import {Observer, Observable} from 'rxjs';
import {on, is} from 'tsfun';
import {FeatureDocument} from 'idai-components-2';
import {ObserverUtil} from '../../core/util/observer-util';


export type MatrixSelectionMode = 'single'|'rect'|'none';

export type MatrixSelectionChange = {

    ids: Array<string>;
    changeType: 'added'|'removed';
}


/**
 * @author Thomas Kleinke
 * @author Daniel de Oliveira
 */
export class MatrixSelection {

    private mode: MatrixSelectionMode = 'none';
    private selectedDocumentsIds: Array<string> = [];
    private observers: Array<Observer<MatrixSelectionChange>> = [];


    public changesNotifications = (): Observable<MatrixSelectionChange> => ObserverUtil.register(this.observers);
    public notifyObservers = (change: MatrixSelectionChange) => ObserverUtil.notify(this.observers, change);


    public getMode(): MatrixSelectionMode {

        return this.mode;
    }


    public setMode(mode: MatrixSelectionMode) {

        if (mode === 'none' && this.mode !== 'none') this.clear();

        this.mode = mode;
    }


    public documentsSelected(): boolean {

        return this.selectedDocumentsIds.length > 0;
    }


    public getSelectedDocuments(documents: Array<FeatureDocument>): Array<FeatureDocument> {

        return this.selectedDocumentsIds.map(id => {
            return documents.find(on('resource.id', is(id))) as FeatureDocument;
        });
    }


    public add(id: string) {

        if (this.selectedDocumentsIds.includes(id)) return;

        this.selectedDocumentsIds.push(id);
        this.notifyObservers({ ids: [id], changeType: 'added' });
    }


    public addOrRemove(id: string) {

        if (this.selectedDocumentsIds.includes(id)) {
            this.selectedDocumentsIds.splice(this.selectedDocumentsIds.indexOf(id), 1);
            this.notifyObservers({ ids: [id], changeType: 'removed' });
        } else {
            this.selectedDocumentsIds.push(id);
            this.notifyObservers({ ids: [id], changeType: 'added' });
        }
    }


    public clear(notify: boolean = true) {

        if (!this.selectedDocumentsIds) return;

        if (notify) this.notifyObservers({ ids: this.selectedDocumentsIds, changeType: 'removed' });
        this.selectedDocumentsIds = [];
    }
}