/* ─── backend/utils/chatFreeEndpoint.js  (TOP-OF-FILE REPLACEMENT) ───────── */
import fs   from "fs/promises";
import path from "path";
import { fileURLToPath } from "url";

import { vectorSearch } from "./vectorSearch.js";
import { fuzzyCareerLookup } from "./fuzzyCareerLookup.js";

/* Resolve current directory ─────────────────────────────────────────────── */
const __filename = fileURLToPath(import.meta.url);
const __dirname  = path.dirname(__filename);

/* Directories ───────────────────────────────────────────────────────────── */
/*   repoRoot = “…/aptiva-dev1-app”               (one level up from backend/) */
const repoRoot   = path.resolve(__dirname, "..", "..");

/*   assetsDir = “…/aptiva-dev1-app/src/assets”   (where the JSONs live)     */
const assetsDir  = path.join(repoRoot, "src", "assets");

/*   FAQ SQLite DB (unchanged) */
const FAQ_PATH   = path.join(repoRoot, "backend", "user_profile.db");

/* Constants ─────────────────────────────────────────────────────────────── */
const FAQ_THRESHOLD = 0.80;
const HELP_TRIGGERS = ["help","error","bug","issue","login","password","support"];
const TASKS_SENTINEL = '<<APTIVA TASK CATALOGUE>>';

/* Load tool manifests just once at boot ─────────────────────────────────── */
const BOT_TOOLS    = JSON.parse(
  await fs.readFile(path.join(assetsDir, "botTools.json"), "utf8")
);
const PAGE_TOOLMAP = JSON.parse(
  await fs.readFile(path.join(assetsDir, "pageToolMap.json"), "utf8")
);

const FREE_PROMPT_MAX_CHARS  = Number(process.env.FREE_PROMPT_MAX_CHARS  || 1500);
const FREE_BURST_WINDOW_MS   = Number(process.env.FREE_BURST_WINDOW_MS   || 5 * 60 * 1000); // 5 min
const FREE_BURST_LIMIT       = Number(process.env.FREE_BURST_LIMIT       || 6);            // 6 chats / 5 min
const FREE_DAILY_LIMIT       = Number(process.env.FREE_DAILY_LIMIT       || 60);           // 60 chats / day
const FREE_CONCURRENCY_PER_U = Number(process.env.FREE_CONCURRENCY_PER_U || 1);

const FREE_ALLOWED_ORIGINS = new Set(
  (process.env.CORS_ALLOWED_ORIGINS || '').split(',').map(s=>s.trim()).filter(Boolean)
);

// in-mem counters (per user if authed, else per IP)
const usage = new Map(); // key -> { win: number[], dayStart: number, dayCount: number, inflight: number }
const DAY = 24*60*60*1000;
function getU(key){ let u=usage.get(key); if(!u){u={win:[],dayStart:Date.now(),dayCount:0,inflight:0}; usage.set(key,u);} return u; }
function clean(u){ if(Date.now()-u.dayStart>=DAY){u.dayStart=Date.now();u.dayCount=0;u.win.length=0;} const cut=Date.now()-FREE_BURST_WINDOW_MS; while(u.win.length&&u.win[0]<cut) u.win.shift(); }

/* ---------- 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.”"
        : "")
  };
};

/** Returns a \n-joined bullet list of banner + page tasks */
const taskListForPage = (page = "", isPremium = false) => {
  const banner = (SUPPORT_TASKS.global_banner || [])
    // hide the “Upgrade” action for premium users
    .filter(t => isPremium || t.id !== "GN-07");

  const pageTasks = SUPPORT_TASKS[page] || [];
  return [...banner, ...pageTasks]
    .map(t => `• ${t.label}`)
    .join("\n");
};

