/*
 * Copyright 1999-2006 Sun Microsystems, Inc.  All Rights Reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Sun designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Sun in the LICENSE file that accompanied this code.
 *
 * This code 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
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
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 */

package javax.sound.midi;

import javax.sound.sampled.Control;


/**
 * A <code>Synthesizer</code> generates sound.  This usually happens when one of
 * the <code>Synthesizer</code>'s {@link MidiChannel} objects receives a
 * {@link MidiChannel#noteOn(int, int) noteOn} message, either
 * directly or via the <code>Synthesizer</code> object.
 * Many <code>Synthesizer</code>s support <code>Receivers</code>, through which
 * MIDI events can be delivered to the <code>Synthesizer</code>.
 * In such cases, the <code>Synthesizer</code> typically responds by sending
 * a corresponding message to the appropriate <code>MidiChannel</code>, or by
 * processing the event itself if the event isn't one of the MIDI channel
 * messages.
 * <p>
 * The <code>Synthesizer</code> interface includes methods for loading and
 * unloading instruments from soundbanks.  An instrument is a specification for synthesizing a
 * certain type of sound, whether that sound emulates a traditional instrument or is
 * some kind of sound effect or other imaginary sound. A soundbank is a collection of instruments, organized
 * by bank and program number (via the instrument's <code>Patch</code> object).
 * Different <code>Synthesizer</code> classes might implement different sound-synthesis
 * techniques, meaning that some instruments and not others might be compatible with a
 * given synthesizer.
 * Also, synthesizers may have a limited amount of memory for instruments, meaning
 * that not every soundbank and instrument can be used by every synthesizer, even if
 * the synthesis technique is compatible.
 * To see whether the instruments from
 * a certain soundbank can be played by a given synthesizer, invoke the
 * {@link #isSoundbankSupported(Soundbank) isSoundbankSupported} method of
 * <code>Synthesizer</code>.
 * <p>
 * "Loading" an instrument means that that instrument becomes available for
 * synthesizing notes.  The instrument is loaded into the bank and
 * program location specified by its <code>Patch</code> object.  Loading does
 * not necessarily mean that subsequently played notes will immediately have
 * the sound of this newly loaded instrument.  For the instrument to play notes,
 * one of the synthesizer's <code>MidiChannel</code> objects must receive (or have received)
 * a program-change message that causes that particular instrument's
 * bank and program number to be selected.
 *
 * @see MidiSystem#getSynthesizer
 * @see Soundbank
 * @see Instrument
 * @see MidiChannel#programChange(int, int)
 * @see Receiver
 * @see Transmitter
 * @see MidiDevice
 *
 * @author Kara Kytle
 */
public interface Synthesizer extends MidiDevice {


    // SYNTHESIZER METHODS


    /**
     * Obtains the maximum number of notes that this synthesizer can sound simultaneously.
     * @return the maximum number of simultaneous notes
     * @see #getVoiceStatus
     */
    public int getMaxPolyphony();


    /**
     * Obtains the processing latency incurred by this synthesizer, expressed in
     * microseconds.  This latency measures the worst-case delay between the
     * time a MIDI message is delivered to the synthesizer and the time that the
     * synthesizer actually produces the corresponding result.
     * <p>
     * Although the latency is expressed in microseconds, a synthesizer's actual measured
     * delay may vary over a wider range than this resolution suggests.  For example,
     * a synthesizer might have a worst-case delay of a few milliseconds or more.
     *
     * @return the worst-case delay, in microseconds
     */
    public long getLatency();


    /**
     * Obtains the set of MIDI channels controlled by this synthesizer.  Each
     * non-null element in the returned array is a <code>MidiChannel</code> that
     * receives the MIDI messages sent on that channel number.
     * <p>
     * The MIDI 1.0 specification provides for 16 channels, so this
     * method returns an array of at least 16 elements.  However, if this synthesizer
     * doesn't make use of all 16 channels, some of the elements of the array
     * might be <code>null</code>, so you should check each element
     * before using it.
     * @return an array of the <code>MidiChannel</code> objects managed by this
     * <code>Synthesizer</code>.  Some of the array elements may be <code>null</code>.
     */
    public MidiChannel[] getChannels();


    /**
     * Obtains the current status of the voices produced by this synthesizer.
     * If this class of <code>Synthesizer</code> does not provide voice
     * information, the returned array will always be of length 0.  Otherwise,
     * its length is always equal to the total number of voices, as returned by
     * <code>getMaxPolyphony()</code>.  (See the <code>VoiceStatus</code> class
     * description for an explanation of synthesizer voices.)
     *
     * @return an array of <code>VoiceStatus</code> objects that supply
     * information about the corresponding synthesizer voices
     * @see #getMaxPolyphony
     * @see VoiceStatus
     */
    public VoiceStatus[] getVoiceStatus();


