import { useCallback, useEffect, useRef, useState } from 'react';
import { Check, CircleAlert, CircleCheck, CircleDashed, Copy, DownloadCloud, Loader2, RefreshCw } from 'lucide-react';
import { useClient } from 'hooks/useClient';
import { copyToClipboard } from 'helpers/clipboard';
import { Button } from '@/components/ui/button';
import { readableError } from './errors';
import { useFlash } from './useFlash';

/**
 * The website checkout under the root location: is it there, clone it, update it.
 *
 * ── It lives inside Root location on purpose ──
 *
 * The path and the thing at the path are one question. Split into its own block, somebody could change
 * the root in one place and read a checkout status about the old one in another — and the two would
 * look equally current.
 *
 * ── git's own output, verbatim, when something fails ──
 *
 * "Permission denied (publickey)" says exactly what is wrong. Anything this could write in its place
 * would be a guess at which of a dozen causes it was, and the guess is what sends somebody looking in
 * the wrong direction.
 *
 * ── The console closes itself on success, and never on failure ──
 *
 * A successful clone or update is worth WATCHING and not worth keeping: "74 packages installed" has
 * been read by the time it finishes, and left on screen it becomes furniture that outlives its own
 * truth — still sitting there after the root has been changed underneath it.
 *
 * A failure is the opposite. It gets no timer at all rather than a long one — the only thing that
 * takes it off the screen is starting the next attempt, which is the one moment it stops being true.
 * That includes the half-done case, which is the most important of the three: a clone that worked
 * followed by an install that did not is a failure, `ok` is false, and the transcript of both stays.
 *
 * ── And it can be copied ──
 *
 * A failure is something somebody pastes — into a search, into a message, back to whoever wrote the
 * thing that broke. Selecting text inside a scrolled box, on a phone, is the point at which people
 * take a screenshot of an error message instead, and a screenshot of a stack trace helps nobody.
 */

type Status = {
  path: string;
  present: boolean;
  isRepo: boolean;
  branch: string | null;
  head: string | null;
  remote: string | null;
  dirty: boolean;
  cloneUrl: string;
};

type RunResult = { ok: boolean; output: string; status: Status };

export const WebsiteCheckout = ({
  rootPath,
  onSettled,
}: {
  rootPath: string;
  onSettled?: (settled: boolean) => void;
}) => {
  const client = useClient();
  const clientRef = useRef(client);
  clientRef.current = client;

  const [status, setStatus] = useState<Status | null>(null);
  const [busy, setBusy] = useState<'clone' | 'update' | null>(null);
  const [output, setOutput] = useState<string | null>(null);
  const [failed, setFailed] = useState(false);
  const [showing, show] = useFlash();
  const [copied, flashCopied] = useFlash(1500);

  const load = useCallback(async () => {
    try {
      setStatus(await clientRef.current.get<Status>('/fofos-admin/_config/website'));
    } catch {
      // Owner-only, so a member gets nothing here. The block above already says why, and repeating it
      // would be two refusals for one cause.
      setStatus(null);
    }
  }, []);

  // Re-checked whenever the ROOT changes, because the answer is about `<root>/website` and a stale one
  // describes a directory nobody is looking at any more.
  useEffect(() => {
    void load();
  }, [load, rootPath]);

  // One bit upward — see the note in `MediaSync`. A checkout that is present but not a repository is
  // NOT settled: something is in the way, and that is exactly the state worth staying open for.
  useEffect(() => {
    onSettled?.(Boolean(status?.isRepo));
  }, [status?.isRepo, onSettled]);

