/* A sink that's not attached to anything, eg. find image average,
 *
 * 28/3/10
 * 	- from im_iterate(), reworked for threadpool
 */

/*

	This file is part of VIPS.

	VIPS is free software; you can redistribute it and/or modify
	it under the terms of the GNU Lesser 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 Lesser General Public License for more details.

	You should have received a copy of the GNU Lesser General Public License
	along with this program; if not, write to the Free Software
	Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
	02110-1301  USA

 */

/*

	These files are distributed with VIPS - http://www.vips.ecs.soton.ac.uk

 */

/*
#define VIPS_DEBUG
 */

#ifdef HAVE_CONFIG_H
#include <config.h>
#endif /*HAVE_CONFIG_H*/
#include <glib/gi18n-lib.h>

#include <stdio.h>
#include <stdlib.h>

#include <vips/vips.h>
#include <vips/thread.h>
#include <vips/internal.h>
#include <vips/debug.h>

#include "sink.h"

/* A part of the image we are scanning.
 *
 * We can't let any threads fall too far behind as that would mess up seq
 * image sources. Keep track of two areas moving down the image, and stall if
 * the previous area still has active threads.
 */
typedef struct _SinkArea {
	struct _Sink *sink;

	VipsRect rect;			/* Part of image this area covers */
	VipsSemaphore n_thread; /* Number of threads scanning this area */
} SinkArea;

/* Per-call state.
 */
typedef struct _Sink {
	SinkBase sink_base;

	/* We need a temp "p" image between the source image and us to
	 * make sure we can't damage the original.
	 */
	VipsImage *t;

	/* Call params.
	 */
	VipsStartFn start_fn;
	VipsGenerateFn generate_fn;
	VipsStopFn stop_fn;
	void *a;
	void *b;

	/* We are current scanning area, we'll delay starting a new
	 * area if old_area (the previous position) hasn't completed.
	 */
	SinkArea *area;
	SinkArea *old_area;

} Sink;

/* Our per-thread state.
 */
typedef struct _SinkThreadState {
	VipsThreadState parent_object;

	/* Sequence value for this thread.
	 */
	void *seq;

	/* The region we walk over sink.t copy. We can't use
	 * parent_object.reg, it's defined on the outer image.
	 */
	VipsRegion *reg;

	/* The area we were allocated from.
	 */
	SinkArea *area;

} SinkThreadState;

typedef struct _SinkThreadStateClass {
	VipsThreadStateClass parent_class;

} SinkThreadStateClass;

G_DEFINE_TYPE(SinkThreadState, sink_thread_state, VIPS_TYPE_THREAD_STATE);

static void
sink_area_free(SinkArea *area)
{
	vips_semaphore_destroy(&area->n_thread);
	g_free(area);
}

static SinkArea *
sink_area_new(Sink *sink)
{
	SinkArea *area;

	if (!(area = VIPS_NEW(NULL, SinkArea)))
		return NULL;
	area->sink = sink;
	vips_semaphore_init(&area->n_thread, 0, "n_thread");

	return area;
}

/* Move an area to a position.
 */
static void
sink_area_position(SinkArea *area, int top, int height)
{
	Sink *sink = area->sink;

	VipsRect all, rect;

	all.left = 0;
	all.top = 0;
	all.width = sink->sink_base.im->Xsize;
	all.height = sink->sink_base.im->Ysize;

	rect.left = 0;
	rect.top = top;
	rect.width = sink->sink_base.im->Xsize;
	rect.height = height;

	vips_rect_intersectrect(&all, &rect, &area->rect);
}

/* Our VipsThreadpoolAllocate function ... move the thread to the next tile
 * that needs doing. If we fill the current area, we block until the previous
 * area is finished, then swap areas.
 *
 * If all tiles are done, we return FALSE to end iteration.
 */
static gboolean
sink_area_allocate_fn(VipsThreadState *state, void *a, gboolean *stop)
{
	SinkThreadState *sstate = (SinkThreadState *) state;
	Sink *sink = (Sink *) a;
	SinkBase *sink_base = (SinkBase *) sink;

	VipsRect image;
	VipsRect tile;

	VIPS_DEBUG_MSG("sink_area_allocate_fn: %p\n", g_thread_self());

	/* Is the state x/y OK? New line or maybe new buffer or maybe even
	 * all done.
	 */
	if (sink_base->x >= sink->area->rect.width) {
		sink_base->x = 0;
		sink_base->y += sink_base->tile_height;

		if (sink_base->y >= VIPS_RECT_BOTTOM(&sink->area->rect)) {
			/* Block until the previous area is done.
			 */
			if (sink->area->rect.top > 0)
				vips_semaphore_downn(
					&sink->old_area->n_thread, 0);

			/* End of image?
			 */
			if (sink_base->y >= sink_base->im->Ysize) {
				*stop = TRUE;
				return 0;
			}

