//
// Licensed to the Apache Software Foundation (ASF) under one
// or more contributor license agreements.  See the NOTICE file
// distributed with this work for additional information
// regarding copyright ownership.  The ASF licenses this file
// to you under the Apache License, Version 2.0 (the
// "License"); you may not use this file except in compliance
// with the License.  You may obtain a copy of the License at
//
//   http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing,
// software distributed under the License is distributed on an
// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
// KIND, either express or implied.  See the License for the
// specific language governing permissions and limitations
// under the License.
//
package com.cloud.agent.direct.download;

import com.cloud.utils.exception.CloudRuntimeException;
import org.apache.cloudstack.utils.security.DigestHelper;
import org.apache.commons.lang.StringUtils;
import org.apache.log4j.Logger;

import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.security.NoSuchAlgorithmException;

public abstract class DirectTemplateDownloaderImpl implements DirectTemplateDownloader {

    private String url;
    private String destPoolPath;
    private Long templateId;
    private String downloadedFilePath;
    private String checksum;
    private boolean redownload = false;
    protected String temporaryDownloadPath;

    public static final Logger s_logger = Logger.getLogger(DirectTemplateDownloaderImpl.class.getName());

    protected DirectTemplateDownloaderImpl(final String url, final String destPoolPath, final Long templateId,
                                           final String checksum, final String temporaryDownloadPath) {
        this.url = url;
        this.destPoolPath = destPoolPath;
        this.templateId = templateId;
        this.checksum = checksum;
        this.temporaryDownloadPath = temporaryDownloadPath;
    }

    private static String directDownloadDir = "template";

    /**
     * Return direct download temporary path to download template
     */
    protected String getDirectDownloadTempPath(Long templateId) {
        String templateIdAsString = String.valueOf(templateId);
        return this.temporaryDownloadPath + File.separator + directDownloadDir + File.separator +
                templateIdAsString.substring(0,1) + File.separator + templateIdAsString;
    }

    /**
     * Create folder on path if it does not exist
     */
    protected void createFolder(String path) {
        File dir = new File(path);
        if (!dir.exists()) {
            dir.mkdirs();
        }
    }

    public String getUrl() {
        return url;
    }

    public void setUrl(String url) {
        this.url = url;
    }

    public String getDestPoolPath() {
        return destPoolPath;
    }

    public Long getTemplateId() {
        return templateId;
    }

    public String getDownloadedFilePath() {
        return downloadedFilePath;
    }

    public void setDownloadedFilePath(String filePath) {
        this.downloadedFilePath = filePath;
    }

    public String getChecksum() {
        return checksum;
    }

    public void setChecksum(String checksum) {
        this.checksum = checksum;
    }

    public boolean isRedownload() {
        return redownload;
    }

    /**
     * Return filename from url
     */
    public String getFileNameFromUrl() {
        String[] urlParts = url.split("/");
        return urlParts[urlParts.length - 1];
    }

    @Override
    public boolean validateChecksum() {
        if (StringUtils.isNotBlank(checksum)) {
            int retry = 3;
            boolean valid = false;
            try {
                while (!valid && retry > 0) {
                    retry--;
                    s_logger.info("Performing checksum validation for downloaded template " + templateId + " using " + checksum + ", retries left: " + retry);
                    valid = DigestHelper.check(checksum, new FileInputStream(downloadedFilePath));
                    if (!valid && retry > 0) {
                        s_logger.info("Checksum validation failded, re-downloading template");
                        redownload = true;
                        resetDownloadFile();
                        downloadTemplate();
                    }
                }
                s_logger.info("Checksum validation for template " + templateId + ": " + (valid ? "succeeded" : "failed"));
                return valid;
            } catch (IOException e) {
                throw new CloudRuntimeException("could not check sum for file: " + downloadedFilePath, e);
            } catch (NoSuchAlgorithmException e) {
                throw new CloudRuntimeException("Unknown checksum algorithm: " + checksum, e);
            }
        }
        s_logger.info("No checksum provided, skipping checksum validation");
        return true;
    }

    /**
     * Delete and create download file
     */
    private void resetDownloadFile() {
        File f = new File(getDownloadedFilePath());
        s_logger.info("Resetting download file: " + getDownloadedFilePath() + ", in order to re-download and persist template " + templateId + " on it");
        try {
            if (f.exists()) {
                f.delete();
            }
            f.createNewFile();
        } catch (IOException e) {
            s_logger.error("Error creating file to download on: " + getDownloadedFilePath() + " due to: " + e.getMessage());
            throw new CloudRuntimeException("Failed to create download file for direct download");
        }
    }

}
