import { useEffect, useMemo, useState } from 'react';
import { Outlet, useLocation, useNavigate } from 'react-router-dom';
import type { LucideIcon } from 'lucide-react';
import { ArrowLeft, CalendarClock, FileText, LogOut, Menu, ShieldCheck, Sparkles, UserCheck, Users, X } from 'lucide-react';
import { cn } from '../lib/cn';
import { Avatar } from '../components/core';
import { ZinoLogo } from '../components/ZinoLogo';
import { canSeeScreen } from '../api/config';
import { useZino } from '../api/provider';
import { useLeads } from '../api/leads';
import type { Lead } from '../types';

interface NavItem {
  to: string;
  label: string;
  Icon: LucideIcon;
  title: string;
  subtitle: string;
}

const NAV: NavItem[] = [
  { to: '/pipeline', label: 'Lead Pipeline', Icon: Users, title: 'Lead pipeline', subtitle: '' },
  { to: '/schedule', label: 'Agent Schedule', Icon: CalendarClock, title: 'Agent schedule', subtitle: 'Sales-agent meetings & booking slots' },
  { to: '/qualify', label: 'Qualify & Assign', Icon: UserCheck, title: 'Qualification & Assignment', subtitle: 'Qualify new leads and assign them to an agent' },
  { to: '/engage', label: 'Customer Interaction', Icon: Sparkles, title: 'Customer Interaction', subtitle: 'Log contact, schedule meetings, recommend products' },
  { to: '/documents', label: 'Documents', Icon: FileText, title: 'Document & Assessment', subtitle: 'KYC collection, OCR, eligibility assessment' },
  { to: '/underwriting', label: 'Underwriting & Policy', Icon: ShieldCheck, title: 'Underwriting & Policy Issuance', subtitle: 'Underwrite, issue policy, onboard customer' },
];

// Pipeline nav subtitle, computed live: "N leads · X% hot · Y% AI-handled".
function pipelineSubtitle(leads: Lead[]): string {
  if (!leads.length) return 'No leads yet';
  const total = leads.length;
  const hot = Math.round((leads.filter((l) => l.segment === 'Hot').length / total) * 100);
  const ai = Math.round((leads.filter((l) => l.ownerAi).length / total) * 100);
  return `${total.toLocaleString('en-IN')} leads · ${hot}% hot · ${ai}% AI-handled`;
}

function BrandLogo() {
  return (
    <div className="flex items-center justify-center px-1">
      <ZinoLogo className="h-7 w-auto" />
    </div>
  );
}

/** Sidebar contents — shared between the static desktop rail and the mobile drawer. */
function SidebarInner({ items, activeTo, onNav }: { items: NavItem[]; activeTo: string; onNav: (to: string) => void }) {
  return (
    <>
      <div className="px-1 pt-1 pb-4 border-b border-white/[0.08]">
        <BrandLogo />
      </div>

      <nav className="flex flex-col gap-1">
        <div className="px-3 pb-1.5 text-2xs font-bold uppercase tracking-[0.14em] text-on-navy-muted/60">
          Workspace
        </div>
        {items.map((n) => {
          const on = activeTo === n.to;
          return (
            <button
              key={n.to}
              onClick={() => onNav(n.to)}
              className={cn(
                'group relative flex items-center gap-3 pl-3 pr-2.5 py-2 rounded-xl border-none cursor-pointer text-left text-[15px] transition-all duration-150',
                on
                  ? 'bg-white/[0.08] text-white font-semibold shadow-[inset_0_1px_0_rgba(255,255,255,0.06)] ring-1 ring-white/10'
                  : 'bg-transparent text-on-navy-muted font-medium hover:bg-white/[0.05] hover:text-on-navy',
              )}
            >
              {/* active accent bar */}
              <span
                className={cn(
                  'absolute left-0 top-1/2 -translate-y-1/2 h-5 w-[3px] rounded-r-full bg-gradient-to-b from-sunrise-400 to-sunrise-300 transition-opacity duration-150',
                  on ? 'opacity-100' : 'opacity-0',
                )}
              />
              <span
                className={cn(
                  'flex h-8 w-8 shrink-0 items-center justify-center rounded-lg transition-colors duration-150',
                  on
                    ? 'bg-sunrise-500/18 text-sunrise-300'
                    : 'bg-white/[0.04] text-on-navy-muted group-hover:text-sunrise-300',
                )}
              >
                <n.Icon size={17} />
              </span>
              <span className="truncate">{n.label}</span>
            </button>
          );
        })}
      </nav>

