import { ViewConfig, GroupingConfig } from './ViewConfig';
import { RenderContext } from './RenderContext';
import { RendererRegistry } from './RendererRegistry';
import { IStoreRegistry } from './IGroupingStore';

interface HierarchyNode {
  type: string;
  id: string;
  data: unknown;
  parentId?: string;
  children: HierarchyNode[];
}

interface GroupingData {
  items: { id: string; data: unknown }[];
  byParent: Map<string, { id: string; data: unknown }[]> | null;
}

export class CalendarOrchestrator {
  constructor(
    private rendererRegistry: RendererRegistry,
    private storeRegistry: IStoreRegistry
  ) {}

  async render(viewConfig: ViewConfig, container: HTMLElement): Promise<void> {
    const headerContainer = container.querySelector('swp-calendar-header') as HTMLElement;
    const columnContainer = container.querySelector('swp-day-columns') as HTMLElement;
    if (!headerContainer || !columnContainer) {
      throw new Error('Missing swp-calendar-header or swp-day-columns');
    }

    const groupingData = this.fetchAllData(viewConfig.groupings);
    const hierarchy = this.buildHierarchy(viewConfig.groupings, groupingData);
    const totalColumns = this.countLeaves(hierarchy);

    container.style.setProperty('--grid-columns', String(totalColumns));

    const types = viewConfig.groupings.map(g => g.type);
    headerContainer.dataset.levels = types.join(' ');

    headerContainer.innerHTML = '';
    columnContainer.innerHTML = '';

    this.renderHierarchy(hierarchy, headerContainer, columnContainer);

    const eventRenderer = this.rendererRegistry.get('event');
    eventRenderer?.render({
      headerContainer,
      columnContainer,
      values: [],
      headerRow: viewConfig.groupings.length + 1,
      columnIndex: 1,
      colspan: 1
    });
  }

  private fetchAllData(groupings: GroupingConfig[]): Map<string, GroupingData> {
    const result = new Map<string, GroupingData>();

    for (const g of groupings) {
      if (g.type === 'date') {
        result.set(g.type, {
          items: g.values.map(v => ({ id: v, data: { id: v } })),
          byParent: null
        });
        continue;
      }

      const rawItems = this.storeRegistry.get(g.type).getByIds(g.values);
      const items = rawItems.map((item: any) => ({ id: item.id, data: item }));
      const byParent = g.parentKey
        ? this.groupBy(items, item => (item.data as any)[g.parentKey!])
        : null;

      result.set(g.type, { items, byParent });
    }

    return result;
  }

  private buildHierarchy(
    groupings: GroupingConfig[],
    data: Map<string, GroupingData>,
    level = 0,
    parentId?: string
  ): HierarchyNode[] {
    if (level >= groupings.length) return [];

    const g = groupings[level];
    const gData = data.get(g.type);
    if (!gData) return [];

    const items = parentId && gData.byParent
      ? gData.byParent.get(parentId) ?? []
      : gData.items;

    return items.map(item => ({
      type: g.type,
      id: item.id,
      data: item.data,
      parentId,
      children: this.buildHierarchy(groupings, data, level + 1, item.id)
    }));
  }

  private groupBy<T>(items: T[], keyFn: (item: T) => string): Map<string, T[]> {
    const map = new Map<string, T[]>();
    for (const item of items) {
      const key = keyFn(item);
      if (key == null) continue;
      if (!map.has(key)) map.set(key, []);
      map.get(key)!.push(item);
    }
    return map;
  }

  private countLeaves(nodes: HierarchyNode[]): number {
    return nodes.reduce((sum, n) =>
      sum + (n.children.length ? this.countLeaves(n.children) : 1), 0);
  }

  private renderHierarchy(
    nodes: HierarchyNode[],
    headerContainer: HTMLElement,
    columnContainer: HTMLElement,
    headerRow = 1
  ): void {
    for (const node of nodes) {
      const renderer = this.rendererRegistry.get(node.type);
      const colspan = this.countLeaves([node]) || 1;

      renderer?.render({
        headerContainer,
        columnContainer,
        values: [node.id],
        headerRow,
        columnIndex: 0, // Not used - grid auto-places
        colspan,
        parentId: node.parentId
      } as RenderContext);

      if (node.children.length) {
        this.renderHierarchy(node.children, headerContainer, columnContainer, headerRow + 1);
      }
    }
  }
}