// (C) 2007-2019 GoodData Corporation
import { has } from "lodash";
import { Application } from "express";
import * as HttpStatusCodes from "http-status-codes";
import {
    IMockProject,
    getAttributes,
    getAttributeDisplayForms,
    getMetrics,
    getFacts,
    getVisualizationObjects,
} from "../../model/MockProject";
import { IMetadataObject } from "../../model/MetadataObject";

export interface IIdentifier {
    identifier: string;
    uri: string;
}

export interface IIdentifierToUriRequest {
    identifierToUri: string[];
}

export interface IUriToIdentifierRequest {
    uriToIdentifier: string[];
}

export interface IIdentifiersResponse {
    identifiers: IIdentifier[];
}

export type IdentifiersRequest = IIdentifierToUriRequest | IUriToIdentifierRequest;

function isIdentifierToUriRequest(request: IdentifiersRequest): request is IIdentifierToUriRequest {
    return !!(request as IIdentifierToUriRequest).identifierToUri;
}

function filterMetadataObjectsByIdentifier(
    objects: IMetadataObject[],
    identifiers: string[],
): IMetadataObject[] {
    const lookup = identifiers.reduce((hash, identifier) => ({ ...hash, [identifier]: true }), {});

    return objects.filter(object => has(lookup, object.meta.identifier));
}

function filterMetadataObjectsByUri(objects: IMetadataObject[], uris: string[]): IMetadataObject[] {
    const lookup = uris.reduce((hash, uri) => ({ ...hash, [uri]: true }), {});

    return objects.filter(object => has(lookup, object.meta.uri));
}

function createPair(object: IMetadataObject): IIdentifier {
    return {
        identifier: object.meta.identifier,
        uri: object.meta.uri,
    };
}

export const identifiers = {
    register(app: Application, project: IMockProject) {
        app.post(`/gdc/md/${project.project.meta.identifier}/identifiers`, (req, res) => {
            const request: IdentifiersRequest = req.body;

            const objects: IMetadataObject[] = [
                ...getVisualizationObjects(project),
                ...getAttributes(project),
                ...getAttributeDisplayForms(project),
                ...getMetrics(project),
                ...getFacts(project),
            ];

            if (isIdentifierToUriRequest(request)) {
                const body: IIdentifiersResponse = {
                    identifiers: filterMetadataObjectsByIdentifier(objects, request.identifierToUri).map(
                        createPair,
                    ),
                };

                res.status(HttpStatusCodes.OK).json(body);
            } else {
                const body: IIdentifiersResponse = {
                    identifiers: filterMetadataObjectsByUri(objects, request.uriToIdentifier).map(createPair),
                };

                res.status(HttpStatusCodes.OK).json(body);
            }
        });

        return app;
    },
};