/*
    Copyright (C) 2002-2007 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 <libgnomecanvasmm/canvas.h>
#include <libgnomecanvasmm/group.h>
#include "tempo_lines.h"
#include "ardour_ui.h"

using namespace std;

#define MAX_CACHED_LINES 128

TempoLines::TempoLines(ArdourCanvas::Canvas& canvas, ArdourCanvas::Group* group, double screen_height)
	: _canvas(canvas)
	, _group(group)
	, _clean_left(DBL_MAX)
	, _clean_right(0.0)
	, _height(screen_height)
{
}

void
TempoLines::tempo_map_changed()
{
	_clean_left = DBL_MAX;
	_clean_right = 0.0;

	double_t d = 1.0;
	// TODO: Dirty/slow, but 'needed' for zoom :(
	for (Lines::iterator i = _lines.begin(); i != _lines.end(); d += 1.0) {
		Lines::iterator next = i;
		++next;
		i->second->property_x1() = - d;
		i->second->property_x2() = - d;
		_lines.erase(i);
		_lines.insert(make_pair(- d, i->second));
		i = next;
	}
}

void
TempoLines::show ()
{
	for (Lines::iterator i = _lines.begin(); i != _lines.end(); ++i) {
		i->second->show();
	}
}

void
TempoLines::hide ()
{
	for (Lines::iterator i = _lines.begin(); i != _lines.end(); ++i) {
		i->second->hide();
	}
}

void
TempoLines::draw (ARDOUR::TempoMap::BBTPointList& points, double frames_per_unit)
{
	ARDOUR::TempoMap::BBTPointList::iterator i;
	ArdourCanvas::SimpleLine *line = NULL;
	gdouble xpos;
	double who_cares;
	double x1, x2, y1, beat_density;

	uint32_t beats = 0;
	uint32_t bars = 0;
	uint32_t color;

	const size_t needed = points.size();

	_canvas.get_scroll_region (x1, y1, x2, who_cares);

	/* get the first bar spacing */

	i = points.end();
	i--;
	bars = (*i).bar - (*points.begin()).bar;
	beats = points.size() - bars;

	beat_density = (beats * 10.0f) / _canvas.get_width ();

	if (beat_density > 4.0f) {
		/* if the lines are too close together, they become useless */
		tempo_map_changed();
		return;
	}

	xpos = rint(((framepos_t)(*i).frame) / (double)frames_per_unit);
	const double needed_right = xpos;

	i = points.begin();

	xpos = rint(((framepos_t)(*i).frame) / (double)frames_per_unit);
	const double needed_left = xpos;

	Lines::iterator left = _lines.lower_bound(xpos); // first line >= xpos

	bool exhausted = (left == _lines.end());
	Lines::iterator li = left;
	if (li != _lines.end())
		line = li->second;

	// Tempo map hasn't changed and we're entirely within a clean
	// range, don't need to do anything.  Yay.
	if (needed_left >= _clean_left && needed_right <= _clean_right) {
		//cout << endl << "*** LINE CACHE PERFECT HIT" << endl;
		return;
	}

	//cout << endl << "*** LINE CACHE MISS" << endl;

	bool inserted_last_time = true;
	bool invalidated = false;

	for (i = points.begin(); i != points.end(); ++i) {

		switch ((*i).type) {
		case ARDOUR::TempoMap::Bar:
			break;

		case ARDOUR::TempoMap::Beat:
			if ((*i).beat == 1) {
				color = ARDOUR_UI::config()->canvasvar_MeasureLineBar.get();
			} else {
				color = ARDOUR_UI::config()->canvasvar_MeasureLineBeat.get();
				if (beat_density > 2.0) {
					break; /* only draw beat lines if the gaps between beats are large. */
				}
			}

			xpos = rint(((framepos_t)(*i).frame) / (double)frames_per_unit);

			if (inserted_last_time && !_lines.empty()) {
				li = _lines.lower_bound(xpos); // first line >= xpos
			}

			line = (li != _lines.end()) ? li->second : NULL;
			assert(!line || line->property_x1() == li->first);

			Lines::iterator next = li;
			if (next != _lines.end())
				++next;

			exhausted = (next == _lines.end());

			// Hooray, line is perfect
			if (line && line->property_x1() == xpos) {
				if (li != _lines.end())
					++li;

				line->property_color_rgba() = color;
				inserted_last_time = false; // don't search next time

			// Use existing line, moving if necessary
			} else if (!exhausted) {
				Lines::iterator steal = _lines.end();
				--steal;

				// Steal from the right
				if (left->first > needed_left && li != steal && steal->first > needed_right) {
					//cout << "*** STEALING FROM RIGHT" << endl;
					line = steal->second;
					_lines.erase(steal);
					line->property_x1() = xpos;
					line->property_x2() = xpos;
					line->property_color_rgba() = color;
					_lines.insert(make_pair(xpos, line));
					inserted_last_time = true; // search next time
					invalidated = true;

					// Shift clean range left
					_clean_left = min(_clean_left, xpos);
					_clean_right = min(_clean_right, steal->first);

				// Move this line to where we need it
				} else {
					Lines::iterator existing = _lines.find(xpos);
					if (existing != _lines.end()) {
						//cout << "*** EXISTING LINE" << endl;
						li = existing;
						li->second->property_color_rgba() = color;
						inserted_last_time = false; // don't search next time
					} else {
						//cout << "*** MOVING LINE" << endl;
						const double x1 = line->property_x1();
						const bool was_clean = x1 >= _clean_left && x1 <= _clean_right;
						invalidated = invalidated || was_clean;
						// Invalidate clean portion (XXX: too harsh?)
						_clean_left  = needed_left;
						_clean_right = needed_right;
						_lines.erase(li);
						line->property_color_rgba() = color;
						line->property_x1() = xpos;
						line->property_x2() = xpos;
						_lines.insert(make_pair(xpos, line));
						inserted_last_time = true; // search next time
					}
				}

			// Create a new line
			} else if (_lines.size() < needed || _lines.size() < MAX_CACHED_LINES) {
				//cout << "*** CREATING LINE" << endl;
				assert(_lines.find(xpos) == _lines.end());
				line = new ArdourCanvas::SimpleLine (*_group);
				line->property_x1() = xpos;
				line->property_x2() = xpos;
				line->property_y1() = 0.0;
				line->property_y2() = _height;
				line->property_color_rgba() = color;
				_lines.insert(make_pair(xpos, line));
				inserted_last_time = true;

			// Steal from the left
			} else {
				//cout << "*** STEALING FROM LEFT" << endl;
				assert(_lines.find(xpos) == _lines.end());
				Lines::iterator steal = _lines.begin();
				line = steal->second;
				_lines.erase(steal);
				line->property_color_rgba() = color;
				line->property_x1() = xpos;
				line->property_x2() = xpos;
				_lines.insert(make_pair(xpos, line));
				inserted_last_time = true; // search next time
				invalidated = true;

				// Shift clean range right
				_clean_left = max(_clean_left, steal->first);
				_clean_right = max(_clean_right, xpos);
			}

			break;
		}
	}

	// Extend range to what we've 'fixed'
	if (!invalidated) {
		_clean_left  = min(_clean_left, needed_left);
		_clean_right = max(_clean_right, needed_right);
	}
}