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/**
 * Copyright 2003-2016 SSHTOOLS Limited. All Rights Reserved.
 *
 * For product documentation visit https://www.sshtools.com/
 *
 * This file is part of J2SSH Maverick.
 *
 * J2SSH Maverick 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.
 *
 * J2SSH Maverick 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 General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with J2SSH Maverick.  If not, see .
 */
package com.sshtools.net;

import java.io.IOException;
import java.io.InputStream;
import java.util.Enumeration;
import java.util.Hashtable;

/**
 * Utility class to process HTTP headers.
 * 
 * @author Lee David Painter
 * 
 */
public abstract class HttpHeader {

	protected final static String white_SPACE = " \t\r";
	Hashtable fields;

	protected String begin;

	protected HttpHeader() {
		fields = new Hashtable();
	}

	protected String readLine(InputStream in) throws IOException {
		StringBuffer lineBuf = new StringBuffer();
		int c;

		while (true) {
			c = in.read();

			if (c == -1) {
				throw new IOException(
						"Failed to read expected HTTP header line");
			}

			if (c == '\n') {
				continue;
			}

			if (c != '\r') {
				lineBuf.append((char) c);
			} else {
				break;
			}
		}

		return new String(lineBuf);
	}

	public String getStartLine() {
		return begin;
	}

	public Hashtable getHeaderFields() {
		return fields;
	}

	public Enumeration getHeaderFieldNames() {
		return fields.keys();
	}

	public String getHeaderField(String headerName) {
		for (Enumeration e = fields.keys(); e.hasMoreElements();) {
			String f = (String) e.nextElement();
			if (f.equalsIgnoreCase(headerName)) {
				return (String) fields.get(f);
			}
		}
		return null;
	}

	public void setHeaderField(String headerName, String value) {
		fields.put(headerName, value);
	}

	public String toString() {
		String str = begin + "\r\n";
		Enumeration it = getHeaderFieldNames();

		while (it.hasMoreElements()) {
			String fieldName = (String) it.nextElement();
			str += (fieldName + ": " + getHeaderField(fieldName) + "\r\n");
		}

		str += "\r\n";

		return str;
	}

	protected void processHeaderFields(InputStream in) throws IOException {
		fields = new Hashtable();

		StringBuffer lineBuf = new StringBuffer();
		String lastHeaderName = null;
		int c;

		while (true) {
			c = in.read();

			if (c == -1) {
				throw new IOException(
						"EOF returned from server but HTTP response is not complete!");
			}

			if (c == '\n') {
				continue;
			}

			if (c != '\r') {
				lineBuf.append((char) c);
			} else {
				if (lineBuf.length() != 0) {
					String line = lineBuf.toString();
					lastHeaderName = processNextLine(line, lastHeaderName);
					lineBuf.setLength(0);
				} else {
					break;
				}
			}
		}

		c = in.read();
	}

	private String processNextLine(String line, String lastHeaderName)
			throws IOException {
		String name;
		String value;
		char c = line.charAt(0);

		if ((c == ' ') || (c == '\t')) {
			name = lastHeaderName;
			value = getHeaderField(lastHeaderName) + " " + line.trim();
		} else {
			int n = line.indexOf(':');

			if (n == -1) {
				throw new IOException(
						"HTTP Header encoutered a corrupt field: '" + line
								+ "'");
			}

			name = line.substring(0, n).toLowerCase();
			value = line.substring(n + 1).trim();
		}

		setHeaderField(name, value);

		return name;
	}
}