      {/* live AI-employee status — pinned to the bottom */}
      <div className="mt-auto pt-4 border-t border-white/[0.08]">
        <div className="flex items-center gap-2.5 px-2.5 py-2.5 rounded-xl bg-white/[0.04] ring-1 ring-white/[0.06]">
          <span className="relative flex h-2.5 w-2.5 shrink-0">
            <span className="absolute inline-flex h-full w-full rounded-full bg-emerald-400 opacity-60 animate-ping" />
            <span className="relative inline-flex h-2.5 w-2.5 rounded-full bg-emerald-400" />
          </span>
          <div className="leading-tight min-w-0">
            <div className="text-xs font-semibold text-on-navy">AI employees active</div>
            <div className="text-2xs text-on-navy-muted truncate">Qualify · Engage · Underwrite</div>
          </div>
        </div>
      </div>
    </>
  );
}

function Topbar({ title, subtitle, onMenu, showBack }: { title: string; subtitle: string; onMenu: () => void; showBack: boolean }) {
  const { user, logout } = useZino();
  const navigate = useNavigate();
  return (
    <header className="sticky top-0 z-30 h-16 shrink-0 bg-card border-b border-border-subtle flex items-center px-4 lg:px-7 gap-3 lg:gap-5 font-sans">
      <button
        onClick={onMenu}
        aria-label="Open menu"
        className="lg:hidden w-[38px] h-[38px] -ml-1 rounded-md border border-border-subtle bg-card cursor-pointer text-muted flex items-center justify-center shrink-0"
      >
        <Menu size={20} />
      </button>
      {showBack && (
        <button
          onClick={() => (window.history.length > 1 ? navigate(-1) : navigate('/pipeline'))}
          aria-label="Go back"
          title="Go back"
          className="w-[38px] h-[38px] rounded-md border border-border-subtle bg-card cursor-pointer text-muted flex items-center justify-center shrink-0 hover:text-strong hover:bg-slate-50"
        >
          <ArrowLeft size={18} />
        </button>
      )}
      <div className="flex-1 min-w-0">
        <h1 className="m-0 text-lg font-bold text-strong truncate">{title}</h1>
        {subtitle && <div className="text-xs text-faint mt-px truncate">{subtitle}</div>}
      </div>
      <div className="flex items-center gap-3.5">
        <div className="flex items-center gap-2 pl-1.5">
          <Avatar name={user?.name || 'User'} size={36} />
          <div className="hidden md:block leading-tight whitespace-nowrap">
            <div className="text-sm font-semibold text-strong">{user?.name || 'User'}</div>
            <div className="text-2xs text-faint">{user?.email || ''}</div>
          </div>
          <button
            onClick={() => {
              logout();
              navigate('/login', { replace: true });
            }}
            title="Sign out"
            className="w-[38px] h-[38px] rounded-md border border-border-subtle bg-card cursor-pointer text-muted flex items-center justify-center ml-1"
          >
            <LogOut size={17} />
          </button>
        </div>
      </div>
    </header>
  );
}

/** App shell — navy sidebar (nav) + topbar, with routed content. */
export function Shell() {
  const location = useLocation();
  const navigate = useNavigate();
  const { leads } = useLeads();
  const { user } = useZino();
  const path = location.pathname;
  // Nav is RBAC-filtered: a user only sees screens their roles allow.
  const visibleNav = useMemo(() => NAV.filter((n) => canSeeScreen(user?.roles, n.to)), [user]);
  const navMatch = NAV.find((n) => path.startsWith(n.to));
  // Routes reached contextually (no sidebar entry) still get a topbar title.
  const active =
    navMatch ??
    (path.startsWith('/leads')
      ? { to: '/leads', label: 'Lead 360', Icon: Users, title: 'Lead 360', subtitle: 'Full lead context, AI decision stream & next action' }
      : path.startsWith('/new')
        ? { to: '/new', label: 'New lead', Icon: Users, title: 'Capture lead', subtitle: 'Add a new lead to the pipeline' }
        : NAV[0]);

  const subtitle = active.to === '/pipeline' ? pipelineSubtitle(leads) : active.subtitle;

  const [navOpen, setNavOpen] = useState(false);
  // Close the mobile drawer whenever the route changes.
  useEffect(() => setNavOpen(false), [path]);

  return (
    <div className="flex min-h-screen bg-app font-sans">
      {/* Static rail — lg and up. Pinned; the page scrolls normally beside it. */}
      <aside className="hidden lg:flex w-[248px] shrink-0 bg-navy-grad flex-col p-4 gap-6 font-sans sticky top-0 h-screen self-start overflow-y-auto">
        <SidebarInner items={visibleNav} activeTo={navMatch?.to ?? ''} onNav={(to) => navigate(to)} />
      </aside>

      {/* Drawer — below lg. */}
      {navOpen && (
        <div className="fixed inset-0 z-50 lg:hidden">
          <div className="absolute inset-0 bg-black/40" onClick={() => setNavOpen(false)} />
          <aside className="absolute inset-y-0 left-0 w-[248px] max-w-[82%] bg-navy-grad flex flex-col p-4 gap-6 font-sans shadow-2xl">
            <button
              onClick={() => setNavOpen(false)}
              aria-label="Close menu"
              className="absolute top-3 right-3 w-9 h-9 rounded-md text-on-navy-muted hover:text-on-navy flex items-center justify-center bg-transparent border-none cursor-pointer"
            >
              <X size={20} />
            </button>
            <SidebarInner items={visibleNav} activeTo={navMatch?.to ?? ''} onNav={(to) => navigate(to)} />
          </aside>
        </div>
      )}

      <div className="flex-1 flex flex-col min-w-0">
        <Topbar title={active.title} subtitle={subtitle} onMenu={() => setNavOpen(true)} showBack={!navMatch} />
        <main className="flex-1 p-4 lg:p-7">
          <Outlet />
        </main>
      </div>
    </div>
  );
}