package database

import (
	"context"
	"fmt"
	_ "github.com/jackc/pgx/v5/stdlib"
	_ "github.com/joho/godotenv/autoload"
	"go.mongodb.org/mongo-driver/mongo"
	"go.mongodb.org/mongo-driver/mongo/options"
	"go.mongodb.org/mongo-driver/mongo/readpref"
	"gorm.io/driver/postgres"
	"gorm.io/gorm"
	"log"
	"os"
	"strconv"
	"strings"
	"time"
)

// Service represents a service that interacts with a database.
type Service interface {
	Health() map[string]string
	Close() error
	GetDB(database string) *gorm.DB
	GetMongoDB() *mongo.Database
}

type service struct {
	simrsDB    *gorm.DB
	satuDataDB *gorm.DB
	client     *mongo.Client
	mongoDB    *mongo.Database
}

var (
	hostSimrs     = os.Getenv("SIMRS_STAG_HOST")
	userNameSimrs = os.Getenv("SIMRS_STAG_USER")
	passwordSimrs = os.Getenv("SIMRS_STAG_PASS")
	dbNameSimrs   = os.Getenv("SIMRS_STAG_NAME")
	portSimrs     = os.Getenv("SIMRS_STAG_PORT")

	hostSatudata     = os.Getenv("SATUDATA_HOST")
	userNameSatudata = os.Getenv("SATUDATA_USER")
	passwordSatudata = os.Getenv("SATUDATA_PASS")
	dbNameSatudata   = os.Getenv("SATUDATA_NAME")
	portSatudata     = os.Getenv("SATUDATA_PORT")

	hostMongo  = os.Getenv("MONGODB_DEV_HOST")
	portMongo  = os.Getenv("MONGODB_DEV_PORT")
	userMongo  = os.Getenv("MONGODB_DEV_USER")
	passMongo  = os.Getenv("MONGODB_DEV_PASS")
	dbInstance *service
)

func New(database ...string) Service {
	mongoDBName := os.Getenv("MONGODB_DEV_MASTER")
	if len(database) > 0 {
		mongoDBName = database[0]
	}
	if dbInstance != nil {
		if database != nil {
			mongoURI := fmt.Sprintf("mongodb://%s:%s@%s:%s/%s?authSource=admin",
				userMongo, passMongo, hostMongo, portMongo, mongoDBName)
			log.Println("Connecting to MongoDB...")
			log.Println(mongoURI)
			clientOptions := options.Client().ApplyURI(mongoURI)
			ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
			defer cancel()
			client, err := mongo.Connect(ctx, clientOptions)
			if err == nil {
				log.Println("Connected to MongoDB")
			}
			if err = client.Ping(ctx, readpref.Primary()); err != nil {
				log.Println("Failed to connect to MongoDB!!!")
				log.Fatalf("Failed to connect to database: %v", err)
			}
			dbInstance.mongoDB = client.Database(mongoDBName)
		}
		return dbInstance
	}
	simrs := fmt.Sprintf("host=%s user=%s password=%s dbname=%s port=%s sslmode=disable TimeZone=Asia/Jakarta", hostSimrs, userNameSimrs, passwordSimrs, dbNameSimrs, portSimrs)

	SimrsDB, err := gorm.Open(postgres.Open(simrs), &gorm.Config{})
	if err != nil {
		log.Fatal("Failed to connect to SIM database: ", err)
	} else {
		log.Println("Successfully connected to the database")
	}
	satudata := fmt.Sprintf("host=%s user=%s password=%s dbname=%s port=%s sslmode=disable TimeZone=Asia/Jakarta", hostSatudata, userNameSatudata, passwordSatudata, dbNameSatudata, portSatudata)

	SatudataDB, err := gorm.Open(postgres.Open(satudata), &gorm.Config{})
	if err != nil {
		log.Fatal("Failed to connect to SIM database: ", err)
	} else {
		log.Println("Successfully connected to the database")
	}
	mongoURI := fmt.Sprintf("mongodb://%s:%s@%s:%s/%s?authSource=admin",
		userMongo, passMongo, hostMongo, portMongo, database)
	var client *mongo.Client
	log.Println("Connecting to MongoDB...")
	log.Println(mongoURI)
	clientOptions := options.Client().ApplyURI(mongoURI)

