// React port of ../../attach.ts's `buildKeyBar` — the Termux-style special-key
// bar for the soft keyboard (Esc/Tab/Ctrl/Alt/cursor keys/symbols it hides
// behind a page switch). Ctrl/Alt are one-shot sticky modifiers: arming one
// folds into the very next key, tapped here or typed on the soft keyboard,
// then disarms.
import { useCallback, useRef, useState } from "react";

import { applyModsToChar, cursorSeq, tildeSeq } from "../../keys.js";

type Modifier = "ctrl" | "alt";
/** CSI final bytes: arrows A-D, Home `H`, End `F`. */
type CursorFinal = "A" | "B" | "C" | "D" | "H" | "F";

type KeyDef =
  | { label: string; mod: Modifier }
  | { label: string; cursor: CursorFinal }
  | { label: string; tilde: number }
  | { label: string; char: string }
  | { label: string; seq: string };

/**
 * Row-major into an 8-column / 2-row grid (#7):
 *
 *     Esc  Tab  Home  ↑   End  PgUp  -  /
 *     Ctrl Alt   ←    ↓    →   PgDn  |  ~
 */
const KEY_DEFS: KeyDef[] = [
  { label: "Esc", seq: "\x1b" },
  { label: "Tab", seq: "\t" },
  { label: "Home", cursor: "H" },
  { label: "↑", cursor: "A" },
  { label: "End", cursor: "F" },
  { label: "PgUp", tilde: 5 },
  { label: "-", char: "-" },
  { label: "/", char: "/" },
  { label: "Ctrl", mod: "ctrl" },
  { label: "Alt", mod: "alt" },
  { label: "←", cursor: "D" },
  { label: "↓", cursor: "B" },
  { label: "→", cursor: "C" },
  { label: "PgDn", tilde: 6 },
  { label: "|", char: "|" },
  { label: "~", char: "~" },
];

/**
 * Pending Ctrl/Alt state plus `consume`, which folds them into a soft-keyboard
 * character before it reaches the PTY — used by the terminal's own `onData`
 * handler, not by this component's own button clicks.
 */
export function useKeyBarModifiers() {
  const armedRef = useRef<{ ctrl: boolean; alt: boolean }>({ ctrl: false, alt: false });
  const [, setTick] = useState(0);
  const rerender = useCallback(() => setTick((n) => n + 1), []);

  const setMod = useCallback(
    (mod: Modifier, on: boolean) => {
      armedRef.current[mod] = on;
      rerender();
    },
    [rerender],
  );

  const clearMods = useCallback(() => {
    if (!armedRef.current.ctrl && !armedRef.current.alt) return;
    armedRef.current = { ctrl: false, alt: false };
    rerender();
  }, [rerender]);

  const consume = useCallback((data: string): string => {
    const { ctrl, alt } = armedRef.current;
    if ((ctrl || alt) && data.length === 1) {
      const out = applyModsToChar(data, ctrl, alt);
      armedRef.current = { ctrl: false, alt: false };
      return out;
    }
    return data;
  }, []);

  return { armed: armedRef.current, setMod, clearMods, consume };
}

export interface KeyBarProps {
  armed: { ctrl: boolean; alt: boolean };
  onToggleMod(mod: Modifier): void;
  onClearMods(): void;
  onSend(data: string): void;
}

export function KeyBar({ armed, onToggleMod, onClearMods, onSend }: KeyBarProps) {
  return (
    <div
      role="toolbar"
      aria-label="Special keys"
      className="flex flex-wrap gap-1 border-t border-white/10 bg-black/20 p-1"
    >
      {KEY_DEFS.map((def) => {
        if ("mod" in def) {
          return (
            <button
              key={def.label}
              type="button"
              aria-pressed={armed[def.mod]}
              aria-label={`${def.label} modifier`}
              className="min-w-8 rounded px-2 py-1 text-xs aria-pressed:bg-emerald-500/40"
              onClick={() => onToggleMod(def.mod)}
            >
              {def.label}
            </button>
          );
        }
        const bytes = () => {
          if ("cursor" in def) return cursorSeq(def.cursor, armed.ctrl, armed.alt);
          if ("tilde" in def) return tildeSeq(def.tilde, armed.ctrl, armed.alt);
          if ("char" in def) return applyModsToChar(def.char, armed.ctrl, armed.alt);
          return def.seq;
        };
        return (
          <button
            key={def.label}
            type="button"
            className="min-w-8 rounded px-2 py-1 text-xs"
            onClick={() => {
              onSend(bytes());
              onClearMods();
            }}
          >
            {def.label}
          </button>
        );
      })}
    </div>
  );
}