/*
 * Copyright (C) 2020-2021 StApps
 * This program is free software: you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by the Free
 * Software Foundation, version 3.
 *
 * This program is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
 * more details.
 *
 * You should have received a copy of the GNU General Public License along with
 * this program. If not, see <https://www.gnu.org/licenses/>.
 */
import {Injectable} from '@angular/core';
import {
  SCFacet,
  SCSearchFilter,
  SCSearchSort,
  SCThingType,
} from '@openstapps/core';
import {Subject} from 'rxjs';
import {
  FilterBucket,
  FilterContext,
  FilterFacet,
  SortContext,
} from './context-type';

/**
 * ContextMenuService provides bidirectional communication of context menu options and search queries
 */
@Injectable()
export class ContextMenuService {
  /**
   * Local filter context object
   */
  contextFilter: FilterContext;

  /**
   * Container for the filter context
   */
  filterOptions = new Subject<FilterContext>();

  /**
   * Observable filterContext streams
   */
  filterContextChanged$ = this.filterOptions.asObservable();

  /**
   * Container for the filter query (SCSearchFilter)
   */
  filterQuery = new Subject<SCSearchFilter>();

  /**
   * Observable filterContext streams
   */
  filterQueryChanged$ = this.filterQuery.asObservable();

  /**
   * Forced SCThingTypeFilter
   */
  forcedType?: SCThingType;

  /**
   * Container for the sort context
   */
  sortOptions = new Subject<SortContext>();

  /**
   * Observable SortContext streams
   */
  sortContextChanged$ = this.sortOptions.asObservable();

  /**
   * Container for the sort query
   */
  sortQuery = new Subject<SCSearchSort[]>();

  /**
   * Observable SortContext streams
   */
  sortQueryChanged$ = this.sortQuery.asObservable();

  /**
   * Returns SCSearchFilter if filterContext value is set, undefined otherwise
   *
   * @param filterContext FilterContext to build SCSearchFilter from
   */
  buildFilterQuery = (
    filterContext: FilterContext,
  ): SCSearchFilter | undefined => {
    const filters: SCSearchFilter[] = [];

    if (typeof this.forcedType !== 'undefined') {
      filters.push({
        arguments: {
          field: 'type',
          value: this.forcedType,
        },
        type: 'value',
      });
    }

    for (const filterFacet of filterContext.options) {
      const optionFilters: SCSearchFilter[] = [];
      for (const filterBucket of filterFacet.buckets) {
        if (filterBucket.checked) {
          optionFilters.push({
            arguments: {
              field: filterFacet.field,
              value: filterBucket.key,
            },
            type: 'value',
          });
        }
      }
      if (optionFilters.length > 0) {
        filters.push({
          arguments: {
            filters: optionFilters,
            operation: 'or',
          },
          type: 'boolean',
        });
      }
    }

    if (filters.length > 0) {
      return {
        arguments: {
          filters: filters,
          operation: 'and',
        },
        type: 'boolean',
      };
    }

    return;
  };

  /**
   * Returns SCSearchSort if sorting value is set, undefined otherwise
   *
   * @param sortContext SortContext to build SCSearchSort from
   */
  buildSortQuery = (sortContext: SortContext): SCSearchSort[] | undefined => {
    if (
      sortContext.value &&
      sortContext.value.length > 0 &&
      (sortContext.value === 'name' || sortContext.value === 'type')
    ) {
      return [
        {
          arguments: {
            field: sortContext.value,
            position: 0,
          },
          order: sortContext.reversed ? 'desc' : 'asc',
          type: 'ducet',
        },
      ];
    }

    return;
  };

  /**
   * Updates filter query from filterContext
   */
  contextFilterChanged(filterContext: FilterContext) {
    this.filterQuery.next(this.buildFilterQuery(filterContext));
  }

  /**
   * Updates sort query from sortContext
   */
  contextSortChanged(sortContext: SortContext) {
    this.sortQuery.next(this.buildSortQuery(sortContext));
  }

  /**
   * Sets sort context
   */
  setContextSort(sortContext: SortContext) {
    this.sortOptions.next(sortContext);
  }

  /**
   * Updates the filter context options from given facets
   */
  updateContextFilter(facets: SCFacet[]) {
    // arrange facet field "type" to first position
    facets.sort((a: SCFacet, b: SCFacet) => {
      if (a.field === 'type') {
        return -1;
      }

      if (b.field === 'type') {
        return 1;
      }

      return 0;
    });

    if (!this.contextFilter) {
      this.contextFilter = {
        name: 'filter',
        options: [],
      };
    }

    this.updateContextFilterOptions(this.contextFilter, facets);
  }

  /**
   * Updates context filter with new facets.
   * It preserves the checked status of existing filter options
   */
  updateContextFilterOptions = (
    contextFilter: FilterContext,
    facets: SCFacet[],
  ) => {
    const newFilterOptions: FilterFacet[] = [];

    // iterate new facets
    for (const facet of facets) {
      if (facet.buckets.length > 0) {
        const newFilterFacet: FilterFacet = {
          buckets: [],
          field: facet.field,
          onlyOnType: facet.onlyOnType,
        };
        newFilterOptions.push(newFilterFacet);

        // search existing filterOption
        const filterOption = contextFilter.options.find(
          (contextFacet: FilterFacet) =>
            contextFacet.field === facet.field &&
            contextFacet.onlyOnType === facet.onlyOnType,
        );
        for (const bucket of facet.buckets) {
          // search existing bucket to preserve checked status
          const existingFilterBucket = filterOption
            ? filterOption.buckets.find(
                (contextBucket: FilterBucket) =>
                  contextBucket.key === bucket.key,
              )
            : undefined;
          const filterBucket: FilterBucket = {
            checked: existingFilterBucket
              ? existingFilterBucket.checked
              : false,
            count: bucket.count,
            key: bucket.key,
          };
          newFilterFacet.buckets.push(filterBucket);
        }
      }
    }

    // update filter options
    contextFilter.options = newFilterOptions;
    this.contextFilter = contextFilter;

    this.filterOptions.next(contextFilter);
  };
}