import { useKeyboard } from '@opentui/react';
import { useCallback, useRef } from 'react';
import { navKeyFromInput, nextCursor, type ScrollEcho, shouldSwallowEcho } from '../state/list-cursor';

const SCROLL_KEY_ECHO_WINDOW_MS = 250;

export interface UseListCursorOptions {
  /** Only handle keys when this is true (e.g. panel is focused, no overlay open). */
  isActive: boolean;
  /** Number of items the cursor can land on. */
  length: number;
  /** Current cursor position (caller's source of truth). */
  currentIndex: number;
  /** Called with the new index when a navigation key is handled. */
  setIndex: (index: number) => void;
  /** Optional guard for `up`/`down` only — used to swallow scroll-echo keys. */
  shouldIgnore?: (key: 'up' | 'down') => boolean;
}

/**
 * Wires `j/k/g/G` (plus arrow keys) to a linear cursor. The hook is
 * intentionally narrow: it owns *only* navigation. Domain keys (Enter, mark
 * read, fetch, etc.) stay in each consumer's own `useKeyboard`.
 */
export function useListCursor(options: UseListCursorOptions): void {
  useKeyboard((key) => {
    if (!options.isActive) return;
    const navKey = navKeyFromInput(key.name, !!key.shift);
    if (!navKey) return;
    if ((navKey === 'down' || navKey === 'up') && options.shouldIgnore?.(navKey)) {
      return;
    }
    const next = nextCursor(options.currentIndex, navKey, options.length);
    if (next !== options.currentIndex) {
      options.setIndex(next);
    } else if (navKey === 'home' || navKey === 'end') {
      // Allow the consumer to react to "jump to edge even if already there"
      // by always firing for home/end. Keeps existing behavior.
      options.setIndex(next);
    }
  });
}

/**
 * Per-direction scroll-echo guard. Mouse-wheel handlers call `armEcho(dir)`
 * after a scroll; the very next matching-direction key is swallowed exactly
 * once. Mismatched-direction keys pass through (so a user who scrolls down
 * with the wheel and then presses `k` to go back doesn't lose that keypress).
 */
export function useScrollEchoGuard(): {
  armEcho: (direction: 'up' | 'down') => void;
  shouldIgnore: (key: 'up' | 'down') => boolean;
} {
  const echoRef = useRef<ScrollEcho | null>(null);

  const armEcho = useCallback((direction: 'up' | 'down') => {
    echoRef.current = { direction, expiresAt: Date.now() + SCROLL_KEY_ECHO_WINDOW_MS };
  }, []);

  const shouldIgnore = useCallback((key: 'up' | 'down') => {
    const echo = echoRef.current;
    if (!shouldSwallowEcho(echo, key, Date.now())) {
      if (echo && Date.now() > echo.expiresAt) echoRef.current = null;
      return false;
    }
    echoRef.current = null;
    return true;
  }, []);

  return { armEcho, shouldIgnore };
}