/** Minimal hash router for Habit Journal pages. */

import { useEffect, useState } from "preact/hooks";

export type Route =
  | { name: "login" }
  | { name: "home" }
  | { name: "log"; remedy?: string; happened?: string }
  | { name: "history" }
  | { name: "entry"; id: string }
  | { name: "daily" }
  | { name: "plan"; date?: string }
  | { name: "stats" }
  | { name: "coach" }
  | { name: "remedies" }
  | { name: "settings" }
  | { name: "unknown"; path: string };

function parseHash(hash: string): Route {
  const raw = hash.replace(/^#/, "") || "/";
  const [path = "/", query = ""] = raw.split("?");
  const params = new URLSearchParams(query);
  if (path === "/login") return { name: "login" };
  if (path === "/" || path === "") return { name: "home" };
  if (path === "/log")
    return {
      name: "log",
      remedy: params.get("remedy") || undefined,
      happened: params.get("happened") || undefined,
    };
  if (path === "/history") return { name: "history" };
  if (path.startsWith("/entry/")) return { name: "entry", id: decodeURIComponent(path.slice(7)) };
  if (path === "/daily") return { name: "daily" };
  if (path === "/plan") return { name: "plan" };
  if (path.startsWith("/plan/")) return { name: "plan", date: decodeURIComponent(path.slice(6)) };
  if (path === "/stats") return { name: "stats" };
  if (path === "/coach") return { name: "coach" };
  if (path === "/remedies") return { name: "remedies" };
  if (path === "/settings") return { name: "settings" };
  return { name: "unknown", path };
}

export function navigate(to: string): void {
  const next = to.startsWith("#") ? to : `#${to.startsWith("/") ? to : `/${to}`}`;
  if (window.location.hash === next) {
    window.dispatchEvent(new HashChangeEvent("hashchange"));
    return;
  }
  window.location.hash = next;
}

export function useRoute(): Route {
  const [route, setRoute] = useState<Route>(() =>
    parseHash(typeof window !== "undefined" ? window.location.hash : "#/"),
  );

  useEffect(() => {
    const onChange = () => setRoute(parseHash(window.location.hash));
    window.addEventListener("hashchange", onChange);
    if (!window.location.hash) {
      window.location.hash = "#/";
    }
    return () => window.removeEventListener("hashchange", onChange);
  }, []);

  return route;
}