import { NextRequest, NextResponse } from "next/server";
import { createClient } from "@/lib/supabase/server";

const GRADIO_URL = process.env.CLAUSEGUARD_GRADIO_URL || "https://gaurv007-clauseguard.hf.space";

// FIX v4.1: Max text size validation (prevent oversized payloads)
const MAX_TEXT_LENGTH = 200_000; // 200KB

export async function POST(req: NextRequest) {
  try {
    const supabase = await createClient();
    const { data: { user } } = await supabase.auth.getUser();

    if (!user) {
      return NextResponse.json({ error: "Unauthorized. Please log in to analyze texts." }, { status: 401 });
    }

    const body = await req.json();
    let { text } = body;

    if (!text || typeof text !== "string" || text.trim().length < 50) {
      return NextResponse.json(
        { error: "Please provide at least 50 characters of text to analyze." },
        { status: 400 }
      );
    }

    // FIX v4.1: Input size validation
    if (text.length > MAX_TEXT_LENGTH) {
      return NextResponse.json(
        { error: `Text too long (${(text.length / 1000).toFixed(0)}KB). Maximum is ${MAX_TEXT_LENGTH / 1000}KB.` },
        { status: 400 }
      );
    }

    // FIX v4.1: REMOVED the XSS sanitization that corrupted contract text.
    // The old code did: text = text.replace(/</g, "&lt;").replace(/>/g, "&gt;");
    // This PERMANENTLY MUTATED the text before analysis, corrupting contracts
    // that contain < or > characters (e.g., "shall not exceed >$10,000").
    // Sanitization should happen at RENDER TIME in the frontend, not at analysis time.
    // The frontend already uses React which auto-escapes HTML in JSX.

    // Check scan limits — FIX v4.1: query the CORRECT table name
    const { data: profile } = await supabase
      .from("profiles")
      .select("plan, role, analyses_this_month")
      .eq("id", user.id)
      .single();

    const isAdmin = profile?.role === "admin";
    const plan = profile?.plan || "free";

    // FIX v4.1: Use analyses_this_month from profiles (already tracked), not a separate count query
    const scanCount = profile?.analyses_this_month ?? 0;
    const limit = isAdmin ? 999999 : plan === "free" ? 10 : 999999;
    if (scanCount >= limit) {
      return NextResponse.json({ error: "Monthly scan limit reached. Please upgrade to Pro." }, { status: 403 });
    }

    // Step 1: Submit to Gradio Space
    // FIX v4.3: Use the explicit api_name="analyze" set in app.py scan_btn.click()
    const submitRes = await fetch(`${GRADIO_URL}/gradio_api/call/analyze`, {
      method: "POST",
      headers: { "Content-Type": "application/json" },
      body: JSON.stringify({ data: [text] }),
    });

    if (!submitRes.ok) {
      throw new Error(`Gradio submit failed: ${submitRes.status}`);
    }

    const { event_id } = await submitRes.json();
    if (!event_id) throw new Error("No event_id from Gradio");

    // FIX v4.1: Improved SSE polling with proper streaming support
    // Uses exponential backoff instead of fixed 1s intervals
    let resultText = "";
    let attempts = 0;
    const maxAttempts = 90; // 90 seconds max (increased from 60)
    let delay = 500; // Start at 500ms, increase

    while (attempts < maxAttempts) {
      const resultRes = await fetch(
        `${GRADIO_URL}/gradio_api/call/analyze/${event_id}`,
        { headers: { Accept: "text/event-stream" } }
      );

      resultText = await resultRes.text();

      if (resultText.includes("event: complete")) break;
      if (resultText.includes("event: error")) {
        const errMatch = resultText.match(/data:\s*(.+)/);
        throw new Error(errMatch ? errMatch[1] : "Analysis failed in backend");
      }

      await new Promise(r => setTimeout(r, delay));
      delay = Math.min(delay * 1.2, 2000); // Cap at 2s
      attempts++;
    }

    if (!resultText.includes("event: complete")) {
      throw new Error("Analysis timed out. The backend may be loading models. Please try again in 30 seconds.");
    }

    // Step 3: Parse the SSE data
    const completeIdx = resultText.indexOf("event: complete");
    const dataIdx = resultText.indexOf("data: ", completeIdx);
    if (dataIdx === -1) throw new Error("No data in response");

    const dataStr = resultText.substring(dataIdx + 6).trim();

    let gradioData: any[];
    try {
      gradioData = JSON.parse(dataStr);
    } catch {
      const cleaned = dataStr.replace(/[\x00-\x1f]/g, (ch: string) => {
        if (ch === "\n") return "\\n";
        if (ch === "\r") return "\\r";
        if (ch === "\t") return "\\t";
        return "";
      });
      gradioData = JSON.parse(cleaned);
    }

    // Step 4: Download the JSON report file (structured data)
    const jsonFileObj = gradioData[8];
    if (!jsonFileObj?.url) {
      throw new Error("No JSON report generated");
    }

    const jsonRes = await fetch(jsonFileObj.url);
    if (!jsonRes.ok) throw new Error("Failed to download analysis JSON");
    const analysisData = await jsonRes.json();

