/*
    Copyright (C) 2004-2011 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 <inttypes.h>

#include <cmath>
#include <cerrno>
#include <fstream>
#include <cstdlib>
#include <string>
#include <cstdio>
#include <locale.h>
#include <unistd.h>
#include <float.h>
#include <iomanip>

#include <glibmm.h>

#include "pbd/cartesian.h"
#include "pbd/convert.h"
#include "pbd/error.h"
#include "pbd/failed_constructor.h"
#include "pbd/xml++.h"
#include "pbd/enumwriter.h"

#include "evoral/Curve.hpp"

#include "ardour/session.h"
#include "ardour/panner.h"
#include "ardour/utils.h"
#include "ardour/audio_buffer.h"

#include "ardour/debug.h"
#include "ardour/runtime_functions.h"
#include "ardour/buffer_set.h"
#include "ardour/audio_buffer.h"
#include "ardour/pannable.h"

#include "i18n.h"
#include "panner_1in2out.h"

#include "pbd/mathfix.h"

using namespace std;
using namespace ARDOUR;
using namespace PBD;

static PanPluginDescriptor _descriptor = {
        "Mono to Stereo Panner",
        1, 2, 
        Panner1in2out::factory
};

extern "C" { PanPluginDescriptor* panner_descriptor () { return &_descriptor; } }

Panner1in2out::Panner1in2out (boost::shared_ptr<Pannable> p)
	: Panner (p)
{
        if (!_pannable->has_state()) {
                _pannable->pan_azimuth_control->set_value (0.5);
        }
        
        update ();

        left = desired_left;
        right = desired_right;
        left_interp = left;
        right_interp = right;

        _pannable->pan_azimuth_control->Changed.connect_same_thread (*this, boost::bind (&Panner1in2out::update, this));
}

Panner1in2out::~Panner1in2out ()
{
}

void
Panner1in2out::update ()
{
        float panR, panL;
        float const pan_law_attenuation = -3.0f;
        float const scale = 2.0f - 4.0f * powf (10.0f,pan_law_attenuation/20.0f);

        panR = _pannable->pan_azimuth_control->get_value();
        panL = 1 - panR;

        desired_left = panL * (scale * panL + 1.0f - scale);
        desired_right = panR * (scale * panR + 1.0f - scale);
}

void
Panner1in2out::set_position (double p)
{
        if (clamp_position (p)) {
                _pannable->pan_azimuth_control->set_value (p);
        }
}

bool
Panner1in2out::clamp_position (double& p)
{
        /* any position between 0.0 and 1.0 is legal */
        DEBUG_TRACE (DEBUG::Panning, string_compose ("want to move panner to %1 - always allowed in 0.0-1.0 range\n", p));
        p = max (min (p, 1.0), 0.0);
        return true;
}

double 
Panner1in2out::position () const
{
        return _pannable->pan_azimuth_control->get_value ();
}

void
Panner1in2out::distribute_one (AudioBuffer& srcbuf, BufferSet& obufs, gain_t gain_coeff, pframes_t nframes, uint32_t /* not used */)
{
	assert (obufs.count().n_audio() == 2);

	pan_t delta;
	Sample* dst;
	pan_t pan;

	Sample* const src = srcbuf.data();
        
	/* LEFT OUTPUT */

	dst = obufs.get_audio(0).data();

	if (fabsf ((delta = (left - desired_left))) > 0.002) { // about 1 degree of arc

		/* we've moving the pan by an appreciable amount, so we must
		   interpolate over 64 frames or nframes, whichever is smaller */

		pframes_t const limit = min ((pframes_t) 64, nframes);
		pframes_t n;

		delta = -(delta / (float) (limit));

		for (n = 0; n < limit; n++) {
			left_interp = left_interp + delta;
			left = left_interp + 0.9 * (left - left_interp);
			dst[n] += src[n] * left * gain_coeff;
		}

		/* then pan the rest of the buffer; no need for interpolation for this bit */

		pan = left * gain_coeff;

		mix_buffers_with_gain (dst+n,src+n,nframes-n,pan);

	} else {

		left = desired_left;
		left_interp = left;

		if ((pan = (left * gain_coeff)) != 1.0f) {

			if (pan != 0.0f) {

				/* pan is 1 but also not 0, so we must do it "properly" */

				mix_buffers_with_gain(dst,src,nframes,pan);

				/* mark that we wrote into the buffer */

				// obufs[0] = 0;

			}

		} else {

			/* pan is 1 so we can just copy the input samples straight in */

			mix_buffers_no_gain(dst,src,nframes);
                        
