import { createContext, useContext, useMemo, useState, type ReactNode } from 'react';

//
// - ONE ANSWER TO "IS THE MANDATORY AGREEMENT GATE STILL OUTSTANDING?", so that ordering is
// decided by DATA and not by paint order.
//
// THE OBSERVED DEFECT, on the first screen every new patient meets: the Terms of Service gate and an
// ORGANIZATION-authorization dialog were open at the same time, and the dismissible one was on top.
// `elementFromPoint()` at the centre of the Terms gate's **Accept** returned the other dialog's overlay;
// dismissing that dialog with "Not now" flipped it back. One variable, measured both ways.
//
// AND THE MECHANISM IS WHY A Z-INDEX FIX WOULD BE THE WRONG ONE: both dialogs carry `z-index: 1100`, so
// the winner was decided by **DOM order alone**. That is a tie broken by accident, and it could invert on
// any render change. Raising one z-index keeps the accident and merely picks a side.
//
// THE DEFECT IS THE SEQUENCE, NOT THE OVERLAP. A patient was asked to let an organization into their
// health record before they had accepted - or even been able to READ - Akashic's own Terms. If they decline
// the Terms they should not have an account at all, yet they had already been offered an authorization
// decision. That is wrong independently of any stacking.
//
// SO THE RULE IS: the mandatory gate resolves FIRST, and nothing optional speaks until it has. This
// module is the channel. `FirstSignInGate` publishes what its own fetch found; anything that would render a
// competing dialog reads `useFirstSignInGateStatus()` and stays silent until it is `'clear'`.
//
// THE DEFAULT WITHOUT A PROVIDER IS `'clear'`, DELIBERATELY, AND THE WIRING IS PINNED SEPARATELY. The
// alternative - defaulting to `'outstanding'` - fails safe in production but silently hides the org prompt
// in every test and every surface that does not mount the provider, which is a worse failure to debug than
// the one being fixed. Instead the App-level wiring is asserted against source in
// `__tests__/theMandatoryGateGoesFirst.test.tsx`, exactly as the gate's own mount position already is.
// Do not "simplify" this by removing that test: without it, this file is a mechanism nothing reaches.
//

// 'unknown' is a real, distinct state and must never be collapsed into 'clear'. It means the gate has not
// finished asking - and something that mounts during that window is exactly what produced the stacked
// dialogs, because "nothing is showing yet" and "nothing is owed" look identical for one render.
export type FirstSignInGateStatus = 'unknown' | 'outstanding' | 'clear';

type ContextValue = {
    status: FirstSignInGateStatus;
    publish: (status: FirstSignInGateStatus) => void;
};

const FirstSignInGateStatusContext = createContext<ContextValue | undefined>(undefined);

export const FirstSignInGateStatusProvider = ({ children }: { children: ReactNode }) => {
    const [status, setStatus] = useState<FirstSignInGateStatus>('unknown');
    const value = useMemo(() => ({ status, publish: setStatus }), [status]);

    return (
        <FirstSignInGateStatusContext.Provider value={value}>
            {children}
        </FirstSignInGateStatusContext.Provider>
    );
};

/**
 * What a competing surface should do. Render nothing - and fetch nothing - unless this is `'clear'`.
 *
 * Returns `'clear'` when no provider is mounted, so an isolated component under test behaves exactly as
 * it did before this card. See the header for why that default is the right one and where the real wiring
 * is guarded.
 */
export const useFirstSignInGateStatus = (): FirstSignInGateStatus =>
    useContext(FirstSignInGateStatusContext)?.status ?? 'clear';

/**
 * The status only where a gate is actually mounted: undefined without a provider, so a surface that needs the
 * real first-sign-in answer never reads the isolated default as "cleared".
 */
export const useMountedFirstSignInGateStatus = (): FirstSignInGateStatus | undefined =>
    useContext(FirstSignInGateStatusContext)?.status;

/**
 * The gate's own side of the channel. A no-op when no provider is mounted, so the gate's 16 existing tests
 * render it standalone unchanged.
 */
export const usePublishFirstSignInGateStatus = (): ((status: FirstSignInGateStatus) => void) => {
    const context = useContext(FirstSignInGateStatusContext);
    return context?.publish ?? NOOP;
};

const NOOP = () => {};