/* This file is part of GEGL-GTK
 *
 * GEGL-GTK 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 3 of the License, or (at your option) any later version.
 *
 * GEGL-GTK 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 GEGL-GTK; if not, see <http://www.gnu.org/licenses/>.
 *
 * Copyright (C) 2003, 2004, 2006 Øyvind Kolås <pippin@gimp.org>
 * Copyright (C) 2011 Jon Nordby <jononor@gmail.com>
 */

#include "gegl-gtk-view-helper.h"

#include <math.h>
#include <babl/babl.h>


G_DEFINE_TYPE(ViewHelper, view_helper, G_TYPE_OBJECT)


enum {
    SIGNAL_REDRAW_NEEDED,
    SIGNAL_SIZE_CHANGED,
    N_SIGNALS
};

static guint view_helper_signals[N_SIGNALS] = { 0 };


static void
finalize(GObject *gobject);
void
trigger_processing(ViewHelper *self, GeglRectangle roi);
void
trigger_redraw(ViewHelper *self, GeglRectangle *redraw_rect);


static void
view_helper_class_init(ViewHelperClass *klass)
{
    GObjectClass *gobject_class = G_OBJECT_CLASS(klass);

    gobject_class->finalize = finalize;

    /* Emitted when a redraw is needed, with the area that needs redrawing. */
    view_helper_signals[SIGNAL_REDRAW_NEEDED] = g_signal_new("redraw-needed",
            G_TYPE_FROM_CLASS(klass),
            G_SIGNAL_RUN_LAST | G_SIGNAL_ACTION,
            0,
            NULL, NULL,
            g_cclosure_marshal_VOID__BOXED,
            G_TYPE_NONE, 1,
            GEGL_TYPE_RECTANGLE);

    /* Emitted when the size of the view changes, with the new size. */
    view_helper_signals[SIGNAL_SIZE_CHANGED] = g_signal_new("size-changed",
            G_TYPE_FROM_CLASS(klass),
            G_SIGNAL_RUN_LAST | G_SIGNAL_ACTION,
            0,
            NULL, NULL,
            g_cclosure_marshal_VOID__BOXED,
            G_TYPE_NONE, 1,
            GEGL_TYPE_RECTANGLE);
}

static void
view_helper_init(ViewHelper *self)
{
    GdkRectangle invalid_gdkrect = {0, 0, -1, -1};

    self->node        = NULL;
    self->x           = 0;
    self->y           = 0;
    self->scale       = 1.0;
    self->autoscale_policy = GEGL_GTK_VIEW_AUTOSCALE_CONTENT;
    self->block = FALSE;

    self->monitor_id  = 0;
    self->processor = NULL;
    self->processing_queue = g_queue_new();
    self->currently_processed_rect = NULL;

    self->widget_allocation = invalid_gdkrect;
}

static void
finalize(GObject *gobject)
{
    ViewHelper *self = VIEW_HELPER(gobject);

    if (self->monitor_id) {
        g_source_remove(self->monitor_id);
        self->monitor_id = 0;
    }

    if (self->node)
        g_object_unref(self->node);

    if (self->processor)
        g_object_unref(self->processor);

    g_queue_free_full(self->processing_queue, g_free);

    if (self->currently_processed_rect) {
        g_free(self->currently_processed_rect);
    }
}

/* Transform a rectangle from model to view coordinates. */
static void
model_rect_to_view_rect(ViewHelper *self, GeglRectangle *rect)
{
    GeglRectangle temp;

    temp.x = self->scale * (rect->x) - self->x;
    temp.y = self->scale * (rect->y) - self->y;
    temp.width = ceil(self->scale * rect->width);
    temp.height = ceil(self->scale * rect->height);

    *rect = temp;
}

static void
update_autoscale(ViewHelper *self)
{
    GdkRectangle viewport = self->widget_allocation;
    GeglRectangle bbox = gegl_node_get_bounding_box(self->node);
    model_rect_to_view_rect(self, &bbox);

    if (!self->node || viewport.width < 0 || viewport.height < 0
            || bbox.width < 0 || bbox.height < 0)
        return;

    if (self->autoscale_policy == GEGL_GTK_VIEW_AUTOSCALE_WIDGET) {
        /* Request widget size change */
        /* XXX: Should we reset scale/x/y here? */
        g_signal_emit(self, view_helper_signals[SIGNAL_SIZE_CHANGED],
                      0, &bbox, NULL);

