HttpMethod.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 HttpMethod {
	GET, POST, HEAD, PUT, OPTIONS, DELETE, TRACE, CONNECT, MOVE, PROXY, PRI;

	/**
	 * Optimized lookup to find a method name and trailing space 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 HttpMethod lookAheadGet(byte[] bytes, final int position,
			int limit) {
		int length = limit - position;
		if (length < 4)
			return null;
		switch (bytes[position]) {
		case 'G':
			if (bytes[position + 1] == 'E' && bytes[position + 2] == 'T'
					&& bytes[position + 3] == ' ')
				return GET;
			break;
		case 'P':
			if (bytes[position + 1] == 'O' && bytes[position + 2] == 'S'
					&& bytes[position + 3] == 'T' && length >= 5
					&& bytes[position + 4] == ' ')
				return POST;
			if (bytes[position + 1] == 'R' && bytes[position + 2] == 'O'
					&& bytes[position + 3] == 'X' && length >= 6
					&& bytes[position + 4] == 'Y' && bytes[position + 5] == ' ')
				return PROXY;
			if (bytes[position + 1] == 'U' && bytes[position + 2] == 'T'
					&& bytes[position + 3] == ' ')
				return PUT;
			if (bytes[position + 1] == 'R' && bytes[position + 2] == 'I'
					&& bytes[position + 3] == ' ')
				return PRI;
			break;
		case 'H':
			if (bytes[position + 1] == 'E' && bytes[position + 2] == 'A'
					&& bytes[position + 3] == 'D' && length >= 5
					&& bytes[position + 4] == ' ')
				return HEAD;
			break;
		case 'O':
			if (bytes[position + 1] == 'P' && bytes[position + 2] == 'T'
					&& bytes[position + 3] == 'I' && length >= 8
					&& bytes[position + 4] == 'O' && bytes[position + 5] == 'N'
					&& bytes[position + 6] == 'S' && bytes[position + 7] == ' ')
				return OPTIONS;
			break;
		case 'D':
			if (bytes[position + 1] == 'E' && bytes[position + 2] == 'L'
					&& bytes[position + 3] == 'E' && length >= 7
					&& bytes[position + 4] == 'T' && bytes[position + 5] == 'E'
					&& bytes[position + 6] == ' ')
				return DELETE;
			break;
		case 'T':
			if (bytes[position + 1] == 'R' && bytes[position + 2] == 'A'
					&& bytes[position + 3] == 'C' && length >= 6
					&& bytes[position + 4] == 'E' && bytes[position + 5] == ' ')
				return TRACE;
			break;
		case 'C':
			if (bytes[position + 1] == 'O' && bytes[position + 2] == 'N'
					&& bytes[position + 3] == 'N' && length >= 8
					&& bytes[position + 4] == 'E' && bytes[position + 5] == 'C'
					&& bytes[position + 6] == 'T' && bytes[position + 7] == ' ')
				return CONNECT;
			break;
		case 'M':
			if (bytes[position + 1] == 'O' && bytes[position + 2] == 'V'
					&& bytes[position + 3] == 'E' && length >= 5
					&& bytes[position + 4] == ' ')
				return MOVE;
			break;

		default:
			break;
		}
		return null;
	}

	/**
	 * Optimized lookup to find a method name and trailing space in a byte
	 * array.
	 * 
	 * @param buffer
	 *            buffer containing ISO-8859-1 characters, it is not modified.
	 * @return A HttpMethod if a match or null if no easy match.
	 */
	public static HttpMethod lookAheadGet(ByteBuffer buffer) {
		if (buffer.hasArray())
			return lookAheadGet(buffer.array(),
					buffer.arrayOffset() + buffer.position(),
					buffer.arrayOffset() + buffer.limit());

		int l = buffer.remaining();
		if (l >= 4) {
			HttpMethod m = CACHE.getBest(buffer, 0, l);
			if (m != null) {
				int ml = m.asString().length();
				if (l > ml && buffer.get(buffer.position() + ml) == ' ')
					return m;
			}
		}
		return null;
	}

	public final static Trie<HttpMethod> CACHE = new ArrayTrie<>();
	static {
		for (HttpMethod method : HttpMethod.values())
			CACHE.put(method.toString(), method);
	}

	private final ByteBuffer buffer;
	private final byte[] bytes;

	HttpMethod() {
		bytes = toString().getBytes(StandardCharsets.UTF_8);
		buffer = ByteBuffer.wrap(bytes);
	}

	public byte[] getBytes() {
		return bytes;
	}

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

	public ByteBuffer asBuffer() {
		return buffer.asReadOnlyBuffer();
	}

	public String asString() {
		return toString();
	}

	/**
	 * Converts the given String parameter to an HttpMethod
	 * 
	 * @param method
	 *            the String to get the equivalent HttpMethod from
	 * @return the HttpMethod or null if the parameter method is unknown
	 */
	public static HttpMethod fromString(String method) {
		return CACHE.get(method);
	}
}