DBMagic

class DBMagic {
  constructor( db_name, db_version, stores ) {
    this.stores = stores;
    this.db_name = db_name;
    this.db_version = db_version;
    var indexedDB = window.indexedDB || window.mozIndexedDB || window.webkitIndexedDB || window.msIndexedDB;
    this.indexedDB = indexedDB;

    this.db_delete();
    this.db_create();
  }

  add( name, items, callback ) {
    const db_name = this.db_name;
    let req = this.indexedDB.open( db_name, this.db_version );

    req.onsuccess = () => {
      let db = req.result;
      let tx = db.transaction ( [ name ], 'readwrite' );

      tx.oncomplete = () => {
        if ( debug )
          console.log( 'SUCCESS: Transaction [add] on database [' + db_name + '] store [' + name + '] completed successfully.' );
      };

      tx.onerror = ( e ) => {
        if ( debug )
          console.log( 'ERROR: Transaction method add() has failed.\n', e.srcElement.error );
      };

      items.forEach( item => {
        let storeReq = tx.objectStore( name ).add( item );
        storeReq.onsuccess = ( e ) => {
          if ( debug )
            console.log( 'SUCCESS: Added key ['+ item.id +'] to store [' + name + '] on database [' + db_name + '] successfully.' );
            if ( callback ) callback( e );
        };

        storeReq.onerror = ( e ) => {
          if ( debug )
            console.log( 'ERROR: Adding key ['+ item.id +'] to store [' + name + '] on database [' + db_name + '] failed.\n', e.srcElement.error );
          if ( callback ) callback( e );
        };
      });
    };

    req.onerror = ( e ) => {
      if ( debug )
        console.log( 'ERROR: Could not connect to database [' + db_name + '].\n', e.srcElement.error );
    };
  }

  get( name, items, callback ) {
    const db_name = this.db_name;
    const req = this.indexedDB.open( db_name, this.db_version );

    req.onsuccess = () => {
      let db = req.result;

      let tx = db.transaction ( [ name ], 'readonly' );
      let store = tx.objectStore( name );

      tx.onerror = ( e ) => {
        if ( debug )
          console.log( 'ERROR: Transaction on database [' + db_name + '] failed.\n', e.srcElement.error );
      };

      tx.oncomplete = () => {
        if ( debug )
          console.log( 'SUCCESS: Transaction [get] on database [' + db_name + '] store [' + name + '] completed successfully.' );
      };

      items.forEach( item => {
        let storeReq = store.get( item );

        storeReq.onerror = ( e ) => {
          if ( debug )
            console.log('ERROR: Could not connect to database ['+ db_name +'].\n', e.srcElement.error );

          if ( callback ) callback( e );
        };

        storeReq.onsuccess = ( e ) => {
          if ( debug )
            console.log( 'SUCCESS: Retrieved key ['+ item +'] from store [' + name + '] on database ['+ db_name +'] successfully.' );
          if ( callback ) callback( e.target.result );
        };
      });
    };

    req.onerror = ( e ) => {
      if ( debug )
        console.log('ERROR: Could not connect to database ['+ db_name +'].\n', e.srcElement.error );
    };
  }

  getAll( name, callback ) {
    const db_name = this.db_name;
    const req = this.indexedDB.open( db_name, this.db_version );

    req.onsuccess = () => {
      let db = req.result;
      let tx = db.transaction ( [ name ], 'readonly' );
      let store = tx.objectStore( name );

      tx.oncomplete = () => {
        if ( debug )
          console.log( 'SUCCESS: Transaction [getAll] on database [' + db_name + '] store [' + name + '] completed successfully.' );
      };

      let storeReq = store.getAll();
      storeReq.onsuccess = ( e ) => {
        if ( callback ) callback( e.target.result );
      };
    };

    req.onerror = ( e ) => {
      if ( debug )
        console.log('ERROR: Could not connect to database ['+ db_name +'].\n', e.srcElement.error );
    };

