import { slides } from "@state/slides.svelte";
import { site } from "@state/site.svelte";
import { locale } from "@state/locale.svelte";

let siteInitialized = false;

function normalizePath(path) {
  return path === "/" ? "/home" : path;
}

async function loadSlide(path) {
  const idx = slides.getIndexByPath(path);
  if (idx !== -1) {
    const slide = slides.all[idx];
    if (slide.loaded || slide.loading) return;
    slides.setLoading(path, true);
  }

  try {
    const response = await fetch(`${path}.json`);
    if (!response.ok) throw new Error(`HTTP ${response.status}`);
    const data = await response.json();

    if (!siteInitialized && data.site) {
      site.set(data.site);
      locale.initialize(data.site.language, data.site.languages);
      slides.init(data.site.navigation);
      siteInitialized = true;
    }

    slides.setData(path, data);
  } catch (error) {
    console.error(`[router] Failed to load slide ${path}:`, error);
    slides.setLoading(path, false);
  }
}

function loadAllSlidesInBackground(exceptPath) {
  slides.all
    .filter((s) => s.path !== exceptPath)
    .forEach((s) => loadSlide(s.path));
}

export function slideTo(path, { skipHistory = false } = {}) {
  path = normalizePath(path);

  if (!skipHistory) {
    history.pushState({}, "", path === "/home" ? "/" : path);
  }

  const idx = slides.getIndexByPath(path);
  if (idx !== -1 && slides.all[idx].title) {
    document.title = `${slides.all[idx].title} — World Game`;
  }

  slides.slideTo(path);

  if (idx !== -1 && !slides.all[idx].loaded) {
    loadSlide(path);
  }
}

export async function initRouter() {
  const initialPath = normalizePath(window.location.pathname);

  await loadSlide(initialPath);

  const idx = slides.getIndexByPath(initialPath);
  if (idx !== -1) {
    slides.setActiveIndex(idx);
  }

  loadAllSlidesInBackground(initialPath);

  window.addEventListener("popstate", () => {
    const path = normalizePath(window.location.pathname);
    slideTo(path, { skipHistory: true });
  });

  document.addEventListener("click", (e) => {
    const link = e.target.closest("a");
    if (!link) return;

    const url = new URL(link.href, window.location.origin);
    if (
      url.origin === window.location.origin &&
      !link.target &&
      !link.hasAttribute("download")
    ) {
      e.preventDefault();
      slideTo(url.pathname);
    }
  });
}

// Keep navigateTo as alias so existing views don't break
export const navigateTo = slideTo;