import {
  useCallback,
  useMemo,
  useRef,
  useState,
  type PointerEvent as ReactPointerEvent,
} from "react";

import { matchesShortcut, useKeyScope } from "../../lib/keymap";
import { pointOnSelection } from "../../lib/textSelection";
import { useAnchoredPopover } from "./anchoredPopoverHooks";

// E10 S2 — the right-click context menu's INPUT half: the gestures that open it and the row they
// belong to. The surface itself is `<ContextMenu>` (ContextMenu.tsx); they are two files only so
// that the component file exports a component and nothing else (react-refresh).
//
// This is an INPUT PATH onto the menu the app already has rather
// than a second menu component. `ActionMenu` (the ⋯ overflow menu) and this one render the same
// `ActionMenuItem[]` through the same `MenuItemList`, on the same `.glass-menu` surface, so a row
// cannot grow a right-click menu that looks or behaves unlike its own ⋯ menu.
//
// Three ways in, because a menu that only opens one way does not exist on the device that lacks it:
//   - right-click anywhere on the row (the desktop browser, and the reason this sprint exists) —
//     except on selected words, where the browser's own menu opens so they can be copied,
//   - long-press (touch/pen only) — the tablet has no right button,
//   - Shift+F10 / the Menu key, which is free once the row is in the tab order.
// The left button is untouched: it keeps the row's own default action (select / play).
//
// ONE menu per list, not one per row. The popover is anchored to a VIRTUAL element at the pointer
// (native-menu behaviour: it opens where you clicked, not at the row's corner), so a table of 200
// rows mounts a single closed popover and `target` says which row it belongs to. Mounting one per
// row would build ~200 floating contexts to keep 199 of them shut.

/** Long-press timing. 500 ms is the platform convention on both Android and iOS; below ~400 ms it
 *  fires while the user is still deciding whether to scroll. */
const LONG_PRESS_MS = 500;
/** Movement (px) that reclassifies a press as a scroll and cancels the pending menu. */
const LONG_PRESS_SLOP = 10;

type Rect = {
  x: number;
  y: number;
  width: number;
  height: number;
  top: number;
  right: number;
  bottom: number;
  left: number;
};
const pointRect = (x: number, y: number): Rect => ({
  x,
  y,
  width: 0,
  height: 0,
  top: y,
  right: x,
  bottom: y,
  left: x,
});

export interface ContextMenuController<T> {
  /** The row the open menu belongs to; `null` while closed. Build the items from it. */
  target: T | null;
  open: boolean;
  close: () => void;
  /** The element the open menu came from — the row, or its "…" button. A follow-up an item opens
   *  (a panel anchored beside the object) anchors here. `null` while closed. */
  anchor: Element | null;
  /** Spread on the element that should answer a right-click — the whole row, not a handle. */
  triggerProps: (payload: T) => Record<string, unknown>;
  /** Spread on the row's visible "…" button (E28 C1: nothing is reachable only by a gesture). A
   *  click opens the SAME menu under the button; a second click on it while its menu is open closes
   *  it, like any menu button. Pair it with `aria-expanded` from the caller, which knows its row. */
  buttonProps: (payload: T) => Record<string, unknown>;
  /** Opens the menu at a viewport point for `payload`, anchored to `contextElement` — for an input
   *  path the two props above do not cover (the page's background menu, `ui/PageMenu`). */
  openAt: (x: number, y: number, payload: T, contextElement?: Element) => void;
  /** Consumed by `<ContextMenu>`; not part of the call site's vocabulary. */
  popover: ReturnType<typeof useAnchoredPopover>;
}

const identity = (payload: unknown): unknown => payload;

