HttpVersion.java

package com.firefly.codec.http2.model;

import java.nio.ByteBuffer;
import java.nio.charset.StandardCharsets;

import com.firefly.utils.collection.ArrayTrie;
import com.firefly.utils.collection.Trie;

public enum HttpVersion {
	HTTP_0_9("HTTP/0.9", 9), HTTP_1_0("HTTP/1.0", 10), HTTP_1_1("HTTP/1.1", 11), HTTP_2("HTTP/2.0", 20);

	public final static Trie<HttpVersion> CACHE = new ArrayTrie<HttpVersion>();

	static {
		for (HttpVersion version : HttpVersion.values())
			CACHE.put(version.toString(), version);
	}

	/**
	 * Optimized lookup to find a HTTP Version and whitespace in a byte array.
	 * 
	 * @param bytes
	 *            Array containing ISO-8859-1 characters
	 * @param position
	 *            The first valid index
	 * @param limit
	 *            The first non valid index
	 * @return A HttpMethod if a match or null if no easy match.
	 */
	public static HttpVersion lookAheadGet(byte[] bytes, int position, int limit) {
		int length = limit - position;
		if (length < 9)
			return null;

		if (bytes[position + 4] == '/' && bytes[position + 6] == '.'
				&& Character.isWhitespace((char) bytes[position + 8])
				&& ((bytes[position] == 'H' && bytes[position + 1] == 'T' && bytes[position + 2] == 'T'
						&& bytes[position + 3] == 'P')
						|| (bytes[position] == 'h' && bytes[position + 1] == 't' && bytes[position + 2] == 't'
								&& bytes[position + 3] == 'p'))) {
			switch (bytes[position + 5]) {
			case '1':
				switch (bytes[position + 7]) {
				case '0':
					return HTTP_1_0;
				case '1':
					return HTTP_1_1;
				}
				break;
			case '2':
				switch (bytes[position + 7]) {
				case '0':
					return HTTP_2;
				}
				break;
			}
		}

		return null;
	}

	/**
	 * Optimised lookup to find a HTTP Version and trailing white space in a
	 * byte array.
	 * 
	 * @param buffer
	 *            buffer containing ISO-8859-1 characters
	 * @return A HttpVersion if a match or null if no easy match.
	 */
	public static HttpVersion lookAheadGet(ByteBuffer buffer) {
		if (buffer.hasArray())
			return lookAheadGet(buffer.array(), buffer.arrayOffset() + buffer.position(),
					buffer.arrayOffset() + buffer.limit());
		return null;
	}

	private final String _string;
	private final byte[] _bytes;
	private final ByteBuffer _buffer;
	private final int _version;

	HttpVersion(String s, int version) {
		_string = s;
		_bytes = s.getBytes(StandardCharsets.UTF_8);
		_buffer = ByteBuffer.wrap(_bytes);
		_version = version;
	}

	public byte[] toBytes() {
		return _bytes;
	}

	public ByteBuffer toBuffer() {
		return _buffer.asReadOnlyBuffer();
	}

	public int getVersion() {
		return _version;
	}

	public boolean is(String s) {
		return _string.equalsIgnoreCase(s);
	}

	public String asString() {
		return _string;
	}

	@Override
	public String toString() {
		return _string;
	}

	/**
	 * Case insensitive fromString() conversion
	 * 
	 * @param version
	 *            the String to convert to enum constant
	 * @return the enum constant or null if version unknown
	 */
	public static HttpVersion fromString(String version) {
		return CACHE.get(version);
	}

	public static HttpVersion fromVersion(int version) {
		switch (version) {
		case 9:
			return HttpVersion.HTTP_0_9;
		case 10:
			return HttpVersion.HTTP_1_0;
		case 11:
			return HttpVersion.HTTP_1_1;
		case 20:
			return HttpVersion.HTTP_2;
		default:
			throw new IllegalArgumentException();
		}
	}
}