    /**
     * Informs the caller whether this synthesizer is capable of loading
     * instruments from the specified soundbank.
     * If the soundbank is unsupported, any attempts to load instruments from
     * it will result in an <code>IllegalArgumentException</code>.
     * @param soundbank soundbank for which support is queried
     * @return <code>true</code> if the soundbank is supported, otherwise <code>false</code>
     * @see #loadInstruments
     * @see #loadAllInstruments
     * @see #unloadInstruments
     * @see #unloadAllInstruments
     * @see #getDefaultSoundbank
     */
    public boolean isSoundbankSupported(Soundbank soundbank);


    /**
     * Makes a particular instrument available for synthesis.  This instrument
     * is loaded into the patch location specified by its <code>Patch</code>
     * object, so that if a program-change message is
     * received (or has been received) that causes that patch to be selected,
     * subsequent notes will be played using the sound of
     * <code>instrument</code>.  If the specified instrument is already loaded,
     * this method does nothing and returns <code>true</code>.
     * <p>
     * The instrument must be part of a soundbank
     * that this <code>Synthesizer</code> supports.  (To make sure, you can use
     * the <code>getSoundbank</code> method of <code>Instrument</code> and the
     * <code>isSoundbankSupported</code> method of <code>Synthesizer</code>.)
     * @param instrument instrument to load
     * @return <code>true</code> if the instrument is successfully loaded (or
     * already had been), <code>false</code> if the instrument could not be
     * loaded (for example, if the synthesizer has insufficient
     * memory to load it)
     * @throws <code>IllegalArgumentException</code> if this
     * <code>Synthesizer</code> doesn't support the specified instrument's
     * soundbank
     * @see #unloadInstrument
     * @see #loadInstruments
     * @see #loadAllInstruments
     * @see #remapInstrument
     * @see SoundbankResource#getSoundbank
     * @see MidiChannel#programChange(int, int)
     */
    public boolean loadInstrument(Instrument instrument);


    /**
     * Unloads a particular instrument.
     * @param instrument instrument to unload
     * @throws <code>IllegalArgumentException</code> if this
     * <code>Synthesizer</code> doesn't support the specified instrument's
     * soundbank
     * @see #loadInstrument
     * @see #unloadInstruments
     * @see #unloadAllInstruments
     * @see #getLoadedInstruments
     * @see #remapInstrument
     */
    public void unloadInstrument(Instrument instrument);


    /**
     * Remaps an instrument. Instrument <code>to</code> takes the
     * place of instrument <code>from</code>.<br>
     * For example, if <code>from</code> was located at bank number 2,
     * program number 11, remapping causes that bank and program location
     * to be occupied instead by <code>to</code>.<br>
     * If the function succeeds,  instrument <code>from</code> is unloaded.
     * <p>To cancel the remapping reload instrument <code>from</code> by
     * invoking one of {@link #loadInstrument}, {@link #loadInstruments}
     * or {@link #loadAllInstruments}.
     *
     * @param from the <code>Instrument</code> object to be replaced
     * @param to the <code>Instrument</code> object to be used in place
     * of the old instrument, it should be loaded into the synthesizer
     * @return <code>true</code> if the instrument succeessfully remapped,
     * <code>false</code> if feature is not implemented by synthesizer
     * @throws <code>IllegalArgumentException</code> if instrument
     * <code>from</code> or instrument <code>to</code> aren't supported by
     * synthesizer or if instrument <code>to</code> is not loaded
     * @throws <code>NullPointerException</code> if <code>from</code> or
     * <code>to</code> parameters have null value
     * @see #loadInstrument
     * @see #loadInstruments
     * @see #loadAllInstruments
     */
    public boolean remapInstrument(Instrument from, Instrument to);


    /**
     * Obtains the default soundbank for the synthesizer, if one exists.
     * (Some synthesizers provide a default or built-in soundbank.)
     * If a synthesizer doesn't have a default soundbank, instruments must
     * be loaded explicitly from an external soundbank.
     * @return default soundbank, or <code>null</code> if one does not exist.
     * @see #isSoundbankSupported
     */
    public Soundbank getDefaultSoundbank();


    /**
     * Obtains a list of instruments that come with the synthesizer.  These
     * instruments might be built into the synthesizer, or they might be
     * part of a default soundbank provided with the synthesizer, etc.
     * <p>
     * Note that you don't use this method  to find out which instruments are
     * currently loaded onto the synthesizer; for that purpose, you use
     * <code>getLoadedInstruments()</code>.
     * Nor does the method indicate all the instruments that can be loaded onto
     * the synthesizer; it only indicates the subset that come with the synthesizer.
     * To learn whether another instrument can be loaded, you can invoke
     * <code>isSoundbankSupported()</code>, and if the instrument's
     * <code>Soundbank</code> is supported, you can try loading the instrument.
     *
     * @return list of available instruments. If the synthesizer
     * has no instruments coming with it, an array of length 0 is returned.
     * @see #getLoadedInstruments
     * @see #isSoundbankSupported(Soundbank)
     * @see #loadInstrument
     */
    public Instrument[] getAvailableInstruments();


