/**
 * What a submission row calls the form it came from.
 *
 * THE DEFECT THIS EXISTS FOR, measured on Great River: every row read
 * `24335589fc6d5b461c86fec07c3d99e1`. Not a title, not a slug - thirty-two hex characters, identical on
 * every row, in the column whose whole job is to say which form a submission came from.
 *
 * WHY THE OLD FALLBACK WAS REASONABLE AND STILL WRONG. It fell back to the form HANDLE, on the stated
 * grounds that *"the handle is what the practice named the URL, so it is recognisable rather than
 * opaque."* That is true of a handle a practice CHOSE. But the server mints one when the practice does
 * not:
 *
 *     register-post.ts:  body.formHandle || randomBytes(16).toString('hex')
 *
 * An auto-generated handle is sixteen random bytes. Printing it as a name tells a receptionist
 * nothing, and worse, it LOOKS like an identifier they ought to recognise.
 *
 * WHY NO TITLE RESOLVES AT ALL RIGHT NOW, which is the actual cause and is NOT in this file:
 * `GET /R4/public-forms` answers `{"forms":[]}` for every practice - measured 2026-08-23 and again
 * 2026-08-31, a week apart. So the title lookup this fallback backs up can never succeed today.
 * -> This module cannot fix that. What it can do is stop the failure being reported to a human as a
 * uuid.
 */

/** Sixteen random bytes, hex-encoded - what the server mints when a practice names no handle. */
const GENERATED_HANDLE = /^[0-9a-f]{32}$/;

/**
 * A handle a practice chose is worth showing; one the server invented is not.
 *
 * Deliberately narrow: only the exact shape the server generates is treated as meaningless. A practice
 * that names a form `intake2026` keeps seeing `intake2026`, which is the half of the old behaviour that
 * was right.
 */
export const isGeneratedFormHandle = (handle: string | undefined): boolean =>
    GENERATED_HANDLE.test((handle ?? '').trim());

/**
 * WHAT THE ROW SHOWS, in order of how much it actually tells somebody:
 *
 *     the published title        the practice named this form
 *     the handle                 the practice named the URL
 *     "Unnamed form"             we have neither, and a uuid is not a name
 *
 * The last case says what is true rather than printing the id anyway. A receptionist cannot act on
 * thirty-two hex characters, and showing them implies the value means something to somebody.
 */
export const formLabelFor = (
    title: string | undefined,
    handle: string | undefined,
): string => {
    const named = (title ?? '').trim();
    if (named) return named;

    const raw = (handle ?? '').trim();
    if (raw && !isGeneratedFormHandle(raw)) return raw;

    return 'Unnamed form';
};

/** A submission's label: the title the server sent with it, else one from the published-forms list. */
export const submissionFormLabel = (
    submission: { formHandle: string; formTitle?: string },
    listedTitle?: string,
): string => formLabelFor(submission.formTitle?.trim() || listedTitle, submission.formHandle);