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

export async function POST(request: NextRequest) {
  try {
    const formData = await request.formData();
    const file = formData.get("file") as File | null;
    const dirPath = formData.get("dirPath") as string | null;

    if (!file) {
      return NextResponse.json({ error: "No file provided" }, { status: 400 });
    }
    if (!file.type.startsWith("image/")) {
      return NextResponse.json({ error: "Only images allowed" }, { status: 400 });
    }

    const bytes = await file.arrayBuffer();
    const buffer = Buffer.from(bytes);

    // Determine upload directory
    let uploadDir: string;
    let isArticleFolder = false;
    if (dirPath && fs.existsSync(dirPath)) {
      uploadDir = dirPath;
      isArticleFolder = true;
    } else {
      // Fallback to static/image
      const year = new Date().getFullYear().toString();
      uploadDir = path.join(process.cwd(), "..", "static", "image", year);
    }

    if (!fs.existsSync(uploadDir)) {
      fs.mkdirSync(uploadDir, { recursive: true });
    }

    // Generate unique filename
    const ext = file.name.split(".").pop() || "png";
    const baseName = Date.now().toString(36) + Math.random().toString(36).slice(2, 6);
    const fileName = `${baseName}.${ext}`;
    const filePath = path.join(uploadDir, fileName);
    fs.writeFileSync(filePath, buffer);

    // Article folder: bare filename. Static fallback: absolute from Hugo root
    const url = isArticleFolder ? fileName : `/image/${new Date().getFullYear()}/${fileName}`;
    return NextResponse.json({ url, fileName });
  } catch (error: unknown) {
    return NextResponse.json(
      { error: error instanceof Error ? error.message : "Upload failed" },
      { status: 500 }
    );
  }
}