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

const PORT = process.env.PORT || 3000;
const MAX_BODY = 40 * 1024 * 1024;
const AI_TIMEOUT_MS = 90000;

const ALLOWED = {
  "/": "index.html",
  "/index.html": "index.html",
  "/monitor.html": "monitor.html",
  "/kfu-client.js": "kfu-client.js",
  "/vendor/xlsx.full.min.js": "vendor/xlsx.full.min.js",
  "/design-system/kt-ai-fonts.css": "design-system/kt-ai-fonts.css",
  "/design-system/kt-ai-tokens.css": "design-system/kt-ai-tokens.css",
  "/design-system/kt-ai-components.css": "design-system/kt-ai-components.css",
  "/design-system/kt-ai-page.css": "design-system/kt-ai-page.css",
  "/design-system/kt-ai-print.css": "design-system/kt-ai-print.css",
  "/design-system/vibe-theme.css": "design-system/vibe-theme.css",
  "/design-system/kt-ai-chart-tip.js": "design-system/kt-ai-chart-tip.js",
  "/design-system/kt-ai-composer.js": "design-system/kt-ai-composer.js",
  "/design-system/kt-ai-feedback.js": "design-system/kt-ai-feedback.js",
  "/design-system/kt-ai-orb.js": "design-system/kt-ai-orb.js",
  "/design-system/icons/kt-ai-icons.js": "design-system/icons/kt-ai-icons.js",
  "/design-system/icons/kt-ai-lucide-sprite.svg": "design-system/icons/kt-ai-lucide-sprite.svg",
  "/design-system/fonts/InterVariable-subset.woff2": "design-system/fonts/InterVariable-subset.woff2",
  "/design-system/fonts/JetBrainsMono-subset.woff2": "design-system/fonts/JetBrainsMono-subset.woff2"
};
const MIME = {
  ".html": "text/html", ".css": "text/css", ".js": "application/javascript",
  ".json": "application/json", ".svg": "image/svg+xml", ".png": "image/png",
  ".ico": "image/x-icon", ".woff2": "font/woff2"
};

function loadPdfParse() {
  try { return require("pdf-parse"); } catch (e) {}
  if (process.env.NODE_PATH) {
    for (const p of String(process.env.NODE_PATH).split(path.delimiter)) {
      if (p) { try { return require(path.join(p, "pdf-parse")); } catch (e) {} }
    }
  }
  return null;
}

function readBody(req) {
  return new Promise((resolve, reject) => {
    let s = "";
    req.setEncoding("utf8");
    req.on("data", (c) => { s += c; if (s.length > MAX_BODY) { reject(new Error("body too large")); req.destroy(); } });
    req.on("end", () => { try { resolve(s ? JSON.parse(s) : {}); } catch (e) { reject(new Error("invalid JSON body")); } });
    req.on("error", reject);
  });
}

function send(res, code, obj) {
  res.writeHead(code, { "Content-Type": "application/json; charset=utf-8" });
  res.end(JSON.stringify(obj));
}

// Anthropic blocks -> OpenAI user content parts
async function toOpenAIContent(content, pdfParse) {
  if (typeof content === "string") return content;
  if (!Array.isArray(content)) return JSON.stringify(content);
  const parts = [];
  for (const b of content) {
    if (!b || typeof b !== "object") continue;
    if (b.type === "text" && typeof b.text === "string") {
      parts.push({ type: "text", text: b.text });
    } else if (b.type === "file" && b.file === "image" && b.data) {
      parts.push({ type: "image_url", image_url: { url: "data:" + (b.media || "image/png") + ";base64," + b.data } });
    } else if (b.type === "file" && b.file === "pdf" && b.data) {
      if (!pdfParse) throw new Error("PDF-парсер недоступен на сервере");
      const buf = Buffer.from(b.data, "base64");
      if (buf.length > 32 * 1024 * 1024) throw new Error("PDF больше 32 МБ");
      let t;
      try { t = (await pdfParse(buf)).text; } catch (e) { throw new Error("не удалось разобрать PDF: " + (e.message || e)); }
      t = String(t || "").trim();
      if (!t) throw new Error("из PDF не удалось извлечь текст (скан?) — добавьте фрагменты текстом");
      parts.push({ type: "text", text: (b.name ? "PDF «" + b.name + "»:\n" : "PDF:\n") + t.slice(0, 400000) });
    }
  }
  return parts.length ? parts : "";
}

