/*
 * 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.samza.sql.client.cli;

import org.apache.samza.sql.client.impl.CliCommandType;
import org.apache.samza.sql.client.util.CliUtil;
import org.jline.reader.Highlighter;
import org.jline.reader.LineReader;
import org.jline.utils.AttributedString;
import org.jline.utils.AttributedStringBuilder;
import org.jline.utils.AttributedStyle;

import java.util.ArrayList;
import java.util.List;

/**
 * A primitive highlighter.
 */
public class CliHighlighter implements Highlighter {
  private static final List<String> KEYWORDS;

  static {
    KEYWORDS = CliCommandType.getAllCommands();
    KEYWORDS.add("FROM");
    KEYWORDS.add("WHERE");
  }

  private static List<String> splitWithSpace(String buffer) {
    List<String> list = new ArrayList<String>();
    if (CliUtil.isNullOrEmpty(buffer))
      return list;

    boolean prevIsSpace = Character.isSpaceChar(buffer.charAt(0));
    int prevPos = 0;
    for (int i = 1; i < buffer.length(); ++i) {
      char c = buffer.charAt(i);
      boolean isSpace = Character.isSpaceChar(c);
      if (isSpace != prevIsSpace) {
        list.add(buffer.substring(prevPos, i));
        prevPos = i;
        prevIsSpace = isSpace;
      }
    }
    list.add(buffer.substring(prevPos));
    return list;
  }

  public AttributedString highlight(LineReader reader, String buffer) {
    AttributedStringBuilder builder = new AttributedStringBuilder();
    List<String> tokens = splitWithSpace(buffer);

    for (String token : tokens) {
      if (isKeyword(token)) {
        builder.style(AttributedStyle.BOLD.foreground(AttributedStyle.YELLOW))
                .append(token);
      } else {
        builder.style(AttributedStyle.DEFAULT)
                .append(token);
      }
    }

    return builder.toAttributedString();
  }

  private boolean isKeyword(String token) {
    for (String keyword : KEYWORDS) {
      if (keyword.compareToIgnoreCase(token) == 0)
        return true;
    }
    return false;

  }
}