#!/usr/bin/env node
// bc-mcp-bridge.js
// Lokal stdio <-> streamable-HTTP bro mellem Claude Code og BC MCP-serveren.
// S2S-auth (client credentials) - ingen bruger-login. Broen henter + fornyer token selv,
// og injicerer routing-headers. Claude Code taler stdio til broen (intet DCR/OAuth-problem).
//
// Config: Scripts/bc-mcp.config.json (GITIGNORED) eller env-vars:
//   BC_MCP_TENANT, BC_MCP_CLIENT_ID, BC_MCP_CLIENT_SECRET,
//   BC_MCP_ENVIRONMENT (default Production), BC_MCP_COMPANY, BC_MCP_CONFIG (default CURABIS_DEV)
//
// .mcp.json:
//   "businesscentral": { "command": "node", "args": ["Scripts/bc-mcp-bridge.js"] }

const fs = require("fs");
const path = require("path");

const ENDPOINT = "https://mcp.businesscentral.dynamics.com";

function die(m) { process.stderr.write(`[bc-mcp-bridge] ${m}\n`); process.exit(1); }

function loadConfig() {
  let c = {};
  // Soeger: 1) repo-lokal Scripts/bc-mcp.config.json  2) pr-maskine ~/.bc-mcp.config.json
  const home = process.env.USERPROFILE || process.env.HOME || "";
  for (const f of [path.join(__dirname, "bc-mcp.config.json"), path.join(home, ".bc-mcp.config.json")]) {
    if (fs.existsSync(f)) {
      try { c = JSON.parse(fs.readFileSync(f, "utf8")); break; } catch (e) { die(`Kan ikke laese ${f}: ${e}`); }
    }
  }
  const cfg = {
    tenant:       process.env.BC_MCP_TENANT        || c.tenant,
    clientId:     process.env.BC_MCP_CLIENT_ID     || c.clientId,
    clientSecret: process.env.BC_MCP_CLIENT_SECRET || c.clientSecret,
    environment:  process.env.BC_MCP_ENVIRONMENT   || c.environment       || "Production",
    company:      process.env.BC_MCP_COMPANY       || c.company,
    config:       process.env.BC_MCP_CONFIG        || c.configurationName  || "CURABIS_DEV",
  };
  for (const k of ["tenant", "clientId", "clientSecret", "company"]) {
    if (!cfg[k]) die(`Mangler config '${k}' - saet i Scripts/bc-mcp.config.json eller env-var.`);
  }
  return cfg;
}

const cfg = loadConfig();
let token = null, tokenExp = 0, sessionId = null;

async function getToken() {
  if (token && Date.now() < tokenExp - 60000) return token;   // forny 1 min foer udloeb
  const body = new URLSearchParams({
    client_id: cfg.clientId,
    client_secret: cfg.clientSecret,
    scope: `${ENDPOINT}/.default`,
    grant_type: "client_credentials",
  });
  const r = await fetch(`https://login.microsoftonline.com/${cfg.tenant}/oauth2/v2.0/token`, {
    method: "POST",
    headers: { "Content-Type": "application/x-www-form-urlencoded" },
    body,
  });
  if (!r.ok) throw new Error(`token ${r.status}: ${await r.text()}`);
  const j = await r.json();
  token = j.access_token;
  tokenExp = Date.now() + (j.expires_in || 3600) * 1000;
  return token;
}

