package database

import (
	"database/sql"
	"embed"
	"io/fs"

	_ "github.com/mattn/go-sqlite3"
)

//go:embed sql/*.sql
var schemaFiles embed.FS

func (db *DB) migrate() error {
	statements := make([]string, 0)
	err := fs.WalkDir(schemaFiles, ".", func(path string, d fs.DirEntry, err error) error {
		if d.IsDir() || err != nil {
			return err
		}
		var stmts []byte
		if stmts, err = schemaFiles.ReadFile(path); err != nil {
			return err
		} else {
			statements = append(statements, string(stmts))
		}
		return nil
	})
	if err != nil {
		return err
	}

	return db.WithTransaction(func(tx *sql.Tx) error {
		var version int
		if err = tx.QueryRowContext(db.ctx, `SELECT version FROM schema_version;`).Scan(&version); err != nil {
			if err.Error() == "no such table: schema_version" {
				version = 0
			} else {
				return err
			}
		}

		for version < len(statements) {
			if _, err = tx.ExecContext(db.ctx, statements[version]); err != nil {
				return err
			}
			version++
		}
		_, err = tx.ExecContext(db.ctx, `DELETE FROM schema_version; INSERT INTO schema_version (version) VALUES (?);`, version)
		return err
	})
}