export function useContextMenu<T>({
  keyOf = identity,
}: {
  /** What makes two payloads the SAME row, for the "…" closing its own menu. Identity by default;
   *  a list whose rows are rebuilt each render (a wrapper object) or refetched while the menu is
   *  open (a poll replaces the job it lists) passes its id, or a second press would reopen. A
   *  module-scope function: a fresh one per render would rebuild `buttonProps` on every render. */
  keyOf?: (payload: T) => unknown;
} = {}): ContextMenuController<T> {
  // Register the scope HERE, so the cheat sheet lists Shift+F10 exactly on the surfaces that answer it.
  useKeyScope("contextMenu");
  const [target, setTarget] = useState<T | null>(null);
  const [anchor, setAnchor] = useState<Element | null>(null);
  const [open, setOpen] = useState(false);
  // What is open right now, for the "…" button's toggle. Read in a handler only, so a ref: state
  // would change `buttonProps` on every open and re-render every memoized row that holds it.
  const openFor = useRef<{ payload: T } | null>(null);
  // The press that dismissed the menu, and whose menu it was: floating-ui's outside-press runs in
  // the CAPTURE phase, so a press on the open row's own "…" closes the menu before the button's
  // handler sees it (see `buttonProps`).
  const dismissedBy = useRef<{ event: Event; payload: T } | null>(null);
  const pop = useAnchoredPopover({
    open,
    onOpenChange: (next, event) => {
      setOpen(next);
      // Drop the target on close so a stale row can't drive a re-open's first paint.
      if (!next) {
        dismissedBy.current =
          event && openFor.current ? { event, payload: openFor.current.payload } : null;
        setTarget(null);
        setAnchor(null);
        openFor.current = null;
      }
    },
    // A native context menu drops down-and-right from the pointer; flip()/shift() take it the other
    // way near an edge.
    placement: "bottom-start",
    offset: 0,
    fitHeight: true,
    // The anchor is a fixed POINT, not an element, so scrolling cannot move the panel with its row —
    // it would sit over a different row than the one its actions target. Native menus close; so do we.
    dismissOnScroll: true,
  });

  const { setPositionReference } = pop.refs;
  const openAt = useCallback(
    (x: number, y: number, payload: T, contextElement?: Element) => {
      setPositionReference({ getBoundingClientRect: () => pointRect(x, y), contextElement });
      setTarget(payload);
      setAnchor(contextElement ?? null);
      openFor.current = { payload };
      setOpen(true);
    },
    [setPositionReference],
  );

  // Long-press bookkeeping. Refs, not state: none of it paints, and a re-render per pointermove
  // during a scroll would be a real cost on the device this path exists for.
  const timer = useRef<number | null>(null);
  const startedAt = useRef<{ x: number; y: number } | null>(null);
  // A long-press is followed by a click on release. Without this the menu would open and the row's
  // own default action (play / select) would fire underneath it.
  //
  // It is armed by the timer and disarmed by the click it was armed FOR — but plenty of long presses
  // never produce that click (a pan ends in pointercancel, the finger lifts over the portalled menu,
  // Android Chrome suppresses the trailing click after its own contextmenu). The flag then stayed
  // armed, and since it is one ref per LIST, the next genuine tap on ANY row of that list was eaten
  // and the row looked dead until tapped twice (E10 review round 1). So a fresh press also disarms
  // it: whatever the last gesture left behind cannot outlive the start of the next one.
  const swallowClick = useRef(false);
  const cancelPress = useCallback(() => {
    if (timer.current !== null) window.clearTimeout(timer.current);
    timer.current = null;
    startedAt.current = null;
  }, []);