// BC kraever Base64 hvis header-vaerdien har ikke-ASCII (ae/oe/aa).
const enc = v => /[^\x00-\x7F]/.test(v) ? `=?base64?${Buffer.from(v, "utf8").toString("base64")}?=` : v;

function parseSSE(text) {
  const msgs = [];
  for (const block of text.split(/\r?\n\r?\n/)) {
    const data = block.split(/\r?\n/).filter(l => l.startsWith("data:")).map(l => l.slice(5).replace(/^ /, ""));
    if (data.length) { const p = data.join("\n").trim(); if (p && p !== "[DONE]") msgs.push(p); }
  }
  return msgs;
}

async function forward(msg) {
  const tok = await getToken();
  const headers = {
    "Authorization": `Bearer ${tok}`,
    "Content-Type": "application/json",
    "Accept": "application/json, text/event-stream",
    "TenantId": cfg.tenant,
    "EnvironmentName": cfg.environment,
    "Company": enc(cfg.company),
    "ConfigurationName": enc(cfg.config),
  };
  if (sessionId) headers["Mcp-Session-Id"] = sessionId;
  const r = await fetch(ENDPOINT, { method: "POST", headers, body: JSON.stringify(msg) });
  const sid = r.headers.get("mcp-session-id"); if (sid) sessionId = sid;
  const ct = r.headers.get("content-type") || "";
  const text = await r.text();
  if (!r.ok && !text) throw new Error(`HTTP ${r.status}`);
  return ct.includes("text/event-stream") ? parseSSE(text) : (text.trim() ? [text.trim()] : []);
}

// Splits text into chunks of max maxLen chars, breaking at word boundaries.
function splitTextToChunks(text, maxLen = 250) {
  const chunks = [];
  while (text.length > maxLen) {
    let cut = text.lastIndexOf(" ", maxLen);
    if (cut <= 0) cut = maxLen; // no space found — hard cut
    chunks.push(text.slice(0, cut).trimEnd());
    text = text.slice(cut).trimStart();
  }
  if (text) chunks.push(text);
  return chunks;
}

// Intercepts Create_TaskComment calls with comment > 250 chars and splits into multiple lines.
// Each chunk is sent in its own fresh BC session so GetNextLineNo sees previously committed records.
async function dispatchCreateComment(msg) {
  const args = (msg.params && msg.params.arguments) || {};
  const comment = args.comment || "";
  const chunks = splitTextToChunks(comment);
  let tempId = Date.now();
  const savedSessionId = sessionId;   // preserve the main conversation session
  for (const chunk of chunks) {
    sessionId = null;                  // fresh session per chunk → independent BC transaction
    const chunkMsg = {
      ...msg,
      id: tempId++,
      params: { ...msg.params, arguments: { ...args, comment: chunk } },
    };
    await forward(chunkMsg);
    sessionId = null;                  // discard the chunk session — never bleed into next chunk
  }
  sessionId = savedSessionId;          // restore main session for subsequent calls
  return [JSON.stringify({
    jsonrpc: "2.0", id: msg.id,
    result: { content: [{ type: "text", text: `Kommentar gemt i ${chunks.length} linje(r).` }] },
  })];
}

// stdio-loop: newline-delimited JSON-RPC (MCP stdio-transport).
let buf = "";
process.stdin.setEncoding("utf8");
process.stdin.on("data", async (chunk) => {
  buf += chunk;
  let i;
  while ((i = buf.indexOf("\n")) >= 0) {
    const line = buf.slice(0, i).trim();
    buf = buf.slice(i + 1);
    if (!line) continue;
    let msg;
    try { msg = JSON.parse(line); } catch { continue; }
    try {
      const isCreateComment =
        msg.method === "tools/call" &&
        msg.params?.name === "Create_TaskComment_PAG6102902" &&
        (msg.params?.arguments?.comment || "").length > 250;
      const responses = isCreateComment
        ? await dispatchCreateComment(msg)
        : await forward(msg);
      for (const out of responses) process.stdout.write(out + "\n");
    } catch (e) {
      process.stderr.write(`[bc-mcp-bridge] ${e.message || e}\n`);
      if (msg.id !== undefined && msg.id !== null) {
        process.stdout.write(JSON.stringify({
          jsonrpc: "2.0", id: msg.id, error: { code: -32000, message: String(e.message || e) },
        }) + "\n");
      }
    }
  }
});
process.stdin.on("end", () => process.exit(0));