'use client';
import { FunctionComponent, useState } from 'react';
import Box from '@mui/material/Box';
import Typography from '@mui/material/Typography';
import { useTranslations } from 'next-intl';
import { useDiscardFailedMessage, usePostMessage } from '@/services/tickets';
import type { TicketMessage } from '@/services/tickets/types';
import { makeClientMessageId } from './clientMessageId';
import MessageComposer from './MessageComposer';
import TicketMessageList from './TicketMessageList';

export interface TicketConversationPanelProps {
  ticketId: number;
  /** Closed tickets show a notice instead of the composer. */
  closed: boolean;
}

/**
 * The interactive body of a thread — the message list + the sticky composer, owning the one
 * `usePostMessage` mutation + draft state both share (so a failed bubble's retry/discard and the
 * composer's own send are the same optimistic pipeline, never two disconnected ones). Mounted **keyed by
 * `ticketId`** from `TicketThreadScreen` so navigating thread→thread (the App Router reuses the `[id]`
 * subtree) remounts this whole panel — the draft/in-flight/failed state never crosses tickets (§5).
 * @component TicketConversationPanel
 */
const TicketConversationPanel: FunctionComponent<TicketConversationPanelProps> = ({ ticketId, closed }) => {
  const t = useTranslations('tickets');
  const [draft, setDraft] = useState('');
  const postMessage = usePostMessage(ticketId);
  const discardFailedMessage = useDiscardFailedMessage();
  const sending = postMessage.isPending;

  const submit = () => {
    const body = draft.trim();
    if (!body || sending || closed) return;
    postMessage.mutate(
      { body, clientMessageId: makeClientMessageId() },
      { onSuccess: () => setDraft('') }, // clear the draft ONLY on server confirm (§3.5)
    );
  };

  const retry = (message: TicketMessage) => {
    if (!message.clientMessageId) return;
    postMessage.mutate({ body: message.body, clientMessageId: message.clientMessageId });
  };

  const discard = (message: TicketMessage) => {
    if (!message.clientMessageId) return;
    discardFailedMessage(ticketId, message.clientMessageId);
    setDraft(message.body); // a failure never loses typed text — restore it for editing (§3.3)
  };

  return (
    <>
      <TicketMessageList ticketId={ticketId} onRetry={retry} onDiscard={discard} />

      <Box
        sx={{
          position: 'sticky',
          bottom: 0,
          bgcolor: 'var(--bal-bg-default)',
          borderTop: '1px solid',
          borderColor: 'divider',
          pt: 1,
          pb: 0.5,
        }}
      >
        {closed ? (
          <Typography variant="body2" sx={{ textAlign: 'center', color: 'var(--bal-text-secondary)', py: 1 }}>
            {t('closed_notice')}
          </Typography>
        ) : (
          <MessageComposer value={draft} onChange={setDraft} onSubmit={submit} sending={sending} />
        )}
      </Box>
    </>
  );
};

export default TicketConversationPanel;