async function handleAI(req, res) {
  const body = await readBody(req);
  const model = process.env.AI_MODEL;
  if (!process.env.AI_BASE_URL || !process.env.AI_API_KEY || !model) {
    return send(res, 503, { error: "ИИ не настроен на сервере (нет AI_BASE_URL/AI_API_KEY/AI_MODEL). Перезапустите проект (run), чтобы обновить окружение." });
  }
  const pdfParse = loadPdfParse();
  const out = [];
  if (typeof body.system === "string" && body.system) out.push({ role: "system", content: body.system });
  const msgs = Array.isArray(body.messages) ? body.messages : [];
  if (!msgs.length) return send(res, 400, { error: "нет сообщений" });
  for (const m of msgs) {
    if (!m || (m.role !== "user" && m.role !== "assistant")) continue;
    const c = await toOpenAIContent(m.content, pdfParse);
    if (c === "" && m.role === "user") continue;
    out.push({ role: m.role, content: c });
  }
  const maxTok = Math.min(Math.max(parseInt(body.max_tokens, 10) || 4096, 256), 8192);
  const ctrl = new AbortController();
  const t = setTimeout(() => ctrl.abort(), AI_TIMEOUT_MS);
  try {
    const r = await fetch(String(process.env.AI_BASE_URL).replace(/\/+$/, "") + "/chat/completions", {
      method: "POST",
      headers: { "Content-Type": "application/json", Authorization: "Bearer " + process.env.AI_API_KEY },
      body: JSON.stringify({ model, messages: out, max_tokens: maxTok }),
      signal: ctrl.signal
    });
    const j = await r.json().catch(() => ({}));
    if (!r.ok) {
      const msg = (j && (j.error && (j.error.message || j.error) || j.message)) || ("сервер ИИ вернул " + r.status);
      const msgStr = typeof msg === "string" ? msg : JSON.stringify(msg);
      return send(res, 502, { error: "ИИ: " + msgStr.slice(0, 500) });
    }
    const choice = (j.choices && j.choices[0]) || {};
    const text = (choice.message && choice.message.content) || "";
    return send(res, 200, { content: String(text), truncated: choice.finish_reason === "length" });
  } catch (e) {
    const what = e.name === "AbortError" ? "таймаут (90 с) — запрос слишком большой" : (e.message || String(e));
    return send(res, 502, { error: "ИИ недоступен: " + what.slice(0, 300) });
  } finally {
    clearTimeout(t);
  }
}

http.createServer(async (req, res) => {
  const url = (req.url || "/").split("?")[0];
  try {
    if (req.method === "POST" && url === "/api/ai") return await handleAI(req, res);
    if ((req.method === "GET" || req.method === "POST") && url === "/api/health") {
      return send(res, 200, { ok: true, version: "1.3", ai: !!(process.env.AI_BASE_URL && process.env.AI_API_KEY && process.env.AI_MODEL) });
    }
    if (req.method === "GET") {
      let file = ALLOWED[url];
      if (!file && (url === "/" || url.endsWith("/"))) file = "index.html";
      if (!file && url.startsWith("/design-system/")) {
        let rel = path.normalize(decodeURIComponent(url.replace(/%20/g, " ")));
        if (!rel.startsWith("../") && !path.isAbsolute(rel)) file = rel;
      }
      if (file) {
        const full = path.join(__dirname, file);
        if (full.startsWith(__dirname) && fs.existsSync(full) && fs.statSync(full).isFile()) {
          const ext = path.extname(full);
          res.writeHead(200, { "Content-Type": (MIME[ext] || "application/octet-stream") + "; charset=utf-8", "Cache-Control": "no-cache" });
          return res.end(fs.readFileSync(full));
        }
      }
      res.writeHead(404, { "Content-Type": "text/plain; charset=utf-8" });
      return res.end("Not found");
    }
    res.writeHead(404, { "Content-Type": "application/json" });
    return res.end(JSON.stringify({ error: "not found" }));
  } catch (e) {
    try { send(res, 500, { error: (e && e.message) || "ошибка сервера" }); } catch (_) {}
  }
}).listen(PORT, "0.0.0.0", () => console.log("КФУ-агент сервер на порту " + PORT));