import { useCallback, useEffect, useState } from "react";
import { useNavigate } from "react-router-dom";
import { Plus, RefreshCw, AlertTriangle, CircleAlert, Info, Link2Off } from "lucide-react";
import { api } from "../api.js";
import { useAuth } from "../App.jsx";
import { Badge, Button, cx, Empty, ErrorNote, fmt, fmtDate, Panel, Spark, Spinner, Stat, StatCell, StatRow, timeAgo } from "../ui.jsx";
import AddClientDialog from "./AddClientDialog.jsx";
import GettingStarted from "../GettingStarted.jsx";

const LEVEL = {
  bad: { icon: CircleAlert, cls: "text-bad" },
  warn: { icon: AlertTriangle, cls: "text-warn" },
  info: { icon: Info, cls: "text-brand" },
};

export default function Overview() {
  const { isAdmin } = useAuth();
  const nav = useNavigate();
  const [data, setData] = useState(null);
  const [error, setError] = useState(null);
  const [refreshing, setRefreshing] = useState(false);
  const [adding, setAdding] = useState(false);

  const load = useCallback(() => api("/api/overview").then(setData).catch(setError), []);
  useEffect(() => { load(); }, [load]);

  // While any client is refreshing, poll so numbers fill in as they arrive.
  const anyRefreshing = refreshing || data?.clients.some((c) => c.refreshing);
  useEffect(() => {
    if (!anyRefreshing) return;
    const t = setInterval(load, 6000);
    return () => clearInterval(t);
  }, [anyRefreshing, load]);

  const refreshAll = async () => {
    setRefreshing(true);
    await api("/api/refresh-all", { method: "POST" }).catch(setError);
    setTimeout(load, 1500);
    setTimeout(() => setRefreshing(false), 20000);
  };

  if (!data && !error) return <Spinner />;
  const t = data?.totals;
  const oldest = data?.clients.filter((c) => c.fetchedAt).map((c) => c.fetchedAt).sort()[0];

  return (
    <div className="space-y-5">
      <header className="flex items-end justify-between gap-4">
        <div>
          <h1 className="text-[22px] font-extrabold">Clients</h1>
          <p className="text-muted mt-0.5">
            Instagram and Facebook, last 28 days{oldest ? ` · numbers as of ${timeAgo(oldest)}` : ""}
          </p>
        </div>
        <div className="flex gap-2">
          <Button icon={RefreshCw} onClick={refreshAll} loading={anyRefreshing}>
            {anyRefreshing ? "Refreshing" : "Refresh numbers"}
          </Button>
          {isAdmin && (
            <Button variant="primary" icon={Plus} onClick={() => setAdding(true)}>
              Add business
            </Button>
          )}
        </div>
      </header>

      <ErrorNote error={error} />
      <GettingStarted />

      {t && (
        <StatRow className="grid-cols-5">
          <StatCell><Stat label="Active clients" value={fmt(t.clients)} note={t.linked < t.clients ? `${t.clients - t.linked} not linked` : "all linked to Meta"} /></StatCell>
          <StatCell><Stat label="IG followers" value={fmt(t.igFollowers)} note="across all clients" /></StatCell>
          <StatCell><Stat label="IG accounts reached" value={fmt(t.igReach28)} note="28 days, summed" /></StatCell>
          <StatCell><Stat label="IG posts" value={fmt(t.postsLast28)} note="published in 28 days" /></StatCell>
          <StatCell><Stat label="FB followers" value={fmt(t.fbFollowers)} note="across all Pages" /></StatCell>
        </StatRow>
      )}

      <div className="grid grid-cols-[minmax(0,1fr)_280px] gap-5 items-start">
        <Panel bodyClass="overflow-x-auto">
          {data?.clients.length ? (
            <table className="tbl [&_td]:px-3 [&_th]:px-3">
              <thead>
                <tr>
                  <th>Client</th>
                  <th className="text-right">Followers</th>
                  <th className="text-right">Reached</th>
                  <th className="text-right">Posts</th>
                  <th>Last post</th>
                  <th>Reach per post</th>
                  <th>Last audit</th>
                </tr>
              </thead>
              <tbody>
                {data.clients.map((c) => (
                  <tr key={c.slug} className="clickable" onClick={() => nav(`/clients/${c.slug}`)}>
                    <td className="max-w-[220px]">
                      <div className="font-medium text-ink truncate">{c.name}</div>
                      <div className="text-[12px] text-muted truncate">
                        {c.linked ? (c.igUsername ? `@${c.igUsername}` : "Facebook only") : (
                          <span className="inline-flex items-center gap-1 text-warn"><Link2Off className="size-3" /> not linked</span>
                        )}
                      </div>
                    </td>
                    <td className="text-right num">{fmt(c.igFollowers)}</td>
                    <td className="text-right num">{fmt(c.igReach28)}</td>
                    <td className="text-right num">{fmt(c.postsLast28)}</td>
                    <td>
                      {c.refreshing ? (
                        <span className="text-muted">updating…</span>
                      ) : c.daysSinceLastPost == null ? (
                        <span className="text-faint">—</span>
                      ) : (
                        <span className={cx("num", c.daysSinceLastPost >= 14 ? "text-bad font-medium" : c.daysSinceLastPost >= 7 ? "text-warn font-medium" : "text-ink-2")}>
                          {c.daysSinceLastPost === 0 ? "today" : `${c.daysSinceLastPost}d ago`}
                        </span>
                      )}
                    </td>
                    <td><Spark values={c.reachSpark} width={84} /></td>
                    <td className="text-ink-2 whitespace-nowrap">
                      {c.lastAuditAt ? fmtDate(c.lastAuditAt) : <Badge>none</Badge>}
                    </td>
                  </tr>
                ))}
              </tbody>
            </table>
          ) : (
            <Empty title="No clients yet" action={isAdmin && <Button variant="primary" icon={Plus} onClick={() => setAdding(true)}>Add business</Button>}>
              Connect a Facebook Page to the agency's Meta account, then add it here.
            </Empty>
          )}
          {data?.clients.some((c) => !c.fetchedAt && c.linked) && (
            <div className="px-4 py-2.5 border-t border-line text-[12.5px] text-muted">
              Some clients haven't been fetched yet. Use <b className="text-ink-2">Refresh numbers</b>; each account takes about a minute.
            </div>
          )}
        </Panel>

        <Panel title="Needs attention" subtitle={data ? `${data.attention.length} item${data.attention.length === 1 ? "" : "s"}` : null} bodyClass="max-h-[560px] overflow-y-auto">
          {data?.attention.length ? (
            <ul className="divide-y divide-line">
              {data.attention.map((a, i) => {
                const L = LEVEL[a.level] || LEVEL.info;
                return (
                  <li key={i}>
                    <button onClick={() => nav(`/clients/${a.slug}`)} className="w-full text-left flex gap-2.5 px-4 py-3 hover:bg-[#f8fafc]">
                      <L.icon className={cx("size-4 mt-0.5 shrink-0", L.cls)} strokeWidth={2} />
                      <span className="min-w-0">
                        <span className="block text-[12.5px] font-medium text-ink truncate">{a.name}</span>
                        <span className="block text-[12.5px] text-muted">{a.text}</span>
                      </span>
                    </button>
                  </li>
                );
              })}
            </ul>
          ) : (
            <Empty title="All clear">Nothing needs attention right now.</Empty>
          )}
        </Panel>
      </div>

      <AddClientDialog open={adding} onClose={() => setAdding(false)} onAdded={(c) => nav(`/clients/${c.slug}`)} />
    </div>
  );
}