"use client";

import { useState, useEffect, useRef } from "react";
import { createPortal } from "react-dom";
import Link from "next/link";
import { usePathname } from "next/navigation";
import { Menu, X } from "lucide-react";
import { Button } from "@/components/ui/button";
import {
  LayoutDashboard,
  Users,
  Tag,
  Package,
  Banknote,
  Truck,
  Fuel,
  Send,
  BarChart3,
  ScrollText,
  Settings,
} from "lucide-react";
import { cn } from "@/lib/utils";

type NavItem = {
  href: string;
  label: string;
  icon: React.ComponentType<{ className?: string }>;
};

const groups: { label: string; items: NavItem[] }[] = [
  {
    label: "Overview",
    items: [{ href: "/dashboard", label: "Dashboard", icon: LayoutDashboard }],
  },
  {
    label: "Operations",
    items: [
      { href: "/customers", label: "Customers", icon: Users },
      { href: "/delivery-notes", label: "Delivery Notes", icon: Package },
      { href: "/cash-customers", label: "Cash Customers", icon: Banknote },
      { href: "/suppliers", label: "Suppliers", icon: Truck },
      { href: "/fuel-purchases", label: "Fuel Purchases", icon: Fuel },
    ],
  },
  {
    label: "Pricing & reports",
    items: [
      { href: "/pricing", label: "Pricing", icon: Tag },
      { href: "/send-statement", label: "Send Statement", icon: Send },
      { href: "/custom-reports", label: "Custom Reports", icon: BarChart3 },
      { href: "/statements", label: "Statement Log", icon: ScrollText },
    ],
  },
  {
    label: "Admin",
    items: [{ href: "/settings", label: "Settings", icon: Settings }],
  },
];

export function MobileNav() {
  const [open, setOpen] = useState(false);
  const [rendered, setRendered] = useState(false);
  const [mounted, setMounted] = useState(false);
  const pathname = usePathname();
  const triggerRef = useRef<HTMLButtonElement>(null);

  // Track mount so we only portal on the client (avoids SSR mismatch)
  useEffect(() => {
    setMounted(true);
  }, []);

  // Close the menu whenever the route changes
  useEffect(() => {
    setOpen(false);
  }, [pathname]);

  // Keep the sheet mounted briefly after closing so the exit animation plays
  useEffect(() => {
    if (open) {
      setRendered(true);
      return;
    }
    const t = setTimeout(() => setRendered(false), 250);
    return () => clearTimeout(t);
  }, [open]);

  // Lock body scroll while open
  useEffect(() => {
    if (!open) return;
    const prev = document.body.style.overflow;
    document.body.style.overflow = "hidden";
    return () => {
      document.body.style.overflow = prev;
    };
  }, [open]);

  // Close on Escape, restore focus to the trigger
  useEffect(() => {
    if (!open) return;
    function onKey(e: KeyboardEvent) {
      if (e.key === "Escape") {
        setOpen(false);
        triggerRef.current?.focus();
      }
    }
    window.addEventListener("keydown", onKey);
    return () => window.removeEventListener("keydown", onKey);
  }, [open]);

  const trigger = (
    <Button
      ref={triggerRef}
      variant="ghost"
      size="icon"
      className="md:hidden -ml-2"
      onClick={() => setOpen(true)}
      aria-label="Open navigation"
      aria-expanded={open}
    >
      <Menu className="h-5 w-5" />
    </Button>
  );

  if (!rendered || !mounted) {
    return trigger;
  }

  const sheet = (
    <>
      {/* Backdrop — fades in/out */}
      <div
        className={cn(
          "fixed inset-0 z-[100] bg-black/50 md:hidden transition-opacity duration-200 ease-out",
          open ? "opacity-100" : "opacity-0 pointer-events-none"
        )}
        onClick={() => setOpen(false)}
        aria-hidden
      />

      {/* Sheet — slides in from the left.
          Rendered via portal at document.body so it escapes any containing
          block created by parent transforms/filters (e.g. backdrop-blur). */}
      <aside
        className={cn(
          "fixed inset-y-0 left-0 z-[101] w-72 max-w-[85vw] h-screen bg-sidebar text-sidebar-foreground border-r border-sidebar-border md:hidden flex flex-col shadow-2xl",
          "transition-transform duration-250 ease-out",
          open ? "translate-x-0" : "-translate-x-full"
        )}
        style={{ transitionDuration: "250ms" }}
        role="dialog"
        aria-label="Navigation"
        aria-modal="true"
        aria-hidden={!open}
      >
        <div className="flex h-16 items-center justify-between border-b border-sidebar-border px-4">
          <div className="flex items-center gap-2.5">
            <div className="flex h-9 w-9 items-center justify-center rounded-md bg-sidebar-primary text-sidebar-primary-foreground font-bold text-sm">
              RJ
            </div>
            <div className="flex flex-col leading-tight">
              <span className="text-sm font-semibold">RJ Bulk Supplies</span>
              <span className="text-[11px] text-muted-foreground">Back office</span>
            </div>
          </div>
          <Button
            variant="ghost"
            size="icon"
            onClick={() => setOpen(false)}
            aria-label="Close navigation"
            className="-mr-2"
          >
            <X className="h-5 w-5" />
          </Button>
        </div>
        <nav className="flex-1 overflow-y-auto px-3 py-4 space-y-5">
          {groups.map((group, gi) => (
            <div key={group.label}>
              {gi > 0 && <div className="border-t border-sidebar-border mb-4" />}
              <div className="px-3 mb-2 text-[11px] font-semibold uppercase tracking-[0.12em] text-primary/80">
                {group.label}
              </div>
              <div className="space-y-0.5">
                {group.items.map((item) => {
                  const Icon = item.icon;
                  const active = pathname === item.href || (item.href !== "/" && pathname.startsWith(item.href + "/"));
                  return (
                    <Link
                      key={item.href}
                      href={item.href}
                      tabIndex={open ? 0 : -1}
                      className={cn(
                        "flex items-center gap-3 rounded-md px-3 py-2.5 text-sm transition-colors",
                        active
                          ? "bg-sidebar-accent text-sidebar-accent-foreground font-medium"
                          : "hover:bg-sidebar-accent/50",
                        group.label === "Admin" && !active && "text-muted-foreground"
                      )}
                    >
                      <Icon className={cn("h-4 w-4", active && "text-primary")} />
                      {item.label}
                    </Link>
                  );
                })}
              </div>
            </div>
          ))}
        </nav>
        <div className="px-4 py-3 border-t border-sidebar-border text-[10px] text-muted-foreground">
          RJ Bulk v1.0
        </div>
      </aside>
    </>
  );

  return (
    <>
      {trigger}
      {createPortal(sheet, document.body)}
    </>
  );
}