/**

  * Copyright (c) 2008-2011, http://www.snakeyaml.org

  *

  * Licensed 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.yaml.snakeyaml.reader;

 import java.io.IOException;

 import java.io.Reader;

 import java.nio.charset.Charset;

 import java.util.regex.Matcher;

 import java.util.regex.Pattern;

 import org.yaml.snakeyaml.error.Mark;

 import org.yaml.snakeyaml.error.YAMLException;

 import org.yaml.snakeyaml.scanner.Constant;

 /**

  * Reader: checks if characters are in allowed range, adds '\0' to the end.

  */

 public class StreamReader {

     // NON_PRINTABLE changed from PyYAML: \uFFFD excluded because Java returns

     // it in case of data corruption

     final static Pattern NON_PRINTABLE = Pattern

             .compile("[^\t\n\r\u0020-\u007E\u0085\u00A0-\uD7FF\uE000-\uFFFC]");

     private String name;

     private final Reader stream;

     private int pointer = 0;

     private boolean eof = true;

     private String buffer;

     private int index = 0;

     private int line = 0;

     private int column = 0;

     private char[] data;

     public StreamReader(String stream) {

         this.name = "<string>";

         this.buffer = ""; // to set length to 0

         checkPrintable(stream);

         this.buffer = stream + "\0";

         this.stream = null;

         this.eof = true;

         this.data = null;

     }

     public StreamReader(Reader reader) {

         this.name = "<reader>";

         this.buffer = "";

         this.stream = reader;

         this.eof = false;

         this.data = new char[1024];

         this.update();

     }

     void checkPrintable(CharSequence data) {

         Matcher em = NON_PRINTABLE.matcher(data);

         if (em.find()) {

             int position = this.index + this.buffer.length() - this.pointer + em.start();

             throw new ReaderException(name, position, em.group().charAt(0),

                     "special characters are not allowed");

         }

     }

     /**

      * Checks <code>chars</chars> for the non-printable characters.

      * 

      * @param chars

      *            the array where to search.

      * @param begin

      *            the beginning index, inclusive.

      * @param end

      *            the ending index, exclusive.

      * @throws ReaderException

      *             if <code>chars</code> contains non-printable character(s).

      */

     void checkPrintable(final char[] chars, final int begin, final int end) {

         for (int i = begin; i < end; i++) {

             final char c = chars[i];

             if ((c >= '\u0020' && c <= '\u007E') || c == '\n' || c == '\r' || c == '\t'

                     || c == '\u0085' || (c >= '\u00A0' && c <= '\uD7FF')

                     || (c >= '\uE000' && c <= '\uFFFC')) {

                 continue;

             }

             int position = this.index + this.buffer.length() - this.pointer + i;

             throw new ReaderException(name, position, c, "special characters are not allowed");

         }

     }

     public Mark getMark() {

         return new Mark(name, this.index, this.line, this.column, this.buffer, this.pointer);

     }

     public void forward() {

         forward(1);

     }

     /**

      * read the next length characters and move the pointer.

      * 

      * @param length

      */

     public void forward(int length) {

         if (this.pointer + length + 1 >= this.buffer.length()) {

             update();

         }

         char ch = 0;

         for (int i = 0; i < length; i++) {

             ch = this.buffer.charAt(this.pointer);

             this.pointer++;

             this.index++;

             if (Constant.LINEBR.has(ch) || (ch == '\r' && buffer.charAt(pointer) != '\n')) {

                 this.line++;

                 this.column = 0;

             } else if (ch != '\uFEFF') {

                 this.column++;

             }

         }

     }

     public char peek() {

         return this.buffer.charAt(this.pointer);

     }

     /**

      * Peek the next index-th character

      * 

      * @param index

      * @return

      */

     public char peek(int index) {

         if (this.pointer + index + 1 > this.buffer.length()) {

             update();

         }

         return this.buffer.charAt(this.pointer + index);

     }

     /**

      * peek the next length characters

      * 

      * @param length

      * @return

      */

     public String prefix(int length) {

         if (this.pointer + length >= this.buffer.length()) {

             update();

         }

         if (this.pointer + length > this.buffer.length()) {

             return this.buffer.substring(this.pointer);

         }

         return this.buffer.substring(this.pointer, this.pointer + length);

     }

     /**

      * prefix(length) immediately followed by forward(length)

      */

     public String prefixForward(int length) {

         final String prefix = prefix(length);

         this.pointer += length;

         this.index += length;

         // prefix never contains new line characters

         this.column += length;

         return prefix;

     }

     private void update() {

         if (!this.eof) {

             this.buffer = buffer.substring(this.pointer);

             this.pointer = 0;

             try {

                 int converted = this.stream.read(data);

                 if (converted > 0) {

                     /*

                      * Let's create StringBuilder manually. Anyway str1 + str2

                      * generates new StringBuilder(str1).append(str2).toSting()

                      * Giving correct capacity to the constructor prevents

                      * unnecessary operations in appends.

                      */

                     checkPrintable(data, 0, converted);

                     this.buffer = new StringBuilder(buffer.length() + converted).append(buffer)

                             .append(data, 0, converted).toString();

                 } else {

                     this.eof = true;

                     this.buffer += "\0";

                 }

             } catch (IOException ioe) {

                 throw new YAMLException(ioe);

             }

         }

     }

     public int getColumn() {

         return column;

     }

     public Charset getEncoding() {

         return Charset.forName(((UnicodeReader) this.stream).getEncoding());

     }

     public int getIndex() {

         return index;

     }

     public int getLine() {

         return line;

     }

 }