import { CommandHandler, ICommandHandler } from '@nestjs/cqrs';
import { ForbiddenError } from '@task-stream/api/shared/domain';
import { CommandResult, ack } from './command-result';
import { WatchIssueCommand } from './watch-issue.command';
import { WriteAccess } from './write-access';

/**
 * Following is for members, viewers included: reading a ticket is enough to
 * want to hear about it. People only follow or unfollow for themselves.
 */
@CommandHandler(WatchIssueCommand)
export class WatchIssueCommandHandler
  implements ICommandHandler<WatchIssueCommand>
{
  constructor(private readonly access: WriteAccess) {}

  async execute(command: WatchIssueCommand): Promise<CommandResult> {
    const issue = await this.access.issue(command.issueId);
    const project = await this.access.project(issue.projectId);
    if (command.actorId !== command.userId) {
      throw new ForbiddenError('You can only follow tickets yourself');
    }
    if (!project.isMember(command.userId)) {
      throw new ForbiddenError(
        `You are not a member of project ${project.key}`,
      );
    }
    if (command.watching) issue.watch(command.actorId, command.userId);
    else issue.unwatch(command.actorId, command.userId);
    await issue.commitAndWait();
    return ack(issue);
  }
}