const INTEREST_PLAYBOOK = `
### When the user is on **CareerExplorer** and no career tiles are visible
1. Explain there are two ways to begin:
   • Interest Inventory (7-minute, 60-question survey)  
   • Manual search (type a career in the “Search for Career” bar)
2. If the user chooses **Interest Inventory**
   1. Tell them to open the Interest Inventory from the top by Clicking "Find Your Career" then "Interest Inventory".  
   2. Explain the answer keys (A = Agree, U = Unsure, D = Dislike); each click moves to the next question.  
   3. Wait while the UI runs the survey (do **not** collect answers in chat).  
   4. When the survey finishes, blue career tiles appear; tell them to click any tile to open its detail modal.
3. If the user chooses **Career Search**
3. If the user chooses **Manual search**
   1. Tell them to click the **search bar** and type at least three letters.  
   2. When the suggestion list appears, they should select the desired career.  
   3. A detail modal opens automatically — no blue tile in this flow.
4. After a modal is open, you can guide them to salary, projections, AI-risk, etc.
`;

const CAREER_EXPLORER_FEATURES = `
### Aptiva Career Explorer — features you can (and should) guide the user to
• **Search bar** – type ≥3 letters, pick a suggestion, then click the blue tile.  
• **Interest Inventory** – green “Start Interest Inventory” button (60 Qs, 7 min).  
• **Blue career tile** – opens a modal with:
  • *Overview* tab (description & “Day-in-the-Life” tasks)  
  • *Salary* tab (regional & national percentiles)  
  • *Projections* tab (state + national growth)  
  • *AI Risk* tab (Aptiva’s proprietary impact level)  
• **Add to Comparison** button – builds a side-by-side table above the tiles.  
• **Filters** dropdowns – “Preparation Level” (Job Zone 1-5) and “Fit Level” (Best / Great / Good).  
• **Reload Career Suggestions** – re-runs your interest-based match with updated filters.  
• **Select for Education** – jumps to Educational Programs with the career’s CIP codes.  
• When users ask:
  • “Which is better?” → tell them to add both careers and open the comparison table.  
  • “What’s a day in the life?” → tell them to open the modal’s *Overview* tab.  
  • “How do I plan education?” → tell them to click *Select for Education*.   
`;

const SUPPORT_TASKS = JSON.parse(
  await fs.readFile(
    path.join(repoRoot, "src", "ai", "agent_support_reference.json"),
    "utf8"
  )
);
/* ----------------------------------------------------------------------------
   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 {

            // ---- Guards (before writing any headers) ----
    const origin = req.headers.origin || '';
    if (origin && !FREE_ALLOWED_ORIGINS.has(origin)) {
      return res.status(403).json({ error: 'origin_not_allowed' });
    }

  const { prompt = "", chatHistory = [], pageContext = "", snapshot = {} } = req.body || {};
    const p = String(prompt || '').trim();
    if (!p) return res.status(400).json({ error: "Empty prompt" });
    if (p.length > FREE_PROMPT_MAX_CHARS) {
      return res.status(413).json({ error: "prompt_too_long" });
    }

    // per-user/IP light limits: 5-min burst, daily, 1 concurrent
    const key = String((req.user && (req.user.id || req.user.sub)) || req.ip);
    const u = getU(key);
    clean(u);
    if (u.inflight >= FREE_CONCURRENCY_PER_U) {
      res.set('Retry-After','3'); return res.status(429).json({ error:'chat_in_progress' });
    }
    if (u.dayCount >= FREE_DAILY_LIMIT) return res.status(429).json({ error:'daily_limit_reached' });
    if (u.win.length >= FREE_BURST_LIMIT) {
      const retryMs = Math.max(0, (u.win[0] + FREE_BURST_WINDOW_MS) - Date.now());
      res.set('Retry-After', String(Math.ceil(retryMs/1000)));
      return res.status(429).json({ error:'slow_down' });
    }
    u.inflight++; u.dayCount++; u.win.push(Date.now());
    res.on('finish', ()=>{ u.inflight = Math.max(0, u.inflight-1); });
    res.on('close',  ()=>{ u.inflight = Math.max(0, u.inflight-1); });

