package schema

import (
    "fmt"
    "log"
    "os"
    "time"

    "gorm.io/driver/postgres"
    "gorm.io/gorm"
    "gorm.io/gorm/logger"
    
)

var DB *gorm.DB

func Connect() {
    // Build the connection string from environment variables
    // This keeps sensitive credentials out of the codebase
    dsn := fmt.Sprintf(
        "host=%s user=%s password=%s dbname=%s port=%s sslmode=disable",
        os.Getenv("DB_HOST"),
        os.Getenv("DB_USER"),
        os.Getenv("DB_PASSWORD"),
        os.Getenv("DB_NAME"),
        os.Getenv("DB_PORT"),
    )

    // Configure GORM with custom settings
    // The logger helps with debugging SQL queries during development
    db, err := gorm.Open(postgres.Open(dsn), &gorm.Config{
        Logger: logger.Default.LogMode(logger.Info),
    })
    if err != nil {
        log.Fatal("Failed to connect to database:", err)
    }

    // Get the underlying SQL database connection for pool configuration
    sqlDB, err := db.DB()
    if err != nil {
        log.Fatal("Failed to get database instance:", err)
    }

    // Configure connection pool settings
    // MaxIdleConns: number of connections kept open when idle
    sqlDB.SetMaxIdleConns(10)
    // MaxOpenConns: maximum total connections to the database
    sqlDB.SetMaxOpenConns(100)
    // ConnMaxLifetime: how long a connection can be reused
    sqlDB.SetConnMaxLifetime(time.Hour)

    DB = db
    log.Println("Database connected successfully")
}

func RunMigrations() {
    // AutoMigrate creates tables, missing columns, and missing indexes
    // It will NOT delete unused columns to protect your data
    err := DB.AutoMigrate(
        &MediaActor{},
        &MediaFile{},
        &MediaActorFile{},
    )
    if err != nil {
        log.Fatal("Migration failed:", err)
    }

    log.Println("Database migration completed")
}