import { Settings } from "lucide-react";
import { NavLink, useLocation } from "react-router-dom";
import { useEffect, useMemo, useState } from "react";
import type { AuthInfo, PlatformNavItem } from "../types";
import { hasAnyScope, hasScope } from "../utils/permissions";

const MODULE_NAV_STORAGE_KEY = "govoplan.lastModuleNav";

function visibleNavItems(auth: AuthInfo | null | undefined, navItems: PlatformNavItem[]): PlatformNavItem[] {
  return [...navItems]
    .sort((left, right) => (left.order ?? 100) - (right.order ?? 100))
    .filter((item) => {
      if (item.allOf?.length && !item.allOf.every((scope) => hasScope(auth, scope))) return false;
      if (item.anyOf?.length && !hasAnyScope(auth, item.anyOf)) return false;
      return true;
    });
}

export default function IconRail({
  compact = false,
  auth = null,
  navItems = []
}: {
  compact?: boolean;
  auth?: AuthInfo | null;
  navItems?: PlatformNavItem[];
}) {
  const location = useLocation();
  const items = visibleNavItems(auth, navItems);
  const [rememberedTargets, setRememberedTargets] = useState<Record<string, string>>(() => loadRememberedTargets());
  const topLevelItems = useMemo(() => items.map((item) => item.to), [items]);

  useEffect(() => {
    const currentRoot = topLevelItems.find((root) => modulePathActive(location.pathname, root));
    if (!currentRoot || location.pathname === currentRoot) return;
    const target = `${location.pathname}${location.search}${location.hash}`;
    setRememberedTargets((current) => {
      if (current[currentRoot] === target) return current;
      const next = { ...current, [currentRoot]: target };
      saveRememberedTargets(next);
      return next;
    });
  }, [location.hash, location.pathname, location.search, topLevelItems]);

  return (
    <aside className={`icon-rail ${compact ? "compact" : ""}`}>
      <div className="brand-mark" title="GovOPlaN">G</div>

      {!compact && (
        <>
          <nav className="icon-nav">
            {items.map(({ to, label, icon: Icon }) => {
              const target = rememberedTargets[to] ?? to;
              const active = modulePathActive(location.pathname, to);
              return (
                <NavLink key={to} to={target} className={`icon-nav-item ${active ? "active" : ""}`} title={label}>
                  {Icon ? <Icon size={20} /> : label.slice(0, 1)}
                </NavLink>
              );
            })}
          </nav>
          <div className="icon-rail-bottom">
            <NavLink to="/settings" className={({ isActive }) => `icon-nav-item ${isActive ? "active" : ""}`} title="Settings">
              <Settings size={20} />
            </NavLink>
          </div>
        </>
      )}
    </aside>
  );
}

function modulePathActive(pathname: string, root: string): boolean {
  if (root === "/") return pathname === "/";
  return pathname === root || pathname.startsWith(`${root}/`);
}

function loadRememberedTargets(): Record<string, string> {
  if (typeof window === "undefined") return {};
  try {
    const raw = window.localStorage.getItem(MODULE_NAV_STORAGE_KEY);
    const parsed = raw ? JSON.parse(raw) : {};
    if (!parsed || typeof parsed !== "object" || Array.isArray(parsed)) return {};
    return Object.fromEntries(
      Object.entries(parsed).filter((entry): entry is [string, string] => {
        const [root, target] = entry;
        return typeof root === "string" && typeof target === "string" && root.startsWith("/") && target.startsWith(`${root}/`);
      }),
    );
  } catch {
    return {};
  }
}

function saveRememberedTargets(targets: Record<string, string>): void {
  if (typeof window === "undefined") return;
  try {
    window.localStorage.setItem(MODULE_NAV_STORAGE_KEY, JSON.stringify(targets));
  } catch {
    // Remembered navigation is a convenience only.
  }
}