import { Injectable } from '@nestjs/common';
import { TrackerStreamsRepository } from '@task-stream/api/tracker/application';
import {
  CommentAddedEvent,
  IssueCreatedEvent,
  IssueLinkedEvent,
  ReleaseCreatedEvent,
} from '@task-stream/api/tracker/domain';
import { DataSource } from 'typeorm';

/** Reads the event store directly: which streams hang off a project or a ticket. */
@Injectable()
export class PostgresTrackerStreamsRepository extends TrackerStreamsRepository {
  constructor(private readonly dataSource: DataSource) {
    super();
  }

  issueIdsOfProject(projectId: string): Promise<string[]> {
    return this.streams(
      IssueCreatedEvent.name,
      `data->>'projectId'`,
      projectId,
    );
  }

  releaseIdsOfProject(projectId: string): Promise<string[]> {
    return this.streams(
      ReleaseCreatedEvent.name,
      `data->>'projectId'`,
      projectId,
    );
  }

  commentIdsOfIssue(issueId: string): Promise<string[]> {
    return this.streams(
      CommentAddedEvent.name,
      `data->'comment'->>'issueId'`,
      issueId,
    );
  }

  issueIdsLinkingTo(issueId: string): Promise<string[]> {
    return this.streams(
      IssueLinkedEvent.name,
      `data->'link'->>'targetIssueId'`,
      issueId,
    );
  }

  /** `field` is one of the fixed JSON paths above, never user input. */
  private async streams(
    type: string,
    field: string,
    value: string,
  ): Promise<string[]> {
    const rows: { stream_id: string }[] = await this.dataSource.query(
      `SELECT DISTINCT stream_id FROM events WHERE type = $1 AND ${field} = $2`,
      [type, value],
    );
    return rows.map((row) => row.stream_id);
  }
}