import {
  DomContainerProps,
  DerivedRowOptions,
  LayoutType,
  LayoutDensityType
} from '../public-api/interfaces';
import { DEFAULT_ROW_HEIGHT, DENSITY_TO_PX_MAP, LayoutObject, CardLayout, VizRecordDomainConfig, PaginationState } from '../globals/helpers/helpers';
interface ScrollInputConfig {
  lazyRendering: boolean,
  dataLength: number,
  domContainer: DomContainerProps,
  rowConfig: DerivedRowOptions,
  stores: any
}
interface DomUpdateState {
  prevVizStartPx: number,
  prevVizEndPx: number
}
interface HorizontalScrollConfig {
  lazyRendering: boolean,
  layoutType: LayoutType,
  dataLength: number,
  vizStartRowPx: number,
  vizEndRowPx: number,
  vizStartRowBufferPx: number,
  vizEndRowBufferPx: number,
  lazyRenderingHeight: number,
  rowConfig?: DerivedRowOptions,
  cardConfig?: CardLayout,
  layoutObject: LayoutObject,
  prevDomUpdateState: DomUpdateState,
  autoHeight: boolean
}
interface StoreUnsubscribeFn {
  vizRecDomainUnsub: Function,
  layoutObjectUnsub: Function,
  autoHeightUnsub: Function
}
let scrollCounter = 0;
class InfiniteScrollManager {
  private hScrollConfig: HorizontalScrollConfig;
  private storeUnsubscribeFn: StoreUnsubscribeFn = <StoreUnsubscribeFn>{};
  private vizRecDomain: VizRecordDomainConfig = <VizRecordDomainConfig>{};
  private _paginationEnabled: boolean;
  private _stores: any;
  constructor(config: ScrollInputConfig) {
    let hScrollConf = this.hScrollConfig = <HorizontalScrollConfig>{ prevDomUpdateState: {} },
      rowConf = config.rowConfig,
      rowHeight: number = (rowConf.pxRowHeight|| DEFAULT_ROW_HEIGHT) + 2 * DENSITY_TO_PX_MAP[LayoutDensityType.Default],
      headerHeight: number = (rowConf.pxHeaderRowHeight || DEFAULT_ROW_HEIGHT) + 2 * DENSITY_TO_PX_MAP[LayoutDensityType.Default],
      rowConfig: DerivedRowOptions = <DerivedRowOptions>{
        pxRowHeight: rowHeight,
        pxHeaderRowHeight: headerHeight
      };
    this._paginationEnabled = false;
    this._stores = config.stores;  
    this.vizRecDomain = {
      start: 0,
      end: 0,
      bodyTransLateY: 0
    };
    this._stores.paginationState.subscribe((state: PaginationState)=>{
      this._paginationEnabled = state.enable;
      if (typeof this._paginationEnabled !== 'undefined' && !this._paginationEnabled){
        this._stores.vizRecordDomain.update((tmpVizRecDomain:VizRecordDomainConfig) => {
          tmpVizRecDomain.start = 0;
          tmpVizRecDomain.end = this.getEndRow();
          return tmpVizRecDomain;
        });
      }
    });
    this.storeUnsubscribeFn.vizRecDomainUnsub = this._stores.vizRecordDomain.subscribe((tmpVizRecDom: VizRecordDomainConfig) => {
      this.vizRecDomain = <VizRecordDomainConfig>tmpVizRecDom;
    });
    this.storeUnsubscribeFn.autoHeightUnsub = this._stores.autoHeight.subscribe((tmpAutoHeight: boolean) => {
      this.hScrollConfig.autoHeight = tmpAutoHeight;
    });
    this.storeUnsubscribeFn.layoutObjectUnsub = this._stores.layoutObject.subscribe( (tmpLayoutObject:LayoutObject) => {
      hScrollConf.layoutObject = tmpLayoutObject;
      if (tmpLayoutObject.layout.type !== 'card') {
        if (tmpLayoutObject.layout.density && tmpLayoutObject.layout.density !== LayoutDensityType.Default)  {
          rowConfig = <DerivedRowOptions>{
            pxRowHeight:(rowConf.pxRowHeight|| DEFAULT_ROW_HEIGHT) + 2 * DENSITY_TO_PX_MAP[tmpLayoutObject.layout.density],
            pxHeaderRowHeight: (rowConf.pxHeaderRowHeight|| DEFAULT_ROW_HEIGHT) + 2 * DENSITY_TO_PX_MAP[tmpLayoutObject.layout.density]
          };
        }
        hScrollConf.rowConfig = rowConfig;
      } else {
        hScrollConf.cardConfig = tmpLayoutObject.layoutState.cardLayout;
      }
      if ((hScrollConf.layoutType !== tmpLayoutObject.layout.type )&& !this._paginationEnabled) {
        if ((tmpLayoutObject.layout.type !== 'card' && tmpLayoutObject.layoutState.rowLayout) || 
          tmpLayoutObject.layoutState.cardLayout) {
          hScrollConf.layoutType = tmpLayoutObject.layout.type!;
          // dataLength has to be provided, 1 is set just to avoid NaN calculations.
