import {BaseSerializer, ObjectSerializer} from '../../support/bus'
import {Model} from './Model'
import {Awaitable, ErrorWithContext, JSONState, Maybe} from '../../util'
import {QueryRow} from '../types'
import {Inject, Injectable, isInstantiable} from '../../di'
import {Canon} from '../../service/Canon'

export interface ModelSerialPayload extends JSONState {
    canonicalResolver: string,
    primaryKey: any,
    objectValues: QueryRow,
}

@ObjectSerializer()
@Injectable()
export class ModelSerializer extends BaseSerializer<Model<any>, ModelSerialPayload> {
    @Inject()
    protected readonly canon!: Canon

    protected async decodeSerial(serial: ModelSerialPayload): Promise<Model<any>> {
        const ModelClass = this.canon.getFromFullyQualified(serial.canonicalResolver) as typeof Model
        if ( !ModelClass || !(ModelClass.prototype instanceof Model) || !isInstantiable<Model<any>>(ModelClass) ) {
            throw new ErrorWithContext('Cannot decode serialized model as canonical resolver is invalid', {
                serial,
            })
        }

        let inst: Maybe<Model<any>> = this.make<Model<any>>(ModelClass)
        if ( serial.primaryKey ) {
            inst = await ModelClass.query()
                .whereKey(serial.primaryKey)
                .first()
        }

        if ( !inst ) {
            throw new ErrorWithContext('Could not look up serialized model', {
                serial,
            })
        }

        await inst.assume(serial.objectValues)
        return inst
    }

    protected encodeActual(actual: Model<any>): Awaitable<ModelSerialPayload> {
        const ctor = actual.constructor as typeof Model
        const canonicalResolver = ctor.getFullyQualifiedCanonicalResolver()
        if ( !canonicalResolver ) {
            throw new ErrorWithContext('Unable to serialize model: no Canonical resolver', {
                actual,
            })
        }

        return {
            canonicalResolver,
            primaryKey: actual.key(),
            objectValues: actual.toObject(),
        }
    }

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

    matchActual(some: Model<any>): boolean {
        return some instanceof Model
    }
}