/**
 * WHO WROTE THIS MESSAGE, and never a raw identifier.
 *
 * - WHAT A CLINICIAN ACTUALLY SAW. Great River, the practitioner workspace,
 * Messages Collaboration Teams Test Team, 2026-08-23:
 *
 * cb68ee44-4c9e-4147-98a1-1480675cf278 8:49 AM
 * Dr Whitfield here - I have accepted the referral and can see the record now...
 *
 * The only reason anybody could tell who wrote it is that the human typed their own name into the
 * message body. The interface attributed a clinical collaboration message to a hex string.
 *
 * THE CAUSE WAS A FALLBACK ORDER, NOT A MISSING FEATURE:
 *
 * communication.sender?.display || senderReference.split("/")[1] || "Participant"
 *
 * The middle term is the defect, and the code already had a better answer one term to its right -
 * `"Participant"` could essentially never run, because a reference always has an id.
 *
 * AND THE FIX IS NOT TO HIDE THE SENDER LINE. An unattributed message in a clinical thread is worse
 * than an ugly one; the card says so outright.
 */

/**
 * A reference's id, when the reference has one.
 *
 * Exported for the guard below rather than for callers - a label must never be built from this.
 */
const referenceId = (reference: string): string => reference.split('/')[1] ?? '';

/**
 * DOES THIS LOOK LIKE AN IDENTIFIER RATHER THAN A PERSON?
 *
 * SHAPE, NOT PROVENANCE. A denormalised `display` is written by whoever sent the message, and a writer
 * that stamped an id into it produces exactly the string this card is about - so trusting `display`
 * merely because it exists is what let this through. The label is judged on what it looks like.
 *
 * Catches a UUID, a bare hex blob, and any single token with no letters - the shapes an id takes here.
 */
export const looksLikeAnIdentifier = (value: string): boolean => {
    const trimmed = value.trim();
    if (!trimmed) return true;

    if (/^[0-9a-f]{8}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{12}$/i.test(trimmed)) return true;
    if (/^[0-9a-f]{16,}$/i.test(trimmed)) return true;

    /*
 * A LONG SINGLE TOKEN WITH NO VOWEL - and the length bound is not decoration.
 *
 * A first draft flagged any vowel-less token with no space, and its own control caught it: **`Ng` is
 * a real surname**, and the rule would have replaced a colleague's name with "Participant". That is
 * the same defect this file exists to fix, wearing the opposite face - and worse, because a wrong
 * name is quieter than an obvious id.
 *
 * 12 characters is far beyond any surname and far below the ids actually seen here. When in
 * doubt this must fall on the side of PRINTING what it was given: an ugly label is recoverable, a
 * silently withheld identity is not.
 */
    return !trimmed.includes(' ') && trimmed.length >= 12 && !/[aeiouy]/i.test(trimmed);
};

export interface SenderLabelInput {
    /** What the writer denormalised onto the message, if anything. */
    display?: string;
    /** The sender reference, e.g. `Practitioner/abc`. */
    reference?: string;
    /** Names resolved from the team roster, keyed by reference. The server's answer, not a second one. */
    rosterNames?: Record<string, string | undefined>;
}

/**
 * The label to render for a message author.
 *
 * THE ROSTER IS CONSULTED BEFORE GIVING UP, and it is the SERVER's answer rather than a second
 * resolution path - the collaboration-team read now returns a `displayName` for every practitioner
 * member, so the name is already in hand. Two resolution paths for one fact is how they drift; that is
 * the Captain's steer on this card and the reason this does not fetch anything.
 *
 * AND IT NEVER RETURNS AN ID. When nothing resolves, the reader gets a role-shaped word - honest about
 * what is not known, and still attributing the message to somebody.
 */
export const senderLabel = ({ display, reference, rosterNames }: SenderLabelInput): string => {
    const stamped = (display ?? '').trim();
    if (stamped && !looksLikeAnIdentifier(stamped)) return stamped;

    const fromRoster = (rosterNames ?? {})[(reference ?? '').trim()]?.trim();
    if (fromRoster && !looksLikeAnIdentifier(fromRoster)) return fromRoster;

    return 'Participant';
};

export { referenceId };