"use client";

// Settings › Discord — the admin page from design-canvas/discord-system-mockup.html
// ("DRB admin" view), server-26#213 item 2. Desired state lives here; nodes
// reconcile and report back. Platform admin only for now: every route behind
// it (GET /discord/admin/overview, /tokens, PUT /discord/guilds/{id}/link) is
// require_admin_token. The mockup's "Alert routes" tab, incident-forum /
// roles / plan columns and per-channel talkgroup chips have no backend yet and
// are left out rather than shown as dead controls.

import { useCallback, useEffect, useState } from "react";
import { useRouter } from "next/navigation";
import { useAuth } from "@/components/AuthProvider";
import { c2api } from "@/lib/c2api";
import { type DiscordAdminOverview, type RadioBot, parseC2Error, streamHealth } from "@/lib/discord";
import { ErrorBanner } from "@/components/ui/EmptyState";
import { SkeletonCard } from "@/components/ui/Skeleton";
import { StreamsPanel } from "@/components/discord/StreamsPanel";
import { ServersPanel } from "@/components/discord/ServersPanel";
import { RadioBotsPanel } from "@/components/discord/RadioBotsPanel";
import { Panel } from "@/components/discord/ui";

type Tab = "streams" | "guilds" | "bots" | "how";

const TABS: { key: Tab; label: string }[] = [
  { key: "streams", label: "Radio channels" },
  { key: "guilds", label: "Servers" },
  { key: "bots", label: "Radio bots" },
  { key: "how", label: "How it works" },
];

const POLL_MS = 10_000;

function Kpi({ k, v, s }: { k: string; v: string; s: string }) {
  return (
    <div className="bg-surface border border-line rounded-xl p-3">
      <div className="text-xs text-ink-muted">{k}</div>
      <div className="text-xl font-semibold text-ink mt-0.5">{v}</div>
      <div className="text-xs text-ink-muted">{s}</div>
    </div>
  );
}

function HowItWorks() {
  const steps = [
    ["1 · Desired", "/join in Discord or this page writes a discord_streams doc."],
    ["2 · Lease", "C2 picks an online node on that system and a radio bot already in that server, in one transaction."],
    ["3 · Reconcile", "A retained MQTT message tells the node its full channel list (token ids, never token strings)."],
    ["4 · Voice", "The node logs in as the leased bot and plays its PulseAudio capture — never Icecast."],
    ["5 · Actual", "The node reports each channel's real state; this page and the Discord reply show it."],
  ];
  return (
    <Panel
      title="How a radio channel stays up"
      note="Node reboot, C2 sweep, Discord voice drop: the node re-reads its desired state and reconnects; persistent channels whose node went away are re-placed on another node. A channel desired-on but not connected for 2 minutes turns red on the Radio channels tab."
    >
      <div className="grid gap-2 p-4 grid-cols-1 sm:grid-cols-2 lg:grid-cols-5">
        {steps.map(([t, d]) => (
          <div key={t} className="bg-raised border border-line rounded-lg p-3 text-xs text-ink-muted">
            <b className="block text-ink text-sm mb-1">{t}</b>
            {d}
          </div>
        ))}
      </div>
    </Panel>
  );
}

export default function DiscordSettingsPage() {
  const { isAdmin, loading: authLoading } = useAuth();
  const router = useRouter();
  const [tab, setTab] = useState<Tab>("streams");
  const [overview, setOverview] = useState<DiscordAdminOverview | null>(null);
  const [bots, setBots] = useState<RadioBot[]>([]);
  const [error, setError] = useState<string | null>(null);

  useEffect(() => {
    if (!authLoading && !isAdmin) router.replace("/settings/organization");
  }, [authLoading, isAdmin, router]);

  useEffect(() => {
    const h = window.location.hash.slice(1);
    if (TABS.some((t) => t.key === h)) setTab(h as Tab);
  }, []);

  const load = useCallback(async () => {
    try {
      const [o, t] = await Promise.all([c2api.getDiscordAdmin(), c2api.getTokens()]);
      setOverview(o);
      setBots(t as RadioBot[]);
      setError(null);
    } catch (err) {
      setError(parseC2Error(err).message);
    }
  }, []);

  useEffect(() => {
    if (!isAdmin) return;
    load();
    // Actual state is reported by nodes; poll while the tab is visible.
    const id = setInterval(() => {
      if (document.visibilityState === "visible") load();
    }, POLL_MS);
    return () => clearInterval(id);
  }, [isAdmin, load]);

  // Every hook runs before this guard (React error #310 — see app/nodes/page.tsx).
  if (authLoading || !isAdmin) return null;

  const linked = overview?.guilds.filter((g) => g.linked).length ?? 0;
  const unlinked = (overview?.guilds.length ?? 0) - linked;
  const live = overview?.streams.filter((s) => s.desired === "on") ?? [];
  const connected = live.filter((s) => streamHealth(s).health === "ok").length;
  const stuck = live.filter((s) => streamHealth(s).health === "bad").length;
  const leased = bots.filter((b) => b.lease).length;
  const byo = bots.filter((b) => b.org_id).length;
  const attention = bots.filter((b) => b.valid === false || b.guild_ids == null).length;

  return (
    <div className="space-y-4">
      <div>
        <h2 className="text-ink font-semibold text-lg">Discord</h2>
        <p className="text-ink-muted text-sm mt-0.5">
          Desired state lives here; nodes reconcile and report back. Voice audio comes from each node&apos;s PulseAudio
          monitor, never Icecast.
        </p>
      </div>

      {error && <ErrorBanner message={error} />}

      {!overview && !error ? (
        <div className="grid gap-3 sm:grid-cols-2 lg:grid-cols-4">
          {Array.from({ length: 4 }).map((_, i) => <SkeletonCard key={i} />)}
        </div>
      ) : overview ? (
        <>
          <div className="grid gap-3 grid-cols-2 lg:grid-cols-4">
            <Kpi k="Linked servers" v={String(linked)} s={unlinked ? `${unlinked} seen but unlinked` : "all linked"} />
            <Kpi k="Radio channels" v={`${connected} / ${live.length}`} s={stuck ? `connected / desired · ${stuck} failing` : "connected / desired"} />
            <Kpi k="Radio bots leased" v={`${leased} / ${bots.length}`} s={byo ? `pool + ${byo} BYO` : "platform pool"} />
            <Kpi k="Bots needing a check" v={String(attention)} s="rejected or membership unknown" />
          </div>

          <div className="flex gap-1 border-b border-line overflow-x-auto">
            {TABS.map((t) => (
              <button
                key={t.key}
                onClick={() => {
                  setTab(t.key);
                  history.replaceState(null, "", `#${t.key}`);
                }}
                className={`px-3 py-2 text-sm whitespace-nowrap border-b-2 -mb-px transition-colors ${
                  tab === t.key ? "border-accent text-ink" : "border-transparent text-ink-muted hover:text-ink"
                }`}
              >
                {t.label}
              </button>
            ))}
          </div>

          {tab === "streams" && <StreamsPanel overview={overview} bots={bots} onChanged={load} />}
          {tab === "guilds" && <ServersPanel overview={overview} onChanged={load} />}
          {tab === "bots" && <RadioBotsPanel bots={bots} overview={overview} onChanged={load} />}
          {tab === "how" && <HowItWorks />}
        </>
      ) : null}
    </div>
  );
}