    // Step 5: Transform to frontend format
    const riskScore = analysisData.risk?.score ?? 0;
    const grade = analysisData.risk?.grade ?? "A";
    const totalClauses = analysisData.metadata?.total_clauses ?? 0;
    const flaggedCount = analysisData.metadata?.flagged_clauses ?? 0;

    // Group clauses by text (multiple labels per clause)
    const clauseMap = new Map<string, any>();
    for (const cr of (analysisData.clauses || [])) {
      if (!clauseMap.has(cr.text)) {
        clauseMap.set(cr.text, { text: cr.text, categories: [] });
      }
      clauseMap.get(cr.text)!.categories.push({
        name: cr.label,
        severity: cr.risk,
        confidence: cr.confidence,
        description: cr.description,
      });
    }
    const results = Array.from(clauseMap.values());

    // FIX v4.1: Parse redlines from structured JSON data instead of fragile HTML regex
    const redlines: any[] = [];

    // Try to extract redlines from the analysis JSON first (if available)
    if (analysisData.redlines && Array.isArray(analysisData.redlines)) {
      for (const rl of analysisData.redlines) {
        redlines.push({
          clause_label: rl.clause_label || "",
          risk_level: rl.risk_level || "MEDIUM",
          original_text: rl.original_text || "",
          safe_alternative: rl.safe_alternative || "",
          template_alternative: rl.template_alternative || "",
          legal_basis: rl.legal_basis || "",
          consumer_standard: rl.consumer_standard || "",
          tier: rl.tier || "template",
        });
      }
    }

    // Fallback: try parsing from HTML only if no structured data
    if (redlines.length === 0) {
      const redlineHtml = typeof gradioData[7] === "string" ? gradioData[7] : "";
      if (redlineHtml.includes("Clause Redlining")) {
        const blocks = redlineHtml.split(/border-left:4px solid #/);
        for (let i = 1; i < blocks.length; i++) {
          const block = blocks[i];
          const labelMatch = block.match(/font-weight:600[^>]*>([^<]+)<\/span>\s*<span[^>]*font-weight:600[^>]*>([^<]+)/);
          const origMatch = block.match(/<del>([^<]*)<\/del>/);
          const safeBlock = block.match(/Suggested Alternative[\s\S]*?<div[^>]*color:#166534[^>]*>([\s\S]*?)<\/div>/);
          const legalMatch = block.match(/Legal Basis<\/div>\s*<div[^>]*>([^<]+)/);
          const consumerMatch = block.match(/Consumer Standard<\/div>\s*<div[^>]*>([^<]+)/);
          const isLLM = block.includes("LLM Refined");

          if (labelMatch) {
            redlines.push({
              clause_label: labelMatch[1].trim(),
              risk_level: labelMatch[2].trim(),
              original_text: origMatch ? origMatch[1].trim() : "",
              safe_alternative: safeBlock ? safeBlock[1].replace(/<[^>]+>/g, "").trim() : "",
              legal_basis: legalMatch ? legalMatch[1].trim() : "",
              consumer_standard: consumerMatch ? consumerMatch[1].trim() : "",
              tier: isLLM ? "llm_refined" : "template",
            });
          }
        }
      }
    }

    const modelStatus = analysisData.metadata?.model || "";

    // FIX v4.1: Increment scan count in profiles table
    await supabase
      .from("profiles")
      .update({ analyses_this_month: scanCount + 1 })
      .eq("id", user.id);

    // FIX v4.3: Save analysis to DB so it shows in history
    // Wrapped in Promise.resolve() because Supabase returns PromiseLike (no .catch)
    Promise.resolve(
      supabase.from("analyses").insert({
        user_id: user.id,
        total_clauses: totalClauses,
        flagged_count: flaggedCount,
        risk_score: riskScore,
        grade,
        clauses: results,
        entities: analysisData.entities || [],
        contradictions: analysisData.contradictions || [],
        obligations: analysisData.obligations || [],
        compliance: analysisData.compliance || {},
        model: modelStatus.includes("loaded") ? "ml" : "regex",
      })
    ).catch(() => {}); // fire-and-forget, don't block response

    return NextResponse.json({
      risk_score: riskScore,
      grade,
      total_clauses: totalClauses,
      flagged_count: flaggedCount,
      results,
      entities: analysisData.entities || [],
      contradictions: analysisData.contradictions || [],
      obligations: analysisData.obligations || [],
      compliance: analysisData.compliance || {},
      redlines,
      model: modelStatus.includes("loaded") ? "ml" : "regex",
      latency_ms: 0,
      session_id: null,
    });
  } catch (error: any) {
    console.error("Analyze error:", error.message);
    return NextResponse.json(
      { error: "Analysis failed: " + (error.message || "Try again in 30 seconds.") },
      { status: 500 }
    );
  }
}