// Slash menu — appears when the user types `/`. Shows the four chip kinds.
// On selection, inserts a chip with a placeholder label that the user can
// then rename inline.

"use client";

import { useEffect, useImperativeHandle, useState, forwardRef } from "react";
import type { ChipKind } from "../../lib/fixtures/aristotle";

export interface SlashItem {
  kind: ChipKind;
  label: string;
  hint: string;
  glyph: string;
}

export const SLASH_ITEMS: SlashItem[] = [
  { kind: "block", label: "Block", hint: "an entity in the system", glyph: "▢" },
  { kind: "property", label: "Property", hint: "an attribute of a block", glyph: "·" },
  { kind: "association", label: "Association", hint: "a relationship", glyph: "→" },
  { kind: "requirement", label: "Requirement", hint: "a stated goal (REQ-NNN)", glyph: "§" },
];

export interface SlashMenuHandle {
  onKeyDown: (event: KeyboardEvent) => boolean;
}

interface SlashMenuProps {
  query: string;
  command: (item: SlashItem) => void;
}

export const SlashMenu = forwardRef<SlashMenuHandle, SlashMenuProps>(function SlashMenu(
  { query, command },
  ref
) {
  const filtered = SLASH_ITEMS.filter(
    item =>
      query.length === 0 ||
      item.kind.toLowerCase().startsWith(query.toLowerCase()) ||
      item.label.toLowerCase().startsWith(query.toLowerCase())
  );
  const [activeIndex, setActiveIndex] = useState(0);

  useEffect(() => {
    setActiveIndex(0);
  }, [query]);

  useImperativeHandle(ref, () => ({
    onKeyDown(event: KeyboardEvent) {
      if (filtered.length === 0) return false;
      if (event.key === "ArrowUp") {
        setActiveIndex(prev => (prev - 1 + filtered.length) % filtered.length);
        return true;
      }
      if (event.key === "ArrowDown") {
        setActiveIndex(prev => (prev + 1) % filtered.length);
        return true;
      }
      if (event.key === "Enter" || event.key === "Tab") {
        const choice = filtered[activeIndex];
        if (choice) {
          command(choice);
          return true;
        }
      }
      // Number-key shortcut: 1–4 picks the corresponding item
      const num = parseInt(event.key, 10);
      if (!Number.isNaN(num) && num >= 1 && num <= filtered.length) {
        const choice = filtered[num - 1];
        if (choice) {
          command(choice);
          return true;
        }
      }
      return false;
    },
  }));

  if (filtered.length === 0) {
    return (
      <div className="slash-menu slash-menu-empty">
        <span className="slash-menu-empty-text">no matches for “{query}”</span>
      </div>
    );
  }

  return (
    <div className="slash-menu">
      {filtered.map((item, idx) => (
        <button
          key={item.kind}
          type="button"
          className={`slash-menu-item ${idx === activeIndex ? "slash-menu-item-active" : ""}`}
          onMouseEnter={() => setActiveIndex(idx)}
          onMouseDown={e => {
            // mousedown so the click registers before the editor blurs
            e.preventDefault();
            command(item);
          }}
        >
          <span className={`slash-menu-glyph slash-menu-glyph-${item.kind}`}>{item.glyph}</span>
          <span className="slash-menu-label">{item.label}</span>
          <span className="slash-menu-hint">{item.hint}</span>
          <span className="slash-menu-key">{idx + 1}</span>
        </button>
      ))}
    </div>
  );
});