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package com.groupbyinc.common.util;

import com.groupbyinc.common.util.exception.GroupByUtilException;
import org.apache.commons.lang3.StringUtils;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.StringWriter;
import java.net.URL;

import static java.nio.charset.StandardCharsets.UTF_8;

public final class ResourceUtils {

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

  private static final String ERROR_MSG_RESOURCE_PATH_BLANK = "Unable to read resource, resource name cannot be empty";
  private static final String TEMP_FILENAME_PREFIX = "jvmTempFile_";

  private ResourceUtils() {
    // not publicly instantiable
  }

  public static String getPath(String resourcePath) {
    return getUrl(resourcePath).getPath();
  }

  public static URL getUrl(String resourcePath) {
    if (StringUtils.isBlank(resourcePath)) {
      throw new IllegalArgumentException(ERROR_MSG_RESOURCE_PATH_BLANK);
    }

    return ResourceUtils.class.getResource(resourcePath);
  }

  public static File getAsFile(String resourcePath) {
    return new File(getUrl(resourcePath).getPath());
  }

  public static File copyResourceToTempFile(String resourcePath) {
    LOG.trace("Copying resource [{}] into temporary file", resourcePath);

    if (StringUtils.isBlank(resourcePath)) {
      throw new IllegalArgumentException(ERROR_MSG_RESOURCE_PATH_BLANK);
    }

    File file;
    try {
      file = File.createTempFile(TEMP_FILENAME_PREFIX, null);
    } catch (IOException e) {
      LOG.error("Unable to create temp file on filesystem, check that you have write access", e);
      throw new GroupByUtilException("Unable to create temp file on filesystem, check that you have write access", e);
    }

    LOG.debug("Reading resource [{}] and writing to temporary file: {}", resourcePath, file.getAbsolutePath());

    try (BufferedOutputStream bufferedOutputStream = new BufferedOutputStream(new FileOutputStream(file))) {
      pipeResourceIntoBufferedOutputStream(resourcePath, bufferedOutputStream);
    } catch (IOException e) {
      LOG.error(e.getMessage(), e);
      throw new GroupByUtilException(e.getMessage(), e);
    }

    return file;
  }

  public static void pipeResourceIntoBufferedOutputStream(String resourcePath, BufferedOutputStream bufferedOutputStream) {
    try (BufferedInputStream bufferedInputStream = readResourceIntoBufferedInputStream(resourcePath)) {
      pipe(bufferedInputStream, bufferedOutputStream);
    } catch (IOException e) {
      LOG.error(e.getMessage(), e);
      throw new GroupByUtilException("Exception occurred while piping input into output", e);
    }
  }

  public static BufferedInputStream readResourceIntoBufferedInputStream(String resourcePath) {
    return new BufferedInputStream(readResourceIntoInputStream(resourcePath));
  }

  private static void pipe(BufferedInputStream input, BufferedOutputStream output) throws IOException {
    int character;
    while ((character = input.read()) != -1) {
      output.write(character);
    }
    output.flush();
  }

  public static InputStream readResourceIntoInputStream(String resourcePath) {
    if (StringUtils.isBlank(resourcePath)) {
      throw new IllegalArgumentException(ERROR_MSG_RESOURCE_PATH_BLANK);
    }

    InputStream resourceInputStream = ResourceUtils.class.getResourceAsStream(resourcePath);

    if (resourceInputStream == null) {
      String errorMessage = "Unable to read resource into input stream, please check that resource exists";
      LOG.error("{}: {}", errorMessage, resourcePath);
      throw new IllegalArgumentException(errorMessage);
    }

    return resourceInputStream;
  }

  public static String readResourceIntoString(String resourcePath) {
    LOG.trace("Reading resource [{}] into memory (String)", resourcePath);

    if (StringUtils.isBlank(resourcePath)) {
      throw new IllegalArgumentException(ERROR_MSG_RESOURCE_PATH_BLANK);
    }

    StringWriter stringWriter = new StringWriter();
    try (BufferedWriter bufferedWriter = new BufferedWriter(stringWriter)) {
      pipeResourceIntoBufferedWriter(resourcePath, bufferedWriter);
      return stringWriter.toString();
    } catch (GroupByUtilException e) {
      throw e;
    } catch (IOException e) {
      LOG.error(e.getMessage(), e);
      throw new GroupByUtilException("Exception occurred while reading resource into string", e);
    }
  }

  public static void pipeResourceIntoBufferedWriter(String resourcePath, BufferedWriter bufferedWriter) {
    try (BufferedReader bufferedReader = readResourceIntoBufferedReader(resourcePath)) {
      pipe(bufferedReader, bufferedWriter);
    } catch (IOException e) {
      LOG.error(e.getMessage(), e);
      throw new GroupByUtilException("Exception occurred while piping input into output", e);
    }
  }

  public static BufferedReader readResourceIntoBufferedReader(String resourcePath) {
    return new BufferedReader(new InputStreamReader(readResourceIntoInputStream(resourcePath), UTF_8));
  }

  private static void pipe(BufferedReader input, BufferedWriter output) throws IOException {
    int character;
    while ((character = input.read()) != -1) {
      output.write(character);
    }
    output.flush();
  }
}