import { IQueryHandler, QueryHandler } from '@nestjs/cqrs';
import {
  HomeReadModel,
  OnlineReadModel,
} from '@task-stream/api/tracker/domain';
import { computeHome, HomeProjectInput, lastDays } from '../analytics/home';
import { CalendarFeedsRepository } from '../ports/calendar-feeds.repository';
import { FindActivityRepository } from '../ports/find-activity.repository';
import { FindIssuesRepository } from '../ports/find-issues.repository';
import { FindProjectsRepository } from '../ports/find-projects.repository';
import { FindReleasesRepository } from '../ports/find-releases.repository';
import { FindSprintsRepository } from '../ports/find-sprints.repository';
import { FindTimelineRepository } from '../ports/find-timeline.repository';
import { PresenceStore } from '../ports/presence.store';
import { PRESENCE_TTL_MS } from '../presence.service';
import { GetMyHomeQuery } from './get-my-home.query';
import { guestOnly } from './read-access';

/** How much activity the home page lists. */
const ACTIVITY = 30;

@QueryHandler(GetMyHomeQuery)
export class GetMyHomeQueryHandler
  implements IQueryHandler<GetMyHomeQuery, HomeReadModel>
{
  constructor(
    private readonly findProjects: FindProjectsRepository,
    private readonly findIssues: FindIssuesRepository,
    private readonly findTimeline: FindTimelineRepository,
    private readonly findSprints: FindSprintsRepository,
    private readonly findReleases: FindReleasesRepository,
    private readonly findActivity: FindActivityRepository,
    private readonly feeds: CalendarFeedsRepository,
    private readonly presence: PresenceStore,
  ) {}

  async execute(query: GetMyHomeQuery): Promise<HomeReadModel> {
    const me = query.viewerId;
    const now = new Date();
    const projects = (await this.findProjects.findByMember(me)).filter(
      (p) => !p.archivedAt,
    );
    // Project-wide views only of the projects I see whole (not as a guest).
    const whole = projects.filter((p) => !guestOnly(p, me));
    const days = lastDays(now);
    const [inputs, activity, counts, feed, online] = await Promise.all([
      Promise.all(
        projects.map(async (project) => {
          const [issues, timeline, sprints, releases] = await Promise.all([
            this.findIssues.findByProject(project.id),
            this.findTimeline.findByProject(project.id),
            this.findSprints.findByProject(project.id),
            this.findReleases.findByProject(project.id),
          ]);
          return { project, issues, timeline, sprints, releases };
        }),
      ),
      this.findActivity.findAcross(
        whole.map((p) => p.id),
        ACTIVITY,
      ),
      this.findActivity.dailyCounts(
        whole.map((p) => p.id),
        days[0],
      ),
      this.feeds.findByUser(me),
      Promise.all(
        whole.map(async (project) =>
          (
            await this.presence.listProject(
              project.id,
              now.getTime() - PRESENCE_TTL_MS,
            )
          )
            .filter((entry) => entry.user.id !== me)
            .map(
              (entry): OnlineReadModel => ({
                user: entry.user,
                projectKey: project.key,
                issueKey: entry.issue?.key ?? null,
                issueTitle: entry.issue?.title ?? null,
                editing: entry.editing,
                at: entry.at,
              }),
            ),
        ),
      ),
    ]);
    const perDay = (projectId: string) =>
      days.map(
        (day) =>
          counts.find((c) => c.projectId === projectId && c.day === day)
            ?.count ?? 0,
      );
    return computeHome({
      viewerId: me,
      projects: inputs.map(
        (i): HomeProjectInput => ({ ...i, activity: perDay(i.project.id) }),
      ),
      activity,
      hasCalendar: !!feed,
      // One line per person: the latest ticket they are on.
      online: online
        .flat()
        .sort((a, b) => b.at.localeCompare(a.at))
        .filter(
          (entry, i, all) =>
            all.findIndex((e) => e.user.id === entry.user.id) === i,
        ),
      now,
    });
  }
}