// frontend/components/Dialog.tsx
// 앱 전역 통합 다이얼로그 — window.confirm/alert 대체.
// useDialog().confirm({...}) → Promise<boolean>, .alert({...}) → Promise<void>.
"use client";
import {
  createContext,
  useCallback,
  useContext,
  useEffect,
  useRef,
  useState,
} from "react";

type DialogTone = "danger" | "primary";
export type DialogOptions = {
  title?: string;
  message?: string;
  confirmText?: string;
  cancelText?: string; // confirm 전용
  tone?: DialogTone;
};
type DialogState = DialogOptions & { kind: "confirm" | "alert" };

type DialogApi = {
  confirm: (opts: DialogOptions) => Promise<boolean>;
  alert: (opts: DialogOptions) => Promise<void>;
};

const Ctx = createContext<DialogApi | null>(null);

export function useDialog(): DialogApi {
  const c = useContext(Ctx);
  if (!c) throw new Error("useDialog must be used within <DialogProvider>");
  return c;
}

function DialogModal({
  state,
  onClose,
}: {
  state: DialogState;
  onClose: (ok: boolean) => void;
}) {
  const isConfirm = state.kind === "confirm";
  const tone: DialogTone = state.tone ?? (isConfirm ? "danger" : "primary");
  const okRef = useRef<HTMLButtonElement>(null);

  useEffect(() => {
    okRef.current?.focus();
    const h = (e: KeyboardEvent) => {
      if (e.key === "Escape") {
        e.preventDefault();
        onClose(false);
      } else if (e.key === "Enter") {
        e.preventDefault();
        onClose(true);
      }
    };
    window.addEventListener("keydown", h);
    return () => window.removeEventListener("keydown", h);
  }, [onClose]);

  return (
    <div className="dlg-backdrop" onClick={() => onClose(false)} role="presentation">
      <div
        className="dlg-card"
        role="alertdialog"
        aria-modal="true"
        aria-label={state.title ?? "확인"}
        onClick={(e) => e.stopPropagation()}
      >
        {state.title && <h2 className="dlg-title">{state.title}</h2>}
        {state.message && <p className="dlg-msg">{state.message}</p>}
        <div className="dlg-actions">
          {isConfirm && (
            <button className="dlg-btn ghost" onClick={() => onClose(false)}>
              {state.cancelText ?? "취소"}
            </button>
          )}
          <button
            ref={okRef}
            className={"dlg-btn " + tone}
            onClick={() => onClose(true)}
          >
            {state.confirmText ?? "확인"}
          </button>
        </div>
      </div>
    </div>
  );
}

export function DialogProvider({ children }: { children: React.ReactNode }) {
  const [state, setState] = useState<DialogState | null>(null);
  const resolver = useRef<((ok: boolean) => void) | null>(null);

  const close = useCallback((ok: boolean) => {
    resolver.current?.(ok);
    resolver.current = null;
    setState(null);
  }, []);

  const confirm = useCallback(
    (opts: DialogOptions) =>
      new Promise<boolean>((resolve) => {
        resolver.current = resolve;
        setState({ kind: "confirm", ...opts });
      }),
    [],
  );

  const alert = useCallback(
    (opts: DialogOptions) =>
      new Promise<void>((resolve) => {
        resolver.current = () => resolve();
        setState({ kind: "alert", ...opts });
      }),
    [],
  );

  return (
    <Ctx.Provider value={{ confirm, alert }}>
      {children}
      {state && <DialogModal state={state} onClose={close} />}
    </Ctx.Provider>
  );
}