/*
    * Copyright 2014 The Netty Project
    *
    * The Netty Project 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.jboss.netty.handler.ssl;
  
  import org.jboss.netty.buffer.ChannelBuffer;
  import org.jboss.netty.buffer.ChannelBuffers;
  import org.jboss.netty.handler.codec.base64.Base64;
  import org.jboss.netty.logging.InternalLogger;
  import org.jboss.netty.logging.InternalLoggerFactory;
  import org.jboss.netty.util.CharsetUtil;
  
  import java.io.ByteArrayOutputStream;
  import java.io.File;
  import java.io.FileInputStream;
  import java.io.IOException;
  import java.io.InputStream;
  import java.io.OutputStream;
  import java.security.KeyException;
  import java.security.KeyStore;
  import java.security.cert.CertificateException;
  import java.util.ArrayList;
  import java.util.List;
  import java.util.regex.Matcher;
  import java.util.regex.Pattern;
  
  /**
   * Reads a PEM file and converts it into a list of DERs so that they are imported into a {@link KeyStore} easily.
   */
  final class PemReader {
  
      private static final InternalLogger logger = InternalLoggerFactory.getInstance(PemReader.class);
  
      private static final Pattern CERT_PATTERN = Pattern.compile(
              "-+BEGIN\\s+.*CERTIFICATE[^-]*-+(?:\\s|\\r|\\n)+" + // Header
                      "([a-z0-9+/=\\r\\n]+)" +                    // Base64 text
                      "-+END\\s+.*CERTIFICATE[^-]*-+",            // Footer
              Pattern.CASE_INSENSITIVE);
      private static final Pattern KEY_PATTERN = Pattern.compile(
              "-+BEGIN\\s+.*PRIVATE\\s+KEY[^-]*-+(?:\\s|\\r|\\n)+" + // Header
                      "([a-z0-9+/=\\r\\n]+)" +                       // Base64 text
                      "-+END\\s+.*PRIVATE\\s+KEY[^-]*-+",            // Footer
              Pattern.CASE_INSENSITIVE);
  
      static ChannelBuffer[] readCertificates(File file) throws CertificateException {
          String content;
          try {
              content = readContent(file);
          } catch (IOException e) {
              throw new CertificateException("failed to read a file: " + file, e);
          }
  
          List<ChannelBuffer> certs = new ArrayList<ChannelBuffer>();
          Matcher m = CERT_PATTERN.matcher(content);
          int start = 0;
          for (;;) {
              if (!m.find(start)) {
                  break;
              }
  
              certs.add(Base64.decode(ChannelBuffers.copiedBuffer(m.group(1), CharsetUtil.US_ASCII)));
              start = m.end();
          }
  
          if (certs.isEmpty()) {
              throw new CertificateException("found no certificates: " + file);
          }
  
          return certs.toArray(new ChannelBuffer[certs.size()]);
      }
  
      static ChannelBuffer readPrivateKey(File file) throws KeyException {
          String content;
          try {
              content = readContent(file);
          } catch (IOException e) {
              throw new KeyException("failed to read a file: " + file, e);
          }
  
          Matcher m = KEY_PATTERN.matcher(content);
          if (!m.find()) {
              throw new KeyException("found no private key: " + file);
          }
  
          return Base64.decode(ChannelBuffers.copiedBuffer(m.group(1), CharsetUtil.US_ASCII));
      }
 
     private static String readContent(File file) throws IOException {
         InputStream in = new FileInputStream(file);
         ByteArrayOutputStream out = new ByteArrayOutputStream();
         try {
             byte[] buf = new byte[8192];
             for (;;) {
                 int ret = in.read(buf);
                 if (ret < 0) {
                     break;
                 }
                 out.write(buf, 0, ret);
             }
             return out.toString(CharsetUtil.US_ASCII.name());
         } finally {
             safeClose(in);
             safeClose(out);
         }
     }
 
     private static void safeClose(InputStream in) {
         try {
             in.close();
         } catch (IOException e) {
             logger.warn("Failed to close a stream.", e);
         }
     }
 
     private static void safeClose(OutputStream out) {
         try {
             out.close();
         } catch (IOException e) {
             logger.warn("Failed to close a stream.", e);
         }
     }
 
     private PemReader() { }
 }