import { IQueryHandler, QueryHandler } from '@nestjs/cqrs';
import {
  DEFAULT_PROJECT_SETTINGS,
  StatusCategory,
} from '@task-stream/api/tracker/domain';
import {
  FindIssuesRepository,
  IssueSort,
} from '../ports/find-issues.repository';
import { FindProjectsRepository } from '../ports/find-projects.repository';
import { BoardColumn, GetBoardQuery } from './get-board.query';
import { ReadAccess } from './read-access';

@QueryHandler(GetBoardQuery)
export class GetBoardQueryHandler
  implements IQueryHandler<GetBoardQuery, BoardColumn[]>
{
  constructor(
    private readonly findIssues: FindIssuesRepository,
    private readonly findProjects: FindProjectsRepository,
    private readonly access: ReadAccess,
  ) {}

  /**
   * Columns follow the project's statuses in order. Cancelled ones stay off the
   * board; archived ones only show while they still hold tickets.
   */
  async execute(query: GetBoardQuery): Promise<BoardColumn[]> {
    await this.access.assertCanView(query.filter.projectId, query.viewerId);
    const participantId =
      (await this.access.participantScope(
        query.filter.projectId,
        query.viewerId,
      )) ?? undefined;
    const project = await this.findProjects.findById(query.filter.projectId);
    const statuses = (
      project?.settings ?? DEFAULT_PROJECT_SETTINGS
    ).statuses.filter((status) => status.category !== StatusCategory.CANCELLED);
    const columns = await Promise.all(
      statuses.map(async (status) => {
        const page = await this.findIssues.search({
          ...query.filter,
          participantId,
          statuses: [status.id],
          // Each column follows the backlog order.
          sort: IssueSort.RANK,
          limit: Math.min(query.perColumn, 200),
          offset: 0,
        });
        return {
          column: { status: status.id, issues: page.items, total: page.total },
          archived: status.archived,
        };
      }),
    );
    return columns
      .filter(({ column, archived }) => !archived || column.total > 0)
      .map(({ column }) => column);
  }
}