/*
 * Copyright 2015 The Netty Project
 *
 * The Netty Project licenses this file to you 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 io.netty.util;

/**
 * Provides a mechanism to iterate over a collection of bytes.
 */
public interface ByteProcessor {
    /**
     * A {@link ByteProcessor} which finds the first appearance of a specific byte.
     */
    class IndexOfProcessor implements ByteProcessor {
        private final byte byteToFind;

        public IndexOfProcessor(byte byteToFind) {
            this.byteToFind = byteToFind;
        }

        @Override
        public boolean process(byte value) {
            return value != byteToFind;
        }
    }

    /**
     * A {@link ByteProcessor} which finds the first appearance which is not of a specific byte.
     */
    class IndexNotOfProcessor implements ByteProcessor {
        private final byte byteToNotFind;

        public IndexNotOfProcessor(byte byteToNotFind) {
            this.byteToNotFind = byteToNotFind;
        }

        @Override
        public boolean process(byte value) {
            return value == byteToNotFind;
        }
    }

    /**
     * Aborts on a {@code NUL (0x00)}.
     */
    ByteProcessor FIND_NUL = new IndexOfProcessor((byte) 0);

    /**
     * Aborts on a non-{@code NUL (0x00)}.
     */
    ByteProcessor FIND_NON_NUL = new IndexNotOfProcessor((byte) 0);

    /**
     * Aborts on a {@code CR ('\r')}.
     */
    ByteProcessor FIND_CR = new IndexOfProcessor((byte) '\r');

    /**
     * Aborts on a non-{@code CR ('\r')}.
     */
    ByteProcessor FIND_NON_CR = new IndexNotOfProcessor((byte) '\r');

    /**
     * Aborts on a {@code LF ('\n')}.
     */
    ByteProcessor FIND_LF = new IndexOfProcessor((byte) '\n');

    /**
     * Aborts on a non-{@code LF ('\n')}.
     */
    ByteProcessor FIND_NON_LF = new IndexNotOfProcessor((byte) '\n');

    /**
     * Aborts on a {@code CR (';')}.
     */
    ByteProcessor FIND_SEMI_COLON = new IndexOfProcessor((byte) ';');

    /**
     * Aborts on a {@code CR ('\r')} or a {@code LF ('\n')}.
     */
    ByteProcessor FIND_CRLF = new ByteProcessor() {
        @Override
        public boolean process(byte value) {
            return value != '\r' && value != '\n';
        }
    };

    /**
     * Aborts on a byte which is neither a {@code CR ('\r')} nor a {@code LF ('\n')}.
     */
    ByteProcessor FIND_NON_CRLF = new ByteProcessor() {
        @Override
        public boolean process(byte value) {
            return value == '\r' || value == '\n';
        }
    };

    /**
     * Aborts on a linear whitespace (a ({@code ' '} or a {@code '\t'}).
     */
    ByteProcessor FIND_LINEAR_WHITESPACE = new ByteProcessor() {
        @Override
        public boolean process(byte value) {
            return value != ' ' && value != '\t';
        }
    };

    /**
     * Aborts on a byte which is not a linear whitespace (neither {@code ' '} nor {@code '\t'}).
     */
    ByteProcessor FIND_NON_LINEAR_WHITESPACE = new ByteProcessor() {
        @Override
        public boolean process(byte value) {
            return value == ' ' || value == '\t';
        }
    };

    /**
     * @return {@code true} if the processor wants to continue the loop and handle the next byte in the buffer.
     *         {@code false} if the processor wants to stop handling bytes and abort the loop.
     */
    boolean process(byte value) throws Exception;
}