import { useCallback, useRef, useState } from 'react';
import type { ConversationDetailResponse } from '../../../../../packages/api-contracts/src/index.js';
import { RedditUsernameLink, redditUsernameLabel } from '../../components/reddit-username-link.js';
import { OriginPostCard } from '../../components/origin-post.js';
import { useConversationDetailQuery, useSendReplyMutation, useSuggestMediaAskMutation, useSuggestReplyMutation } from './conversation-queries.js';
import { SendConfirmationDialog } from './send-confirmation-dialog.js';
import { AccountOwnerBadge } from '../../components/account-owner-badge.js';

interface ConversationDetailProps {
  conversationId: string;
  onClose(): void;
}

function formatMessageTime(timestamp: number): string {
  return new Intl.DateTimeFormat(undefined, { dateStyle: 'medium', timeStyle: 'short' }).format(timestamp);
}

function mediaPath(localPath: string): string {
  return `/media/${localPath.split(/[\\/]/).map(encodeURIComponent).join('/')}`;
}

function MessageHistory({ conversation }: { conversation: ConversationDetailResponse }) {
  if (!conversation.messages || conversation.messages.length === 0) {
    return <div className="conversation-empty-detail">No messages have been loaded for this conversation.</div>;
  }

  return (
    <ol aria-label="Message history" className="conversation-messages">
      {conversation.messages.map((message) => (
        <li className={message.isSelf ? 'is-self' : 'is-recipient'} key={message.eventId ?? `${message.timestamp}-${message.sender}-${message.text}`}>
          <div>
            <strong>{message.isSelf
              ? `You${conversation.owner ? ` (u/${conversation.owner.redditUsername})` : ''}`
              : <RedditUsernameLink username={conversation.username} />}</strong>
            <time dateTime={new Date(message.timestamp).toISOString()}>{formatMessageTime(message.timestamp)}</time>
          </div>
          <p>{message.text}</p>
          {message.media?.length ? (
            <div className="conversation-message-images">
              {message.media.map((media) => (
                <a
                  aria-label={`View original image ${message.isSelf ? 'sent by you' : `received from ${redditUsernameLabel(conversation.username)}`}`}
                  href={mediaPath(media.localPath)}
                  key={`${message.timestamp}-${media.localPath}`}
                  rel="noreferrer"
                  target="_blank"
                >
                  <img
                    alt={`Image ${message.isSelf ? 'sent by you' : `received from ${redditUsernameLabel(conversation.username)}`}`}
                    loading="lazy"
                    src={mediaPath(media.localPath)}
                  />
                </a>
              ))}
            </div>
          ) : null}
        </li>
      ))}
    </ol>
  );
}

function ConversationComposer({ conversation, conversationId }: { conversation: ConversationDetailResponse; conversationId: string }) {
  const [draft, setDraft] = useState('');
  const [isConfirming, setIsConfirming] = useState(false);
  const [wasSent, setWasSent] = useState(false);
  const sendButtonRef = useRef<HTMLButtonElement>(null);
  const suggestionMutation = useSuggestReplyMutation(conversationId);
  const mediaAskMutation = useSuggestMediaAskMutation(conversationId);
  const sendMutation = useSendReplyMutation(conversationId);
  const canSend = draft.trim().length > 0 && !sendMutation.isPending;

  const closeConfirmation = useCallback(() => {
    setIsConfirming(false);
    queueMicrotask(() => sendButtonRef.current?.focus());
  }, []);

  function suggestReply() {
    setWasSent(false);
    suggestionMutation.mutate(undefined, { onSuccess: (suggestion) => setDraft(suggestion) });
  }

  function suggestMediaAsk() {
    setWasSent(false);
    mediaAskMutation.mutate(undefined, { onSuccess: (suggestion) => setDraft(suggestion) });
  }

  function sendReply() {
    if (!canSend) return;
    sendMutation.mutate(draft, {
      onSuccess() {
        setDraft('');
        setWasSent(true);
      },
      onSettled: closeConfirmation,
    });
  }

