/**
 * big-ellipse.c
 *   A very basic GIMP plugin, attached to images, that draws a really
 *   big ellipse when called.
 *
 *   Copyright (c) 2013 Samuel A. Rebelsky.  All rights reserved.
 *
 *   This file is part of The Glimmer Guide to GIMP Plugins (aka GGGP).
 *
 *   GGGP 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 3 of the License, or
 *   (at your option) any later version.
 *
 *   GGGP 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 GGGP.  If not, see <http://www.gnu.org/licenses/>.
 */


// +---------+---------------------------------------------------------
// | Headers |
// +---------+

#include <libgimp/gimp.h>

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


// +--------+----------------------------------------------------------
// | Macros |
// +--------+

/**
 * Print a string (somewhere).  Right now, this prints to stderr, which
 * means it only works when the program is run from the terminal.
 */
#define REPORT(str) fprintf (stderr, "*** %s ***\n", str)

/**
 * Print an integer.
 */
#define REPORT_INT(i) fprintf (stderr, "*** %s: %d ***\n", #i, i)


// +--------------------------+----------------------------------------
// | Function Predeclarations |
// +--------------------------+

static void ellipse_query (void);
static void ellipse_run (const gchar *name,
                       gint nparams,
                       const GimpParam *params,
                       gint *nreturn_vals,
                       GimpParam **return_vals);


// +-------------+-----------------------------------------------------
// | Boilerplate |
// +-------------+

/**
 * The four key functions.  This structure *must* be called PLUG_IN_INFO.
 */
GimpPlugInInfo PLUG_IN_INFO =
  {
    NULL,
    NULL,
    ellipse_query,
    ellipse_run
  };

/**
 * Indicate that we're ready to begin the main part of the code.
 */
MAIN ()


// +-------------------------+-----------------------------------------
// | Standard GIMP Functions |
// +-------------------------+

static void
ellipse_init (void)
{
} // ellipse_init

static void
ellipse_quit (void)
{
} // ellipse_quit

static void 
ellipse_query (void)
{
  // Build the description of the parameters that the function expects.  
  // Each parameter has a type, a name, and a description
  // All plug-ins must take a run-mode.   Plug-ins associated with an
  // image
  static GimpParamDef args[] =
    {
      { GIMP_PDB_INT32, "run-mode", "Run mode" },
      { GIMP_PDB_IMAGE, "image", "Input image" },
      { GIMP_PDB_DRAWABLE, "drawable", "Input layer or other drawable" }
    }; // args

  // Tell the GIMP about our plugin.
  gimp_install_procedure (
    "gggp/image/big-ellipse",                           // Name
    "Select a big ellipse",                             // Blurb
    "Selects an ellipse the size of the image",         // Help
    "Samuel A. Rebelsky",                               // Author
    "Copyright (c) Samuel A. Rebelsky.  All rights reserved.",
                                                        // Copyright
    "2013",                                             // Year
    "<Image>/GGGP/BigE",                                // Path
    "RGB",                                              // Image types
    GIMP_PLUGIN,                                        // Type
    3,                                                  // Number of params
    0,                                                  // Number of return vals
    args,                                               // Param descriptions
    NULL                                                // Return descriptions
    );

} // ellipse_query

static void
ellipse_run (const gchar      *name,
           gint              nparams,
           const GimpParam  *params,
           gint             *nreturn_vals,
           GimpParam       **return_vals)
{
  // Prepare return values
  static GimpParam results[1];
  results[0].type = GIMP_PDB_STATUS;
  results[0].data.d_status = GIMP_PDB_SUCCESS;
  *nreturn_vals = 1;
  *return_vals = results;

  int image = params[1].data.d_image;
  REPORT_INT (image);

  // Sanity check
  if (! gimp_image_is_valid (image))
    {
      results[0].data.d_status = GIMP_PDB_CALLING_ERROR;
      REPORT ("invalid image");
      return;
    }

  // Get the width and the height of the image
  int width = gimp_image_width (image);
  int height = gimp_image_height (image);
  REPORT_INT (width);
  REPORT_INT (height);

  // Make a nice color
  GimpRGB color;
  gimp_rgb_set_uchar (&color, 128, 0, 255);

  // Select and stroke
  gimp_ellipse_select (image, 0, 0, width, height, 
                       GIMP_CHANNEL_OP_REPLACE, 1, 1, 5.0);
  gimp_context_set_foreground (&color);
  gimp_edit_stroke (params[2].data.d_drawable);
  gimp_selection_none (image);
  gimp_displays_flush ();
} // ellipse_run