"use client";

// Settings → Organization → "Linked Discord servers" (server-26#213 item 1).
// Matches design-canvas/discord-system-mockup.html's Servers panel, minus the
// plan / incident-forum / roles / limits columns: none of those exist
// server-side yet, and a column with nothing behind it is a dead surface.

import { useCallback, useEffect, useRef, useState } from "react";
import { c2api } from "@/lib/c2api";
import { Card, CardHeader } from "@/components/ui/Card";
import { Badge } from "@/components/ui/Badge";
import { Button } from "@/components/ui/Button";

type Guild = { guild_id: string; guild_name: string | null; linked_at: string | null; linked_via: string };
type Code = { code: string; expires_at: string; command: string };

const POLL_MS = 5000;

function shortId(id: string) {
  return id.length > 8 ? `${id.slice(0, 2)}…${id.slice(-4)}` : id;
}

function fmtDate(iso: string | null) {
  if (!iso) return "—";
  return new Date(iso).toLocaleDateString("en-US", { month: "short", day: "numeric", year: "numeric" });
}

function fmtLeft(ms: number) {
  const s = Math.max(0, Math.ceil(ms / 1000));
  return `${Math.floor(s / 60)}:${String(s % 60).padStart(2, "0")}`;
}

export function DiscordServersCard({ canEdit, isAdmin }: { canEdit: boolean; isAdmin: boolean }) {
  const [guilds, setGuilds] = useState<Guild[] | null>(null);
  const [restricted, setRestricted] = useState(true);
  const [loadError, setLoadError] = useState<string | null>(null);
  const [code, setCode] = useState<Code | null>(null);
  const [justLinked, setJustLinked] = useState<string | null>(null);
  const [busy, setBusy] = useState(false);
  const [actionError, setActionError] = useState<string | null>(null);
  const [copied, setCopied] = useState(false);
  const [now, setNow] = useState(() => Date.now());
  const known = useRef<Set<string> | null>(null);

  const load = useCallback(async () => {
    try {
      const res = await c2api.listLinkedDiscordGuilds();
      setRestricted(res.unlinked_guilds_restricted);
      setLoadError(null);
      setGuilds(res.guilds);
      return res.guilds;
    } catch (err) {
      setLoadError(err instanceof Error ? err.message : "Could not load Discord servers.");
      return null;
    }
  }, []);

  useEffect(() => {
    if (!canEdit) return;
    load().then((g) => { if (g) known.current = new Set(g.map((x) => x.guild_id)); });
  }, [canEdit, load]);

  const msLeft = code ? new Date(code.expires_at).getTime() - now : 0;
  const live = !!code && msLeft > 0;

  // While a code is live: tick the countdown, and poll the list so the page
  // notices the moment someone runs /drb link in Discord.
  useEffect(() => {
    if (!live) return;
    const tick = setInterval(() => setNow(Date.now()), 1000);
    const poll = setInterval(async () => {
      const g = await load();
      if (!g) return;
      const prev = known.current;
      const added = prev ? g.find((x) => !prev.has(x.guild_id)) : undefined;
      known.current = new Set(g.map((x) => x.guild_id));
      if (added) {
        setCode(null);
        setJustLinked(added.guild_name || `guild ${shortId(added.guild_id)}`);
      }
    }, POLL_MS);
    return () => { clearInterval(tick); clearInterval(poll); };
  }, [live, load]);

  async function generate() {
    setBusy(true);
    setActionError(null);
    setJustLinked(null);
    setCopied(false);
    try {
      const res = await c2api.createDiscordLinkCode();
      setNow(Date.now());
      setCode(res);
    } catch (err) {
      setActionError(err instanceof Error ? err.message : "Could not generate a code.");
    } finally {
      setBusy(false);
    }
  }

  async function unlink(g: Guild) {
    const name = g.guild_name || `guild ${shortId(g.guild_id)}`;
    if (!window.confirm(`Unlink ${name}? Its radio channels stop, and it can't use DRB until it is linked again.`)) {
      return;
    }
    setActionError(null);
    try {
      await c2api.unlinkDiscordGuild(g.guild_id);
      const next = await load();
      if (next) known.current = new Set(next.map((x) => x.guild_id));
    } catch (err) {
      setActionError(err instanceof Error ? err.message : "Could not unlink that server.");
    }
  }

  function copy() {
    if (!code) return;
    navigator.clipboard?.writeText(code.command).then(() => {
      setCopied(true);
      setTimeout(() => setCopied(false), 2000);
    });
  }

  return (
    <Card padding="none" className="overflow-hidden">
      <div className="p-5 pb-0">
        <CardHeader
          title="Linked Discord servers"
          subtitle={<>A link code is run as <span className="font-mono">/drb link</span> by someone with Manage Server in that Discord server.</>}
          action={
            <Button size="sm" onClick={generate} disabled={!canEdit || busy}
              title={!canEdit ? "Only the organization owner can link Discord servers" : undefined}>
              {busy ? "Generating…" : live ? "New code" : "Generate link code"}
            </Button>
          }
        />
      </div>

