/**
 * Evidence capture for passing tests.
 *
 * Playwright keeps screenshots and traces only when something fails, which is
 * the right default for debugging but useless as a record of what the suite
 * actually proved. This fixture lets a test mark the moments that matter and
 * record the data it observed, so a successful run produces a readable report
 * rather than a row of green ticks.
 *
 *   await evidence.step('Search results for JFK to LHR', { total: 42, fare: 483.3 });
 *
 * Each call attaches a screenshot plus a JSON blob. `reporters/evidence.ts`
 * turns those attachments into the report.
 */
import { Page, TestInfo } from '@playwright/test';

/** Attachment name prefixes the reporter looks for. */
export const SHOT_PREFIX = 'evidence';
export const DATA_PREFIX = 'evidence-data';

export type Facts = Record<string, unknown>;

export class Evidence {
  private sequence = 0;

  constructor(
    private readonly page: Page,
    private readonly info: TestInfo,
  ) {}

  /**
   * Records a named moment: a screenshot of the current page, and optionally
   * the data the test observed there.
   */
  async step(name: string, facts?: Facts): Promise<void> {
    const seq = this.next();

    const shot = await this.page.screenshot({ fullPage: false, animations: 'disabled' });
    await this.info.attach(`${SHOT_PREFIX}:${seq}:${name}`, {
      body: shot,
      contentType: 'image/png',
    });

    if (facts) {
      await this.attachFacts(seq, name, facts);
    }
  }

  /** Records data with no screenshot -- for values read across several pages. */
  async note(name: string, facts: Facts): Promise<void> {
    await this.attachFacts(this.next(), name, facts);
  }

  /**
   * Records the whole scrollable page rather than the viewport. Slower, so it
   * is reserved for the screens worth showing in full.
   */
  async fullPage(name: string, facts?: Facts): Promise<void> {
    const seq = this.next();

    const shot = await this.page.screenshot({ fullPage: true, animations: 'disabled' });
    await this.info.attach(`${SHOT_PREFIX}:${seq}:${name}`, {
      body: shot,
      contentType: 'image/png',
    });

    if (facts) {
      await this.attachFacts(seq, name, facts);
    }
  }

  private async attachFacts(seq: string, name: string, facts: Facts): Promise<void> {
    await this.info.attach(`${DATA_PREFIX}:${seq}:${name}`, {
      body: Buffer.from(JSON.stringify(facts, null, 2), 'utf8'),
      contentType: 'application/json',
    });
  }

  private next(): string {
    this.sequence += 1;
    return String(this.sequence).padStart(2, '0');
  }
}