        /* ---------- 0️⃣  FAQ fast-path ---------- */
        let faqHit = null;
        try {
          const { data } = await openai.embeddings.create({
            model: "text-embedding-3-small",
            input: p
          });
          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);

      /* ---------- system-prompt scaffold ---------- */
        let { system } = buildContext(req.user || {}, pageContext, intent);

        /* 1) Add master playbooks per page (optional) */
        if (pageContext === "CareerExplorer") {
          system += INTEREST_PLAYBOOK + CAREER_EXPLORER_FEATURES;
        }

        /* ----  EducationalProgramsPage  ------------------------------------ */
          if (pageContext === "EducationalProgramsPage") {
            /* snapshot already comes over the wire from the front-end */
            const {
              careerCtx = {},     // { socCode, careerTitle, cipCodes[] }
              ksaCtx    = {},     // { total, topKnow[], topSkill[] }
              filterCtx = {},     // { sortBy, maxTuition, maxDistance, inStateOnly }
              schoolCtx = {}      // { count }
            } = snapshot || {};

            system += `
        ### Current context: Educational Programs
        ${careerCtx.socCode
          ? `Career          : ${careerCtx.careerTitle} (SOC ${careerCtx.socCode})
        CIP codes       : ${careerCtx.cipCodes?.join(", ") || "n/a"}`
          : "No career selected"}

        ${ksaCtx.total
          ? `KSA summary     : ${ksaCtx.total} items
          • Top Knowledge : ${ksaCtx.topKnow?.join(", ") || "—"}
          • Top Skills    : ${ksaCtx.topSkill?.join(", ") || "—"}`
          : ""}

        Filters in effect
          • Sort by       : ${filterCtx.sortBy || "tuition"}
          • Max tuition   : $${filterCtx.maxTuition ?? "—"}
          • Max distance  : ${filterCtx.maxDistance ?? "—"} mi
          • In-state only : ${filterCtx.inStateOnly ? "yes" : "no"}

        Matching schools : ${schoolCtx.count ?? 0}
      ${Array.isArray(schoolCtx.sample) && schoolCtx.sample.length
          ? `Sample (top ${schoolCtx.sample.length})
        ${schoolCtx.sample
                .map((s,i)=>`${i+1}. ${s.name} – $${s.inState||"?"} in-state, ${s.distance!==null? s.distance+" mi":"distance n/a"}`)
                .join("\n")}`
            : ""}
        (Remember: you can’t click—just explain the steps.)`;
                  }

                /* 2) Append task catalogue once per conversation  ─────────── */
        const alreadySent = chatHistory.some(
          m => m.role === 'system' && m.content?.includes(TASKS_SENTINEL)
        );

        if (!alreadySent) {
          const isPremium = req.user?.plan_type === 'premium';
          system +=
            `\n\n${TASKS_SENTINEL}\n` +                      // ← sentinel tag
            '### What the user can do on this screen\n' +
            taskListForPage(pageContext, isPremium) +
            '\n\n(Remember: do not click for the user; only explain the steps.)';
        }

          const modalPayload = snapshot?.modalCtx;

          if (modalPayload) {
            const {
              socCode     = "n/a",
              title       = "n/a",
              aiRisk      = "n/a",
              salary      = {},
              projections = {},
              description = {},
              tasks       = []
            } = modalPayload;

            system +=
              `\n\n### Current career in focus\n` +
              `SOC: ${socCode} | Title: ${title}\n` +
              `AI-risk: ${aiRisk}\n` +
              `Median salary – regional: $${salary.regional ?? "n/a"}, ` +
              `national: $${salary.national ?? "n/a"}\n` +
              `Projections: ${JSON.stringify(projections)}` +
              `Description: ${description}\n` +
              `Key tasks: ${tasks.slice(0,5).join("; ")}\n`;
          }

