/*
    * 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.accumulo.core.security;
  
  import java.io.Serializable;
  import java.io.UnsupportedEncodingException;
  import java.nio.ByteBuffer;
  import java.nio.charset.Charset;
  import java.util.ArrayList;
  import java.util.Collection;
  import java.util.Collections;
  import java.util.HashSet;
  import java.util.Iterator;
  import java.util.List;
  import java.util.Set;
  import java.util.TreeSet;
  
  import org.apache.accumulo.core.data.ArrayByteSequence;
  import org.apache.accumulo.core.data.ByteSequence;
  import org.apache.accumulo.core.util.ArgumentChecker;
  import org.apache.accumulo.core.util.ByteBufferUtil;
  import org.apache.commons.codec.binary.Base64;
  
  public class Authorizations implements Iterable<byte[]>, Serializable {
    
    private static final long serialVersionUID = 1L;
    
    private Set<ByteSequence> auths = new HashSet<ByteSequence>();
    private List<byte[]> authsList = new ArrayList<byte[]>();
    private List<byte[]> immutableList = Collections.unmodifiableList(authsList);
    
    private static final boolean[] validAuthChars = new boolean[256];
    
    public static final String HEADER = "!AUTH1:";
  
    static {
      for (int i = 0; i < 256; i++) {
        validAuthChars[i] = false;
      }
      
      for (int i = 'a'; i <= 'z'; i++) {
        validAuthChars[i] = true;
      }
      
      for (int i = 'A'; i <= 'Z'; i++) {
        validAuthChars[i] = true;
      }
      
      for (int i = '0'; i <= '9'; i++) {
        validAuthChars[i] = true;
      }
      
      validAuthChars['_'] = true;
      validAuthChars['-'] = true;
      validAuthChars[':'] = true;
      validAuthChars['.'] = true;
      validAuthChars['/'] = true;
    }
    
    static final boolean isValidAuthChar(byte b) {
      return validAuthChars[0xff & b];
    }
    
    private void checkAuths() {
      Set<ByteSequence> sortedAuths = new TreeSet<ByteSequence>(auths);
      
      for (ByteSequence bs : sortedAuths) {
        if (bs.length() == 0) {
          throw new IllegalArgumentException("Empty authorization");
        }
        
        authsList.add(bs.toArray());
      }
    }
    
    public Authorizations(Collection<byte[]> authorizations) {
      ArgumentChecker.notNull(authorizations);
      for (byte[] auth : authorizations)
        auths.add(new ArrayByteSequence(auth));
      checkAuths();
    }
    
    public Authorizations(List<ByteBuffer> authorizations) {
      ArgumentChecker.notNull(authorizations);
      for (ByteBuffer buffer : authorizations) {
       auths.add(new ArrayByteSequence(ByteBufferUtil.toBytes(buffer)));
     }
     checkAuths();
   }
   
   /**
    * @param authorizations
    *          a serialized authorizations string produced by {@link #getAuthorizationsArray()} or {@link #serialize()}
    */
 
   public Authorizations(byte[] authorizations) {
     
     ArgumentChecker.notNull(authorizations);
 
     String authsString = new String(authorizations);
     if (authsString.startsWith(HEADER)) {
       // its the new format
       authsString = authsString.substring(HEADER.length());
       if (authsString.length() > 0) {
         for (String encAuth : authsString.split(",")) {
           byte[] auth = Base64.decodeBase64(encAuth.getBytes());
           auths.add(new ArrayByteSequence(auth));
         }
         checkAuths();
       }
     } else {
       // its the old format
       ArgumentChecker.notNull(authorizations);
       if (authorizations.length > 0)
         setAuthorizations(authsString.split(","));
     }
   }
   
   public Authorizations() {}
   
   /**
    * 
    * @param charset
    *          used to convert each authorization to a byte array
    * @param authorizations
    *          array of authorizations
    */
   
   public Authorizations(Charset charset, String... authorizations) {
     setAuthorizations(charset, authorizations);
   }
 
   public Authorizations(String... authorizations) {
     setAuthorizations(authorizations);
   }
   
   private void setAuthorizations(String... authorizations) {
     setAuthorizations(Charset.defaultCharset(), authorizations);
   }
   
   private void setAuthorizations(Charset charset, String... authorizations) {
     ArgumentChecker.notNull(authorizations);
     auths.clear();
     for (String str : authorizations) {
       str = str.trim();
       try {
         auths.add(new ArrayByteSequence(str.getBytes(charset.name())));
       } catch (UnsupportedEncodingException e) {
         throw new RuntimeException(e);
       }
     }
     
     checkAuths();
   }
   
   public byte[] getAuthorizationsArray() {
     return serialize().getBytes();
   }
   
   public List<byte[]> getAuthorizations() {
     return immutableList;
   }
   
   public List<ByteBuffer> getAuthorizationsBB() {
     return ByteBufferUtil.toByteBuffers(immutableList);
   }
   
   public String toString() {
     StringBuilder sb = new StringBuilder();
     String sep = "";
     for (ByteSequence auth : auths) {
       sb.append(sep);
       sep = ",";
       sb.append(new String(auth.toArray()));
     }
     
     return sb.toString();
   }
   
   public boolean contains(byte[] auth) {
     return auths.contains(new ArrayByteSequence(auth));
   }
   
   public boolean contains(ByteSequence auth) {
     return auths.contains(auth);
   }
   
   public boolean equals(Object o) {
     if (o == null) {
       return false;
     }
     
     if (o instanceof Authorizations) {
       Authorizations ao = (Authorizations) o;
       
       return auths.equals(ao.auths);
     }
     
     return false;
   }
   
   public int hashCode() {
     int result = 0;
     for (ByteSequence b : auths)
       result += b.hashCode();
     return result;
   }
   
   public int size() {
     return auths.size();
   }
   
   public boolean isEmpty() {
     return auths.isEmpty();
   }
   
   @Override
   public Iterator<byte[]> iterator() {
     return immutableList.iterator();
   }
   
   public String serialize() {
     StringBuilder sb = new StringBuilder(HEADER);
     String sep = "";
     for (byte[] auth : immutableList) {
       sb.append(sep);
       sep = ",";
       sb.append(new String(Base64.encodeBase64(auth)));
     }
     
     return sb.toString();
   }
 }