swaf/src/db/ModelFactory.ts

import ModelComponent from "./ModelComponent";
import Model from "./Model";
import ModelQuery, {ModelQueryResult} from "./ModelQuery";
import {Request} from "express";
import {Type} from "../Utils";

export default class ModelFactory<T extends Model> {
    private static readonly factories: { [modelType: string]: ModelFactory<any> } = {};

    public static register<M extends Model>(modelType: Type<M>) {
        if (this.factories[modelType.name]) throw new Error(`Factory for type ${modelType.name} already defined.`);
        this.factories[modelType.name] = new ModelFactory<M>(modelType);
    }

    public static get<M extends Model>(modelType: Type<M>): ModelFactory<M> {
        const factory = this.factories[modelType.name];
        if (!factory) throw new Error(`No factory registered for ${modelType.name}.`);
        return factory;
    }

    private readonly modelType: Type<T>;
    private readonly components: ModelComponentFactory<T>[] = [];

    protected constructor(modelType: Type<T>) {
        this.modelType = modelType;
    }


    public addComponent(modelComponentFactory: ModelComponentFactory<T>) {
        this.components.push(modelComponentFactory);
    }

    public make(data: any): T {
        const model = new this.modelType(data);
        for (const component of this.components) {
            model.addComponent(new component(model));
        }
        model.setFactory(this);
        return model;
    }

    public get table(): string {
        return this.constructor.name
                .replace(/(?:^|\.?)([A-Z])/g, (x, y) => '_' + y.toLowerCase())
                .replace(/^_/, '')
            + 's';
    }

    public select(...fields: string[]): ModelQuery<T> {
        return ModelQuery.select(this, ...fields);
    }

    public update(data: { [key: string]: any }): ModelQuery<T> {
        return ModelQuery.update(this, data);
    }

    public delete(): ModelQuery<T> {
        return ModelQuery.delete(this);
    }

    public getPrimaryKeyFields(): string[] {
        return ['id'];
    }

    public getPrimaryKey(modelData: any): any[] {
        return this.getPrimaryKeyFields().map(f => modelData[f]);
    }

    public getPrimaryKeyString(modelData: any): string {
        return this.getPrimaryKey(modelData).join(',');
    }

    public async getById(...id: any): Promise<T | null> {
        let query = this.select();
        const primaryKeyFields = this.getPrimaryKeyFields();
        for (let i = 0; i < primaryKeyFields.length; i++) {
            query = query.where(primaryKeyFields[i], id[i]);
        }
        return query.first();
    }

    public async paginate(request: Request, perPage: number = 20, query?: ModelQuery<T>): Promise<ModelQueryResult<T>> {
        let page = request.params.page ? parseInt(request.params.page) : 1;
        if (!query) query = this.select();
        if (request.params.sortBy) {
            const dir = request.params.sortDirection;
            query = query.sortBy(request.params.sortBy, dir === 'ASC' || dir === 'DESC' ? dir : undefined);
        } else {
            query = query.sortBy('id');
        }
        return await query.paginate(page, perPage);
    }

    public async loadRelation(models: T[], relation: string, model: Function, localField: string) {
        const loadMap: { [p: number]: (model: T) => void } = {};
        const ids = models.map(m => {
            m.relations[relation] = null;
            if (m[localField]) loadMap[m[localField]] = v => m.relations[relation] = v;
            return m[localField];
        }).filter(id => id);
        for (const v of await (<any>model).models((<any>model).select().whereIn('id', ids))) {
            loadMap[v.id!](v);
        }
    }
}

export type ModelComponentFactory<T extends Model> = new (model: T) => ModelComponent<T>;