          /* ---- CareerRoadmap extras ---- */
            if (pageContext === "CareerRoadmap" && snapshot) {
              const { careerCtx={}, salaryCtx={}, econCtx={}, roadmapCtx={} } = snapshot;

              system += "\n\n### Current context: Career Road-map\n";

              if (careerCtx.title) {
                system += `Career : ${careerCtx.title} (SOC ${careerCtx.socCode||'n/a'})\n`;
              } else {
                system += "No career selected yet\n";
              }

              if (salaryCtx.userSalary) {
                system += `Salary : $${salaryCtx.userSalary.toLocaleString()} (you)\n`;
                if (salaryCtx.regionalMedian)
                  system += `  • Regional median : $${salaryCtx.regionalMedian.toLocaleString()}\n`;
                if (salaryCtx.nationalMedian)
                  system += `  • National median : $${salaryCtx.nationalMedian.toLocaleString()}\n`;
              }

              if (econCtx.stateGrowth || econCtx.nationalGrowth) {
                system += "Growth outlook\n";
                if (econCtx.stateGrowth !== null)
                  system += `  • State  : ${econCtx.stateGrowth}%\n`;
                if (econCtx.nationalGrowth !== null)
                  system += `  • Nation : ${econCtx.nationalGrowth}%\n`;
              }

              system += `Road-map : ${roadmapCtx.done}/${roadmapCtx.milestones} milestones complete, ` +
                        `${roadmapCtx.yearsAhead} y horizon\n`;

              system += "(Explain steps only; never click for the user.)";
            }

            /* ──────────────────────────────────────────────────────────────
            RetirementPlanner extras  (NEW)
            - front-end <RetirementPlanner> already sends `snapshot` shaped
              like: {
                scenarioCtx  : { count, selectedId, selectedTitle },
                simCtx       : { years, interest },   // eg 50 | "No Interest"
                chartCtx     : { nestEgg }            // projected value, number
              }
            ---------------------------------------------------------------- */
          if (pageContext === "RetirementPlanner" && snapshot) {
            const { scenarioCtx = {}, simCtx = {}, chartCtx = {} } = snapshot;

            system += "\n\n### Current context: Retirement Planner\n";

            if (scenarioCtx.count != null) {
              system += `Scenarios loaded : ${scenarioCtx.count}\n`;
              if (scenarioCtx.selectedTitle)
                system += `Active scenario : “${scenarioCtx.selectedTitle}”\n`;
            }

            if (simCtx.years != null)
              system += `Simulation horizon : ${simCtx.years} years\n`;

            if (simCtx.interest)
              system += `Interest model     : ${simCtx.interest}\n`;

            if (chartCtx.nestEgg != null)
              system += `Projected nest-egg : $${chartCtx.nestEgg.toLocaleString()}\n`;

            system +=
              "(Explain steps only; never click for the user. Refer to buttons/inputs by their labels from the task catalogue.)";
          }


       /* ── Build tool list for this request ────────────────────── */
      const tools = [...SUPPORT_TOOLS];   // guidance mode → support-only;
          let messages = [
            { role: "system", content: system },
            ...chatHistory,
            { role: "user",   content: p }
          ];

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

const headers = {
  "Content-Type": "text/event-stream; charset=utf-8",
  "Cache-Control": "no-cache",
  "X-Accel-Buffering": "no"          // disables Nginx/ALB buffering
};
 if (req.httpVersionMajor < 2) headers.Connection = "keep-alive";
 res.writeHead(200, headers);
 res.flushHeaders?.();
 const sendChunk = (txt="") => { res.write(txt); res.flush?.(); };
 for await (const part of chatStream) {
    const txt = part.choices?.[0]?.delta?.content;
    if (txt) sendChunk(txt);
  }

  // tell the front-end we are done and close the stream
  res.write("\n");
res.end();                                 
                        
              
    } catch (err) {           
      console.error("/api/chat/free error:", err);
  if (!res.headersSent) {
    res.status(500).json({ error: "Internal server error" });
  }
    }
  }                          
);               
}