  const act = async (what: 'clone' | 'update') => {
    setBusy(what);
    setOutput(null);
    setFailed(false);
    try {
      const result = await clientRef.current.post<RunResult>(`/fofos-admin/_config/website/${what}`, {});
      setStatus(result.status);
      setOutput(result.output || null);
      setFailed(!result.ok);
      // Only on the way out. A failure has no timer at all rather than a long one — nothing should be
      // able to take it off the screen except the next attempt.
      if (result.ok) show();
    } catch (failure) {
      // A 400 carries git's own words in the body; `readableError` surfaces them.
      setOutput(readableError(failure));
      setFailed(true);
      void load();
    } finally {
      setBusy(null);
    }
  };

  if (!status) return null;

  const Icon = status.isRepo ? CircleCheck : status.present ? CircleAlert : CircleDashed;
  const tone = status.isRepo ? 'text-success' : status.present ? 'text-destructive' : 'text-muted-foreground';

  return (
    <div className="flex flex-col gap-2 border-t border-border pt-3">
      <div className="flex items-start gap-2">
        <Icon className={`mt-0.5 size-3.5 shrink-0 ${tone}`} />
        <div className="min-w-0 flex-1 space-y-0.5">
          <p className="font-mono text-xs break-all">{status.path}</p>

          {status.isRepo ? (
            <p className="text-xs text-muted-foreground">
              {status.branch ?? 'detached'} · {status.head ?? 'no commits'}
              {status.dirty && <span className="text-destructive"> · uncommitted changes</span>}
            </p>
          ) : status.present ? (
            // Present but not a checkout is the one state worth being loud about: cloning will refuse,
            // and the reason is something already sitting there.
            <p className="text-xs text-destructive">Something is already here, and it is not a git checkout.</p>
          ) : (
            <p className="text-xs text-muted-foreground">Not cloned yet.</p>
          )}

          {/* Only when it is NOT what this plugin would clone. Shown always it is noise; shown on a
              mismatch it is the answer to why an update is pulling something unexpected. */}
          {status.isRepo && status.remote && status.remote !== status.cloneUrl && (
            <p className="font-mono text-xs break-all text-destructive">origin: {status.remote}</p>
          )}
        </div>

        <div className="flex shrink-0 items-center gap-2">
          {status.isRepo ? (
            <Button variant="outline" size="sm" onClick={() => void act('update')} disabled={busy !== null}>
              {busy === 'update' ? <Loader2 className="size-3.5 animate-spin" /> : <RefreshCw className="size-3.5" />}
              Update
            </Button>
          ) : (
            <Button size="sm" onClick={() => void act('clone')} disabled={busy !== null || status.present}>
              {busy === 'clone' ? (
                <Loader2 className="size-3.5 animate-spin" />
              ) : (
                <DownloadCloud className="size-3.5" />
              )}
              Clone
            </Button>
          )}
        </div>
      </div>

      {/* git's own words, in git's own shape — a console, so it looks like the thing it is quoting
          rather than like a paragraph of the form. Scrolled, not truncated: the useful line of a
          failure is usually the last one. */}
      {output && (failed || showing) && (
        <div className="relative">
          <pre className="max-h-40 overflow-auto rounded-md border border-border bg-black p-3 pr-10 font-mono text-[11px] leading-relaxed whitespace-pre-wrap">
            <code className={failed ? 'text-red-400' : 'text-neutral-200'}>{output}</code>
          </pre>

          {/* Pinned to the corner of the BOX, not scrolled with the text — a copy button that leaves
              the viewport when the transcript is long is missing exactly when the transcript is worth
              copying. `pr-10` above keeps the text out from under it. Its own dark background because
              it sits over the output rather than beside it. */}
          <button
            type="button"
            onClick={async () => {
              if (await copyToClipboard(output)) flashCopied();
            }}
            aria-label="Copy this output"
            title="Copy"
            className="absolute top-1.5 right-1.5 rounded border border-border/60 bg-black/80 p-1.5 text-neutral-400 transition-colors hover:text-neutral-100"
          >
            {copied ? <Check className="size-3.5 text-success" /> : <Copy className="size-3.5" />}
          </button>
        </div>
      )}
    </div>
  );
};