/*
 * Copyright (C) 2009 University of Washington
 *
 * Licensed 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 org.odk.collect.android.utilities;

import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.util.Log;
import android.view.Display;
import android.view.WindowManager;

import org.apache.commons.io.IOUtils;
import org.javarosa.xform.parse.XFormParser;
import org.kxml2.kdom.Document;
import org.kxml2.kdom.Element;
import org.kxml2.kdom.Node;
import org.odk.collect.android.R;
import org.odk.collect.android.application.Collect;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.UnsupportedEncodingException;
import java.math.BigInteger;
import java.nio.channels.FileChannel;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.util.HashMap;

/**
 * Static methods used for common file operations.
 *
 * @author Carl Hartung (carlhartung@gmail.com)
 */
public class FileUtils {
  private final static String t = "FileUtils";

  // Used to validate and display valid form names.
  public static final String VALID_FILENAME = "[ _\\-A-Za-z0-9]*.x[ht]*ml";

  public static final String FORMID = "formid";
  public static final String VERSION = "version"; // arbitrary string in OpenRosa 1.0
  public static final String TITLE = "title";
  public static final String SUBMISSIONURI = "submission";
  public static final String BASE64_RSA_PUBLIC_KEY = "base64RsaPublicKey";


  public static boolean createFolder(String path) {
    boolean made = true;
    File dir = new File(path);
    if (!dir.exists()) {
      made = dir.mkdirs();
    }
    return made;
  }


  public static byte[] getFileAsBytes(File file) {
    byte[] bytes = null;
    InputStream is = null;
    try {
      is = new FileInputStream(file);

      // Get the size of the file
      long length = file.length();
      if (length > Integer.MAX_VALUE) {
        Log.e(t, "File " + file.getName() + "is too large");
        return null;
      }

      // Create the byte array to hold the data
      bytes = new byte[(int) length];

      // Read in the bytes
      int offset = 0;
      int read = 0;
      try {
        while (offset < bytes.length && read >= 0) {
          read = is.read(bytes, offset, bytes.length - offset);
          offset += read;
        }
      } catch (IOException e) {
        Log.e(t, "Cannot read " + file.getName());
        e.printStackTrace();
        return null;
      }

      // Ensure all the bytes have been read in
      if (offset < bytes.length) {
        try {
          throw new IOException("Could not completely read file " + file.getName());
        } catch (IOException e) {
          e.printStackTrace();
          return null;
        }
      }

      return bytes;

    } catch (FileNotFoundException e) {
      Log.e(t, "Cannot find " + file.getName());
      e.printStackTrace();
      return null;

    } finally {
      // Close the input stream
      try {
        is.close();
      } catch (IOException e) {
        Log.e(t, "Cannot close input stream for " + file.getName());
        e.printStackTrace();
        return null;
      }
    }
  }


  public static String getMd5Hash(File file) {
    try {
      // CTS (6/15/2010) : stream file through digest instead of handing it the byte[]
      MessageDigest md = MessageDigest.getInstance("MD5");
      int chunkSize = 256;

      byte[] chunk = new byte[chunkSize];

      // Get the size of the file
      long lLength = file.length();

      if (lLength > Integer.MAX_VALUE) {
        Log.e(t, "File " + file.getName() + "is too large");
        return null;
      }

      int length = (int) lLength;

      InputStream is = null;
      is = new FileInputStream(file);

      int l = 0;
      for (l = 0; l + chunkSize < length; l += chunkSize) {
        is.read(chunk, 0, chunkSize);
        md.update(chunk, 0, chunkSize);
      }

      int remaining = length - l;
      if (remaining > 0) {
        is.read(chunk, 0, remaining);
        md.update(chunk, 0, remaining);
      }
      byte[] messageDigest = md.digest();

      BigInteger number = new BigInteger(1, messageDigest);
      String md5 = number.toString(16);
      while (md5.length() < 32) {
        md5 = "0" + md5;
      }
      is.close();
      return md5;

    } catch (NoSuchAlgorithmException e) {
      Log.e("MD5", e.getMessage());
      return null;

