package db

import (
	"context"
	"database/sql"
	"fmt"
	"os"
	"time"

	"doormile/config"
	"doormile/utils"

	nats "github.com/nats-io/nats.go"
	"github.com/redis/go-redis/v9"
	"gorm.io/driver/postgres"
	"gorm.io/gorm"
	"gorm.io/gorm/logger"
)

var (
	DB  *gorm.DB
	Rdb *redis.Client
	Ctx = context.Background()
	Nc  *nats.Conn
	Js  nats.JetStreamContext
)

func Connect(cfg *config.Config) {
	dsn := fmt.Sprintf(
		"host=%s user=%s password=%s dbname=%s port=%s sslmode=disable TimeZone=Asia/Kolkata",
		cfg.DBHost,
		cfg.DBUser,
		cfg.DBPassword,
		cfg.DBName,
		cfg.DBPort,
	)

	var err error
	maxRetries := 5
	backoff := 2 * time.Second

	for i := 1; i <= maxRetries; i++ {
		utils.Info("Connecting to database", "attempt", i, "host", cfg.DBHost, "port", cfg.DBPort)

		DB, err = gorm.Open(postgres.Open(dsn), &gorm.Config{
			Logger: logger.Default.LogMode(logger.Error),
		})

		if err == nil {
			sqlDB, dbErr := DB.DB()
			if dbErr == nil {
				ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
				defer cancel()

				if pingErr := sqlDB.PingContext(ctx); pingErr == nil {
					setupDB(DB)
					utils.Info("✅ Database connected successfully")
					startDBHealthCheck(sqlDB)
					return
				} else {
					err = pingErr
				}
			} else {
				err = dbErr
			}
		}

		utils.Error("❌ DB connection failed", "attempt", i, "error", err)
		time.Sleep(backoff)
		backoff *= 2
	}

	utils.Logger.Fatal("☢️ CRITICAL: DB connection failed after retries")
}

func setupDB(database *gorm.DB) {
	sqlDB, err := database.DB()
	if err != nil {
		utils.Error("Failed to get sql.DB", "error", err)
		return
	}

	sqlDB.SetMaxOpenConns(30)
	sqlDB.SetMaxIdleConns(5)
	sqlDB.SetConnMaxLifetime(5 * time.Minute)
	sqlDB.SetConnMaxIdleTime(2 * time.Minute)
}

func startDBHealthCheck(sqlDB *sql.DB) {
	go func() {
		for {
			ctx, cancel := context.WithTimeout(context.Background(), 3*time.Second)
			err := sqlDB.PingContext(ctx)
			cancel()

			if err != nil {
				utils.Error("❌ DB connection lost", "error", err)
			}

			time.Sleep(30 * time.Second)
		}
	}()
}

func CloseDB() {
	if DB == nil {
		return
	}
	sqlDB, err := DB.DB()
	if err != nil {
		utils.Error("Error retrieving sql.DB for close", "error", err)
		return
	}
	utils.Info("Closing DB connection")
	sqlDB.Close()
}

func InitRedis(cfg *config.Config) {
	addr := fmt.Sprintf("%s:%s", cfg.RedisHost, cfg.RedisPort)

	Rdb = redis.NewClient(&redis.Options{
		Addr:         addr,
		Username:     cfg.RedisUser,
		Password:     cfg.RedisPassword,
		DB:           0,
		DialTimeout:  5 * time.Second,
		ReadTimeout:  3 * time.Second,
		WriteTimeout: 3 * time.Second,
		PoolSize:     10,
		MinIdleConns: 2,
	})

	ctx, cancel := context.WithTimeout(context.Background(), 3*time.Second)
	defer cancel()

	_, err := Rdb.Ping(ctx).Result()
	if err != nil {
		utils.Error("⚠️ Redis connection failed, continuing in fallback mode", "addr", addr, "error", err)
	} else {
		utils.Info("✅ Redis connected successfully", "addr", addr)
	}
}

func InitNATS(cfg *config.Config) {
	var err error
	Nc, err = nats.Connect(
		cfg.NatsURL,
		nats.UserInfo(cfg.NatsUser, cfg.NatsPassword),
		nats.ReconnectWait(2*time.Second),
		nats.MaxReconnects(-1),
	)
	if err != nil {
		utils.Error("⚠️ NATS connection failed, continuing without NATS", "url", cfg.NatsURL, "error", err)
		return
	}

	Js, err = Nc.JetStream()
	if err != nil {
		utils.Error("⚠️ NATS JetStream init failed", "error", err)
		Nc.Close()
		Nc = nil
		return
	}

	utils.Info("✅ NATS JetStream connected successfully", "url", cfg.NatsURL)
}

func getEnv(key, fallback string) string {
	if val := os.Getenv(key); val != "" {
		return val
	}
	return fallback
}