"use client";

import { create } from "zustand";

export type Screen =
  | "home"
  | "auth"
  | "profile"
  | "friends"
  | "online" // online lobby (create room / play random)
  | "room"
  | "matchmaking"
  | "leaderboard"
  | "shop"
  | "chat"
  | "notifications"
  | "game"; // the table (used for both ai + online)

const ALL_SCREENS: Screen[] = [
  "home", "auth", "profile", "friends", "online",
  "room", "matchmaking", "leaderboard", "shop", "chat", "notifications", "game",
];

/** Screens safe to restore from a URL on a cold load (no transient state needed). */
export const STATIC_SCREENS: Screen[] = [
  "home", "auth", "profile", "friends", "online", "leaderboard", "shop", "notifications",
];

export function screenFromHash(): Screen {
  if (typeof window === "undefined") return "home";
  const h = window.location.hash.replace(/^#\/?/, "");
  return (ALL_SCREENS.includes(h as Screen) ? (h as Screen) : "home");
}

function urlFor(screen: Screen): string {
  if (typeof window === "undefined") return "/";
  const base = window.location.pathname + window.location.search;
  return screen === "home" ? base : `${base}#/${screen}`;
}

function pushHistory(screen: Screen, replace = false) {
  if (typeof window === "undefined") return;
  const state = { screen };
  if (replace) window.history.replaceState(state, "", urlFor(screen));
  else window.history.pushState(state, "", urlFor(screen));
}

interface UIStore {
  screen: Screen;
  /** screen to return to from the game table */
  returnTo: Screen;
  dailyModalOpen: boolean;

  go: (screen: Screen) => void;
  goGame: (returnTo?: Screen) => void;
  /** Browser/hardware back. */
  back: (fallback?: Screen) => void;
  /** Sync from a popstate event (does not touch history). */
  syncFromPop: (screen: Screen) => void;
  /** Establish a home base entry + restore a deep-linked screen on load. */
  initHistory: () => void;

  openDaily: () => void;
  closeDaily: () => void;
}

export const useUIStore = create<UIStore>((set, get) => ({
  screen: "home",
  returnTo: "home",
  dailyModalOpen: false,

  go: (screen) => {
    if (get().screen === screen) return;
    pushHistory(screen);
    set({ screen });
  },

  goGame: (returnTo = "home") => {
    pushHistory("game");
    set({ screen: "game", returnTo });
  },

  back: (fallback) => {
    if (typeof window !== "undefined") {
      window.history.back();
      return;
    }
    if (fallback) set({ screen: fallback });
  },

  syncFromPop: (screen) => set({ screen }),

  initHistory: () => {
    // Always anchor a "home" base entry so back() has somewhere to land.
    pushHistory("home", true);
    const target = screenFromHash();
    if (target !== "home" && STATIC_SCREENS.includes(target)) {
      pushHistory(target);
      set({ screen: target });
    } else {
      set({ screen: "home" });
    }
  },

  openDaily: () => set({ dailyModalOpen: true }),
  closeDaily: () => set({ dailyModalOpen: false }),
}));