			/* Swap buffers.
			 */
			VIPS_SWAP(SinkArea *,
				sink->area, sink->old_area);

			/* Position buf at the new y.
			 */
			sink_area_position(sink->area,
				sink_base->y, sink_base->n_lines);
		}
	}

	/* x, y and buf are good: save params for thread.
	 */
	image.left = 0;
	image.top = 0;
	image.width = sink_base->im->Xsize;
	image.height = sink_base->im->Ysize;
	tile.left = sink_base->x;
	tile.top = sink_base->y;
	tile.width = sink_base->tile_width;
	tile.height = sink_base->tile_height;
	vips_rect_intersectrect(&image, &tile, &state->pos);

	/* The thread needs to know which area it's writing to.
	 */
	sstate->area = sink->area;

	VIPS_DEBUG_MSG("  %p allocated %d x %d:\n",
		g_thread_self(), state->pos.left, state->pos.top);

	/* Add to the number of writers on the area.
	 */
	vips_semaphore_upn(&sink->area->n_thread, -1);

	/* Move state on.
	 */
	sink_base->x += sink_base->tile_width;

	/* Add the number of pixels we've just allocated to progress.
	 */
	sink_base->processed += state->pos.width * state->pos.height;

	return 0;
}

/* Call a thread's stop function.
 */
static int
sink_call_stop(Sink *sink, SinkThreadState *state)
{
	if (state->seq && sink->stop_fn) {
		int result;

		VIPS_DEBUG_MSG("sink_call_stop: state = %p\n", state);

		result = sink->stop_fn(state->seq, sink->a, sink->b);

		if (result) {
			SinkBase *sink_base = (SinkBase *) sink;

			vips_error("vips_sink",
				_("stop function failed for image \"%s\""),
				sink_base->im->filename);
			return -1;
		}

		state->seq = NULL;
	}

	return 0;
}

static void
sink_thread_state_dispose(GObject *gobject)
{
	SinkThreadState *state = (SinkThreadState *) gobject;
	Sink *sink = (Sink *) ((VipsThreadState *) state)->a;

	sink_call_stop(sink, state);
	VIPS_UNREF(state->reg);

	G_OBJECT_CLASS(sink_thread_state_parent_class)->dispose(gobject);
}

/* Call the start function for this thread, if necessary.
 */
static int
sink_call_start(Sink *sink, SinkThreadState *state)
{
	if (!state->seq && sink->start_fn) {
		VIPS_DEBUG_MSG("sink_call_start: state = %p\n", state);

		state->seq = sink->start_fn(sink->t, sink->a, sink->b);

		if (!state->seq) {
			SinkBase *sink_base = (SinkBase *) sink;

			vips_error("vips_sink",
				_("start function failed for image \"%s\""),
				sink_base->im->filename);
			return -1;
		}
	}

	return 0;
}

static int
sink_thread_state_build(VipsObject *object)
{
	SinkThreadState *state = (SinkThreadState *) object;
	Sink *sink = (Sink *) ((VipsThreadState *) state)->a;

	if (!(state->reg = vips_region_new(sink->t)) ||
		sink_call_start(sink, state))
		return -1;

	return VIPS_OBJECT_CLASS(sink_thread_state_parent_class)->build(object);
}

static void
sink_thread_state_class_init(SinkThreadStateClass *class)
{
	GObjectClass *gobject_class = G_OBJECT_CLASS(class);
	VipsObjectClass *object_class = VIPS_OBJECT_CLASS(class);

	gobject_class->dispose = sink_thread_state_dispose;

	object_class->build = sink_thread_state_build;
	object_class->nickname = "sinkthreadstate";
	object_class->description = _("per-thread state for sink");
}

static void
sink_thread_state_init(SinkThreadState *state)
{
	state->seq = NULL;
	state->reg = NULL;
}

VipsThreadState *
vips_sink_thread_state_new(VipsImage *im, void *a)
{
	return VIPS_THREAD_STATE(vips_object_new(
		sink_thread_state_get_type(),
		vips_thread_state_set, im, a));
}

static void
sink_free(Sink *sink)
{
	VIPS_FREEF(sink_area_free, sink->area);
	VIPS_FREEF(sink_area_free, sink->old_area);
	VIPS_FREEF(g_object_unref, sink->t);
}

void
vips_sink_base_init(SinkBase *sink_base, VipsImage *image)
{
	/* Always clear kill before we start looping. See the
	 * call to vips_image_iskilled() below.
	 */
	vips_image_set_kill(image, FALSE);

	sink_base->im = image;
	sink_base->x = 0;
	sink_base->y = 0;

	vips_get_tile_size(image,
		&sink_base->tile_width, &sink_base->tile_height,
		&sink_base->n_lines);

