import { EventsHandler, IEventHandler } from '@nestjs/cqrs';
import {
  ActivityReadModel,
  CommentAddedEvent,
  CommentDeletedEvent,
  CommentEditedEvent,
  IssueAssignedEvent,
  IssueCreatedEvent,
  IssueLinkedEvent,
  IssueReleaseChangedEvent,
  IssueStatusChangedEvent,
  IssueUnlinkedEvent,
  IssueUpdatedEvent,
  ProjectCreatedEvent,
  ProjectMemberAddedEvent,
  ProjectMemberRemovedEvent,
  ProjectMemberRoleChangedEvent,
  ProjectUpdatedEvent,
  ReleaseArchivedEvent,
  ReleaseCreatedEvent,
  ReleaseShippedEvent,
  ReleaseUpdatedEvent,
  TrackerEvent,
  DEFAULT_PROJECT_SETTINGS,
  SYSTEM_ACTOR_ID,
  SYSTEM_ACTOR_NAME,
  ProjectSettingsChangedEvent,
  ProjectWorkflow,
} from '@task-stream/api/tracker/domain';
import { ChangeFeed } from '../ports/change-feed';
import { FindIssuesRepository } from '../ports/find-issues.repository';
import { FindProjectsRepository } from '../ports/find-projects.repository';
import { FindReleasesRepository } from '../ports/find-releases.repository';
import { UpsertMaterializedActivityRepository } from '../ports/upsert-materialized-activity.repository';
import { UserDirectory } from '../ports/user-directory';
import { describeEvent } from './activity-summary';
import { versionOf } from './read-model-notifier';

/** Project activity feed / ticket history: one entry per domain event. */
@EventsHandler(
  ProjectCreatedEvent,
  ProjectUpdatedEvent,
  ProjectSettingsChangedEvent,
  ProjectMemberAddedEvent,
  ProjectMemberRemovedEvent,
  ProjectMemberRoleChangedEvent,
  IssueCreatedEvent,
  IssueUpdatedEvent,
  IssueStatusChangedEvent,
  IssueAssignedEvent,
  IssueLinkedEvent,
  IssueUnlinkedEvent,
  IssueReleaseChangedEvent,
  CommentAddedEvent,
  CommentEditedEvent,
  CommentDeletedEvent,
  ReleaseCreatedEvent,
  ReleaseUpdatedEvent,
  ReleaseShippedEvent,
  ReleaseArchivedEvent,
)
export class ActivityEventHandler implements IEventHandler<TrackerEvent> {
  constructor(
    private readonly upsertMaterializedActivityRepository: UpsertMaterializedActivityRepository,
    private readonly findProjects: FindProjectsRepository,
    private readonly findIssues: FindIssuesRepository,
    private readonly findReleases: FindReleasesRepository,
    private readonly users: UserDirectory,
    private readonly changeFeed: ChangeFeed,
  ) {}

  async handle(event: TrackerEvent) {
    const issueId = this.issueIdOf(event);
    const issueKey =
      event instanceof IssueCreatedEvent
        ? event.issue.key
        : issueId
          ? ((await this.findIssues.findById(issueId))?.key ?? null)
          : null;
    const releaseId = this.releaseIdOf(event);
    const release = releaseId
      ? await this.findReleases.findById(releaseId)
      : null;
    const project = await this.findProjects.findById(event.projectId);
    // The project was deleted (cascade in progress): no feed to write to.
    if (!project) return;
    const mentioned = [
      event.actorId,
      (event as { userId?: string }).userId,
      (event as { assigneeId?: string }).assigneeId,
    ];
    const users = await this.users.refs(mentioned);
    const actorOf = (id: string) =>
      id === SYSTEM_ACTOR_ID ? { id, name: SYSTEM_ACTOR_NAME } : users.of(id);

    const activity: ActivityReadModel = {
      id: `${event.aggregateId}:${versionOf(event)}`,
      type: event.constructor.name,
      projectId: event.projectId,
      issueId,
      issueKey,
      actor: actorOf(event.actorId),
      summary: describeEvent(event, {
        actor: actorOf(event.actorId).name,
        user: (id) => users.ofNullable(id)?.name ?? '?',
        issueKey: issueKey ?? '',
        projectKey: project?.key ?? '',
        releaseName: release?.name ?? '',
        workflow: new ProjectWorkflow(
          project?.settings ?? DEFAULT_PROJECT_SETTINGS,
        ),
      }),
      occurredAt: event.occurredAt,
    };
    if (await this.upsertMaterializedActivityRepository.insert(activity)) {
      await this.changeFeed.publishActivity(activity);
    }
  }

  private issueIdOf(event: TrackerEvent): string | null {
    if (event.constructor.name.startsWith('Issue')) return event.aggregateId;
    if (event instanceof CommentAddedEvent) return event.comment.issueId;
    if (
      event instanceof CommentEditedEvent ||
      event instanceof CommentDeletedEvent
    )
      return event.issueId;
    return null;
  }

  private releaseIdOf(event: TrackerEvent): string | null {
    if (event.constructor.name.startsWith('Release')) return event.aggregateId;
    if (event instanceof IssueReleaseChangedEvent) return event.releaseId;
    return null;
  }
}