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/*
 * Sonar Delphi Plugin
 * Copyright (C) 2019 Integrated Application Development
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 3 of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02
 */
package au.com.integradev.delphi.antlr;

import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import java.nio.charset.Charset;
import org.antlr.runtime.ANTLRStringStream;
import org.apache.commons.io.ByteOrderMark;
import org.apache.commons.io.input.BOMInputStream;

public class DelphiFileStream extends ANTLRStringStream {
  private final String fileName;
  private final String encoding;

  public DelphiFileStream(String fileName, String encoding) throws IOException {
    this.fileName = fileName;
    this.encoding = this.load(fileName, encoding);
  }

  private String load(String fileName, String encoding) throws IOException {
    if (fileName != null) {
      File f = new File(fileName);
      int size = (int) f.length();
      try (BOMInputStream input = bomInputStream(fileName).get()) {
        ByteOrderMark bom = input.getBOM();
        if (bom != null) {
          encoding = bom.getCharsetName();
        }

        if (encoding == null) {
          encoding = Charset.defaultCharset().name();
        }

        try (InputStreamReader reader = new InputStreamReader(input, encoding)) {
          this.data = new char[size];
          super.n = reader.read(this.data);
        }
      }
    }
    return encoding;
  }

  @Override
  public String getSourceName() {
    return this.fileName;
  }

  public String getEncoding() {
    return this.encoding;
  }

  private static BOMInputStream.Builder bomInputStream(String fileName) throws IOException {
    return BOMInputStream.builder()
        .setInputStream(new FileInputStream(fileName))
        .setInclude(false)
        .setByteOrderMarks(
            ByteOrderMark.UTF_8,
            ByteOrderMark.UTF_16LE,
            ByteOrderMark.UTF_16BE,
            ByteOrderMark.UTF_32LE,
            ByteOrderMark.UTF_32BE);
  }
}