import { NextRequest, NextResponse } from "next/server";
import { writeFile, mkdir } from "fs/promises";
import { join } from "path";
import sharp from "sharp";
import { db } from "@/db";
import { images } from "@/db/schema";
import { nanoid } from "nanoid";
import { auth } from "@/app/lib/auth";

async function getUserId(request: NextRequest): Promise<string | null> {
  try {
    const session = await auth.api.getSession({
      headers: request.headers,
    });
    return session?.user?.id || null;
  } catch {
    return null;
  }
}

function getBaseUrl(request: NextRequest): string {
  // First, check environment variables (production should set this)
  if (process.env.NEXT_PUBLIC_APP_URL) {
    return process.env.NEXT_PUBLIC_APP_URL;
  }
  if (process.env.APP_URL) {
    return process.env.APP_URL;
  }
  
  // Check for reverse proxy headers (X-Forwarded-Host, X-Forwarded-Proto)
  const forwardedHost = request.headers.get("x-forwarded-host");
  const forwardedProto = request.headers.get("x-forwarded-proto");
  
  if (forwardedHost && forwardedProto) {
    return `${forwardedProto}://${forwardedHost}`;
  }
  
  // Fallback to request origin
  return request.nextUrl.origin;
}

export async function POST(request: NextRequest) {
  try {
    const userId = await getUserId(request);
    if (!userId) {
      return NextResponse.json(
        { message: "Yetkisiz erişim" },
        { status: 401 }
      );
    }

    const formData = await request.formData();
    const file = formData.get("file") as File;

    if (!file) {
      return NextResponse.json(
        { message: "Dosya bulunamadı" },
        { status: 400 }
      );
    }

    // File size validation (max 10MB)
    const MAX_FILE_SIZE = 10 * 1024 * 1024; // 10MB
    if (file.size > MAX_FILE_SIZE) {
      return NextResponse.json(
        { message: "Dosya boyutu çok büyük. Maksimum 10MB olmalıdır." },
        { status: 400 }
      );
    }

    // File type validation
    const allowedMimeTypes = ["image/jpeg", "image/jpg", "image/png", "image/gif", "image/webp", "image/avif"];
    if (!allowedMimeTypes.includes(file.type)) {
      return NextResponse.json(
        { message: "Geçersiz dosya tipi. Sadece resim dosyaları kabul edilir." },
        { status: 400 }
      );
    }

    // Input validation
    const widthInput = formData.get("width") as string;
    const heightInput = formData.get("height") as string;
    const qualityInput = formData.get("quality") as string;
    const formatInput = (formData.get("format") as string) || "jpeg";

    const width = Math.max(1, Math.min(10000, parseInt(widthInput) || 800));
    const height = Math.max(1, Math.min(10000, parseInt(heightInput) || 600));
    const quality = Math.max(1, Math.min(100, parseInt(qualityInput) || 90));
    const allowedFormats = ["jpeg", "jpg", "png", "webp", "avif"];
    const format = allowedFormats.includes(formatInput) ? formatInput : "jpeg";

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

    // Resim manipülasyonu - Tam istenen boyuta getir (crop ile, bozmadan)
    // fit: "cover" kullanarak resmi tam boyuta getiriyoruz
    // Aspect ratio korunur, fazla kısımlar ortadan kesilir (crop)
    let processedBuffer = sharp(buffer).resize(width, height, {
      fit: "cover", // Tam boyuta getir, aspect ratio koru, fazla kısımları kes
      position: "center", // Ortadan crop yap
      withoutEnlargement: false, // Gerekirse büyüt de tam boyuta getir
    });

    // Format ve kalite ayarları
    const normalizedFormat = format === "jpg" ? "jpeg" : format;
    if (normalizedFormat === "jpeg") {
      processedBuffer = processedBuffer.jpeg({ quality });
    } else if (normalizedFormat === "png") {
      processedBuffer = processedBuffer.png({ quality });
    } else if (normalizedFormat === "webp") {
      processedBuffer = processedBuffer.webp({ quality });
    } else if (normalizedFormat === "avif") {
      processedBuffer = processedBuffer.avif({ quality });
    }

    const processedImage = await processedBuffer.toBuffer();
    const metadata = await sharp(processedImage).metadata();

    // Dosya adı oluştur
    const fileId = nanoid();
    const originalName = file.name;
    const fileExtension = normalizedFormat === "jpeg" ? "jpg" : normalizedFormat;
    const fileName = `${fileId}.${fileExtension}`;

    // Uploads klasörünü oluştur
    // Docker volume mount: /app/public/uploads
    // Standalone build'de process.cwd() = /app olmalı
    const uploadsDir = join(process.cwd(), "public", "uploads");
    
    try {
      await mkdir(uploadsDir, { recursive: true });
    } catch (mkdirError: any) {
      console.error("Uploads klasörü oluşturulamadı:", mkdirError);
      console.error("Klasör yolu:", uploadsDir);
      console.error("Current working directory:", process.cwd());
      throw new Error(`Uploads klasörü oluşturulamadı: ${mkdirError.message}`);
    }

    // Dosyayı kaydet
    const filePath = join(uploadsDir, fileName);
    try {
      await writeFile(filePath, processedImage);
    } catch (writeError: any) {
      console.error("Dosya yazılamadı:", writeError);
      console.error("Dosya yolu:", filePath);
      console.error("Dosya boyutu:", processedImage.length);
      throw new Error(`Dosya yazılamadı: ${writeError.message}`);
    }

    // Veritabanına kaydet
    const imageUrl = `/uploads/${fileName}`;
    const imageId = nanoid();

    await db.insert(images).values({
      id: imageId,
      userId,
      originalName,
      fileName,
      filePath: filePath,
      url: imageUrl,
      width: metadata.width || null,
      height: metadata.height || null,
      quality,
      format: normalizedFormat,
      fileSize: processedImage.length,
    });

    // Get base URL
    const baseUrl = getBaseUrl(request);
    const fullImageUrl = `${baseUrl}${imageUrl}`;

    return NextResponse.json({
      message: "Resim başarıyla yüklendi",
      image: {
        id: imageId,
        url: fullImageUrl,
        width: metadata.width,
        height: metadata.height,
      },
    });
  } catch (error: any) {
    console.error("Upload hatası:", error);
    console.error("Error stack:", error?.stack);
    console.error("Error message:", error?.message);
    
    // Production'da detaylı hata mesajı döndür (debug için)
    const errorMessage = process.env.NODE_ENV === "production" 
      ? `Yükleme başarısız: ${error?.message || "Bilinmeyen hata"}` 
      : "Yükleme başarısız";
    
    return NextResponse.json(
      { message: errorMessage },
      { status: 500 }
    );
  }
}