    } else if (self->autoscale_policy == GEGL_GTK_VIEW_AUTOSCALE_CONTENT) {
        /* Calculate and set scaling factor to make the content fit inside */
        float width_ratio = bbox.width / (float)viewport.width;
        float height_ratio = bbox.height / (float)viewport.height;
        float max_ratio = width_ratio >= height_ratio ? width_ratio : height_ratio;

        float current_scale = view_helper_get_scale(self);
        view_helper_set_scale(self, current_scale * (1.0 / max_ratio));
    }

}

static void
invalidated_event(GeglNode      *node,
                  GeglRectangle *rect,
                  ViewHelper    *self)
{
    trigger_processing(self, *rect);
}

static gboolean
task_monitor(ViewHelper *self)
{
    if (!self->processor || !self->node) {
        return FALSE;
    }

    // PERFORMANCE: combine all the rects added to the queue during a single
    // iteration of the main loop somehow

    if (!self->currently_processed_rect) {

        if (g_queue_is_empty(self->processing_queue)) {
            // Unregister worker
            self->monitor_id = 0;
            return FALSE;
        }
        else {
            // Fetch next rect to process
            self->currently_processed_rect = (GeglRectangle *)g_queue_pop_tail(self->processing_queue);
            g_assert(self->currently_processed_rect);
            gegl_processor_set_rectangle(self->processor, self->currently_processed_rect);
        }
    }

    gboolean processing_done = !gegl_processor_work(self->processor, NULL);

    if (processing_done) {
        // Go to next region
        if (self->currently_processed_rect) {
            g_free(self->currently_processed_rect);
        }
        self->currently_processed_rect = NULL;
    }

    return TRUE;
}


/* When the GeglNode has been computed,
 * find out if the size of the vie changed and
 * emit the "size-changed" signal to notify view
 * find out which area in the view was computed and emit the
 * "redraw-needed" signal to notify it that a redraw is needed */
static void
computed_event(GeglNode      *node,
               GeglRectangle *rect,
               ViewHelper    *self)
{
    update_autoscale(self);

    /* Emit redraw-needed */
    GeglRectangle redraw_rect = *rect;
    model_rect_to_view_rect(self, &redraw_rect);

    trigger_redraw(self, &redraw_rect);
}

ViewHelper *
view_helper_new(void)
{
    return VIEW_HELPER(g_object_new(VIEW_HELPER_TYPE, NULL));
}

/* Draw the view of the GeglNode to the provided cairo context,
 * taking into account transformations et.c.
 * @rect the bounding box of the area to draw in view coordinates
 *
 * For instance called by widget during the draw/expose */
void
view_helper_draw(ViewHelper *self, cairo_t *cr, GdkRectangle *rect)
{
    cairo_surface_t *surface = NULL;
    guchar          *buf = NULL;
    GeglRectangle   roi;

    roi.x = self->x + rect->x;
    roi.y = self->y + rect->y;
    roi.width  = rect->width;
    roi.height = rect->height;

    buf = g_malloc((roi.width) * (roi.height) * 4);

    gegl_node_blit(self->node,
                   self->scale,
                   &roi,
                   babl_format("B'aG'aR'aA u8"),
                   (gpointer)buf,
                   GEGL_AUTO_ROWSTRIDE,
                   GEGL_BLIT_CACHE | (self->block ? 0 : GEGL_BLIT_DIRTY));

    surface = cairo_image_surface_create_for_data(buf,
              CAIRO_FORMAT_ARGB32,
              roi.width, roi.height,
              roi.width * 4);
    cairo_set_source_surface(cr, surface, rect->x, rect->y);
    cairo_paint(cr);

    cairo_surface_destroy(surface);
    g_free(buf);

}

void
view_helper_set_allocation(ViewHelper *self, GdkRectangle *allocation)
{
    self->widget_allocation = *allocation;
    update_autoscale(self);
}

/* Trigger processing of the GeglNode */
void
trigger_processing(ViewHelper *self, GeglRectangle roi)
{
    //GeglRectangle    roi;

    // PERFORMANCE: determine the area that the view widget is interested in,
    // and calculate the intersection with the invalidated rect
    // and only pass this value as the ROI
    // Would then also have to follow changes in view transformation

    if (!self->node)
        return;

//    roi.x = self->x / self->scale;
//    roi.y = self->y / self->scale;

//    roi.width = ceil(self->widget_allocation.width / self->scale + 1);
//    roi.height = ceil(self->widget_allocation.height / self->scale + 1);

    if (self->monitor_id == 0) {
        self->monitor_id = g_idle_add_full(G_PRIORITY_LOW,
                                           (GSourceFunc) task_monitor, self,
                                           NULL);
    }