  return (
    <section aria-labelledby="reply-composer-heading" className="conversation-composer">
      <div className="conversation-section-heading">
        <h3 id="reply-composer-heading">Reply</h3>
        <button disabled={suggestionMutation.isPending} onClick={suggestReply} type="button">
          {suggestionMutation.isPending ? 'Generating…' : 'Suggest reply'}
        </button>
        <button disabled={mediaAskMutation.isPending} onClick={suggestMediaAsk} type="button">
          {mediaAskMutation.isPending ? 'Generating media ask…' : 'Suggest media ask'}
        </button>
      </div>
      <label className="sr-only" htmlFor="conversation-reply">Reply to {redditUsernameLabel(conversation.username)}</label>
      <textarea
        id="conversation-reply"
        onChange={(event) => {
          setDraft(event.target.value);
          setWasSent(false);
        }}
        placeholder="Write or generate a reply"
        rows={5}
        value={draft}
      />
      {suggestionMutation.isError ? <div className="conversation-inline-error" role="alert">{suggestionMutation.error.message}</div> : null}
      {mediaAskMutation.isError ? <div className="conversation-inline-error" role="alert">{mediaAskMutation.error.message}</div> : null}
      {sendMutation.isError ? <div className="conversation-inline-error" role="alert">{sendMutation.error.message}</div> : null}
      {wasSent ? (
        <div aria-label="Reply sent" className="conversation-inline-success" role="status">Reply sent to <RedditUsernameLink username={conversation.username} /></div>
      ) : null}
      <div className="conversation-actions">
        <span>{draft.length} characters</span>
        <button
          aria-label="Review and send reply"
          className="conversation-primary"
          disabled={!canSend}
          onClick={() => setIsConfirming(true)}
          ref={sendButtonRef}
          type="button"
        >
          Review and send
        </button>
      </div>
      {isConfirming ? (
        <SendConfirmationDialog
          draft={draft.trim()}
          isPending={sendMutation.isPending}
          onCancel={closeConfirmation}
          onConfirm={sendReply}
        />
      ) : null}
    </section>
  );
}

export function ConversationDetail({ conversationId, onClose }: ConversationDetailProps) {
  const detailQuery = useConversationDetailQuery(conversationId);

  if (detailQuery.isPending) {
    return <div aria-label="Loading conversation" className="conversation-detail-state" role="status">Loading conversation…</div>;
  }
  if (detailQuery.isError) {
    return (
      <div className="conversation-detail-state conversation-inline-error" role="alert">
        <strong>Conversation unavailable</strong>
        <span>{detailQuery.error.message}</span>
        <button onClick={() => void detailQuery.refetch()} type="button">Retry conversation</button>
      </div>
    );
  }

  const conversation = detailQuery.data;
  return (
    <article className="conversation-detail">
      <header>
        <div>
          <span className="conversation-eyebrow">Conversation</span>
          <h2><RedditUsernameLink username={conversation.username} /></h2>
          <AccountOwnerBadge owner={conversation.owner} />
          {conversation.unread ? <span className="conversation-badge">Unread</span> : null}
        </div>
        <button aria-label="Close conversation" onClick={onClose} type="button">Close</button>
      </header>
      {conversation.syncInProgress ? (
        <div className="conversation-sync-notice" role="status">
          A {conversation.syncInProgress.kind ?? 'chat'} sync is in progress. Messages may be stale.
        </div>
      ) : null}
      {conversation.triggeringPost ? (
        <div className="triggering-post">
          <OriginPostCard post={{
            title: conversation.triggeringPost.title ?? conversation.triggeringPost.id,
            url: conversation.triggeringPost.url,
            imageUrl: conversation.triggeringPost.imageUrl,
            subreddit: conversation.triggeringPost.subreddit,
          }} />
        </div>
      ) : null}
      <MessageHistory conversation={conversation} />
      <ConversationComposer conversation={conversation} conversationId={conversationId} />
    </article>
  );
}