# Source: becca/entities/brevision.js

    "use strict";

    const protectedSessionService = require('../../services/protected_session');
    const utils = require('../../services/utils');
    const dateUtils = require('../../services/date_utils');
    const becca = require('../becca');
    const AbstractBeccaEntity = require("./abstract_becca_entity");
    const sql = require("../../services/sql");
    const BAttachment = require("./battachment");

    /**
     * Revision represents a snapshot of note's title and content at some point in the past.
     * It's used for seamless note versioning.
     *
     * @extends AbstractBeccaEntity
     */
    class BRevision extends AbstractBeccaEntity {
        static get entityName() { return "revisions"; }
        static get primaryKeyName() { return "revisionId"; }
        static get hashedProperties() { return ["revisionId", "noteId", "title", "isProtected", "dateLastEdited", "dateCreated",
                                                "utcDateLastEdited", "utcDateCreated", "utcDateModified", "blobId"]; }

        constructor(row, titleDecrypted = false) {
            super();

            /** @type {string} */
            this.revisionId = row.revisionId;
            /** @type {string} */
            this.noteId = row.noteId;
            /** @type {string} */
            this.type = row.type;
            /** @type {string} */
            this.mime = row.mime;
            /** @type {boolean} */
            this.isProtected = !!row.isProtected;
            /** @type {string} */
            this.title = row.title;
            /** @type {string} */
            this.blobId = row.blobId;
            /** @type {string} */
            this.dateLastEdited = row.dateLastEdited;
            /** @type {string} */
            this.dateCreated = row.dateCreated;
            /** @type {string} */
            this.utcDateLastEdited = row.utcDateLastEdited;
            /** @type {string} */
            this.utcDateCreated = row.utcDateCreated;
            /** @type {string} */
            this.utcDateModified = row.utcDateModified;
            /** @type {int} */
            this.contentLength = row.contentLength;

            if (this.isProtected && !titleDecrypted) {
                this.title = protectedSessionService.isProtectedSessionAvailable()
                    ? protectedSessionService.decryptString(this.title)
                    : "[protected]";
            }
        }

        getNote() {
            return becca.notes[this.noteId];
        }

        /** @returns {boolean} true if the note has string content (not binary) */
        hasStringContent() {
            return utils.isStringNote(this.type, this.mime);
        }

        isContentAvailable() {
            return !this.revisionId // new note which was not encrypted yet
                || !this.isProtected
                || protectedSessionService.isProtectedSessionAvailable()
        }

        /*
         * Note revision content has quite special handling - it's not a separate entity, but a lazily loaded
         * part of Revision entity with its own sync. The reason behind this hybrid design is that
         * content can be quite large, and it's not necessary to load it / fill memory for any note access even
         * if we don't need a content, especially for bulk operations like search.
         *
         * This is the same approach as is used for Note's content.
         */

        /** @returns {string|Buffer} */
        getContent() {
            return this._getContent();
        }

        /**
         * @returns {*}
         * @throws Error in case of invalid JSON */
        getJsonContent() {
            const content = this.getContent();

            if (!content || !content.trim()) {
                return null;
            }

            return JSON.parse(content);
        }

        /** @returns {*|null} valid object or null if the content cannot be parsed as JSON */
        getJsonContentSafely() {
            try {
                return this.getJsonContent();
            }
            catch (e) {
                return null;
            }
        }

        /**
         * @param content
         * @param {object} [opts]
         * @param {object} [opts.forceSave=false] - will also save this BRevision entity
         */
        setContent(content, opts) {
            this._setContent(content, opts);
        }

        /** @returns {BAttachment[]} */
        getAttachments() {
            return sql.getRows(`
                    SELECT attachments.*
                    FROM attachments
                    WHERE ownerId = ?
                      AND isDeleted = 0`, [this.revisionId])
                .map(row => new BAttachment(row));
        }

        /** @returns {BAttachment|null} */
        getAttachmentById(attachmentId, opts = {}) {
            opts.includeContentLength = !!opts.includeContentLength;

            const query = opts.includeContentLength
                ? `SELECT attachments.*, LENGTH(blobs.content) AS contentLength
                   FROM attachments
                   JOIN blobs USING (blobId)
                   WHERE ownerId = ? AND attachmentId = ? AND isDeleted = 0`
                : `SELECT * FROM attachments WHERE ownerId = ? AND attachmentId = ? AND isDeleted = 0`;

            return sql.getRows(query, [this.revisionId, attachmentId])
                .map(row => new BAttachment(row))[0];
        }

        /** @returns {BAttachment[]} */
        getAttachmentsByRole(role) {
            return sql.getRows(`
                    SELECT attachments.*
                    FROM attachments
                    WHERE ownerId = ?
                      AND role = ?
                      AND isDeleted = 0
                    ORDER BY position`, [this.revisionId, role])
                .map(row => new BAttachment(row));
        }

        /** @returns {BAttachment} */
        getAttachmentByTitle(title) {
            // cannot use SQL to filter by title since it can be encrypted
            return this.getAttachments().filter(attachment => attachment.title === title)[0];
        }

        beforeSaving() {
            super.beforeSaving();

            this.utcDateModified = dateUtils.utcNowDateTime();
        }

        getPojo() {
            return {
                revisionId: this.revisionId,
                noteId: this.noteId,
                type: this.type,
                mime: this.mime,
                isProtected: this.isProtected,
                title: this.title,
                blobId: this.blobId,
                dateLastEdited: this.dateLastEdited,
                dateCreated: this.dateCreated,
                utcDateLastEdited: this.utcDateLastEdited,
                utcDateCreated: this.utcDateCreated,
                utcDateModified: this.utcDateModified,
                content: this.content, // used when retrieving full note revision to frontend
                contentLength: this.contentLength
            };
        }

        getPojoToSave() {
            const pojo = this.getPojo();
            delete pojo.content; // not getting persisted
            delete pojo.contentLength; // not getting persisted

            if (pojo.isProtected) {
                if (protectedSessionService.isProtectedSessionAvailable()) {
                    pojo.title = protectedSessionService.encrypt(this.title);
                }
                else {
                    // updating protected note outside of protected session means we will keep original ciphertexts
                    delete pojo.title;
                }
            }

            return pojo;
        }
    }

    module.exports = BRevision;