package sqlite

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

	"git.phc.dm.unipi.it/phc/website/database"
	"github.com/jmoiron/sqlx"
)

type sqliteDBMigrate struct{ *sqlx.DB }

var _ database.DBMigrate = sqliteDBMigrate{}

func (db sqliteDBMigrate) Migrate(migrationFolder string) error {
	log.Printf(`Creating migrations table`)
	if _, err := db.Exec(`CREATE TABLE IF NOT EXISTS migrations(timestamp TEXT, filename TEXT)`); err != nil {
		return err
	}

	log.Printf(`Loading applied migrations`)
	appliedMigrations := []migration{}
	if err := db.Select(&appliedMigrations, `SELECT * FROM migrations`); err != nil {
		return err
	}

	entries, err := os.ReadDir(migrationFolder)
	if err != nil {
		return err
	}

	for i, entry := range entries {
		if entry.IsDir() {
			return fmt.Errorf("no dirs in migrations folder")
		}

		if i < len(appliedMigrations) {
			if appliedMigrations[i].Filename != entry.Name() {
				return fmt.Errorf("misapplied migration %q with %q", appliedMigrations[i].Filename, entry.Name())
			}

			log.Printf("Found applied migration %q", entry.Name())
			continue
		}

		log.Printf("Applying new migration %q", entry.Name())

		migrationPath := path.Join(migrationFolder, entry.Name())

		sqlStmts, err := os.ReadFile(migrationPath)
		if err != nil {
			return err
		}

		tx, err := db.Beginx()
		if err != nil {
			return err
		}

		if _, err := tx.Exec(string(sqlStmts)); err != nil {
			return err
		}

		if _, err := tx.Exec(`INSERT INTO migrations VALUES (?, ?)`,
			time.Now().Format(time.RFC3339),
			entry.Name(),
		); err != nil {
			return err
		}

		if err := tx.Commit(); err != nil {
			return err
		}
	}

	log.Printf("All migrations applied successfully, database up to date")

	return nil
}