import { DataSource } from '@angular/cdk/collections';
import { EventEmitter } from '@angular/core';
import { MatPaginator, PageEvent } from '@angular/material/paginator';
import { MatSort, Sort } from '@angular/material/sort';
import { merge, Observable, of as observableOf } from 'rxjs';
import { map, tap } from 'rxjs/operators';

import { MenuEngineeringReportItem } from './menu-engineering-report-item';

/** Simple sort comparator for example ID/Name columns (for client-side sorting). */
const compare = (a: string | number | boolean, b: string | number | boolean, isAsc: boolean) =>
  (a < b ? -1 : 1) * (isAsc ? 1 : -1);
export class MenuEngineeringReportDataSource extends DataSource<MenuEngineeringReportItem> {
  private filterValue = '';
  constructor(
    public data: MenuEngineeringReportItem[],
    private filter: Observable<string>,
    private paginator?: MatPaginator,
    private sort?: MatSort,
  ) {
    super();
    this.filter = filter.pipe(
      tap((x) => {
        this.filterValue = x;
      }),
    );
  }

  connect(): Observable<MenuEngineeringReportItem[]> {
    const dataMutations: (EventEmitter<PageEvent> | EventEmitter<Sort>)[] = [];
    if (this.paginator) {
      dataMutations.push((this.paginator as MatPaginator).page);
    }
    if (this.sort) {
      dataMutations.push((this.sort as MatSort).sortChange);
    }
    return merge(observableOf(this.data), this.filter, ...dataMutations)
      .pipe(
        map(() => this.getFilteredData([...this.data])),
        tap((x: MenuEngineeringReportItem[]) => {
          if (this.paginator) {
            this.paginator.length = x.length;
          }
        }),
      )
      .pipe(map((x: MenuEngineeringReportItem[]) => this.getPagedData(this.getSortedData(x))));
  }

  disconnect() {}

  private getFilteredData(data: MenuEngineeringReportItem[]): MenuEngineeringReportItem[] {
    return this.filterValue.split(' ').reduce(
      (p: MenuEngineeringReportItem[], c: string) =>
        p.filter((x) => {
          if (c.startsWith('n:')) {
            return x.name.toLowerCase().indexOf(c.substring(2)) !== -1;
          }
          if (c.startsWith('sc:')) {
            return x.saleCategory.toLowerCase().indexOf(c.substring(3)) !== -1;
          }
          if (c.startsWith('mc:')) {
            return x.menuCategory.toLowerCase().indexOf(c.substring(3)) !== -1;
          }
          if (c.startsWith('q:')) {
            const result = c.match(/^q:(?<sign>=|<=|>=|<|>)(?<amount>\d*)$/);
            if (result && result.groups) {
              return math_it_up(result.groups['sign'])(x.quantity, +result.groups['amount'] ?? '');
            }
          }
          if (c.startsWith('a:')) {
            const result = c.match(/^a:(?<sign>=|<=|>=|<|>)(?<amount>\d*)$/);
            if (result && result.groups) {
              return math_it_up(result.groups['sign'])(x.amount, +result.groups['amount'] ?? '');
            }
          }
          const itemString = `${x.name} ${x.saleCategory} ${x.menuCategory}`.toLowerCase();
          return itemString.indexOf(c) !== -1;
        }),
      Object.assign([], data),
    );
  }

  private getPagedData(data: MenuEngineeringReportItem[]) {
    if (this.paginator === undefined) {
      return data;
    }
    const startIndex = this.paginator.pageIndex * this.paginator.pageSize;
    return data.splice(startIndex, this.paginator.pageSize);
  }

  private getSortedData(data: MenuEngineeringReportItem[]): MenuEngineeringReportItem[] {
    if (this.sort === undefined) {
      return data;
    }
    if (!this.sort.active || this.sort.direction === '') {
      return data;
    }

    const sort = this.sort as MatSort;
    return data.sort((a, b) => {
      const isAsc = sort.direction === 'asc';
      switch (sort.active) {
        case 'name':
          return compare(a.name, b.name, isAsc);
        case 'price':
          return compare(a.price, b.price, isAsc);
        case 'saleCategory':
          return compare(a.saleCategory, b.saleCategory, isAsc);
        case 'menuCategory':
          return compare(a.menuCategory, b.menuCategory, isAsc);
        case 'quantity':
          return compare(a.quantity, b.quantity, isAsc);
        case 'amount':
          return compare(a.amount, b.amount, isAsc);
        default:
          return 0;
      }
    });
  }
}

function eq(x: number, y: number) {
  return x > y;
}
function gt(x: number, y: number) {
  return x > y;
}
function lt(x: number, y: number) {
  return x < y;
}
function gte(x: number, y: number) {
  return x >= y;
}
function lte(x: number, y: number) {
  return x <= y;
}

function math_it_up(sign: string) {
  if (sign == '=') {
    return eq;
  }
  if (sign == '>') {
    return gt;
  }
  if (sign == '<') {
    return lt;
  }
  if (sign == '>=') {
    return gte;
  }
  if (sign == '<=') {
    return lte;
  }
  return eq;
}