfg.Pricing.DefaultMethod == "" {
		cfg.Pricing.DefaultMethod = "weighted_median"
	}
	if cfg.Pricing.DefaultPeriodDays == 0 {
		cfg.Pricing.DefaultPeriodDays = 90
	}
	if cfg.Pricing.FreshnessGreenDays == 0 {
		cfg.Pricing.FreshnessGreenDays = 30
	}
	if cfg.Pricing.FreshnessYellowDays == 0 {
		cfg.Pricing.FreshnessYellowDays = 60
	}
	if cfg.Pricing.FreshnessRedDays == 0 {
		cfg.Pricing.FreshnessRedDays = 90
	}
	if cfg.Pricing.MinQuotesForMedian == 0 {
		cfg.Pricing.MinQuotesForMedian = 3
	}
}

func setupLogger(cfg config.LoggingConfig) {
	var level slog.Level
	switch cfg.Level {
	case "debug":
		level = slog.LevelDebug
	case "warn":
		level = slog.LevelWarn
	case "error":
		level = slog.LevelError
	default:
		level = slog.LevelInfo
	}

	opts := &slog.HandlerOptions{Level: level}

	var handler slog.Handler
	if cfg.Format == "json" {
		handler = slog.NewJSONHandler(os.Stdout, opts)
	} else {
		handler = slog.NewTextHandler(os.Stdout, opts)
	}

	slog.SetDefault(slog.New(handler))
}

func setupDatabaseFromDSN(dsn string) (*gorm.DB, error) {
	gormLogger := logger.Default.LogMode(logger.Silent)

	db, err := gorm.Open(mysql.Open(dsn), &gorm.Config{
		Logger: gormLogger,
	})
	if err != nil {
		return nil, err
	}

	sqlDB, err := db.DB()
	if err != nil {
		return nil, err
	}

	sqlDB.SetMaxOpenConns(25)
	sqlDB.SetMaxIdleConns(5)
	sqlDB.SetConnMaxLifetime(5 * time.Minute)

	return db, nil
}

func setupRouter(cfg *config.Config, connMgr *db.ConnectionManager, mariaDB *gorm.DB, dbUser string) (*gin.Engine, error) {
	var componentRepo *repository.ComponentRepository
	var categoryRepo *repository.CategoryRepository
	var priceRepo *repository.PriceRepository
	var alertRepo *repository.AlertRepository
	var statsRepo *repository.StatsRepository
	var pricelistRepo *repository.PricelistRepository

	if mariaDB != nil {
		componentRepo = repository.NewComponentRepository(mariaDB)
		categoryRepo = repository.NewCategoryRepository(mariaDB)
		priceRepo = repository.NewPriceRepository(mariaDB)
		alertRepo = repository.NewAlertRepository(mariaDB)
		statsRepo = repository.NewStatsRepository(mariaDB)
		pricelistRepo = repository.NewPricelistRepository(mariaDB)
	}

	pricingService := pricing.NewService(componentRepo, priceRepo, cfg.Pricing)
	componentService := services.NewComponentService(componentRepo, categoryRepo, statsRepo)
	alertService := alerts.NewService(alertRepo, componentRepo, priceRepo, statsRepo, cfg.Alerts, cfg.Pricing)
	pricelistService := pricelist.NewService(mariaDB, pricelistRepo, componentRepo, pricingService)
	stockImportService := services.NewStockImportService(mariaDB, pricelistService)

	templatesPath := filepath.Join("web", "templates")
	componentHandler := handlers.NewComponentHandler(componentService)
	pricingHandler := handlers.NewPricingHandler(
		mariaDB,
		pricingService,
		alertService,
		componentRepo,
		priceRepo,
		statsRepo,
		stockImportService,
		dbUser,
	)
	pricelistHandler := handlers.NewPricelistHandler(pricelistService, dbUser)
	webHandler, err := handlers.NewWebHandler(templatesPath, componentService)
	if err != nil {
		return nil, err
	}

	router := gin.New()
	router.Use(gin.Recovery())
	router.Use(requestLogger())
	router.Use(middleware.CORS())
	router.Use(middleware.OfflineDetector(connMgr))

	staticPath := filepath.Join("web", "static")
	if stat, err := os.Stat(staticPath); err == nil && stat.IsDir() {
		router.Static("/static", staticPath)
	} else if staticFS, err := qfassets.StaticFS(); err == nil {
		router.StaticFS("/static", http.FS(staticFS))
	}

	router.GET("/health", func(c *gin.Context) {
		c.JSON(http.StatusOK, gin.H{
			"status": "ok",
			"time":   time.Now().UTC().Format(time.RFC3339),
		})
	})

	router.POST("/api/restart", func(c *gin.Context) {
		slog.Info("Restart requested via API")
		go func() {
			time.Sleep(100 * time.Millisecond)
			restartProcess()
		}()
		c.JSON(http.StatusOK, gin.H{"message": "restarting..."})
	})

	router.GET("/api/db-status", func(c *gin.Context) {
		var lotCount, lotLogCount, metadataCount int64
		var dbOK bool
		var dbError string
		includeCounts := c.Query("include_counts") == "true"

		status := connMgr.GetStatus()
		dbOK = status.IsConnected
		if !status.IsConnected {
			dbError = "Database not connected (offline mode)"
			if status.LastError != "" {
				dbError = status.LastError
			}
		}

