"use client";

import { AlertTriangle, Building2, Clock, FileText, Plus, Radio, ServerCog } from "lucide-react";
import Link from "next/link";
import { useCurrentUser, useSystemStatus } from "@/hooks/use-auth";
import { useCompanies } from "@/hooks/use-companies";
import { useDashboardAnalytics } from "@/hooks/use-analytics";
import { StatCard } from "@/components/ui/stat-card";
import { DashboardAnalyticsSection } from "@/components/dashboard/analytics-section";
import { formatDateTime } from "@/lib/format";
import type { CompanyResponse } from "@/lib/types";

function mostRecentLastRun(companies: CompanyResponse[]): string | null {
  const runs = companies
    .map((c) => c.monitor_configuration?.last_run)
    .filter((v): v is string => Boolean(v));
  if (runs.length === 0) return null;
  return runs.sort().at(-1) ?? null;
}

function nextUpcomingRun(companies: CompanyResponse[]): string | null {
  const runs = companies
    .filter((c) => c.monitor_configuration?.enabled)
    .map((c) => c.monitor_configuration?.next_run)
    .filter((v): v is string => Boolean(v));
  if (runs.length === 0) return null;
  return runs.sort().at(0) ?? null;
}

export default function DashboardPage() {
  const { data: user } = useCurrentUser();
  const { data: systemStatus } = useSystemStatus();
  const { data: companies, isLoading } = useCompanies();
  const { data: analytics } = useDashboardAnalytics();

  const companyList = companies ?? [];
  const activeCount = companyList.filter((c) => c.status === "active").length;
  const reportCount = companyList.reduce((sum, c) => sum + c.report_count, 0);
  const unreadAlertCount = companyList.reduce((sum, c) => sum + c.unresolved_alert_count, 0);

  return (
    <div>
      <div className="flex flex-wrap items-start justify-between gap-4">
        <div>
          <h1 className="text-2xl font-semibold text-slate-900">
            Welcome{user ? `, ${user.display_name}` : ""}
          </h1>
          <p className="mt-1 text-sm text-slate-600">
            Here&apos;s what&apos;s happening across your monitors.
          </p>
        </div>
        <Link
          href="/companies/new"
          className="focus-ring inline-flex items-center gap-2 rounded-md bg-brand-600 px-4 py-2 text-sm font-semibold text-white transition hover:bg-brand-700 active:scale-95"
        >
          <Plus className="h-4 w-4" aria-hidden /> Add company
        </Link>
      </div>

      <div className="mt-6 grid gap-4 sm:grid-cols-2 lg:grid-cols-4">
        <StatCard label="Monitored companies" value={companyList.length} icon={Building2} />
        <StatCard label="Active monitors" value={activeCount} icon={Radio} />
        <StatCard label="Reports generated" value={reportCount} icon={FileText} />
        <StatCard label="Unread alerts" value={unreadAlertCount} icon={AlertTriangle} />
      </div>

      {analytics && <DashboardAnalyticsSection analytics={analytics} />}

      <div className="mt-6 grid gap-4 lg:grid-cols-2">
        <div className="rounded-lg border border-slate-200 bg-white p-5">
          <div className="flex items-center gap-2 text-sm font-medium text-slate-700">
            <Clock className="h-4 w-4" aria-hidden /> Monitoring schedule
          </div>
          <dl className="mt-3 space-y-2 text-sm">
            <div className="flex justify-between">
              <dt className="text-slate-500">Last successful run</dt>
              <dd className="text-slate-900">{formatDateTime(mostRecentLastRun(companyList))}</dd>
            </div>
            <div className="flex justify-between">
              <dt className="text-slate-500">Next scheduled run</dt>
              <dd className="text-slate-900">{formatDateTime(nextUpcomingRun(companyList))}</dd>
            </div>
          </dl>
        </div>

        <div className="rounded-lg border border-slate-200 bg-white p-5">
          <div className="flex items-center gap-2 text-sm font-medium text-slate-700">
            <ServerCog className="h-4 w-4" aria-hidden /> System health
          </div>
          <dl className="mt-3 space-y-2 text-sm">
            {systemStatus?.components.map((c) => (
              <div key={c.name} className="flex justify-between capitalize">
                <dt className="text-slate-500">{c.name}</dt>
                <dd className={c.status === "ok" ? "text-green-700" : "text-red-700"}>
                  {c.status}
                </dd>
              </div>
            ))}
            <div className="flex justify-between">
              <dt className="text-slate-500">LLM provider</dt>
              <dd className="text-slate-900">{systemStatus?.llm_provider ?? "—"}</dd>
            </div>
          </dl>
        </div>
      </div>

      <div className="mt-6 rounded-lg border border-slate-200 bg-white p-5">
        <div className="flex items-center justify-between">
          <h2 className="text-sm font-medium text-slate-700">Companies</h2>
          <Link
            href="/companies"
            className="text-sm font-medium text-brand-600 hover:text-brand-700"
          >
            View all
          </Link>
        </div>
        {isLoading ? (
          <p className="mt-4 text-sm text-slate-500">Loading…</p>
        ) : companyList.length === 0 ? (
          <div className="mt-4 rounded-md border border-dashed border-slate-300 p-6 text-center">
            <p className="text-sm text-slate-600">You&apos;re not monitoring any companies yet.</p>
            <Link
              href="/companies/new"
              className="focus-ring mt-3 inline-block rounded-md bg-brand-600 px-4 py-2 text-sm font-semibold text-white hover:bg-brand-700"
            >
              Add your first company
            </Link>
          </div>
        ) : (
          <ul className="mt-4 divide-y divide-slate-100">
            {companyList.slice(0, 5).map((c) => (
              <li key={c.id} className="flex items-center justify-between py-3 text-sm">
                <Link
                  href={`/companies/${c.id}`}
                  className="font-medium text-slate-900 hover:text-brand-600"
                >
                  {c.name}
                </Link>
                <span className="text-slate-500">{c.status}</span>
              </li>
            ))}
          </ul>
        )}
      </div>
    </div>
  );
}