import { Injectable, isDevMode } from '@angular/core';
import { Result, ok, err } from '@shared/kernel/fp';
import { currentRole } from '@shared/infrastructure/role';
import { currentSubject } from '@shared/infrastructure/subject';
import { problemDetail } from '@shared/infrastructure/api-error';
import { environment } from '@shared/environments/environment';

/** Exported so specs can assert against the same message id instead of retyping the
    Dutch sentence (see `brief.store.spec.ts`'s `previewLetter` failure test). */
export const PREVIEW_FAILED = $localize`:@@brief.preview.failed:De voorvertoning kon niet worden geopend.`;

/**
 * `/brief/preview` returns `text/html`, not JSON, and is `.ExcludeFromDescription()`'d
 * to keep the NSwag-generated client JSON-only (same seam as uploads) — so this is a
 * hand-written fetch, not the `ApiClient`. That also means it bypasses `HttpClient`'s
 * `roleInterceptor` AND `subjectInterceptor`, so both `X-Role` and `X-Subject` are set
 * here explicitly (without `X-Subject` this always previewed
 * `DocumentStore.DemoOwner`'s letter regardless of who was actually logged in). Both are
 * dev-only identity stand-ins (`role.ts`/`subject.ts`) and are sent only under
 * `isDevMode()`, mirroring how the interceptors themselves are only registered in dev
 * (`app.config.ts`) — a production build sends neither header from this call (BIO-012).
 *
 * `cache: 'no-store'`: the endpoint has no `Cache-Control`, only a CORS-driven
 * `Vary: Origin`, and its content changes at the SAME URL as the letter moves
 * draft → sent. Explicitly bypassing the HTTP cache is the correct default for any
 * mutable resource served under one unversioned URL — independent of the
 * identity work above, and not a complete fix by itself: see the KNOWN GAP note below.
 *
 * KNOWN GAP (not fixed here): under a non-`DocumentStore.DemoOwner` `X-Subject`,
 * this repo's own e2e run against a real backend observed this endpoint's SENT
 * response still carrying the draft watermark, even though (a) the outgoing request
 * carried the correct `X-Subject`, and (b) `curl` against the same backend at the
 * same moment correctly returned the frozen, unwatermarked archive. `cache: 'no-store'`
 * did not change the outcome, so it is very unlikely a client-side caching artifact —
 * it looks like a genuine backend-side staleness/race in `BriefStore`'s SQLite-backed
 * read path, reproducible for MULTIPLE distinct owners and NOT reproducible for
 * `DemoOwner`, which needs backend-side investigation (out of this file's scope —
 * see `e2e/brief-v2.spec.ts`'s header comment, which keeps that spec on the shared
 * `zorgverlener` identity until this is root-caused).
 */
@Injectable({ providedIn: 'root' })
export class LetterPreviewAdapter {
  async preview(): Promise<Result<string, Blob>> {
    let res: Response;
    try {
      const subject = currentSubject();
      res = await fetch(`${environment.apiBaseUrl}/api/v1/brief/preview`, {
        cache: 'no-store',
        headers: isDevMode()
          ? { 'X-Role': currentRole(), ...(subject ? { 'X-Subject': subject } : {}) }
          : {},
      });
    } catch {
      return err(PREVIEW_FAILED);
    }
    if (!res.ok) return err(await errorMessage(res));
    return ok(await res.blob());
  }
}

/** Trust boundary (TE-002): maps a non-OK response to a message. Exported so a spec
    can call it directly instead of stubbing `globalThis.fetch`. */
export async function errorMessage(res: Response): Promise<string> {
  try {
    return problemDetail(await res.json(), PREVIEW_FAILED);
  } catch {
    return PREVIEW_FAILED;
  }
}