/*
 * 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.jclouds.digitalocean.domain;

import static com.google.common.base.Preconditions.checkNotNull;
import static com.google.common.base.Strings.nullToEmpty;
import static java.util.regex.Pattern.compile;

import java.util.regex.Matcher;
import java.util.regex.Pattern;

/**
 * The operating system of an image.
 * <p>
 * This class parses the <code>name</code> string (e.g. "Ubuntu 12.10 x64") of the images and properly sets each field
 * to the right value.
 */
public class OperatingSystem {

   // Parse something like "Ubuntu 12.10 x64"
   private static final Pattern VERSION_PATTERN = compile("\\s(\\d+(?:\\.?\\d+)?)");
   private static final Pattern ARCH_PATTERN = compile("x\\d{2}");
   private static final String IS_64_BIT = "x64";

   private final Distribution distribution;
   private final String version;
   private final String arch;

   private OperatingSystem(String distribution, String version, String arch) {
      this.distribution = checkNotNull(Distribution.fromValue(distribution), "distribution cannot be null");
      this.version = checkNotNull(version, "version cannot be null");
      this.arch = checkNotNull(arch, "arch cannot be null");
   }

   public Distribution getDistribution() {
      return distribution;
   }

   public String getVersion() {
      return version;
   }

   public String getArch() {
      return arch;
   }

   public boolean is64bit() {
      return IS_64_BIT.equals(arch);
   }

   public static Builder builder() {
      return new Builder();
   }

   public static class Builder {
      private String name;
      private String distribution;

      public Builder from(String name, String distribution) {
         this.name = checkNotNull(name, "name cannot be null");
         this.distribution = checkNotNull(distribution, "distribution cannot be null");
         return this;
      }

      public OperatingSystem build() {
         return new OperatingSystem(distribution, match(VERSION_PATTERN, name, 1), match(ARCH_PATTERN, name, 0));
      }
   }

   private static String match(final Pattern pattern, final String input, int group) {
      Matcher m = pattern.matcher(input);
      return m.find() ? nullToEmpty(m.group(group)) : "";
   }

   @Override
   public int hashCode() {
      final int prime = 31;
      int result = 1;
      result = prime * result + (arch == null ? 0 : arch.hashCode());
      result = prime * result + (distribution == null ? 0 : distribution.hashCode());
      result = prime * result + (version == null ? 0 : version.hashCode());
      return result;
   }

   @Override
   public boolean equals(final Object obj) {
      if (this == obj) {
         return true;
      }
      if (obj == null) {
         return false;
      }
      if (getClass() != obj.getClass()) {
         return false;
      }
      OperatingSystem other = (OperatingSystem) obj;
      if (arch == null) {
         if (other.arch != null) {
            return false;
         }
      } else if (!arch.equals(other.arch)) {
         return false;
      }
      if (distribution != other.distribution) {
         return false;
      }
      if (version == null) {
         if (other.version != null) {
            return false;
         }
      } else if (!version.equals(other.version)) {
         return false;
      }
      return true;
   }

   @Override
   public String toString() {
      return "OperatingSystem [distribution=" + distribution + ", version=" + version + ", arch=" + arch + "]";
   }

}