feat: Report tag

added a complete tag-reporting system->a backend API with validation + rate limiting, a new DB model (tagreports) to store reports, and a frontend modal.

Removed page up and down buttons , replaced by report Flag.

Author: YOGESH-08

src/app/api/report-tag/route.ts

@@ -0,0 +1,140 @@
+import { NextResponse } from "next/server";
+import { connectToDatabase } from "@/lib/database/mongoose";
+import TagReport from "@/db/tagReport";
+
+const ipCounters = new Map<string, { count: number; resetAt: number }>();
+const IP_LIMIT = 3; // tesing purpose ->> 3 reports/per IP/ per paper/ per hour
+const IP_WINDOW_MS = 1000 * 60 * 60;
+
+const ALLOWED_EXAMS = [
+  "CAT-1",
+  "CAT-2",
+  "FAT",
+];
+const ALLOWED_FIELDS = [
+  "subject",
+  "courseCode",
+  "exam",
+  "slot",
+  "year",
+];
+
+function getClientIp(req: Request) {
+  const forwarded = req.headers.get("x-forwarded-for");
+  if (forwarded) {
+    const first = forwarded.split(",")[0] ?? forwarded;
+    return first.trim();
+  }
+  const real = req.headers.get("x-real-ip");
+  if (real) return real;
+  try {
+    const url = new URL(req.url);
+    return url.hostname || "127.0.0.1";
+  } catch {
+    return "127.0.0.1";
+  }
+}
+
+export async function POST(req: Request) {
+  try {
+    await connectToDatabase();
+    const body = (await req.json()) as {
+      paperId?: string;
+      reportedFields?: { field: string; value?: string }[];
+      comment?: string;
+      reporterEmail?: string;
+      reporterId?: string;
+    };
+
+    const { paperId } = body;
+    if (!paperId)
+      return NextResponse.json(
+        { error: "paperId is required" },
+        { status: 400 },
+      );
+
+    const ip = getClientIp(req);
+    const key = `${ip}::${paperId}`;
+    const now = Date.now();
+    const entry = ipCounters.get(key);
+    if (entry && entry.resetAt > now) {
+      if (entry.count >= IP_LIMIT)
+        return NextResponse.json(
+          { error: "Rate limit exceeded for reporting." },
+          { status: 429 },
+        );
+      entry.count += 1;
+    } else {
+      ipCounters.set(key, { count: 1, resetAt: now + IP_WINDOW_MS });
+    }
+
+    const existingCount = await TagReport.countDocuments({ paperId });
+    const MAX_REPORTS_PER_PAPER = 2;        // for testing purpose kept it to be 2 !!
+    if (existingCount >= MAX_REPORTS_PER_PAPER)
+      return NextResponse.json(
+        { error: "Received many reports; we are currently working on it." },
+        { status: 429 },
+      );
+
+    const reportedFields = (body.reportedFields ?? [])
+      .map((r) => ({ field: String(r.field).trim(), value: r.value?.trim() }))
+      .filter((r) => r.field);
+
+    for (const rf of reportedFields) {
+      if (!ALLOWED_FIELDS.includes(rf.field)) {
+        return NextResponse.json(
+          { error: `Invalid field: ${rf.field}` },
+          { status: 400 },
+        );
+      }
+      if (rf.field === "exam" && rf.value) {
+        if (!ALLOWED_EXAMS.includes(rf.value))
+          return NextResponse.json(
+            { error: `Invalid exam value: ${rf.value}` },
+            { status: 400 },
+          );
+      }
+      if (rf.field === "year" && rf.value) {
+  const val = rf.value.trim();
+
+  const rangeMatch = val.match(/^(\d{4})[-/](\d{4})$/);
+
+  if (rangeMatch) {
+    const start = Number(rangeMatch[1]);
+    const end = Number(rangeMatch[2]);
+    if (
+      start < 1900 || start > 2100 ||
+      end < 1900 || end > 2100 ||
+      end < start
+    ) {
+      return NextResponse.json(
+        { error: `Invalid year range: ${rf.value}` },
+        { status: 400 }
+      );
+    }
+    continue;
+  }
+}
+
+    }
+
+    const newReport = await TagReport.create({
+      paperId,
+      reportedFields,
+      comment: body.comment,
+      reporterEmail: body.reporterEmail,
+      reporterId: body.reporterId,
+    });
+
+    return NextResponse.json(
+      { message: "Report submitted.", report: newReport },
+      { status: 201 },
+    );
+  } catch (err) {
+    console.error(err);
+    return NextResponse.json(
+      { error: "Failed to submit tag report." },
+      { status: 500 },
+    );
+  }
+}

src/app/paper/[id]/page.tsx

@@ -167,6 +167,11 @@ const PaperPage = async ({ params }: { params: { id: string } }) => {
             <PdfViewer
               url={paper.file_url}
               name={`${extractBracketContent(paper.subject)}-${paper.exam}-${paper.slot}-${paper.year}`}
+              paperId={params.id}
+              subject={paper.subject}
+              exam={paper.exam}
+              slot={paper.slot}
+              year={paper.year}
             ></PdfViewer>
           </center>
           <RelatedPapers />

src/components/ReportButton.tsx

@@ -0,0 +1,39 @@
+"use client";
+
+import { useState } from "react";
+import { FaFlag } from "react-icons/fa6";
+import { Button } from "./ui/button";
+import ReportTagModal from "./ReportTagModal";
+
+export default function ReportButton({ 
+  paperId, subject, exam, slot, year 
+}: {
+  paperId: string;
+  subject?: string;
+  exam?: string;
+  slot?: string;
+  year?: string;
+}) {
+  const [open, setOpen] = useState(false);
+
+  return (
+    <>
+      <Button
+        onClick={() => setOpen(true)}
+        className="h-10 w-10 rounded p-0 text-white transition hover:bg-red-600 bg-red-500"
+      >
+        <FaFlag className="text-sm" />
+      </Button>
+
+      <ReportTagModal
+        paperId={paperId}
+        subject={subject}
+        exam={exam}
+        slot={slot}
+        year={year}
+        open={open}
+        setOpen={setOpen}
+      />
+    </>
+  );
+}