chat-auto-exporter

import {
  type PromptPreprocessorController,
  type ChatMessage,
} from "@lmstudio/sdk";
import { globalConfigSchematics } from "./config";
import { writeFile, mkdir, readdir } from "fs/promises";
import { join } from "path";
import { createHash } from "crypto";

/**
 * This function runs every time you press "Send" in a chat.
 * It peeks at the conversation, counts messages, and exports
 * to .md when the threshold is hit.
 *
 * IMPORTANT: We never modify the user's message — we just
 * observe and export, then pass it through unchanged.
 */
export async function preprocess(
  ctl: PromptPreprocessorController,
  userMessage: ChatMessage,
): Promise<ChatMessage> {

  // --- 1. Pull the chat history (does NOT include the current message) ---
  const history = await ctl.pullHistory();

  // --- 2. Count only user + assistant messages (skip system/tool) ---
  const allMessages = history.getMessagesArray();
  const chatMessages = allMessages.filter(
    (msg) => msg.getRole() === "user" || msg.getRole() === "assistant",
  );
  const messageCount = chatMessages.length;

  ctl.debug(`[chat-auto-exporter] History has ${messageCount} messages (not counting this one yet)`);

  // --- 3. Read the user's settings ---
  const globalConfig = ctl.getGlobalPluginConfig(globalConfigSchematics);
  const exportFolder = globalConfig.get("exportFolder");
  const threshold = globalConfig.get("messageThreshold");

  // --- 4. Check: is the count a multiple of the threshold? ---
  if (threshold <= 0 || messageCount === 0 || messageCount % threshold !== 0) {
    // Not time to export yet — pass the message through unchanged
    return userMessage;
  }

  // --- 5. Make sure the user set an export folder ---
  if (!exportFolder || exportFolder.trim() === "") {
    ctl.debug("[chat-auto-exporter] Export folder not set! Skipping export.");
    return userMessage;
  }
  // --- 6. Build a sortable, RAG-friendly filename ---
  // Fingerprint = hash of first user message (same chat = same hash)
  const firstUserMsg = chatMessages.find((msg) => msg.getRole() === "user");
  const fingerprint = firstUserMsg
    ? createHash("md5").update(firstUserMsg.getText()).digest("hex").slice(0, 8)
    : "unknown";

  // Check if a file for this chat already exists (any timestamp prefix)
  // If yes → overwrite that same file (keeps the original date in the name)
  // If no  → create a new file with today's date+time prefix
  await mkdir(exportFolder, { recursive: true });
  const existingFiles = await readdir(exportFolder);
  const existingFile = existingFiles.find((f) => f.includes(`chat-${fingerprint}.md`));

  let filename: string;
  if (existingFile) {
    filename = existingFile; // reuse the old name (preserves original date)
  } else {
    const now = new Date();
    const datePart = now.toISOString().slice(0, 10);
    const timePart = now.toTimeString().slice(0, 5).replace(":", "");
    filename = `${datePart}_${timePart}_chat-${fingerprint}.md`;
  }

  // --- 7. Format the conversation as Markdown ---
  // Include the current user message in the export too
  const exportMessages = [...chatMessages, userMessage];
  const exportTime = new Date();
  const timestamp = exportTime.toISOString().replace("T", " ").split(".")[0];

  let markdown = `# Chat Export\n\n`;
  markdown += `*Exported on: ${timestamp}*  \n`;
  markdown += `*Messages: ${exportMessages.length}*\n\n`;
  markdown += `---\n\n`;

  for (const msg of exportMessages) {
    const role = msg.getRole();
    const label = role === "user" ? "🧑 User" : "🤖 Assistant";
    const text = msg.getText();
    markdown += `### ${label}\n\n${text}\n\n---\n\n`;
  }
  // --- 8. Write the .md file to disk ---
  try {
    const filePath = join(exportFolder, filename);
    await writeFile(filePath, markdown, "utf-8");

    ctl.debug(`[chat-auto-exporter] Exported ${exportMessages.length} messages to: ${filePath}`);
  } catch (err) {
    ctl.debug(`[chat-auto-exporter] Export failed: ${err}`);
  }

  // --- 9. Return the message unchanged (we're just observing!) ---
  return userMessage;
}