  }

  delete( name, items, callback ) {
    const db_name = this.db_name;
    const req = this.indexedDB.open( db_name, this.db_version );

    req.onsuccess = () => {
      let db = req.result;
      let tx = db.transaction ( [ name ], "readwrite" );
      let store = tx.objectStore( name );

      tx.onerror = ( e ) => {
        if ( debug )
          console.log( 'ERROR: Transaction [delete] on database [' + db_name + '] failed.\n', e.srcElement.error );
      };

      tx.oncomplete = () => {
        if ( debug )
          console.log( 'SUCCESS: Transaction [delete] on database [' + db_name + '] store [' + name + '] completed successfully.' );
      };

      items.forEach( item => {
        let storeReq = store.delete( item );

        storeReq.onerror = ( e ) => {
          if ( debug )
            console.log('ERROR: Deleted key ['+ item +'] from store ['+ name +'] failed.\n', e.srcElement.error );

          if ( callback ) callback( e );
        };

        storeReq.onsuccess = ( e ) => {
          if ( debug )
            console.log('SUCCESS: Deleted key ['+ item +'] from store ['+ name +'] successfully.');
          if ( callback ) callback( e );
        };
      });
    };

    req.onerror = ( e ) => {
      if ( debug )
        console.log('ERROR: Could not connect to database ['+ db_name +'].\n', e.srcElement.error );
    };

  }

  update( name, items, callback ) {
    const db_name = this.db_name;
    let req = this.indexedDB.open( db_name, this.db_version );

    req.onsuccess = () => {
      let db = req.result;
      let tx = db.transaction ( [ name ], 'readwrite' );

      tx.oncomplete = () => {
        if ( debug )
          console.log( 'SUCCESS: Transaction [update] on database [' + db_name + '] store [' + name + '] completed successfully.' );
      };

      tx.onerror = ( e ) => {
        if ( debug )
          console.log( 'ERROR: Transaction method update() has failed.\n', e.srcElement.error );
      };
      items.forEach( item => {
        let storeReq = tx.objectStore( name ).put( item );
        storeReq.onsuccess = ( e ) => {
          if ( debug )
            console.log( 'SUCCESS: Updated key ['+ item.id +'] in store [' + name + '] on database [' + db_name + '] successfully.' );
            if ( callback ) callback( e );
        };

        storeReq.onerror = ( e ) => {
          if ( debug )
            console.log( 'ERROR: Updating key ['+ item.id +'] in store [' + name + '] on database [' + db_name + '] failed.\n', e.srcElement.error );
          if ( callback ) callback( e );
        };
      });
    };

    req.onerror = ( e ) => {
      if ( debug )
        console.log( 'ERROR: Could not connect to database [' + db_name + '].\n', e.srcElement.error );
    };
  }

  db_create( callback ) {
    const db_name = this.db_name;
    const self = this;
    const req = this.indexedDB.open( db_name, this.db_version );

    req.onsuccess = () => {
      let db = req.result;
      if ( debug )
        console.log('SUCCESS: Database ['+ db_name +'] opened successfully, [ version = ' + db.version + ' ]');
      if ( callback ) callback( true );
    };

    req.onerror = () => {
      let db = req.result;
      if ( debug )
        console.log('ERROR: Database ['+ db_name +'] could not be opened successfully, [ version = ' + db.version + ' ]');
      if ( callback ) callback( true );
    };

    req.onupgradeneeded = ( e ) => {
      let db = req.result;

      switch( e.oldVersion ) {
        case 0:
          self.stores.forEach( name => {
            db.createObjectStore( name, { keyPath: 'id' } );
          } );
        case 1:
          let oldVersion = e.oldVersion;
          let newVersion = e.newVersion;
          if ( debug ) log( db.objectStoreNames );
      }
    };
  }

  db_delete( callback ) {
    const db_name = this.db_name;
    this.indexedDB.deleteDatabase( db_name, this.db_version );

    if ( debug )
      console.log('SUCCESS: Database ['+ db_name +'] deleted successfully.');
    if ( callback ) callback( true );
  }
}