import {Document} from '../model/document';
import {ReadDatastore} from './read-datastore';

/**
 * The interface for datastores supporting 
 * the idai-components document model.
 *
 * The errors with which the methods reject, like GENERIC_SAVE_ERROR,
 * are constants of {@link DatastoreErrors}, so GENERIC_SAVE_ERROR really
 * is DatastoreErrors.GENERIC_SAVE_ERROR. The brackets [] are array indicators,
 * so [GENERIC_SAVE_ERROR] is an array containing one element, which is the string
 * corresponding to GENERIC_SAVE_ERROR.
 *
 * @author Sebastian Cuy
 * @author Daniel de Oliveira
 */ 
export abstract class Datastore extends ReadDatastore {

    /**
     * Persists a given document. If document.resource.id is not set,
     * it will be set to a generated value. In case of an error it remains undefined.
     *
     * In case of a successful call, document.modified and document.created get set,
     * otherwise they remain undefined.
     *
     * @param doc
     * @returns {Promise<Document>} a document
     * @throws [GENERIC_ERROR (, cause: any)] - in case of error, optionally including a cause
     * @throws [DOCUMENT_RESOURCE_ID_EXISTS] - if a document with doc.resource.id already exists
     * @throws [INVALID_DOCUMENT] - in case doc is not valid
     */
    abstract create(doc: Document): Promise<Document>;

    /**
     * Updates an existing document
     *
     * @param doc
     * @returns {Promise<Document>} a document
     * @throws [GENERIC_ERROR (, cause: any)] - in case of error, optionally including a cause
     * @throws [SAVE_CONFLICT] - in case of conflict
     * @throws [DOCUMENT_NO_RESOURCE_ID] - if doc has no resource id
     * @throws [INVALID_DOCUMENT] - in case doc is not valid
     * @throws [DOCUMENT_NOT_FOUND] - if document has a resource id, but does not exist in the db
     */
    abstract update(doc: Document): Promise<Document>;

    /**
     * Removes an existing document
     *
     * @param doc
     * @returns {Promise<undefined>} undefined
     * @throws [DOCUMENT_NO_RESOURCE_ID] - if document has no resource id
     * @throws [DOCUMENT_NOT_FOUND] - if document has a resource id, but does not exist in the db
     * @throws [GENERIC_ERROR (, cause: any)] - in case of error, optionally including a cause
     */
    abstract remove(doc: Document): Promise<undefined>;
}