/*
 * 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 org.apache.geode.management.internal.cli.converters;

import java.io.File;
import java.util.List;

import org.springframework.shell.core.Completion;
import org.springframework.shell.core.MethodTarget;
import org.springframework.shell.support.util.FileUtils;
import org.springframework.util.Assert;

import org.apache.geode.management.cli.ConverterHint;
import org.apache.geode.management.internal.cli.MultipleValueAdapter;
import org.apache.geode.management.internal.cli.shell.Gfsh;

/**
 *
 * @since GemFire 7.0
 * 
 * 
 */
public class DirConverter extends MultipleValueAdapter<String[]> {

  private static final String HOME_DIRECTORY_SYMBOL = "~";
  // Constants
  private static final String home = System.getProperty("user.home");

  @Override
  public String[] convertFromText(String[] values, Class<?> targetType, String context) {
    return values;
  }

  @Override
  public boolean getAllPossibleValues(List<Completion> completions, Class<?> targetType,
      String[] existingData, String context, MethodTarget target) {
    String adjustedUserInput = convertUserInputIntoAFullyQualifiedPath(
        (existingData != null) ? existingData[existingData.length - 1] : "");

    String directoryData =
        adjustedUserInput.substring(0, adjustedUserInput.lastIndexOf(File.separator) + 1);
    adjustedUserInput =
        adjustedUserInput.substring(adjustedUserInput.lastIndexOf(File.separator) + 1);

    populate(completions, adjustedUserInput,
        ((existingData != null) ? existingData[existingData.length - 1] : ""), directoryData);

    return true;
  }

  protected void populate(final List<Completion> completions, final String adjustedUserInput,
      final String originalUserInput, final String directoryData) {
    File directory = new File(directoryData);

    if (!directory.isDirectory()) {
      return;
    }

    for (File file : directory.listFiles()) {
      if (adjustedUserInput == null || adjustedUserInput.length() == 0
          || file.getName().toLowerCase().startsWith(adjustedUserInput.toLowerCase())) {

        String completion = "";
        if (directoryData.length() > 0)
          completion += directoryData;
        completion += file.getName();

        completion = convertCompletionBackIntoUserInputStyle(originalUserInput, completion);

        if (file.isDirectory()) {
          completions.add(new Completion(completion + File.separator));
        }
      }
    }
  }

  private String convertCompletionBackIntoUserInputStyle(final String originalUserInput,
      final String completion) {
    if (FileUtils.denotesAbsolutePath(originalUserInput)) {
      // Input was originally as a fully-qualified path, so we just keep the
      // completion in that form
      return completion;
    }
    if (originalUserInput.startsWith(HOME_DIRECTORY_SYMBOL)) {
      // Input originally started with this symbol, so replace the user's home
      // directory with it again
      Assert.notNull(home, "Home directory could not be determined from system properties");
      return HOME_DIRECTORY_SYMBOL + completion.substring(home.length());
    }
    // The path was working directory specific, so strip the working directory
    // given the user never typed it
    return completion.substring(getWorkingDirectoryAsString().length());
  }

  /**
   * If the user input starts with a tilde character (~), replace the tilde character with the
   * user's home directory. If the user input does not start with a tilde, simply return the
   * original user input without any changes if the input specifies an absolute path, or return an
   * absolute path based on the working directory if the input specifies a relative path.
   * 
   * @param userInput the user input, which may commence with a tilde (required)
   * @return a string that is guaranteed to no longer contain a tilde as the first character (never
   *         null)
   */
  private String convertUserInputIntoAFullyQualifiedPath(final String userInput) {
    if (FileUtils.denotesAbsolutePath(userInput)) {
      // Input is already in a fully-qualified path form
      return userInput;
    }
    if (userInput.startsWith(HOME_DIRECTORY_SYMBOL)) {
      // Replace this symbol with the user's actual home directory
      Assert.notNull(home, "Home directory could not be determined from system properties");
      if (userInput.length() > 1) {
        return home + userInput.substring(1);
      }
    }
    // The path is working directory specific, so prepend the working directory
    String fullPath = getWorkingDirectoryAsString() + userInput;
    return fullPath;
  }

  private String getWorkingDirectoryAsString() {
    try {
      return getWorkingDirectory().getCanonicalPath() + File.separator;
    } catch (Exception e) {
      throw new IllegalStateException(e);
    }
  }

  /**
   * @return the "current working directory" this {@link DirConverter} should use if the user fails
   *         to provide an explicit directory in their input (required)
   */
  private File getWorkingDirectory() {
    return Gfsh.getCurrentInstance().getHome();
  }

  @Override
  public boolean supports(Class<?> type, String optionContext) {
    if (String[].class.isAssignableFrom(type) && optionContext.equals(ConverterHint.DIRS)) {
      return true;
    }
    return false;
  }

}