/*
    Copyright (C) 2006 Paul Davis 
    
    This program is free software; you can redistribute it and/or modify it
    under the terms of the GNU General Public License as published by the Free
    Software Foundation; either version 2 of the License, or (at your option)
    any later version.
    
    This program 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
    for more details.
    
    You should have received a copy of the GNU General Public License along
    with this program; if not, write to the Free Software Foundation, Inc.,
    675 Mass Ave, Cambridge, MA 02139, USA.
*/

#include <cstring>
#include <cmath>
#include <algorithm>
#include "ardour/amp.h"
#include "ardour/audio_buffer.h"
#include "ardour/buffer_set.h"
#include "ardour/configuration.h"
#include "ardour/io.h"
#include "ardour/session.h"

namespace ARDOUR {

Amp::Amp(Session& s, IO& io)
	: Processor(s, "Amp")
	, _io(io)
	, _mute(false)
	, _apply_gain(true)
	, _apply_gain_automation(false)
	, _current_gain(1.0)
	, _desired_gain(1.0)
{
}

bool
Amp::can_support_io_configuration (const ChanCount& in, ChanCount& out) const
{
	out = in;
	return true;
}

bool
Amp::configure_io (ChanCount in, ChanCount out)
{
	if (out != in) { // always 1:1
		return false;
	}
	
	return Processor::configure_io (in, out);
}

void
Amp::run_in_place (BufferSet& bufs, nframes_t start_frame, nframes_t end_frame, nframes_t nframes)
{
	gain_t* gab = _session.gain_automation_buffer();

	if (_mute && !bufs.is_silent()) {
		Amp::apply_gain (bufs, nframes, _current_mute_gain, _desired_mute_gain, false);
		if (_desired_mute_gain == 0.0f) {
			bufs.is_silent(true);
		}
	}

	if (_apply_gain) {
		
		if (_apply_gain_automation) {
			
			if (_io.phase_invert()) {
				for (BufferSet::audio_iterator i = bufs.audio_begin(); i != bufs.audio_end(); ++i) {
					Sample* const sp = i->data();
					for (nframes_t nx = 0; nx < nframes; ++nx) {
						sp[nx] *= -gab[nx];
					}
				}
			} else {
				for (BufferSet::audio_iterator i = bufs.audio_begin(); i != bufs.audio_end(); ++i) {
					Sample* const sp = i->data();
					for (nframes_t nx = 0; nx < nframes; ++nx) {
						sp[nx] *= gab[nx];
					}
				}
			}
			
		} else { /* manual (scalar) gain */
			
			if (_current_gain != _desired_gain) {
				
				Amp::apply_gain (bufs, nframes, _current_gain, _desired_gain, _io.phase_invert());
				_current_gain = _desired_gain;
				
			} else if (_current_gain != 0.0f && (_io.phase_invert() || _current_gain != 1.0f)) {
				
				/* no need to interpolate current gain value,
				   but its non-unity, so apply it. if the gain
				   is zero, do nothing because we'll ship silence
				   below.
				*/

				gain_t this_gain;
				
				if (_io.phase_invert()) {
					this_gain = -_current_gain;
				} else {
					this_gain = _current_gain;
				}
				
				for (BufferSet::audio_iterator i = bufs.audio_begin(); i != bufs.audio_end(); ++i) {
					Sample* const sp = i->data();
					apply_gain_to_buffer(sp, nframes, this_gain);
				}

			} else if (_current_gain == 0.0f) {
				for (BufferSet::audio_iterator i = bufs.audio_begin(); i != bufs.audio_end(); ++i) {
					i->clear();
				}
			}
		}
	}
}

/** Apply a declicked gain to the audio buffers of @a bufs */
void
Amp::apply_gain (BufferSet& bufs, nframes_t nframes,
		gain_t initial, gain_t target, bool invert_polarity)
{
	if (nframes == 0) {
		return;
	}

	if (bufs.count().n_audio() == 0) {
		return;
	}

	// if we don't need to declick, defer to apply_simple_gain
	if (initial == target) {
		if (target == 0.0) {
			for (BufferSet::audio_iterator i = bufs.audio_begin(); i != bufs.audio_end(); ++i) {
				memset (i->data(), 0, sizeof (Sample) * nframes);
			}
		} else if (target != 1.0) {
			for (BufferSet::audio_iterator i = bufs.audio_begin(); i != bufs.audio_end(); ++i) {
				apply_gain_to_buffer (i->data(), nframes, target);
			}
		}
		return;
	}

	const nframes_t declick = std::min ((nframes_t)128, nframes);
	gain_t         delta;
	double         fractional_shift = -1.0/declick;
	double         fractional_pos;
	gain_t         polscale = invert_polarity ? -1.0f : 1.0f;

	if (target < initial) {
		/* fade out: remove more and more of delta from initial */
		delta = -(initial - target);
	} else {
		/* fade in: add more and more of delta from initial */
		delta = target - initial;
	}

	for (BufferSet::audio_iterator i = bufs.audio_begin(); i != bufs.audio_end(); ++i) {
		Sample* const buffer = i->data();

		fractional_pos = 1.0;

		for (nframes_t nx = 0; nx < declick; ++nx) {
			buffer[nx] *= polscale * (initial + (delta * (0.5 + 0.5 * cos (M_PI * fractional_pos))));
			fractional_pos += fractional_shift;
		}
		
		/* now ensure the rest of the buffer has the target value applied, if necessary. */
		
		if (declick != nframes) {

			if (invert_polarity) {
				target = -target;
			}

			if (target == 0.0) {
				memset (&buffer[declick], 0, sizeof (Sample) * (nframes - declick));
			} else if (target != 1.0) {
				apply_gain_to_buffer (&buffer[declick], nframes - declick, target);
			}
		}
	}
}

void
Amp::apply_simple_gain (BufferSet& bufs, nframes_t nframes, gain_t target)
{
}

XMLNode&
Amp::state (bool full_state)
{
	return get_state();
}

XMLNode&
Amp::get_state()
{
	XMLNode* node = new XMLNode(state_node_name);
	node->add_property("type", "amp");
	return *node;
}

} // namespace ARDOUR