import * as api from '../../client/src/api';
import { EndpointError, EndpointHandler, catchUnhandledErrors } from './types';
import Knex from 'knex';

async function getChildrenRecursive(id: number, trx: any) {
    const directChildren = (await trx.select('id')
        .from('tags')
        .where({ 'parentId': id })).map((r: any) => r.id);

    const indirectChildrenPromises = directChildren.map(
        (child: number) => getChildrenRecursive(child, trx)
    );
    const indirectChildrenNested = await Promise.all(indirectChildrenPromises);
    const indirectChildren = indirectChildrenNested.flat();
    
    return [
        ...directChildren,
        ...indirectChildren,
    ]
}

export const DeleteTagEndpointHandler: EndpointHandler = async (req: any, res: any, knex: Knex) => {
    if (!api.checkDeleteTagRequest(req)) {
        const e: EndpointError = {
            internalMessage: 'Invalid DeleteTag request: ' + JSON.stringify(req.body),
            httpStatus: 400
        };
        throw e;
    }
    const reqObject: api.DeleteTagRequest = req.body;

    console.log("Delete Tag:", reqObject);

    await knex.transaction(async (trx) => {
        try {
            // Start retrieving any child tags.

            const childTagsPromise = 
                getChildrenRecursive(req.params.id, trx);

            // Start retrieving the tag itself.
            const tagPromise = trx.select('id')
                .from('tags')
                .where({ id: req.params.id })
                .then((r: any) => (r && r[0]) ? r[0]['id'] : undefined)

            // Wait for the requests to finish.
            var [tag, children] = await Promise.all([tagPromise, childTagsPromise]);

            // Merge all IDs.
            const toDelete = [ tag, ...children ];
            console.log ("deleting tags: ", toDelete);

            // Check that we found all objects we need.
            if (!tag) {
                const e: EndpointError = {
                    internalMessage: 'Tag or parent does not exist for DeleteTag request: ' + JSON.stringify(req.body),
                    httpStatus: 400
                };
                throw e;
            }

            // Delete the tag and its children.
            await trx('tags')
                .whereIn('id', toDelete)
                .del();

            // Respond to the request.
            res.status(200).send();

        } catch (e) {
            catchUnhandledErrors(e);
            trx.rollback();
        }
    })
}