			/* XXX it would be nice to mark that we wrote into the buffer */
		}
	}

	/* RIGHT OUTPUT */

	dst = obufs.get_audio(1).data();

	if (fabsf ((delta = (right - desired_right))) > 0.002) { // about 1 degree of arc

		/* we're moving the pan by an appreciable amount, so we must
		   interpolate over 64 frames or nframes, whichever is smaller */

		pframes_t const limit = min ((pframes_t) 64, nframes);
		pframes_t n;

		delta = -(delta / (float) (limit));

		for (n = 0; n < limit; n++) {
			right_interp = right_interp + delta;
			right = right_interp + 0.9 * (right - right_interp);
			dst[n] += src[n] * right * gain_coeff;
		}

		/* then pan the rest of the buffer, no need for interpolation for this bit */

		pan = right * gain_coeff;

		mix_buffers_with_gain(dst+n,src+n,nframes-n,pan);

		/* XXX it would be nice to mark the buffer as written to */

	} else {

		right = desired_right;
		right_interp = right;

		if ((pan = (right * gain_coeff)) != 1.0f) {

			if (pan != 0.0f) {

				/* pan is not 1 but also not 0, so we must do it "properly" */
				
				mix_buffers_with_gain(dst,src,nframes,pan);

				/* XXX it would be nice to mark the buffer as written to */
			}

		} else {

			/* pan is 1 so we can just copy the input samples straight in */
			
			mix_buffers_no_gain(dst,src,nframes);

			/* XXX it would be nice to mark the buffer as written to */
		}
	}

}

void
Panner1in2out::distribute_one_automated (AudioBuffer& srcbuf, BufferSet& obufs,
                                         framepos_t start, framepos_t end, pframes_t nframes,
                                         pan_t** buffers, uint32_t which)
{
	assert (obufs.count().n_audio() == 2);

	Sample* dst;
	pan_t* pbuf;
	Sample* const src = srcbuf.data();
        pan_t* const position = buffers[0];

	/* fetch positional data */

	if (!_pannable->pan_azimuth_control->list()->curve().rt_safe_get_vector (start, end, position, nframes)) {
		/* fallback */
                distribute_one (srcbuf, obufs, 1.0, nframes, which);
		return;
	}

	/* apply pan law to convert positional data into pan coefficients for
	   each buffer (output)
	*/

	const float pan_law_attenuation = -3.0f;
	const float scale = 2.0f - 4.0f * powf (10.0f,pan_law_attenuation/20.0f);

	for (pframes_t n = 0; n < nframes; ++n) {

                float panR = position[n];
                const float panL = 1 - panR;

                /* note that are overwriting buffers, but its OK
                   because we're finished with their old contents
                   (position automation data) and are
                   replacing it with panning/gain coefficients 
                   that we need to actually process the data.
                */
                
                buffers[0][n] = panL * (scale * panL + 1.0f - scale);
                buffers[1][n] = panR * (scale * panR + 1.0f - scale);
        }

	/* LEFT OUTPUT */

	dst = obufs.get_audio(0).data();
	pbuf = buffers[0];

	for (pframes_t n = 0; n < nframes; ++n) {
		dst[n] += src[n] * pbuf[n];
	}

	/* XXX it would be nice to mark the buffer as written to */

	/* RIGHT OUTPUT */

	dst = obufs.get_audio(1).data();
	pbuf = buffers[1];

	for (pframes_t n = 0; n < nframes; ++n) {
		dst[n] += src[n] * pbuf[n];
	}

	/* XXX it would be nice to mark the buffer as written to */
}


Panner*
Panner1in2out::factory (boost::shared_ptr<Pannable> p, Speakers& /* ignored */)
{
	return new Panner1in2out (p);
}

XMLNode&
Panner1in2out::get_state (void)
{
	return state (true);
}

XMLNode&
Panner1in2out::state (bool /*full_state*/)
{
	XMLNode& root (Panner::get_state ());
	root.add_property (X_("type"), _descriptor.name);
	return root;
}

int
Panner1in2out::set_state (const XMLNode& node, int version)
{
	LocaleGuard lg (X_("POSIX"));
	Panner::set_state (node, version);
	return 0;
}

std::set<Evoral::Parameter> 
Panner1in2out::what_can_be_automated() const
{
        set<Evoral::Parameter> s;
        s.insert (Evoral::Parameter (PanAzimuthAutomation));
        return s;
}

string
Panner1in2out::describe_parameter (Evoral::Parameter p)
{
        switch (p.type()) {
        case PanAzimuthAutomation:
                return _("L/R");
        default:
                return _pannable->describe_parameter (p);
        }
}