directus/api/src/services/utils.ts

import { AbstractServiceOptions, Accountability, PrimaryKey } from "../types";
import database from '../database';
import Knex from 'knex';
import { InvalidPayloadException, ForbiddenException } from '../exceptions';
import SchemaInspector from 'knex-schema-inspector';

export default class UtilsService {
	knex: Knex;
	accountability: Accountability | null;

	constructor(options?: AbstractServiceOptions) {
		this.knex = options?.knex || database;
		this.accountability = options?.accountability || null;
	}

	async sort(collection: string, { item, to }: { item: PrimaryKey, to: PrimaryKey }) {
		const schemaInspector = SchemaInspector(this.knex);

		const sortFieldResponse = await this.knex
			.select('sort_field')
			.from('directus_collections')
			.where({ collection })
			.first();

		const sortField = sortFieldResponse?.sort_field;

		if (!sortField) {
			throw new InvalidPayloadException(`Collection "${collection}" doesn't have a sort field.`);
		}

		if (this.accountability?.admin !== true) {
			const permissions = await this.knex
				.select('fields')
				.from('directus_permissions')
				.where({
					collection,
					action: 'update',
					role: this.accountability?.role || null,
				})
				.first();

			if (!permissions) {
				throw new ForbiddenException();
			}

			const allowedFields = permissions.fields.split(',');

			if (allowedFields[0] !== '*' && allowedFields.includes(sortField) === false) {
				throw new ForbiddenException();
			}
		}

		const primaryKeyField = await schemaInspector.primary(collection);

		// Make sure all rows have a sort value
		const countResponse = await this.knex
			.count('* as count')
			.from(collection)
			.whereNull(sortField)
			.first();

		if (countResponse?.count && +countResponse.count !== 0) {
			const lastSortValueResponse = await this.knex
				.max(sortField)
				.from(collection)
				.first();

			const rowsWithoutSortValue = await this.knex
				.select(primaryKeyField, sortField)
				.from(collection)
				.whereNull(sortField);

			let lastSortValue = lastSortValueResponse ? Object.values(lastSortValueResponse)[0] : 0;

			for (const row of rowsWithoutSortValue) {
				lastSortValue++;
				await this.knex(collection)
					.update({ [sortField]: lastSortValue })
					.where({ [primaryKeyField]: row[primaryKeyField] });
			}
		}

		const targetSortValueResponse = await this.knex.select(sortField).from(collection).where({ [primaryKeyField]: to }).first();
		const targetSortValue = targetSortValueResponse[sortField];

		const sourceSortValueResponse = await this.knex.select(sortField).from(collection).where({ [primaryKeyField]: item }).first();
		const sourceSortValue = sourceSortValueResponse[sortField];

		// Set the target item to the new sort value
		await this.knex(collection).update({ [sortField]: targetSortValue }).where({ [primaryKeyField]: item });

		if (sourceSortValue < targetSortValue) {
			await this.knex(collection)
				.decrement(sortField, 1)
				.where(sortField, '>', sourceSortValue)
				.andWhere(sortField, '<=', targetSortValue)
				.andWhereNot({ [primaryKeyField]: item });
		} else {
			await this.knex(collection)
				.increment(sortField, 1)
				.where(sortField, '>=', targetSortValue)
				.andWhere(sortField, '<=', sourceSortValue)
				.andWhereNot({ [primaryKeyField]: item });
		}
	}
}