import { FarrisDataState } from './farris-dataitem';
import { BehaviorSubject, Observable } from 'rxjs';
import { map } from 'rxjs/operators';

export class BaseDataFacadeService<T extends FarrisDataState> {
    protected _state = this._initState;
    disableExpress: (item) => boolean;

    readonly store  = new BehaviorSubject<T>(this._state);
    readonly state$ = this.store.asObservable();

    data$: Observable<any> = this.state$.pipe(map((state: T) => state.data));

    constructor(private _initState: T) {
    }

    private initData(data: any) {
        return data.map(d => {
            const _id = d[this._state.idField];
            const disable = () => {
                return this.disableExpress ? this.disableExpress(d) : false;
            };
            return {
                id: _id,
                data: d,
                disabled: disable(),
            };
        });
    }

    protected updateState(state: any) {
        const newState = {...this._state, ...state};
        this.store.next(this._state = newState);
    }

    initState(state: any) {
        this.updateState(state);
    }

    isSelect(id: any) {
        if (this._state.selections && this._state.selections.length) {
            return this._state.selections.find(item => !!item ? item[this._state.idField] == id : false) !== undefined;
        }
        return false;
    }


    loadData(data: any, selectValues: string = '', separator = ',') {
        if (data) {
            const _data = this.initData(data);
            this.updateState({...this._state, data: _data});

            if (selectValues) {
                this.setSelections(selectValues, separator);
            } else {
                this._state.selections = [];
            }
        } else {
            this.updateState({ data: [], selections: [] });
        }
    }

    getSelections() {
        return this._state.selections;
    }

    setSelections(selectValues: string, separator = ',') {
        if (selectValues) {
            let selectedItems = [];
            if (this._state.multiSelect) {
                selectedItems = selectValues.split(separator).map( val => {
                    return this._state.data.find(d => d.data[this._state.valueField] + '' == val);
                }).map( n => {
                    return n ? n.data : '';
                }).filter(n => n);
            } else {
                selectedItems = [this._state.data.find(d => d.data[this._state.valueField] + '' == selectValues)];
            }
            this.updateState({selections: selectedItems });
        }
    }

    selectAll() {
        this.updateState({selections: this._state.data.map(n => n.data) });
    }

    unSelectAll() {
        this.clearSelections();
    }

    selectItem(data: any, index?: number) {
        const idfield = this._state.idField;
        let selections = this.getSelections();

        const id = data[idfield];
        if (!this._state.multiSelect) {
            if (!this.isSelect(id)) {
                selections = [ data ];
            }
        } else {
            if (!this.isSelect(id)) {
                selections.push(data);
            }
        }

        const items = this.cloneArray(selections);

        this.updateState({selections: items});
    }

    unSelectItem(data: any) {
        const idfield = this._state.idField;
        let selections = this.getSelections();
        const id = data[idfield];
        if (!this._state.multiSelect) {
            selections = [];
        } else {
            selections = selections.filter(n => n[idfield] != id) ;
        }

        const items = this.cloneArray(selections);
        this.updateState({selections: items});
    }

    clearSelections() {
        this.updateState({selections: []});
    }

    private cloneArray(arr: any[]) {
        if (arr && arr.length) {
            return arr.map( n => n);
        }

        return arr;
    }
}