import type { InferenceContext } from './inference/index.js';

const NAMING_SYSTEM_PROMPT =
  'You name chat sessions based on what the assistant did. Summarize the topic or outcome — do NOT copy the first few words verbatim. Reply directly with no thinking, reasoning, or explanation. Output ONLY the title, 4 words max, no quotes, no punctuation, no prefix like "Title:".';

const MAX_TITLE_CHARS = 60;

function cleanTitle(raw: string): string {
  let name = raw.trim();
  const quotes = ['"', "'", '`', '‘', '’', '“', '”'];
  while (name.length >= 2 && quotes.includes(name[0]!) && quotes.includes(name[name.length - 1]!)) {
    name = name.slice(1, -1).trim();
  }
  name = name.replace(/^title\s*:\s*/i, '').trim();
  if (name.length > MAX_TITLE_CHARS) {
    name = name.slice(0, MAX_TITLE_CHARS).trim();
  }
  return name;
}

interface NamingResponse {
  choices?: Array<{
    message?: {
      content?: string;
      reasoning_content?: string;
    };
  }>;
}

function pickTitleSource(data: NamingResponse): string {
  const choice = data.choices?.[0]?.message;
  if (!choice) return '';
  if (choice.content && choice.content.trim().length > 0) return choice.content;
  const reasoning = choice.reasoning_content ?? '';
  if (reasoning.length === 0) return '';
  const lines = reasoning
    .split('\n')
    .map((l) => l.trim())
    .filter((l) => l.length > 0);
  return lines[lines.length - 1] ?? '';
}

export async function maybeAutoNameChat(
  ctx: InferenceContext,
  chatId: string,
  sessionId: string
): Promise<void> {
  const counts = await ctx.sql<{ n: number }[]>`
    SELECT COUNT(*)::int AS n
    FROM messages
    WHERE chat_id = ${chatId}
      AND role = 'assistant'
      AND status = 'complete'
      AND content <> ''
  `;
  if ((counts[0]?.n ?? 0) < 1) return;

  const chatRows = await ctx.sql<
    { id: string; name: string | null; session_id: string }[]
  >`
    SELECT id, name, session_id FROM chats WHERE id = ${chatId}
  `;
  const chat = chatRows[0];
  if (!chat) return;
  if (chat.name !== null && chat.name !== '') return;

  const sessionRows = await ctx.sql<{ model: string }[]>`
    SELECT model FROM sessions WHERE id = ${sessionId}
  `;
  // v2.0.5: prefer FAST_MODEL for cheap LLM calls (titles, summaries).
  const model = ctx.config.FAST_MODEL ?? sessionRows[0]?.model;
  if (!model) return;

  const assistantMsg = await ctx.sql<{ content: string }[]>`
    SELECT content FROM messages
    WHERE chat_id = ${chatId}
      AND role = 'assistant'
      AND status = 'complete'
      AND content <> ''
    ORDER BY created_at ASC
    LIMIT 1
  `;
  if (!assistantMsg[0]) return;

  const assistantText = assistantMsg[0].content.slice(0, 2000);

  const body = {
    model,
    messages: [
      { role: 'system', content: NAMING_SYSTEM_PROMPT },
      {
        role: 'user',
        content: assistantText,
      },
    ],
    max_tokens: 30,
    temperature: 0.3,
    stream: false,
    chat_template_kwargs: { enable_thinking: false },
  };

  const res = await fetch(`${ctx.config.LLAMA_SWAP_URL}/v1/chat/completions`, {
    method: 'POST',
    headers: { 'Content-Type': 'application/json' },
    body: JSON.stringify(body),
  });
  if (!res.ok) {
    const text = await res.text().catch(() => '');
    throw new Error(`naming request failed: ${res.status} ${text.slice(0, 200)}`);
  }
  const data = (await res.json()) as NamingResponse;
  const raw = pickTitleSource(data);
  const name = cleanTitle(raw);
  if (!name) {
    ctx.log.warn({ chatId, raw }, 'auto-name: empty title from model');
    return;
  }

  const updated = await ctx.sql<{ id: string; name: string; session_id: string; updated_at: string }[]>`
    UPDATE chats
    SET name = ${name}, updated_at = clock_timestamp()
    WHERE id = ${chatId}
      AND (name IS NULL OR name = '')
    RETURNING id, name, session_id, updated_at
  `;
  if (updated.length === 0) return;

  ctx.publish(sessionId, {
    type: 'chat_renamed',
    chat_id: chatId,
    name,
  });
  ctx.publishUser({
    type: 'chat_updated',
    chat_id: chatId,
    session_id: sessionId,
    name,
    updated_at: updated[0]!.updated_at,
  });
  ctx.log.info({ chatId, name }, 'chat auto-named');

  // Propagate to the parent session if it's still on its default name.
  // The WHERE guard makes the check atomic — if the user has already
  // renamed (or a prior chat already propagated), this UPDATE matches
  // zero rows and we do nothing. First chat wins; manual renames win.
  const renamedSession = await ctx.sql<{ id: string; name: string }[]>`
    UPDATE sessions
    SET name = ${name}
    WHERE id = ${sessionId} AND name = 'New session'
    RETURNING id, name
  `;
  if (renamedSession.length > 0) {
    ctx.publishUser({
      type: 'session_renamed',
      session_id: sessionId,
      name,
    });
    ctx.log.info({ sessionId, name }, 'session auto-named from chat');
  }
}