// Which door a collaboration team's case-conference control opens.
//
// THE DEFECT THIS EXISTS FOR (walked 2026-09-16): the team card rendered "Start case conference"
// whenever no call was running here, so a practitioner whose team already had a live conference
// pressed a control that calls `POST /R4/video-session` - which the server correctly refuses
// **409 `CONTEXT_TAKEN`**. The re-entry door was open the whole time and this surface never knocked
// on it. The card invited the one press that could only be refused.
//
// It is `encounterVideoEntry`'s sibling, not a reuse of it: that resolver is built around an
// encounter id and an encounter STATUS rule, and a team has neither. What carries over unchanged is
// the reasoning, because the same three mistakes are available here.
import { collabTeamContext, type VideoContext } from '../../services/video/videoContract';
import type { AvailableMeeting, CallPhase } from '../../services/video/callMachine';

export type CaseConferenceEntry =
    /** This team's conference is running for this user right now - there is no entry to offer. */
    | { kind: 'live' }
    /** Nothing exists for this team: creating one is correct. */
    | { kind: 'start' }
    /** A conference is live for this team and this user has not been in it. */
    | { kind: 'join'; sessionId: string }
    /** A conference is live for this team and this user has already been in it. */
    | { kind: 'rejoin'; sessionId: string };

interface Args {
    teamId: string;
    phase: CallPhase;
    /** The context of the call this user is IN, if any. */
    callContext?: VideoContext;
    /** The meeting on offer - push, late-joiner lookup, or the re-offer a departure makes. */
    available?: AvailableMeeting;
}

export function caseConferenceEntry({ teamId, phase, callContext, available }: Args): CaseConferenceEntry {
    const context = collabTeamContext(teamId);

    // Anchored on `idle` rather than listing the live phases, so a phase added later fails SAFE - it
    // keeps reporting live instead of offering a second entry into a call already coming up.
    const inACall = phase !== 'idle';
    if (callContext === context && inACall) return { kind: 'live' };

    // SCOPED TO THIS TEAM'S CONTEXT, and that is not tidiness. There is one `available` slot
    // app-wide; an unscoped read would let a meeting offered for one patient's team capture another
    // team's button and walk the practitioner into the wrong conference. That is a PHI exposure, not
    // a wrong label.
    if (available?.context === context) {
        // Absent `returning` reads as "first invitation", never as rejoin. It is SERVER-derived (the
        // caller's own `leftAt`) because a reload destroys whatever the client knew, and a reload is
        // precisely the case the grace window exists for.
        return { kind: available.returning ? 'rejoin' : 'join', sessionId: available.sessionId };
    }

    return { kind: 'start' };
}