  const triggerProps = useCallback(
    (payload: T) => ({
      // Carries the `-webkit-touch-callout: none` rule (index.css) so an iOS long-press opens THIS
      // menu instead of Safari's own link/image callout on top of it.
      "data-context-menu-target": "",
      onContextMenu: (e: React.MouseEvent<HTMLElement>) => {
        // A row inside another context-menu target (a table inside a panel) claims the event.
        e.stopPropagation();
        // On selected words the browser's own menu opens (Copy, Search): DESIGN "Text stays selectable".
        if (pointOnSelection(e.target, e.clientX, e.clientY)) return;
        e.preventDefault();
        openAt(e.clientX, e.clientY, payload, e.currentTarget);
      },
      onPointerDown: (e: ReactPointerEvent<HTMLElement>) => {
        // Before the pointerType guard: a stale arm left by an earlier touch press must not survive
        // into an unrelated interaction, mouse click included.
        swallowClick.current = false;
        // Mouse has a right button; only touch/pen need the timer.
        if (e.pointerType === "mouse") return;
        const { clientX: x, clientY: y } = e;
        const el = e.currentTarget; // read now: currentTarget is null by the time the timer fires
        startedAt.current = { x, y };
        timer.current = window.setTimeout(() => {
          timer.current = null;
          swallowClick.current = true;
          openAt(x, y, payload, el);
        }, LONG_PRESS_MS);
      },
      onPointerMove: (e: ReactPointerEvent<HTMLElement>) => {
        const from = startedAt.current;
        if (!from || timer.current === null) return;
        if (
          Math.abs(e.clientX - from.x) > LONG_PRESS_SLOP ||
          Math.abs(e.clientY - from.y) > LONG_PRESS_SLOP
        )
          cancelPress(); // they are scrolling, not pressing
      },
      onPointerUp: cancelPress,
      onPointerCancel: () => {
        // The gesture was taken over (a pan, the browser's own menu): no click is coming, so the
        // arm has nothing left to swallow and must not wait around for someone else's.
        swallowClick.current = false;
        cancelPress();
      },
      onClickCapture: (e: React.MouseEvent<HTMLElement>) => {
        if (!swallowClick.current) return;
        swallowClick.current = false;
        e.preventDefault();
        e.stopPropagation();
      },
      onKeyDown: (e: React.KeyboardEvent<HTMLElement>) => {
        // The keyboard route every desktop menu has. Anchored to the row's bottom-left rather than a
        // pointer that isn't there.
        // Through the shared parser, against the table's own row: the chords live in ONE place, and
        // `matches` is exact on modifiers (the hand-rolled version answered Ctrl+Shift+F10 too).
        if (!matchesShortcut(e.nativeEvent, "contextMenu", "contextMenu")) return;
        e.preventDefault();
        const r = e.currentTarget.getBoundingClientRect();
        openAt(r.left, r.bottom, payload, e.currentTarget);
      },
    }),
    [openAt, cancelPress],
  );

  const close = useCallback(() => {
    setOpen(false);
    setTarget(null);
    setAnchor(null);
    openFor.current = null;
  }, []);

  // Set on the "…" button's pointerdown when ITS menu was the open one. The press lands outside the
  // panel, so floating-ui's dismiss may already have closed it; either way the click that follows
  // closes rather than opens, or the button could never close its own menu.
  const pressedWhileOpen = useRef(false);
  const buttonProps = useCallback(
    (payload: T) => ({
      "aria-haspopup": "menu",
      onPointerDown: (e: ReactPointerEvent<HTMLElement>) => {
        const dismissed = dismissedBy.current;
        pressedWhileOpen.current =
          (openFor.current !== null && keyOf(openFor.current.payload) === keyOf(payload)) ||
          (dismissed !== null &&
            dismissed.event === e.nativeEvent &&
            keyOf(dismissed.payload) === keyOf(payload));
      },
      onClick: (e: React.MouseEvent<HTMLElement>) => {
        // The button sits on a card that plays on click, and inside a row that may be a link.
        e.preventDefault();
        e.stopPropagation();
        // Only a pointer click (detail > 0) reads the press: a keyboard click has no pointerdown, so
        // a flag left by a press that never became a click must not turn Enter into a close.
        const toggleOff = e.detail > 0 && pressedWhileOpen.current;
        pressedWhileOpen.current = false;
        if (toggleOff) {
          close();
          return;
        }
        const r = e.currentTarget.getBoundingClientRect();
        openAt(r.left, r.bottom, payload, e.currentTarget);
      },
    }),
    [openAt, close, keyOf],
  );

  return { target, anchor, open, close, triggerProps, buttonProps, openAt, popover: pop };
}

/** One trigger per item, stable while the items and the menu are — for a list whose card component
 *  takes `menuProps: () => props` but whose menu acts on a WRAPPER of what the card holds (Home's
 *  unified shelf card around a `Video`). A fresh `() => menu.triggerProps(c)` per render defeats a
 *  `memo` card on every tile each time the menu's own state changes. Index-aligned with `items`. */
export function useItemTriggers<T>(
  items: readonly T[],
  triggerProps: (payload: T) => Record<string, unknown>,
): (() => Record<string, unknown>)[] {
  return useMemo(() => items.map((it) => () => triggerProps(it)), [items, triggerProps]);
}