          hScrollConf.dataLength = config.dataLength || 1;
          hScrollConf.lazyRendering = config.lazyRendering;
          hScrollConf.vizStartRowBufferPx = hScrollConf.vizStartRowPx = 0;
          hScrollConf.lazyRenderingHeight = config.domContainer.height - (rowConfig.pxHeaderRowHeight || headerHeight);
          hScrollConf.vizEndRowPx= 2 * hScrollConf.lazyRenderingHeight;
          // when lazy rendering is set true
          if (hScrollConf.lazyRendering && !hScrollConf.autoHeight) {
            hScrollConf.vizEndRowBufferPx = hScrollConf.vizEndRowPx + config.domContainer.height;
            // intial prevDom update state setting
            hScrollConf.prevDomUpdateState = {
              prevVizStartPx: hScrollConf.vizStartRowPx,
              prevVizEndPx: hScrollConf.vizEndRowPx
            };
          } else {
            // TO-DO, to be replaces by default row height decided
            // when lazy rendering is not required
            hScrollConf.vizEndRowBufferPx = hScrollConf.dataLength * (rowConfig.pxHeaderRowHeight || rowHeight);
            this.calculateStartEndRow();
          }
          this._stores.vizRecordDomain.update((tmpVizRecDomain:VizRecordDomainConfig) => {
            tmpVizRecDomain.bodyTransLateY = 0;
            tmpVizRecDomain.start = 0;
            tmpVizRecDomain.end = this.getEndRow();
            return tmpVizRecDomain;
          });
        }
      }
    });
  }
  // updates scroll property on scroll, also recalculate visible rows
  updateHScrollProps = (e: Event) => {
    let hScrollConf = this.hScrollConfig,
      prevDomUpdateState = hScrollConf.prevDomUpdateState;
    scrollCounter++;
    // To-Do add hscroll check
    if (e.target) {
      let targtEle = <HTMLDivElement> e.target;
      hScrollConf.vizStartRowPx = targtEle.scrollTop;
      hScrollConf.vizEndRowPx = targtEle.scrollTop + hScrollConf.lazyRenderingHeight;
      hScrollConf.vizStartRowBufferPx = (hScrollConf.vizStartRowPx - hScrollConf.lazyRenderingHeight > 0) ? 
        hScrollConf.vizStartRowPx - hScrollConf.lazyRenderingHeight : 0;
      hScrollConf.vizEndRowBufferPx = hScrollConf.vizEndRowPx + (2 * hScrollConf.lazyRenderingHeight);
      scrollCounter--;
      // To-DO, set hScrollConf.vizEndRowBufferPx as hidden div's height
    }
    if (hScrollConf.layoutObject.layout.type !== 'card' && hScrollConf.rowConfig) {
      if((hScrollConf.vizStartRowPx >= prevDomUpdateState.prevVizEndPx) ||
          (hScrollConf.vizEndRowPx <= prevDomUpdateState.prevVizStartPx)) {
        hScrollConf.prevDomUpdateState = {
          prevVizStartPx: hScrollConf.vizStartRowPx,
          prevVizEndPx: hScrollConf.vizEndRowPx
        };
        // calculate update state end row
        if(scrollCounter === 0 && !this._paginationEnabled) this.calculateStartEndRow();
        // update update state end row
      }
    } else {
      if (hScrollConf.vizStartRowPx >= prevDomUpdateState.prevVizEndPx) {
        prevDomUpdateState.prevVizStartPx = hScrollConf.vizStartRowPx;
        prevDomUpdateState.prevVizEndPx = hScrollConf.vizEndRowPx;
        if(scrollCounter === 0 && !this._paginationEnabled) this.calculateStartEndRow();
      }
    }
  }
  getEndRow (): number {
    let hScrollConf = this.hScrollConfig;
    if (hScrollConf.layoutObject.layout.type !== 'card') {
      if (hScrollConf.rowConfig && hScrollConf.rowConfig.pxRowHeight){
        return Math.min(Math.floor(hScrollConf.vizEndRowBufferPx / hScrollConf.rowConfig.pxRowHeight), hScrollConf.dataLength - 1);
      }
    } else if (hScrollConf.layoutObject.layout.type === 'card' && hScrollConf.cardConfig) {
      return Math.min(Math.floor((hScrollConf.vizEndRowBufferPx / hScrollConf.cardConfig.height) * hScrollConf.cardConfig.numCards), hScrollConf.dataLength - 1);
    }
    return (hScrollConf.dataLength - 1);
  }
  // calculates row start and end
  calculateStartEndRow () {
    let hScrollConf = this.hScrollConfig;
    if (hScrollConf.layoutObject.layout.type !== 'card') {
      if (hScrollConf.rowConfig && hScrollConf.rowConfig.pxRowHeight) {
        this.vizRecDomain.end = Math.min(Math.floor(hScrollConf.vizEndRowBufferPx / hScrollConf.rowConfig.pxRowHeight), hScrollConf.dataLength - 1);
        if (this.vizRecDomain.end < hScrollConf.dataLength - 1) {
          this.vizRecDomain.hiddenDivHeight = hScrollConf.vizEndRowBufferPx;
          this.vizRecDomain.bodyTransLateY = hScrollConf.vizStartRowBufferPx;
          this.vizRecDomain.start = Math.max(Math.floor(hScrollConf.vizStartRowBufferPx / hScrollConf.rowConfig.pxRowHeight), 0);
        }
      }
    } else {
      if (hScrollConf.cardConfig) {
        this.vizRecDomain.start = 0;
        this.vizRecDomain.end = Math.min(Math.floor((hScrollConf.vizEndRowBufferPx / hScrollConf.cardConfig.height) * hScrollConf.cardConfig.numCards), hScrollConf.dataLength - 1);
      }
    }
    this._stores.vizRecordDomain.update( (tmpVizRecDomain: any) => this.vizRecDomain);
  }
  setDatalength (val: number) {
    this.hScrollConfig.dataLength = val;
  }
}

export default InfiniteScrollManager;