    } catch (FileNotFoundException e) {
      Log.e("No Cache File", e.getMessage());
      return null;
    } catch (IOException e) {
      Log.e("Problem reading file", e.getMessage());
      return null;
    }

  }

  /**
   * Read a Bitmap from a file scaled appropriately for the screen size.
   *
   * @param context
   *     used to access device information.
   * @param file
   *     the file with the Bitmap.
   *
   * @return a Bitmap image scaled for the device screen or null if no Bitmap could be generated.
   */
  public static Bitmap getBitmapScaledToDisplay(final Context context, final File file) {
    Display display = ((WindowManager) context.getSystemService(Context.WINDOW_SERVICE)).getDefaultDisplay();
    int screenWidth = display.getWidth();
    int screenHeight = display.getHeight();

    if (file.exists()) {
      return getBitmapScaledToDisplay(file, screenHeight / 4, screenWidth / 4);
    } else {
      return null;
    }
  }

  /**
   * Read a Bitmap from a file scaled appropriately for the screen size.
   *
   * @param context
   *     used to access device information.
   * @param file
   *     the file with the Bitmap.
   *
   * @return a Bitmap image scaled for the device screen or null if no Bitmap could be generated.
   */
  public static Bitmap getBitmapThumbnail(final Context context, final File file) {
    Display display = ((WindowManager) context.getSystemService(Context.WINDOW_SERVICE)).getDefaultDisplay();
    int screenWidth = display.getWidth();
    int screenHeight = display.getHeight();

    if (file.exists()) {
      return getBitmapScaledToDisplay(file, screenHeight / 5, screenWidth / 5);
    } else {
      return null;
    }
  }

  /**
   * Read a Bitmap from a file scaled to specified dimensions.
   *
   * @param f
   *     the file containing the image.
   * @param screenHeight
   *     the max height of the image, used to determine scale.
   * @param screenWidth
   *     the max width of the image, used to determine scale.
   *
   * @return the scaled Bitmap or null if no Bitmap could be generated.
   */
  public static Bitmap getBitmapScaledToDisplay(File f, int screenHeight, int screenWidth) {
    // Determine image size of f
    BitmapFactory.Options o = new BitmapFactory.Options();
    o.inJustDecodeBounds = true;
    BitmapFactory.decodeFile(f.getAbsolutePath(), o);

    // Powers of 2 work faster, sometimes, according to the doc.
    // We're just doing closest size that still fills the screen.
    final int scale = Math.max(o.outWidth / screenWidth, o.outHeight / screenHeight);

    // get bitmap with scale ( < 1 is the same as 1)
    BitmapFactory.Options options = new BitmapFactory.Options();
    options.inInputShareable = true;
    options.inPurgeable = true;
    options.inSampleSize = scale;
    Bitmap b = BitmapFactory.decodeFile(f.getAbsolutePath(), options);
    if (b != null) {
      Log.i(t,
          "Screen is " + screenHeight + "x" + screenWidth + ".  Image has been scaled down by "
              + scale + " to " + b.getHeight() + "x" + b.getWidth());
    }
    return b;
  }

  /**
   * With this method we do not care about efficient decoding and focus more on a precise scaling to maximize use of
   * space on the screen
   *
   * @param f
   *     the file containing the image.
   * @param screenWidth
   *     the ideal width of the image.
   * @param screenHeight
   *     the ideal height of the image.
   *
   * @return the scaled Bitmap.
   */
  public static Bitmap getBitmapAccuratelyScaledToDisplay(File f, int screenHeight, int screenWidth) {

    // Determine image size of image
    BitmapFactory.Options o = new BitmapFactory.Options();
    o.inJustDecodeBounds = true;
    BitmapFactory.decodeFile(f.getAbsolutePath(), o);

    // Load full size bitmap image
    BitmapFactory.Options options = new BitmapFactory.Options();
    options.inInputShareable = true;
    options.inPurgeable = true;
    Bitmap bitmap = BitmapFactory.decodeFile(f.getAbsolutePath(), options);

    final int outHeight = o.outHeight;
    final int outWidth = o.outWidth;

    if (outHeight <= screenHeight && outWidth <= screenWidth) {
      return bitmap;
    }

