package internal

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

	"github.com/kelseyhightower/envconfig"
	"github.com/uptrace/bun/driver/pgdriver"

	"github.com/uptrace/bun"
	"github.com/uptrace/bun/dialect/pgdialect"
)

const (
	dbPingTimeout = 10 * time.Second
)

type bunConfig struct {
	DSN                   string        `envconfig:"DSN" required:"true"`
	MaxOpenConnections    int           `envconfig:"MAX_OPEN_CONNECTIONS" default:"5"`
	MaxIdleConnections    int           `envconfig:"MAX_IDLE_CONNECTIONS" default:"2"`
	ConnectionMaxLifetime time.Duration `envconfig:"CONNECTION_MAX_LIFETIME" default:"3m"`
}

func NewBunDB() (*bun.DB, error) {
	var cfg bunConfig
	if err := envconfig.Process("DB", &cfg); err != nil {
		return nil, fmt.Errorf("envconfig.Process: %w", err)
	}

	db := bun.NewDB(newSQLDB(cfg), pgdialect.New())

	ctx, cancel := context.WithTimeout(context.Background(), dbPingTimeout)
	defer cancel()
	if err := db.PingContext(ctx); err != nil {
		return nil, fmt.Errorf("db.PingContext: %w", err)
	}

	return db, nil
}

func newSQLDB(cfg bunConfig) *sql.DB {
	db := sql.OpenDB(pgdriver.NewConnector(pgdriver.WithDSN(cfg.DSN)))
	db.SetMaxOpenConns(cfg.MaxOpenConnections)
	db.SetMaxIdleConns(cfg.MaxIdleConnections)
	db.SetConnMaxLifetime(cfg.ConnectionMaxLifetime)
	return db
}