// api-error.ts — reads a failed fetch `Response` into a `ProblemDetails`
// (RFC 9457, `application/problem+json`) object, shape-agnostically.
//
// Promoted from `dashboard/src/credentials.js`'s original `readErrorBody`,
// which returned a flat message string. This returns the structured object
// instead so a caller — chiefly `ApiErrorPanel` (./api-error-panel/) — can
// render title/status/detail separately and build a useful copy-button
// payload, rather than re-parsing a pre-squashed string.
//
// RFC 9457 is this hive's committed error-body contract for first-party
// APIs (mara: "any api of our own responding with error that is not rfc
// shaped is a bug to be filed against backend") — every first-party route
// emits it as of this writing, so the non-JSON fallback below is NOT
// compatibility with an in-flight backend transition (that transition is
// finished). It's for bodies we did not author: a caller can be pointed
// at something that isn't ours, and an nginx-synthesised 502/504 never
// reaches our handlers at all, so it's plain HTML, not problem+json. A
// first-party route landing here anyway is a bug to file, not something
// this reader should quietly paper over.

export interface ProblemDetails {
  type?: string;
  title?: string;
  status?: number;
  detail?: string;
}

export async function readApiError(resp: Response): Promise<ProblemDetails> {
  const status = resp.status;
  let raw: string;
  try {
    raw = (await resp.text()).trim();
  } catch {
    return { status };
  }
  if (raw && (raw[0] === '{' || raw[0] === '[')) {
    try {
      const body = JSON.parse(raw) as Record<string, unknown>;
      return {
        type: typeof body.type === 'string' ? body.type : undefined,
        title: typeof body.title === 'string' ? body.title : undefined,
        status: typeof body.status === 'number' ? body.status : status,
        detail:
          typeof body.detail === 'string'
            ? body.detail
            : typeof body.error === 'string'
              ? body.error
              : undefined,
      };
    } catch {
      // not JSON after all — fall through to the raw-text path below
    }
  }
  return { status, detail: raw || undefined };
}

// One-line message for a context that only has room for a single string
// (a form's inline result line, a toast) rather than the full panel —
// same fallback order `readErrorBody` used: detail (or its `error` alias,
// already folded in above) → title → a bare status line.
export function problemMessage(p: ProblemDetails): string {
  return p.detail || p.title || (p.status !== undefined ? `http ${p.status}` : 'request failed');
}