    // Figure out scale
    double heightScale = ((double) outHeight) / screenHeight;
    double widthScale = ((double) outWidth) / screenWidth;
    double scale = Math.max(widthScale, heightScale);

    double newHeight = Math.ceil(outHeight / scale);
    double newWidth = Math.ceil(outWidth / scale);

    bitmap = Bitmap.createScaledBitmap(bitmap, (int) newWidth, (int) newHeight, false);

    return bitmap;
  }


  /**
   * Copy a file from one location to another.
   *
   * @param sourceFile
   *     the file to copy.
   * @param destFile
   *     the file to which we will copy the sourceFile.
   *
   * @return the error message if something has gone wrong or null if the copy was successful.
   */
  public static String copyFile(File sourceFile, File destFile) {
    if (sourceFile.exists()) {
      String errorMessage = actualCopy(sourceFile, destFile);
      if (errorMessage != null) {
        try {
          Thread.sleep(500);
          Log.e(t, "Retrying to copy the file after 500ms: " + sourceFile.getAbsolutePath());
          errorMessage = actualCopy(sourceFile, destFile);
        } catch (InterruptedException e) {
          Log.e(t, e.getMessage(), e);
        }
      }
      return errorMessage;
    } else {
      String msg = "Source file does not exist: " + sourceFile.getAbsolutePath();
      Log.e(t, msg);
      return msg;
    }
  }

  private static String actualCopy(File sourceFile, File destFile) {
    FileInputStream fileInputStream = null;
    FileOutputStream fileOutputStream = null;
    FileChannel src = null;
    FileChannel dst = null;
    try {
      fileInputStream = new FileInputStream(sourceFile);
      src = fileInputStream.getChannel();
      fileOutputStream = new FileOutputStream(destFile);
      dst = fileOutputStream.getChannel();
      dst.transferFrom(src, 0, src.size());
      dst.force(true);
      return null;
    } catch (FileNotFoundException e) {
      Log.e(t, "FileNotFoundException while copying file", e);
      return e.getMessage();
    } catch (IOException e) {
      Log.e(t, "IOException while copying file", e);
      return e.getMessage();
    } catch (Exception e) {
      Log.e(t, "Exception while copying file", e);
      return e.getMessage();
    } finally {
      IOUtils.closeQuietly(fileInputStream);
      IOUtils.closeQuietly(fileOutputStream);
      IOUtils.closeQuietly(src);
      IOUtils.closeQuietly(dst);
    }
  }

  public static HashMap<String, String> parseXML(File xmlFile) {
    HashMap<String, String> fields = new HashMap<>();
    InputStream is;
    try {
      is = new FileInputStream(xmlFile);
    } catch (FileNotFoundException e1) {
      throw new IllegalStateException(e1);
    }

    InputStreamReader isr;
    try {
      isr = new InputStreamReader(is, "UTF-8");
    } catch (UnsupportedEncodingException uee) {
      Log.w(t, "UTF 8 encoding unavailable, trying default encoding");
      isr = new InputStreamReader(is);
    }

    if (isr != null) {

      Document doc;
      try {
        doc = XFormParser.getXMLDocument(isr);
      } catch (IOException e) {
        e.printStackTrace();
        throw new IllegalStateException("Unable to parse XML document", e);
      } finally {
        try {
          isr.close();
        } catch (IOException e) {
          Log.w(t, xmlFile.getAbsolutePath() + " Error closing form reader");
          e.printStackTrace();
        }
      }

      String xforms = "http://www.w3.org/2002/xforms";
      String html = doc.getRootElement().getNamespace();

      Element head = doc.getRootElement().getElement(html, "head");
      Element title = head.getElement(html, "title");
      if (title != null) {
        fields.put(TITLE, XFormParser.getXMLText(title, true));
      }

      Element model = getChildElement(head, "model");
      Element cur = getChildElement(model, "instance");

      int idx = cur.getChildCount();
      int i;
      for (i = 0; i < idx; ++i) {
        if (cur.isText(i)) {
          continue;
        }
        if (cur.getType(i) == Node.ELEMENT) {
          break;
        }
      }

      if (i < idx) {
        cur = cur.getElement(i); // this is the first data element
        String id = cur.getAttributeValue(null, "id");
        String xmlns = cur.getNamespace();