		if includeCounts && status.IsConnected {
			if db, err := connMgr.GetDB(); err == nil && db != nil {
				_ = db.Table("lot").Count(&lotCount)
				_ = db.Table("lot_log").Count(&lotLogCount)
				_ = db.Table("qt_lot_metadata").Count(&metadataCount)
			} else if err != nil {
				dbOK = false
				dbError = err.Error()
			} else {
				dbOK = false
				dbError = "Database not connected (offline mode)"
			}
		}

		c.JSON(http.StatusOK, gin.H{
			"connected":      dbOK,
			"error":          dbError,
			"lot_count":      lotCount,
			"lot_log_count":  lotLogCount,
			"metadata_count": metadataCount,
			"db_user":        dbUser,
			"db_host":        status.DSNHost,
		})
	})

	router.GET("/api/current-user", func(c *gin.Context) {
		c.JSON(http.StatusOK, gin.H{
			"username": dbUser,
			"role":     "db_user",
		})
	})

	router.GET("/", webHandler.Index)
	router.GET("/pricelists", webHandler.Pricelists)
	router.GET("/pricelists/:id", webHandler.PricelistDetail)
	router.GET("/admin/pricing", webHandler.AdminPricing)

	partials := router.Group("/partials")
	{
		partials.GET("/components", webHandler.ComponentsPartial)
	}

	api := router.Group("/api")
	{
		api.GET("/ping", func(c *gin.Context) {
			c.JSON(http.StatusOK, gin.H{"message": "pong"})
		})

		components := api.Group("/components")
		{
			components.GET("", componentHandler.List)
			components.GET("/:lot_name", componentHandler.Get)
		}
		api.GET("/categories", componentHandler.GetCategories)

		pricelists := api.Group("/pricelists")
		{
			pricelists.GET("", pricelistHandler.List)
			pricelists.GET("/can-write", pricelistHandler.CanWrite)
			pricelists.GET("/latest", pricelistHandler.GetLatest)
			pricelists.GET("/:id", pricelistHandler.Get)
			pricelists.GET("/:id/items", pricelistHandler.GetItems)
			pricelists.GET("/:id/lots", pricelistHandler.GetLotNames)
			pricelists.POST("", pricelistHandler.Create)
			pricelists.POST("/create-with-progress", pricelistHandler.CreateWithProgress)
			pricelists.PATCH("/:id/active", pricelistHandler.SetActive)
			pricelists.DELETE("/:id", pricelistHandler.Delete)
		}

		pricingAdmin := api.Group("/admin/pricing")
		{
			pricingAdmin.GET("/stats", pricingHandler.GetStats)
			pricingAdmin.GET("/components", pricingHandler.ListComponents)
			pricingAdmin.GET("/components/:lot_name", pricingHandler.GetComponentPricing)
			pricingAdmin.POST("/update", pricingHandler.UpdatePrice)
			pricingAdmin.POST("/preview", pricingHandler.PreviewPrice)
			pricingAdmin.POST("/recalculate-all", pricingHandler.RecalculateAll)
			pricingAdmin.GET("/lots", pricingHandler.ListLots)
			pricingAdmin.GET("/lots-table", pricingHandler.ListLotsTable)
			pricingAdmin.POST("/stock/import", pricingHandler.ImportStockLog)
			pricingAdmin.GET("/stock/mappings", pricingHandler.ListStockMappings)
			pricingAdmin.POST("/stock/mappings", pricingHandler.UpsertStockMapping)
			pricingAdmin.DELETE("/stock/mappings/:partnumber", pricingHandler.DeleteStockMapping)
			pricingAdmin.GET("/stock/ignore-rules", pricingHandler.ListStockIgnoreRules)
			pricingAdmin.POST("/stock/ignore-rules", pricingHandler.UpsertStockIgnoreRule)
			pricingAdmin.DELETE("/stock/ignore-rules/:id", pricingHandler.DeleteStockIgnoreRule)
			pricingAdmin.GET("/alerts", pricingHandler.ListAlerts)
			pricingAdmin.POST("/alerts/:id/acknowledge", pricingHandler.AcknowledgeAlert)
			pricingAdmin.POST("/alerts/:id/resolve", pricingHandler.ResolveAlert)
			pricingAdmin.POST("/alerts/:id/ignore", pricingHandler.IgnoreAlert)
		}

	}

	return router, nil
}

// restartProcess restarts the current process with the same arguments
func restartProcess() {
	executable, err := os.Executable()
	if err != nil {
		slog.Error("failed to get executable path", "error", err)
		os.Exit(1)
	}

	args := os.Args
	env := os.Environ()

	slog.Info("executing restart", "executable", executable, "args", args)

	err = syscall.Exec(executable, args, env)
	if err != nil {
		slog.Error("failed to restart process", "error", err)
		os.Exit(1)
	}
}

func openBrowser(url string) error {
	var cmd string
	var args []string

	switch runtime.GOOS {
	case "windows":
		cmd = "cmd"
		args = []string{"/c", "start", url}
	case "darwin":
		cmd = "open"
		args = []string{url}
	default: // "linux", "freebsd", "openbsd", "netbsd"
		cmd = "xdg-open"
		args = []string{url}
	}

	return exec.Command(cmd, args...).Start()
}

func requestLogger() gin.HandlerFunc {
	return func(c *gin.Context) {
		start := time.Now()
		path := c.Request.URL.Path
		query := c.Request.URL.RawQuery

		c.Next()

		latency := time.Since(start)
		status := c.Writer.Status()

		slog.Info("request",
			"method", c.Request.Method,
			"path", path,
			"query", query,
			"status", status,
			"latency", latency,
			"ip", c.ClientIP(),
		)
	}
}