/*
 * This file is part of vospace-file-service
 * Copyright (C) 2021 Istituto Nazionale di Astrofisica
 * SPDX-License-Identifier: GPL-3.0-or-later
 */
package it.inaf.ia2.transfer.controller;

import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.UncheckedIOException;
import java.net.URLEncoder;
import java.nio.charset.StandardCharsets;
import javax.servlet.http.HttpServletResponse;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import static org.springframework.http.HttpStatus.INTERNAL_SERVER_ERROR;
import static org.springframework.http.HttpStatus.NOT_FOUND;
import org.springframework.http.ResponseEntity;

public class FileResponseUtil {

    private static final Logger LOG = LoggerFactory.getLogger(FileResponseUtil.class);

    public static ResponseEntity<?> getFileResponse(HttpServletResponse response, File file) {
        return getFileResponse(response, file, null);
    }

    public static ResponseEntity<?> getFileResponse(HttpServletResponse response, File file, String fileName) {

        if (!file.exists()) {
            LOG.error("File not found: " + file.getAbsolutePath());
            return new ResponseEntity<>("File " + file.getName() + " not found", NOT_FOUND);
        }

        if (!file.canRead()) {
            LOG.error("File not readable: " + file.getAbsolutePath());
            return new ResponseEntity<>("File " + file.getName() + " is not readable", INTERNAL_SERVER_ERROR);
        }

        response.setHeader("Content-Disposition", "attachment; filename="
                + URLEncoder.encode(fileName == null ? file.getName() : fileName, StandardCharsets.UTF_8));
        response.setHeader("Content-Length", String.valueOf(file.length()));
        response.setCharacterEncoding("UTF-8");

        byte[] bytes = new byte[1024];
        try ( OutputStream out = response.getOutputStream();  InputStream is = new FileInputStream(file)) {
            int read;
            while ((read = is.read(bytes)) != -1) {
                out.write(bytes, 0, read);
            }
        } catch (IOException ex) {
            throw new UncheckedIOException(ex);
        }
        return null;
    }
}