File : core/uiLib/IndexedDb.js

/*

Copyright - 2017 2023 - wwwouaiebe - Contact: https://www.ouaie.be/

This  program is free software;

you can redistribute it and/or modify it under the terms of the

GNU General Public License as published by the Free Software Foundation;

either version 3 of the License, or any later version.

This program is distributed in the hope that it will be useful,

but WITHOUT ANY WARRANTY; without even the implied warranty of

MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

GNU General Public License for more details.

You should have received a copy of the GNU General Public License

along with this program; if not, write to the Free Software

Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA

*/

/*

Changes:

    - v4.0.0:

        - created from v3.6.0

Doc reviewed 202208

 */

/* ------------------------------------------------------------------------------------------------------------------------- */

/**

This class contains methods for accessing the window.indexedDb.

See theIndexedDb for the one and only one instance of this class

*/

/* ------------------------------------------------------------------------------------------------------------------------- */

class IndexedDb {

    /**

    A reference to the opened indexedDB

    @type {IDBFactory}

    */

    #indexedDb;

    /**

    The UUID of the current travel

    @type {String}

    */

    #UUID;

    /**

    A temp variable used to store the data to write in the indexedDb

    @type {String}

    */

    #data;

    /**

    The version of the db to use

    @type {Number}

    */

    // eslint-disable-next-line no-magic-numbers

    static get #DB_VERSION ( ) { return 1; }

    /**

    Perform the open operations

    @param {function} onOk the Ok handler for the Promise

    @param {function} onError the error handler for the Promise

    */

    #open ( onOk, onError ) {

        if ( this.#indexedDb ) {

            onOk ( );

            return;

        }

        const openRequest = window.indexedDB.open ( 'TravelNotesDb', IndexedDb.#DB_VERSION );

        openRequest.onerror = ( ) => {

            this.#indexedDb = null;

            onError ( new Error ( 'Not possible to open the db' ) );

        };

        openRequest.onsuccess = successEvent => {

            this.#indexedDb = successEvent.target.result;

            onOk ( );

        };

        openRequest.onupgradeneeded = upgradeEvent => {

            this.#indexedDb = upgradeEvent.target.result;

            this.#indexedDb.createObjectStore ( 'Travels', { keyPath : 'UUID' } );

        };

    }

    /**

    Perform the read operations

    @param {function} onOk the Ok handler for the Promise

    @param {function} onError the error handler for the Promise

    */

    #read ( onOk, onError ) {

        if ( ! this.#indexedDb ) {

            onError ( new Error ( 'Database not opened' ) );

            return;

        }

        const transaction = this.#indexedDb.transaction ( [ 'Travels' ], 'readonly' );

        transaction.onerror = ( ) => onError ( new Error ( 'Transaction error' ) );

        const travelsObjectStore = transaction.objectStore ( 'Travels' );

        const getRequest = travelsObjectStore.get ( this.#UUID );

        getRequest.onsuccess = successEvent => onOk ( successEvent.target.result ? successEvent.target.result.data : null );

    }

    /**

    Perform the write operations

    @param {function} onOk the Ok handler for the Promise

    @param {function} onError the error handler for the Promise

    */

    #write ( onOk, onError ) {

        if ( ! this.#indexedDb ) {

            onError ( new Error ( 'Database not opened' ) );

            return;

        }

        const transaction = this.#indexedDb.transaction ( [ 'Travels' ], 'readwrite' );

        transaction.onerror = ( ) => onError ( new Error ( 'Transaction error' ) );

        const travelsObjectStore = transaction.objectStore ( 'Travels' );

        const putRequest = travelsObjectStore.put ( { UUID : this.#UUID, data : this.#data } );

        putRequest.onsuccess = ( ) => onOk ( );

    }

    /**

    Perform the close operations

    */

    #close ( ) {

        this.#indexedDb.close ( );

        this.#indexedDb = null;

    }

    /**

    constructor

    */

    constructor ( ) {

        Object.freeze ( this );

    }

    /**

    Open the indexedDb

    @return {Promise} A Promise  that fullfil when the indexedDb is opened or reject when a problem occurs

    */

    getOpenPromise ( ) {

        return new Promise ( ( onOk, onError ) => this.#open ( onOk, onError ) );

    }

    /**

    Read data in the indexedDb.

    @param {String} UUID An UUID used to identify the data in the indexedDb

    @return {Promise} A promise that fullfil when the data are read or reject when a problem occurs

    The success handler receive the data as parameter

    */

    getReadPromise ( UUID ) {

        this.#UUID = UUID;

        return new Promise ( ( onOk, onError ) => this.#read ( onOk, onError ) );

    }

    /**

    Write data in the indexedDb.

    @param {String} UUID An UUID used to identify the data in the indexedDb

    @param {String} data The data to put in the indexedDb

    @return {Promise} A promise that fullfil when the data are written or reject when a problem occurs

    */

    getWritePromise ( UUID, data ) {

        this.#UUID = UUID;

        this.#data = data;

        return new Promise ( ( onOk, onError ) => this.#write ( onOk, onError ) );

    }

    /**

    Remove the data in the indexedDb and close it

    @param {String} UUID An UUID used to identify the data in the indexedDb

    */

    closeDb ( UUID ) {

        if ( ! this.#indexedDb ) {

            return;

        }

        if ( ! UUID ) {

            this.#close ( );

            return;

        }

        const transaction = this.#indexedDb.transaction ( [ 'Travels' ], 'readwrite' );

        transaction.onerror = ( ) => { };

        const travelsObjectStore = transaction.objectStore ( 'Travels' );

        const deleteRequest = travelsObjectStore.delete ( UUID );

        deleteRequest.onerror = ( ) => this.#close ( );

        deleteRequest.onsuccess = ( ) => this.#close ( );

    }

}

/* ------------------------------------------------------------------------------------------------------------------------- */

/**

The one and only one instance of IndexedDb class

@type {IndexedDb}

*/

/* ------------------------------------------------------------------------------------------------------------------------- */

const theIndexedDb = new IndexedDb ( );

export default theIndexedDb;

/* --- End of file --------------------------------------------------------------------------------------------------------- */