import {Injectable} from '../../di'
import {Awaitable} from '../../util'

/**
 * Abstract base-class for one-time migrations.
 */
@Injectable()
export abstract class Migration {
    /** Set by the Migrations unit on load. */
    protected migrationIdentifier!: string

    /**
     * Sets the migration identifier.
     * This is used internally when the Migrations service loads
     * the migration files to determine the ID from the file-name.
     * It shouldn't be used externally.
     * @param name
     */
    public setMigrationIdentifier(name: string): void {
        this.migrationIdentifier = name
    }

    /**
     * Get the unique identifier of this migration.
     */
    public get identifier(): string {
        return this.migrationIdentifier
    }

    /**
     * Apply the migration.
     */
    abstract up(): Awaitable<void>

    /**
     * Undo the migration.
     */
    abstract down(): Awaitable<void>
}