      {(code || justLinked || actionError) && (
        <div className="mx-5 mb-4 rounded-lg border border-line bg-raised p-4 text-sm">
          {actionError && <p className="text-sev-major text-xs">{actionError}</p>}
          {justLinked && <p className="text-ink">Linked <b>{justLinked}</b>. Its <span className="font-mono">/join</span>, <span className="font-mono">/leave</span> and <span className="font-mono">/status</span> now act for this organization.</p>}
          {code && live && (
            <div className="space-y-3">
              <div className="flex flex-wrap items-baseline gap-x-3 gap-y-1">
                <span className="font-mono text-xl font-bold tracking-wider text-ink">{code.code}</span>
                <span className="text-xs text-ink-muted">single use · expires in {fmtLeft(msLeft)}</span>
              </div>
              <div className="flex flex-wrap items-center gap-2">
                <code className="font-mono text-xs text-ink-2 bg-surface border border-line rounded px-2 py-1 break-all">{code.command}</code>
                <Button size="sm" variant="secondary" onClick={copy}>{copied ? "Copied" : "Copy command"}</Button>
              </div>
              <p className="text-xs text-ink-muted">
                Run it in the Discord server you want to link. That server can then use this organization&apos;s
                systems and radio channels — nothing from any other organization. Generating a new code cancels this one.
              </p>
            </div>
          )}
          {code && !live && <p className="text-xs text-ink-muted">That code expired. Generate a new one.</p>}
        </div>
      )}

      <div className="overflow-x-auto">
        <table className="w-full text-sm">
          <thead>
            <tr className="text-xs text-ink-muted uppercase tracking-wider border-y border-line">
              <th className="px-5 py-2.5 text-left font-medium">Server</th>
              <th className="px-5 py-2.5 text-left font-medium hidden sm:table-cell">Linked</th>
              <th className="px-5 py-2.5 text-left font-medium">Status</th>
              <th className="px-5 py-2.5 w-20"></th>
            </tr>
          </thead>
          <tbody>
            {guilds === null && !loadError && (
              <tr><td colSpan={4} className="px-5 py-4 text-xs text-ink-muted">Loading…</td></tr>
            )}
            {loadError && (
              <tr><td colSpan={4} className="px-5 py-4 text-xs text-sev-major">{loadError}</td></tr>
            )}
            {guilds?.length === 0 && (
              <tr><td colSpan={4} className="px-5 py-4 text-xs text-ink-muted">No Discord servers linked yet.</td></tr>
            )}
            {guilds?.map((g) => (
              <tr key={g.guild_id} className="border-b border-line last:border-0">
                <td className="px-5 py-3">
                  <div className="text-ink font-medium">{g.guild_name || "Unnamed server"}</div>
                  <div className="text-xs text-ink-muted font-mono" title={g.guild_id}>guild {shortId(g.guild_id)}</div>
                </td>
                <td className="px-5 py-3 text-xs text-ink-2 hidden sm:table-cell">{fmtDate(g.linked_at)}</td>
                <td className="px-5 py-3"><Badge tone="success">Linked</Badge></td>
                <td className="px-5 py-3 text-right">
                  {canEdit && (
                    <button onClick={() => unlink(g)} className="text-xs text-sev-major hover:brightness-110 transition-colors">
                      Unlink
                    </button>
                  )}
                </td>
              </tr>
            ))}
          </tbody>
        </table>
      </div>

      <div className="px-5 py-3 border-t border-line bg-raised text-xs text-ink-muted">
        {restricted ? (
          <>Unlinked servers see only <b className="text-ink">/drb link</b> and <b className="text-ink">/help</b>. </>
        ) : isAdmin ? (
          <>Platform setting: unlinked servers still act for the default organization (<span className="font-mono">DISCORD_UNLINKED_GUILD_ORG_ID</span>) until linked. </>
        ) : null}
        Every command and autocomplete is scoped to the linked organization — no server sees another
        organization&apos;s nodes, systems or bots.
      </div>
    </Card>
  );
}