"use client";

import Link from "next/link";
import { useMemo, useState } from "react";
import { AlertTriangle, Check, CheckCheck } from "lucide-react";
import { SeverityBadge } from "@/components/ui/badge";
import { Select } from "@/components/ui/select";
import { useAlerts, useMarkAlertRead, useResolveAlert } from "@/hooks/use-alerts";
import { useCompanies } from "@/hooks/use-companies";
import { formatRelative } from "@/lib/format";
import { SEVERITY_LABELS, SEVERITY_LEVELS, type SeverityLevel } from "@/lib/types";

export default function AlertsPage() {
  const [companyId, setCompanyId] = useState<string>("");
  const [severity, setSeverity] = useState<SeverityLevel | "">("");
  const [unreadOnly, setUnreadOnly] = useState(false);
  const [showResolved, setShowResolved] = useState(false);

  const { data: companies } = useCompanies();
  const { data: alerts, isLoading } = useAlerts({
    company_id: companyId || undefined,
    severity: severity || undefined,
    read: unreadOnly ? false : undefined,
    resolved: showResolved ? undefined : false,
  });
  const markRead = useMarkAlertRead();
  const resolve = useResolveAlert();

  const companyNameById = useMemo(
    () => new Map((companies ?? []).map((c) => [c.id, c.name])),
    [companies],
  );

  const alertList = alerts ?? [];

  return (
    <div>
      <div>
        <h1 className="text-2xl font-semibold text-slate-900">Alerts</h1>
        <p className="mt-1 text-sm text-slate-600">
          Meaningful changes detected across your monitored companies.
        </p>
      </div>

      <div className="mt-6 flex flex-wrap items-center gap-3 rounded-lg border border-slate-200 bg-white p-4">
        <Select
          value={companyId}
          onValueChange={setCompanyId}
          placeholder="All companies"
          ariaLabel="Filter by company"
          options={[
            { value: "", label: "All companies" },
            ...(companies ?? []).map((c) => ({ value: c.id, label: c.name })),
          ]}
          triggerClassName="px-3 py-1.5 text-sm"
        />

        <Select
          value={severity}
          onValueChange={(v) => setSeverity(v as SeverityLevel | "")}
          placeholder="All severities"
          ariaLabel="Filter by severity"
          options={[
            { value: "", label: "All severities" },
            ...SEVERITY_LEVELS.map((s) => ({ value: s, label: SEVERITY_LABELS[s] })),
          ]}
          triggerClassName="px-3 py-1.5 text-sm"
        />

        <label className="flex items-center gap-2 text-sm text-slate-600">
          <input
            type="checkbox"
            checked={unreadOnly}
            onChange={(e) => setUnreadOnly(e.target.checked)}
            className="focus-ring rounded border-slate-300"
          />
          Unread only
        </label>

        <label className="flex items-center gap-2 text-sm text-slate-600">
          <input
            type="checkbox"
            checked={showResolved}
            onChange={(e) => setShowResolved(e.target.checked)}
            className="focus-ring rounded border-slate-300"
          />
          Show resolved
        </label>
      </div>

      {isLoading ? (
        <p className="mt-8 text-sm text-slate-500">Loading…</p>
      ) : alertList.length === 0 ? (
        <div className="mt-8 rounded-lg border border-dashed border-slate-300 bg-white p-10 text-center">
          <AlertTriangle className="mx-auto h-8 w-8 text-slate-400" aria-hidden />
          <p className="mt-3 text-sm text-slate-600">No alerts match these filters.</p>
        </div>
      ) : (
        <ul className="mt-6 divide-y divide-slate-100 rounded-lg border border-slate-200 bg-white">
          {alertList.map((alert) => (
            <li key={alert.id} className="flex items-start justify-between gap-4 px-4 py-4">
              <div className="min-w-0 flex-1">
                <div className="flex items-center gap-2">
                  <SeverityBadge severity={alert.severity} />
                  {!alert.read && (
                    <span className="h-1.5 w-1.5 rounded-full bg-brand-600" aria-label="Unread" />
                  )}
                  {alert.resolved && (
                    <span className="text-xs font-medium text-slate-400">Resolved</span>
                  )}
                </div>
                <Link
                  href={`/alerts/${alert.id}`}
                  className="mt-1 block truncate font-medium text-slate-900 hover:text-brand-600"
                >
                  {alert.title}
                </Link>
                <p className="mt-0.5 text-sm text-slate-600">
                  {companyNameById.get(alert.company_id) ?? "Unknown company"} ·{" "}
                  {formatRelative(alert.created_at)} · {Math.round(alert.confidence * 100)}%
                  confidence
                </p>
              </div>
              <div className="flex shrink-0 items-center gap-1">
                {!alert.read && (
                  <button
                    title="Mark read"
                    onClick={() => markRead.mutate(alert.id)}
                    className="focus-ring rounded-md p-2 text-slate-500 hover:bg-slate-100"
                  >
                    <Check className="h-4 w-4" aria-hidden />
                    <span className="sr-only">Mark read</span>
                  </button>
                )}
                {!alert.resolved && (
                  <button
                    title="Resolve"
                    onClick={() => resolve.mutate(alert.id)}
                    className="focus-ring rounded-md p-2 text-slate-500 hover:bg-slate-100"
                  >
                    <CheckCheck className="h-4 w-4" aria-hidden />
                    <span className="sr-only">Resolve</span>
                  </button>
                )}
              </div>
            </li>
          ))}
        </ul>
      )}
    </div>
  );
}