lib/src/orm/migrations/events/MigrationEventSerializer.ts

import {BaseSerializer} from '../../../support/bus'
import {ObjectSerializer} from '../../../support/bus/serial/decorators'
import {Injectable, Instantiable} from '../../../di'
import {Awaitable, ErrorWithContext, JSONState} from '../../../util'
import {MigrationEvent} from './MigrationEvent'
import {Migrations} from '../../services/Migrations'
import {AppliedMigrationEvent} from './AppliedMigrationEvent'
import {ApplyingMigrationEvent} from './ApplyingMigrationEvent'
import {RolledBackMigrationEvent} from './RolledBackMigrationEvent'
import {RollingBackMigrationEvent} from './RollingBackMigrationEvent'

export interface MigrationEventSerialPayload extends JSONState {
    identifier: string
    eventType: string
}

@ObjectSerializer()
@Injectable()
export class MigrationEventSerializer extends BaseSerializer<MigrationEvent, MigrationEventSerialPayload> {
    protected decodeSerial(serial: MigrationEventSerialPayload): Awaitable<MigrationEvent> {
        const migration = this.make<Migrations>(Migrations).get(serial.identifier)
        if ( !migration ) {
            throw new ErrorWithContext(`Invalid serialized migration identifier: ${serial.identifier}`)
        }

        return (new (this.stringToEvent(serial.eventType))(migration))
    }

    protected encodeActual(actual: MigrationEvent): Awaitable<MigrationEventSerialPayload> {
        return {
            identifier: actual.migration.identifier,
            eventType: actual.eventName,
        }
    }

    protected getName(): string {
        return '@extollo/lib.MigrationEventSerializer'
    }

    matchActual(some: MigrationEvent): boolean {
        return some instanceof MigrationEvent
    }

    private stringToEvent(name: string): Instantiable<MigrationEvent> {
        if ( name === '@extollo/lib.AppliedMigrationEvent' ) {
            return AppliedMigrationEvent
        } else if ( name === '@extollo/lib.ApplyingMigrationEvent' ) {
            return ApplyingMigrationEvent
        } else if ( name === '@extollo/lib.RollingBackMigrationEvent' ) {
            return RollingBackMigrationEvent
        } else if ( name === '@extollo/lib.RolledBackMigrationEvent' ) {
            return RolledBackMigrationEvent
        }

        throw new ErrorWithContext(`Invalid migration event name: ${name}`, {
            name,
        })
    }
}