package app

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

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

	"github.com/gochat/gochat/internal/config"
	applogger "github.com/gochat/gochat/pkg/logger"
)

// NewDatabase creates a GORM database connection.
// Pattern follows Chatwoot's ActiveRecord PostgreSQL setup in config/database.yml
func NewDatabase(cfg *config.DatabaseConfig, logLevel string) (*gorm.DB, error) {
	dsn := cfg.DSN

	// Map log level to GORM logger level
	var gormLogLevel gormlogger.LogLevel
	switch logLevel {
	case "silent":
		gormLogLevel = gormlogger.Silent
	case "error":
		gormLogLevel = gormlogger.Error
	case "warn":
		gormLogLevel = gormlogger.Warn
	case "info":
		gormLogLevel = gormlogger.Info
	default:
		gormLogLevel = gormlogger.Info
	}

	db, err := gorm.Open(postgres.Open(dsn), &gorm.Config{
		Logger:                                   newDatabaseLogger(gormLogLevel),
		PrepareStmt:                              true,
		DisableForeignKeyConstraintWhenMigrating: true, // migrate first, add FK constraints later
	})
	if err != nil {
		return nil, fmt.Errorf("failed to connect to database: %w", err)
	}

	// Configure connection pool (ref: Chatwoot config/database.yml pool settings)
	sqlDB, err := db.DB()
	if err != nil {
		return nil, fmt.Errorf("failed to get underlying sql.DB: %w", err)
	}
	sqlDB.SetMaxOpenConns(cfg.MaxOpenConns)
	sqlDB.SetMaxIdleConns(cfg.MaxIdleConns)
	sqlDB.SetConnMaxLifetime(5 * time.Minute)
	sqlDB.SetConnMaxIdleTime(10 * time.Minute)

	// Set default statement timeout (ref: Chatwoot POSTGRES_STATEMENT_TIMEOUT)
	db.Set("gorm:statement_timeout", "5000ms")

	applogger.L().Infof("Connected to PostgreSQL (pool=%d)", cfg.MaxOpenConns)

	return db, nil
}

func newDatabaseLogger(level gormlogger.LogLevel) gormlogger.Interface {
	return gormlogger.New(log.New(os.Stdout, "\r\n", log.LstdFlags), gormlogger.Config{
		SlowThreshold:             200 * time.Millisecond,
		LogLevel:                  level,
		IgnoreRecordNotFoundError: true,
		ParameterizedQueries:      true,
	})
}