    /**
     * Obtains a list of the instruments that are currently loaded onto this
     * <code>Synthesizer</code>.
     * @return a list of currently loaded instruments
     * @see #loadInstrument
     * @see #getAvailableInstruments
     * @see Soundbank#getInstruments
     */
    public Instrument[] getLoadedInstruments();


    /**
     * Loads onto the <code>Synthesizer</code> all instruments contained
     * in the specified <code>Soundbank</code>.
     * @param soundbank the <code>Soundbank</code> whose are instruments are
     * to be loaded
     * @return <code>true</code> if the instruments are all successfully loaded (or
     * already had been), <code>false</code> if any instrument could not be
     * loaded (for example, if the <code>Synthesizer</code> had insufficient memory)
     * @throws IllegalArgumentException if the requested soundbank is
     * incompatible with this synthesizer.
     * @see #isSoundbankSupported
     * @see #loadInstrument
     * @see #loadInstruments
     */
    public boolean loadAllInstruments(Soundbank soundbank);


    /**
     * Unloads all instruments contained in the specified <code>Soundbank</code>.
     * @param soundbank soundbank containing instruments to unload
     * @throws IllegalArgumentException thrown if the soundbank is not supported.
     * @see #isSoundbankSupported
     * @see #unloadInstrument
     * @see #unloadInstruments
     */
    public void unloadAllInstruments(Soundbank soundbank);


    /**
     * Loads the instruments referenced by the specified patches, from the
     * specified <code>Soundbank</code>.  Each of the <code>Patch</code> objects
     * indicates a bank and program number; the <code>Instrument</code> that
     * has the matching <code>Patch</code> is loaded into that bank and program
     * location.
     * @param soundbank the <code>Soundbank</code> containing the instruments to load
     * @param patchList list of patches for which instruments should be loaded
     * @return <code>true</code> if the instruments are all successfully loaded (or
     * already had been), <code>false</code> if any instrument could not be
     * loaded (for example, if the <code>Synthesizer</code> had insufficient memory)
     * @throws IllegalArgumentException thrown if the soundbank is not supported.
     * @see #isSoundbankSupported
     * @see Instrument#getPatch
     * @see #loadAllInstruments
     * @see #loadInstrument
     * @see Soundbank#getInstrument(Patch)
     * @see Sequence#getPatchList()
     */
    public boolean loadInstruments(Soundbank soundbank, Patch[] patchList);

    /**
     * Unloads the instruments referenced by the specified patches, from the MIDI sound bank specified.
     * @param soundbank soundbank containing instruments to unload
     * @param patchList list of patches for which instruments should be unloaded
     * @throws IllegalArgumentException thrown if the soundbank is not supported.
     *
     * @see #unloadInstrument
     * @see #unloadAllInstruments
     * @see #isSoundbankSupported
     * @see Instrument#getPatch
     * @see #loadInstruments
     */
    public void unloadInstruments(Soundbank soundbank, Patch[] patchList);


    // RECEIVER METHODS

    /**
     * Obtains the name of the receiver.
     * @return receiver name
     */
    //  public abstract String getName();


    /**
     * Opens the receiver.
     * @throws MidiUnavailableException if the receiver is cannot be opened,
     * usually because the MIDI device is in use by another application.
     * @throws SecurityException if the receiver cannot be opened due to security
     * restrictions.
     */
    //  public abstract void open() throws MidiUnavailableException, SecurityException;


    /**
     * Closes the receiver.
     */
    //  public abstract void close();


    /**
     * Sends a MIDI event to the receiver.
     * @param event event to send.
     * @throws IllegalStateException if the receiver is not open.
     */
    //  public void send(MidiEvent event) throws IllegalStateException {
    //
    //  }


    /**
     * Obtains the set of controls supported by the
     * element.  If no controls are supported, returns an
     * array of length 0.
     * @return set of controls
     */
    // $$kk: 03.04.99: josh bloch recommends getting rid of this:
    // what can you really do with a set of untyped controls??
    // $$kk: 03.05.99: i am putting this back in.  for one thing,
    // you can check the length and know whether you should keep
    // looking....
    // public Control[] getControls();

    /**
     * Obtains the specified control.
     * @param controlClass class of the requested control
     * @return requested control object, or null if the
     * control is not supported.
     */
    // public Control getControl(Class controlClass);
}