// utils/chatFreeEndpoint.js
import path            from "path";
import { fileURLToPath } from "url";
import { vectorSearch }   from "./vectorSearch.js";

const __filename  = fileURLToPath(import.meta.url);
const __dirname   = path.dirname(__filename);
const rootPath    = path.resolve(__dirname, "..", "..");          // backend/
const FAQ_PATH    = path.join(rootPath, "user_profile.db");
const FAQ_THRESHOLD = 0.80;
const HELP_TRIGGERS = ["help","error","bug","issue","login","password","support"];

/* ---------- helpers ---------- */
const classifyIntent = txt =>
  HELP_TRIGGERS.some(k => txt.toLowerCase().includes(k)) ? "support" : "guide";

const buildContext = (user = {}, page = "", intent = "guide") => {
  const { firstname = "User", career_situation = "planning" } = user;
  const mode = intent === "guide" ? "Aptiva Guide" : "Aptiva Support";
  return {
    system:
      `${mode} for page “${page}”. User: ${firstname}. Situation: ${career_situation}.` +
      (intent === "support"
        ? " Resolve issues quickly and end with: “Let me know if that fixed it.”"
        : "")
  };
};

/* ----------------------------------------------------------------------------
   FACTORY: registers POST /api/chat/free on the passed-in Express app
----------------------------------------------------------------------------- */
export default function chatFreeEndpoint(
  app,
  {
    openai,
    chatLimiter,
    userProfileDb,
    authenticateUser = (_req, _res, next) => next()
  }
) {
  /* -------- support-intent tool handlers now in scope -------- */
  const toolResolvers = {
    async clearLocalCache() { return { status: "ok" }; },

    async openTicket({ summary = "", user = {} }) {
      try {
        await userProfileDb.run(
          `INSERT INTO support_tickets (user_id, summary, created_at)
             VALUES (?,?,datetime('now'))`,
          [user.id || 0, summary]
        );
        return { ticket: "created" };
      } catch (err) {
        console.error("[openTicket] DB error:", err);
        return { ticket: "error" };
      }
    },

    async pingStatus() {
      try {
        await userProfileDb.get("SELECT 1");
        return { status: "healthy" };
      } catch {
        return { status: "db_error" };
      }
    }
  };

  const SUPPORT_TOOLS = [
 {
    type: "function",
    function: {
      name: "clearLocalCache",
      description: "Instruct front-end to purge its cache",
      parameters: { type: "object", properties: {} }
    }
  },
  {
    type: "function",
    function: {
      name: "openTicket",
      description: "Create a support ticket",
      parameters: {
        type: "object",
        properties: { summary: { type: "string" } },
        required: ["summary"]
      }
    }
  },
  {
    type: "function",
    function: {
      name: "pingStatus",
      description: "Ping DB/health",
      parameters: { type: "object", properties: {} }
    }
  }
];

  /* -----------------------------  ROUTE  ----------------------------- */
  app.post(
    "/api/chat/free",
    chatLimiter,
    authenticateUser,
    async (req, res) => {
      try {
        const { prompt = "", chatHistory = [], pageContext = "" } = req.body || {};
        if (!prompt.trim()) return res.status(400).json({ error: "Empty prompt" });

        /* ---------- 0️⃣  FAQ fast-path ---------- */
        let faqHit = null;
        try {
          const { data } = await openai.embeddings.create({
            model: "text-embedding-3-small",
            input: prompt
          });
          const hits = await vectorSearch(FAQ_PATH, data[0].embedding, 1);
          if (hits.length && hits[0].score >= FAQ_THRESHOLD) faqHit = hits[0];
        } catch { /* silently ignore if table/function missing */ }

        if (faqHit) return res.json({ answer: faqHit.answer });
        /* --------------------------------------- */

        const intent     = classifyIntent(prompt);
        const { system } = buildContext(req.user || {}, pageContext, intent);
        const tools      = intent === "support" ? SUPPORT_TOOLS : [];

        const messages = [
          { role:"system", content: system },
          ...chatHistory,
          { role:"user",   content: prompt }
        ];

        const chatStream = await openai.chat.completions.create({
          model       : "gpt-4o-mini",
          stream      : true,
          messages,
          tools,
          tool_choice : tools.length ? "auto" : undefined
        });

        /* ---------- SSE headers ---------- */
        res.setHeader("Content-Type", "text/event-stream");
        res.setHeader("Cache-Control", "no-cache");
        res.setHeader("Connection", "keep-alive");

        for await (const part of chatStream) {
          const delta  = part.choices?.[0]?.delta || {};
          const chunk  = delta.content || "";
          if (chunk) res.write(chunk);          // ← plain text, no “data:” prefix
        }
        res.end();

        /* ---------- tool calls ---------- */
        chatStream.on("tool", async call => {
          const fn   = toolResolvers[call.name];
          if (!fn) return;
          try {
            const args = JSON.parse(call.arguments || "{}");
            await fn({ ...args, user: req.user || {} });
          } catch (err) {
            console.error("[tool resolver]", err);
          }
        });
      } catch (err) {
        console.error("/api/chat/free error:", err);
        res.status(500).json({ error: "Internal server error" });
      }
    }
  );
}