    // Add the invalidated region to the dirty
    GeglRectangle *rect = g_new(GeglRectangle, 1);
    rect->x = roi.x;
    rect->y = roi.y;
    rect->width = roi.width;
    rect->height = roi.height;
    g_queue_push_head(self->processing_queue, rect);
}

void
trigger_redraw(ViewHelper *self, GeglRectangle *redraw_rect)
{
    if (!redraw_rect) {
        GeglRectangle invalid_rect = {0, 0, -1, -1}; /* Indicates full redraw */
        redraw_rect = &invalid_rect;
    }

    g_signal_emit(self, view_helper_signals[SIGNAL_REDRAW_NEEDED],
                  0, redraw_rect, NULL);
}

void
view_helper_set_node(ViewHelper *self, GeglNode *node)
{
    if (self->node == node)
        return;

    if (self->node)
        g_object_unref(self->node);

    if (node) {
        g_object_ref(node);
        self->node = node;

        g_signal_connect_object(self->node, "computed",
                                G_CALLBACK(computed_event),
                                self, 0);
        g_signal_connect_object(self->node, "invalidated",
                                G_CALLBACK(invalidated_event),
                                self, 0);

        if (self->processor)
            g_object_unref(self->processor);

        GeglRectangle bbox = gegl_node_get_bounding_box(self->node);
        self->processor = gegl_node_new_processor(self->node, &bbox);

        update_autoscale(self);
        trigger_processing(self, bbox);

    } else
        self->node = NULL;
}

GeglNode *
view_helper_get_node(ViewHelper *self)
{
    return self->node;
}

void
view_helper_set_scale(ViewHelper *self, float scale)
{
    if (self->scale == scale)
        return;

    self->scale = scale;
    update_autoscale(self);
    trigger_redraw(self, NULL);
}

float
view_helper_get_scale(ViewHelper *self)
{
    return self->scale;
}

void
view_helper_set_x(ViewHelper *self, float x)
{
    if (self->x == x)
        return;

    self->x = x;
    update_autoscale(self);
    trigger_redraw(self, NULL);
}

float
view_helper_get_x(ViewHelper *self)
{
    return self->x;
}

void
view_helper_set_y(ViewHelper *self, float y)
{
    if (self->y == y)
        return;

    self->y = y;
    update_autoscale(self);
    trigger_redraw(self, NULL);
}

float
view_helper_get_y(ViewHelper *self)
{
    return self->y;
}

void view_helper_get_transformation(ViewHelper *self, GeglMatrix3 *matrix)
{
    /* XXX: Below gives the right result, but is it really the
     * way we want transformations to work? */

    /* API change in GEGL 1.7 (1.6+git):
     * GeglMatrix3 changed from float[3][3] to
     * struct with a float[3][3] coeff member */

#if GEGL_MINOR_VERSION == 1 && GEGL_MICRO_VERSION >= 7 || GEGL_MINOR_VERSION >= 2
    matrix->coeff [0][0] = self->scale; /* xx */
    matrix->coeff [0][1] = 0.0; /* xy */
    matrix->coeff [0][2] = -self->x; /* x0 */

    matrix->coeff [1][0] = 0.0; /* yx */
    matrix->coeff [1][1] = self->scale; /* yy */
    matrix->coeff [1][2] = -self->y; /* y0 */

    matrix->coeff [2][0] = 0.0;
    matrix->coeff [2][1] = 0.0;
    matrix->coeff [2][2] = 1.0;
#else
    (*matrix) [0][0] = self->scale;
    (*matrix) [0][1] = 0.0;
    (*matrix) [0][2] = -self->x;

    (*matrix) [1][0] = 0.0;
    (*matrix) [1][1] = self->scale;
    (*matrix) [1][2] = -self->y;

    (*matrix) [2][0] = 0.0;
    (*matrix) [2][1] = 0.0;
    (*matrix) [2][2] = 1.0;
#endif

}

void
view_helper_set_autoscale_policy(ViewHelper *self, GeglGtkViewAutoscale autoscale)
{
    if (self->autoscale_policy == autoscale)
        return;

    self->autoscale_policy = autoscale;
    update_autoscale(self);
}

GeglGtkViewAutoscale
view_helper_get_autoscale_policy(ViewHelper *self)
{
    return self->autoscale_policy;
}
