import { Mongo } from 'meteor/mongo';
import { linkStorage } from './symbols.js';
import Linker from './linker.js';

_.extend(Mongo.Collection.prototype, {
    /**
     * The data we add should be valid for config.schema.js
     */
    addLinks(data) {
        if (!this[linkStorage]) {
            this[linkStorage] = {};
        }

        _.each(data, (linkConfig, linkName) => {
            if (this[linkStorage][linkName]) {
                throw new Meteor.Error(`You cannot add the link with name: ${linkName} because it was already added to ${this._name} collection`)
            }

            const linker = new Linker(this, linkName, linkConfig);

            _.extend(this[linkStorage], {
                [linkName]: linker
            });
        });
    },
    
    getLinks() {
        return this[linkStorage];
    },

    getLinker(name) {
        if (this[linkStorage]) {
            return this[linkStorage][name];
        }
    },

    hasLink(name) {
        if (!this[linkStorage]) {
            return false;
        }

        return !!this[linkStorage][name];
    },

    getLink(objectOrId, name) {
        let linkData = this[linkStorage];

        if (!linkData) {
            throw new Meteor.Error(`There are no links defined for collection: ${this._name}`);
        }

        if (!linkData[name]) {
            throw new Meteor.Error(`There is no link ${name} for collection: ${this._name}`);
        }

        const linker = linkData[name];
        let object = objectOrId;
        if (typeof(objectOrId) == 'string') {
            if (!linker.isVirtual()) {
                object = this.findOne(objectOrId, {
                    fields: {
                        [linker.linkStorageField]: 1
                    }
                });
            } else {
                object = {_id: objectOrId};
            }

            if (!object) {
                throw new Meteor.Error(`We could not find any object with _id: "${objectOrId}" within the collection: ${this._name}`);
            }
        }

        return linkData[name].createLink(object);
    }
});