package main

import (
	"context"
	"errors"
	"fmt"
	"log"
	"os"
	"os/signal"

	"github.com/golang-migrate/migrate/v4"

	// Use it to append postgres sql and file drivers.
	_ "github.com/golang-migrate/migrate/v4/database/postgres"
	_ "github.com/golang-migrate/migrate/v4/source/file"
)

func main() {
	ctx, cancel := signal.NotifyContext(context.Background(), os.Interrupt)
	defer cancel()

	err := app(ctx)
	if err != nil {
		log.Fatalf("unable to run app: %v", err)
	}
}

func app(_ context.Context) (err error) {
	const filepath = "file:///app/db/migrations"
	pgdsn := os.Getenv("DEVSIM_PG_DSN")
	if pgdsn == "" {
		return nil
	}

	filedsn := os.Getenv("DEVSIM_PG_MIGRATION")
	if filedsn == "" {
		filedsn = filepath
	}

	log.Println("going to apply migrations from path: " + filedsn)
	migrations, err := migrate.New(
		filedsn,
		pgdsn,
	)
	if err != nil {
		return fmt.Errorf("making migrator: %w", err)
	}

	defer func() {
		sourceErr, dbErr := migrations.Close()
		err = errors.Join(err, sourceErr, dbErr)
	}()

	version, dirty, err := migrations.Version()
	if errors.Is(err, migrate.ErrNilVersion) {
		log.Println("no migrations applied to database")
	} else if err != nil {
		return fmt.Errorf("getting version: %w", err)
	} else {
		log.Printf("current migration version: %d (dirty: %t)", version, dirty)
	}

	err = migrations.Up()
	if err != nil {
		return fmt.Errorf("applying migrations: %w", err)
	}

	version, dirty, err = migrations.Version()
	if errors.Is(err, migrate.ErrNilVersion) {
		log.Println("no migrations applied to database")
	} else if err != nil {
		return fmt.Errorf("getting version: %w", err)
	} else {
		log.Printf("updated to migration version: %d (dirty: %t)", version, dirty)
	}

	return nil
}