	sink_base->processed = 0;
}

static int
sink_init(Sink *sink,
	VipsImage *image,
	VipsStartFn start_fn, VipsGenerateFn generate_fn, VipsStopFn stop_fn,
	void *a, void *b)
{
	g_assert(generate_fn);

	vips_sink_base_init(&sink->sink_base, image);

	sink->t = NULL;
	sink->start_fn = start_fn;
	sink->generate_fn = generate_fn;
	sink->stop_fn = stop_fn;
	sink->a = a;
	sink->b = b;

	sink->area = NULL;
	sink->old_area = NULL;

	if (!(sink->t = vips_image_new()) ||
		!(sink->area = sink_area_new(sink)) ||
		!(sink->old_area = sink_area_new(sink)) ||
		vips_image_write(sink->sink_base.im, sink->t)) {
		sink_free(sink);
		return -1;
	}

	return 0;
}

static int
sink_work(VipsThreadState *state, void *a)
{
	SinkThreadState *sstate = (SinkThreadState *) state;
	Sink *sink = (Sink *) a;
	SinkArea *area = sstate->area;

	int result;

	result = vips_region_prepare(sstate->reg, &state->pos);
	if (!result)
		result = sink->generate_fn(sstate->reg, sstate->seq,
			sink->a, sink->b, &state->stop);

	/* Tell the allocator we're done.
	 */
	vips_semaphore_upn(&area->n_thread, 1);

	return result;
}

int
vips_sink_base_progress(void *a)
{
	SinkBase *sink_base = (SinkBase *) a;

	VIPS_DEBUG_MSG("vips_sink_base_progress:\n");

	/* Trigger any eval callbacks on our source image and
	 * check for errors.
	 */
	vips_image_eval(sink_base->im, sink_base->processed);
	if (vips_image_iskilled(sink_base->im))
		return -1;

	return 0;
}

/**
 * vips_sink_tile: (method)
 * @im: scan over this image
 * @tile_width: tile width
 * @tile_height: tile height
 * @start_fn: start sequences with this function
 * @generate_fn: generate pixels with this function
 * @stop_fn: stop sequences with this function
 * @a: user data
 * @b: user data
 *
 * Loops over an image. @generate_fn is called for every
 * pixel in the image, with
 * the @reg argument being a region of calculated pixels.
 *
 * Each set of pixels is @tile_width by @tile_height pixels (less at the
 * image edges). This is handy for things like writing a tiled TIFF image,
 * where tiles have to be generated with a certain size.
 *
 * See also: vips_sink(), vips_get_tile_size().
 *
 * Returns: 0 on success, or -1 on error.
 */
int
vips_sink_tile(VipsImage *im,
	int tile_width, int tile_height,
	VipsStartFn start_fn, VipsGenerateFn generate_fn, VipsStopFn stop_fn,
	void *a, void *b)
{
	Sink sink;
	int result;

	g_assert(vips_object_sanity(VIPS_OBJECT(im)));

	/* We don't use this, but make sure it's set in case any old binaries
	 * are expecting it.
	 */
	im->Bbits = vips_format_sizeof(im->BandFmt) << 3;

	if (sink_init(&sink, im, start_fn, generate_fn, stop_fn, a, b))
		return -1;

	if (tile_width > 0) {
		sink.sink_base.tile_width = tile_width;
		sink.sink_base.tile_height = tile_height;
	}

	/* vips_sink_base_progress() signals progress on im, so we have to do
	 * pre/post on that too.
	 */
	vips_image_preeval(im);

	sink_area_position(sink.area, 0, sink.sink_base.n_lines);
	result = vips_threadpool_run(im,
		vips_sink_thread_state_new,
		sink_area_allocate_fn,
		sink_work,
		vips_sink_base_progress,
		&sink);

	vips_image_posteval(im);

	sink_free(&sink);

	vips_image_minimise_all(im);

	return result;
}

/**
 * vips_sink: (method)
 * @im: scan over this image
 * @start_fn: start sequences with this function
 * @generate_fn: generate pixels with this function
 * @stop_fn: stop sequences with this function
 * @a: user data
 * @b: user data
 *
 * Loops over an image. @generate_fn is called for every pixel in
 * the image, with
 * the @reg argument being a region of calculated pixels. vips_sink() is
 * used to implement operations like vips_avg() which have no image output.
 *
 * Each set of pixels is sized according to the requirements of the image
 * pipeline that generated @im.
 *
 * See also: vips_image_generate(), vips_image_new().
 *
 * Returns: 0 on success, or -1 on error.
 */
int
vips_sink(VipsImage *im,
	VipsStartFn start_fn, VipsGenerateFn generate_fn, VipsStopFn stop_fn,
	void *a, void *b)
{
	return vips_sink_tile(im, -1, -1, start_fn, generate_fn, stop_fn, a, b);
}
