// Copyright 2001, FreeHEP.
package org.freehep.util.io;

import java.io.IOException;

/**
 * Generic Action, to be used with the TagIn/OutputStreams. An action can have
 * an ActionCode, a length as well as parameters.
 * 
 * @author Mark Donszelmann
 * @author Charles Loomis
 * @version $Id: Action.java 8584 2006-08-10 23:06:37Z duns $
 */
public abstract class Action {

    private int code;

    private String name;

    protected Action(int code) {
        this.code = code;

        name = getClass().getName();
        int dot = name.lastIndexOf(".");
        name = (dot >= 0) ? name.substring(dot + 1) : name;
    }

    /**
     * Read an action from the input, with given actioncode and length
     * 
     * @param actionCode decoded actionCode
     * @param input input to read from
     * @param length length to read
     * @return action corresponding to actionCode
     * @throws IOException if read fails
     */
    public abstract Action read(int actionCode, TaggedInputStream input,
            int length) throws IOException;

    /**
     * Write an action to output
     * 
     * @param actionCode actionCode to use for this action
     * @param output output to write to
     * @throws IOException if write fails
     */
    public abstract void write(int actionCode, TaggedOutputStream output)
            throws IOException;

    /**
     * @return actionCode
     */
    public int getCode() {
        return code;
    }

    /**
     * @return name of the action
     */
    public String getName() {
        return name;
    }

    public String toString() {
        return "Action " + getName() + " (" + getCode() + ")";
    }

    /**
     * Used for not recognized actions.
     */
    public static class Unknown extends Action {
        private int[] data;

        /**
         * Create a special Action for Unknown Actions, with actioncode 0.
         */
        public Unknown() {
            super(0x00);
        }

        /**
         * Create a special Action for Unknown Actions, with given action code.
         * 
         * @param actionCode code to be used for Unknown Action.
         */
        public Unknown(int actionCode) {
            super(actionCode);
        }

        public Action read(int actionCode, TaggedInputStream input, int length)
                throws IOException {

            Unknown action = new Unknown(actionCode);
            action.data = input.readUnsignedByte(length);
            return action;
        }

        public void write(int actionCode, TaggedOutputStream output)
                throws IOException {

            output.writeUnsignedByte(data);
        }

        public String toString() {
            return super.toString() + " UNKNOWN!, length " + data.length;
        }
    }

}