import { MatrixClient, SimpleFsStorageProvider } from "matrix-bot-sdk";
import { runChatTask } from "./runner.js";
import { routeMessage, chatReply } from "./router.js";

const HOMESERVER_URL = process.env.MATRIX_HOMESERVER_URL;
const ACCESS_TOKEN = process.env.MATRIX_BOT_TOKEN;
const CONTROL_ROOM_ID = process.env.MATRIX_CONTROL_ROOM_ID;
const GITEA_URL = process.env.GITEA_URL;
// Set explicitly rather than fetched via client.getUserId() — that call hits /whoami,
// which (like /joined_rooms before it) 404s against Continuwuity for reasons unrelated
// to the endpoint itself. This is also the only reliable way to filter the bot's own
// messages now that there's no command prefix to naturally exclude them by.
const BOT_USER_ID = process.env.MATRIX_BOT_USER_ID;
const KNOWN_REPOS = (process.env.KNOWN_REPOS || "")
  .split(",")
  .map((r) => r.trim())
  .filter(Boolean);

const MAX_REPLY_LENGTH = 4000;

function truncate(text) {
  if (text.length <= MAX_REPLY_LENGTH) return text;
  return `${text.slice(0, MAX_REPLY_LENGTH)}\n\n[truncated]`;
}

export async function startMatrixBot() {
  if (!HOMESERVER_URL || !ACCESS_TOKEN || !CONTROL_ROOM_ID) {
    console.warn("Matrix env vars not set — skipping bot startup");
    return;
  }
  if (!BOT_USER_ID) {
    console.warn("MATRIX_BOT_USER_ID not set — bot could reply to its own messages, skipping startup");
    return;
  }

  const storage = new SimpleFsStorageProvider("/workspace/matrix-bot-storage.json");
  const client = new MatrixClient(HOMESERVER_URL, ACCESS_TOKEN, storage);

  client.on("room.invite", async (roomId) => {
    try {
      await client.joinRoom(roomId);
    } catch (err) {
      console.error("failed to join invited room", roomId, err.message);
    }
  });

  client.on("room.message", async (roomId, event) => {
    if (roomId !== CONTROL_ROOM_ID) return;
    if (event.sender === BOT_USER_ID) return;
    const body = event.content?.body;
    if (!body) return;

    try {
      const decision = await routeMessage(body, KNOWN_REPOS);

      if (decision.type === "code_task") {
        const [owner, repo] = decision.repo.split("/");
        await client.sendText(roomId, `Working on it: ${decision.repo} — ${decision.instruction}`);
        const cloneUrl = `${GITEA_URL}/${owner}/${repo}.git`;
        const pr = await runChatTask({ owner, repo, cloneUrl, instruction: decision.instruction });
        await client.sendText(roomId, `Opened PR: ${pr.html_url}`);
        return;
      }

      const reply = await chatReply(body);
      await client.sendText(roomId, truncate(reply));
    } catch (err) {
      console.error("message handling failed", err);
      await client.sendText(roomId, `Failed: ${err.message}`);
    }
  });

  await client.start();
  console.log("Matrix bot started, room:", CONTROL_ROOM_ID);
}