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

	for i := 0; i < 5; i++ {
		client, err = mongo.Connect(ctx, clientOptions)
		if err == nil {
			log.Println("Connected to MongoDB")
			break
		}
		log.Printf("Attempt %d: Failed to connect to MongoDB, retrying in 5 seconds...\n", i+1)
		time.Sleep(5 * time.Second)
	}

	if err != nil {
		log.Fatalf("Failed to create client: %v", err)
	}

	// Verify connection
	if err = client.Ping(ctx, readpref.Primary()); err != nil {
		log.Println("Failed to connect to MongoDB!!!")
		log.Fatalf("Failed to connect to database: %v", err)
	}

	log.Println("Successfully connected to MongoDB!")
	dbInstance = &service{
		simrsDB:    SimrsDB,
		satuDataDB: SatudataDB,
		mongoDB:    client.Database(mongoDBName),
	}
	return dbInstance
}

// Health checks the health of the database connection by pinging the database.
// It returns a map with keys indicating various health statistics.
func (s *service) Health() map[string]string {
	ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
	defer cancel()

	stats := make(map[string]string)

	// Ping the database using GORM
	db, err := s.simrsDB.DB() // Retrieve the underlying sql.DB instance from GORM
	if err != nil {
		stats["status"] = "down"
		stats["error"] = fmt.Sprintf("failed to get sql.DB from GORM: %v", err)
		log.Fatalf("failed to get sql.DB from GORM: %v", err) // Log the error and terminate the program
		return stats
	}

	err = db.PingContext(ctx)
	if err != nil {
		stats["status"] = "down"
		stats["error"] = fmt.Sprintf("db down: %v", err)
		log.Fatalf("db down: %v", err) // Log the error and terminate the program
		return stats
	}

	// Database is up, add more statistics
	stats["status"] = "up"
	stats["message"] = "It's healthy"

	// Get database stats
	dbStats := db.Stats()
	stats["open_connections"] = strconv.Itoa(dbStats.OpenConnections)
	stats["in_use"] = strconv.Itoa(dbStats.InUse)
	stats["idle"] = strconv.Itoa(dbStats.Idle)
	stats["wait_count"] = strconv.FormatInt(dbStats.WaitCount, 10)
	stats["wait_duration"] = dbStats.WaitDuration.String()
	stats["max_idle_closed"] = strconv.FormatInt(dbStats.MaxIdleClosed, 10)
	stats["max_lifetime_closed"] = strconv.FormatInt(dbStats.MaxLifetimeClosed, 10)

	// Evaluate stats to provide a health message
	if dbStats.OpenConnections > 40 { // Assuming 50 is the max for this example
		stats["message"] = "The database is experiencing heavy load."
	}

	if dbStats.WaitCount > 1000 {
		stats["message"] = "The database has a high number of wait events, indicating potential bottlenecks."
	}

	if dbStats.MaxIdleClosed > int64(dbStats.OpenConnections)/2 {
		stats["message"] = "Many idle connections are being closed, consider revising the connection pool settings."
	}

	if dbStats.MaxLifetimeClosed > int64(dbStats.OpenConnections)/2 {
		stats["message"] = "Many connections are being closed due to max lifetime, consider increasing max lifetime or revising the connection usage pattern."
	}

	return stats
}

// Close closes the database connection.
// It logs a message indicating the disconnection from the specific database.
// If the connection is successfully closed, it returns nil.
// If an error occurs while closing the connection, it returns the error.
func (s *service) Close() error {
	db, err := s.simrsDB.DB() // Retrieve the underlying sql.DB instance from GORM
	if err != nil {
		log.Printf("Failed to retrieve sql.DB from GORM: %v", err)
		return err
	}

	err = db.Close()
	if err != nil {
		log.Printf("Error closing the database connection: %v", err)
		return err
	}

	log.Printf("Disconnected from database successfully")
	return nil
}

func (s *service) GetDB(database string) *gorm.DB {
	if strings.ToLower(database) == "simrs" {
		return s.simrsDB
	} else if strings.ToLower(database) == "satudata" {
		return s.satuDataDB
	}
	log.Println("Database tidak ditemukan")
	return nil
}

func (s *service) GetMongoDB() *mongo.Database {
	return s.mongoDB
}