        String version = cur.getAttributeValue(null, "version");
        String uiVersion = cur.getAttributeValue(null, "uiVersion");
        if (uiVersion != null) {
          // pre-OpenRosa 1.0 variant of spec
          Log.e(t, "Obsolete use of uiVersion -- IGNORED -- only using version: " + version);
        }

        fields.put(FORMID, (id == null) ? xmlns : id);
        fields.put(VERSION, (version == null) ? null : version);
      } else {
        throw new IllegalStateException(xmlFile.getAbsolutePath() + " could not be parsed");
      }
      try {
        Element submission = model.getElement(xforms, "submission");
        String submissionUri = submission.getAttributeValue(null, "action");
        fields.put(SUBMISSIONURI, (submissionUri == null) ? null : submissionUri);
        String base64RsaPublicKey = submission.getAttributeValue(null, "base64RsaPublicKey");
        fields.put(BASE64_RSA_PUBLIC_KEY,
            (base64RsaPublicKey == null || base64RsaPublicKey.trim().length() == 0)
                ? null : base64RsaPublicKey.trim());
      } catch (Exception e) {
        Log.i(t, xmlFile.getAbsolutePath() + " does not have a submission element");
        // and that's totally fine.
      }

    }
    return fields;
  }

  // needed because element.getelement fails when there are attributes
  private static Element getChildElement(Element parent, String childName) {
    Element e = null;
    int c = parent.getChildCount();
    int i = 0;
    for (i = 0; i < c; i++) {
      if (parent.getType(i) == Node.ELEMENT) {
        if (parent.getElement(i).getName().equalsIgnoreCase(childName)) {
          return parent.getElement(i);
        }
      }
    }
    return e;
  }

  public static void deleteAndReport(File file) {
    if (file != null && file.exists()) {
      // remove garbage
      if (!file.delete()) {
        Log.w(t, file.getAbsolutePath() + " will be deleted upon exit.");
        file.deleteOnExit();
      } else {
        Log.w(t, file.getAbsolutePath() + " has been deleted.");
      }
    }
  }

  public static String constructMediaPath(String formFilePath) {
    String pathNoExtension = formFilePath.substring(0, formFilePath.lastIndexOf("."));
    return pathNoExtension + "-media";
  }

  /**
   * @param mediaDir
   *     the media folder
   */
  public static void checkMediaPath(File mediaDir) {
    if (mediaDir.exists() && mediaDir.isFile()) {
      Log.e(t, "The media folder is already there and it is a FILE!! We will need to delete it and create a folder " +
          "instead");
      boolean deleted = mediaDir.delete();
      if (!deleted) {
        throw new RuntimeException(Collect.getInstance().getString(R.string.fs_delete_media_path_if_file_error,
            mediaDir.getAbsolutePath()));
      }
    }

    // the directory case
    boolean createdOrExisted = createFolder(mediaDir.getAbsolutePath());
    if (!createdOrExisted) {
      throw new RuntimeException(Collect.getInstance().getString(R.string.fs_create_media_folder_error, mediaDir
          .getAbsolutePath()));
    }
  }

  public static void purgeMediaPath(String mediaPath) {
    File tempMediaFolder = new File(mediaPath);
    File[] tempMediaFiles = tempMediaFolder.listFiles();
    if (tempMediaFiles == null || tempMediaFiles.length == 0) {
      deleteAndReport(tempMediaFolder);
    } else {
      for (File tempMediaFile : tempMediaFiles) {
        deleteAndReport(tempMediaFile);
      }
    }
  }

  public static void moveMediaFiles(String tempMediaPath, File formMediaPath) throws IOException {
    File tempMediaFolder = new File(tempMediaPath);
    File[] mediaFiles = tempMediaFolder.listFiles();
    if (mediaFiles == null || mediaFiles.length == 0) {
      deleteAndReport(tempMediaFolder);
    } else {
      for (File mediaFile : mediaFiles) {
        org.apache.commons.io.FileUtils.moveFileToDirectory(mediaFile, formMediaPath, true);
      }
      deleteAndReport(tempMediaFolder);
    }
  }
}
