import { NextRequest, NextResponse } from "next/server";

const MODEL = process.env.GEMINI_MODEL || 'gemini-2.0-flash-exp';
const API_KEY = process.env.GOOGLE_API_KEY || '';
const GEMINI_URL = `https://generativelanguage.googleapis.com/v1beta/models/${MODEL}:generateContent`;

export async function POST(request: NextRequest) {
  try {
    const { content, title } = await request.json();

    if (!content) {
      return NextResponse.json({ error: "Content is required" }, { status: 400 });
    }

    const maxContentLength = 30000;
    const truncatedContent = content.length > maxContentLength
      ? content.substring(0, maxContentLength) + "..."
      : content;

    const prompt = `Read this document titled "${title}" and provide a concise 1-2 sentence summary that captures the main topic and key points. Be specific and actionable.

Document content:
${truncatedContent}

Summary:`;

    const response = await fetch(`${GEMINI_URL}?key=${API_KEY}`, {
      method: 'POST',
      headers: { 'Content-Type': 'application/json' },
      body: JSON.stringify({
        contents: [{ role: 'user', parts: [{ text: prompt }] }],
        generationConfig: { temperature: 0.3 },
      }),
    });

    if (!response.ok) {
      throw new Error(`Gemini API error (${response.status}): ${await response.text()}`);
    }

    const result = await response.json();
    const summary = result.candidates?.[0]?.content?.parts?.[0]?.text?.trim() || 'Summary unavailable';

    return NextResponse.json({ summary });
  } catch (error) {
    console.error("Error generating summary:", error);
    return NextResponse.json(
      { error: "Failed to generate summary", details: error instanceof Error ? error.message : String(error) },
      { status: 500 }
    );
  }
}