/*
 * Cogl
 *
 * An object oriented GL/GLES Abstraction/Utility Layer
 *
 * Copyright (C) 2007,2008,2009 Intel Corporation.
 *
 * This library 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 library 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 library. If not, see <http://www.gnu.org/licenses/>.
 *
 *
 */

#ifdef HAVE_CONFIG_H
#include "config.h"
#endif

#include "cogl.h"
#include "cogl-object.h"
#include "cogl-internal.h"
#include "cogl-private.h"
#include "cogl-winsys-private.h"
#include "cogl-profile.h"
#include "cogl-util.h"
#include "cogl-context-private.h"
#include "cogl-journal-private.h"
#include "cogl-texture-private.h"
#include "cogl-pipeline-private.h"
#include "cogl-pipeline-opengl-private.h"
#include "cogl-framebuffer-private.h"
#include "cogl2-path.h"

#include <string.h>

#ifdef HAVE_COGL_GL
#include "cogl-pipeline-fragend-arbfp-private.h"
#define glActiveTexture _context->drv.pf_glActiveTexture
#endif

/* This isn't defined in the GLES headers */
#ifndef GL_POINT_SPRITE
#define GL_POINT_SPRITE 0x8861
#endif

static void _cogl_context_free (CoglContext *context);

COGL_OBJECT_DEFINE (Context, context);

extern void
_cogl_create_context_driver (CoglContext *context);

static CoglContext *_context = NULL;

static void
_cogl_init_feature_overrides (CoglContext *ctx)
{
  if (G_UNLIKELY (COGL_DEBUG_ENABLED (COGL_DEBUG_DISABLE_VBOS)))
    ctx->feature_flags &= ~COGL_FEATURE_VBOS;

  if (G_UNLIKELY (COGL_DEBUG_ENABLED (COGL_DEBUG_DISABLE_PBOS)))
    ctx->feature_flags &= ~COGL_FEATURE_PBOS;

  if (G_UNLIKELY (COGL_DEBUG_ENABLED (COGL_DEBUG_DISABLE_ARBFP)))
    ctx->feature_flags &= ~COGL_FEATURE_SHADERS_ARBFP;

  if (G_UNLIKELY (COGL_DEBUG_ENABLED (COGL_DEBUG_DISABLE_GLSL)))
    ctx->feature_flags &= ~COGL_FEATURE_SHADERS_GLSL;

  if (G_UNLIKELY (COGL_DEBUG_ENABLED (COGL_DEBUG_DISABLE_NPOT_TEXTURES)))
    ctx->feature_flags &= ~(COGL_FEATURE_TEXTURE_NPOT |
                            COGL_FEATURE_TEXTURE_NPOT_BASIC |
                            COGL_FEATURE_TEXTURE_NPOT_MIPMAP |
                            COGL_FEATURE_TEXTURE_NPOT_REPEAT);
}

/* For reference: There was some deliberation over whether to have a
 * constructor that could throw an exception but looking at standard
 * practices with several high level OO languages including python, C++,
 * C# Java and Ruby they all support exceptions in constructors and the
 * general consensus appears to be that throwing an exception is neater
 * than successfully constructing with an internal error status that
 * would then have to be explicitly checked via some form of ::is_ok()
 * method.
 */
CoglContext *
cogl_context_new (CoglDisplay *display,
                  GError **error)
{
  CoglContext *context;
  GLubyte default_texture_data[] = { 0xff, 0xff, 0xff, 0x0 };
  unsigned long enable_flags = 0;
  int i;

#ifdef CLUTTER_ENABLE_PROFILE
  /* We need to be absolutely sure that uprof has been initialized
   * before calling _cogl_uprof_init. uprof_init (NULL, NULL)
   * will be a NOP if it has been initialized but it will also
   * mean subsequent parsing of the UProf GOptionGroup will have no
   * affect.
   *
   * Sadly GOptionGroup based library initialization is extremely
   * fragile by design because GOptionGroups have no notion of
   * dependencies and so the order things are initialized isn't
   * currently under tight control.
   */
  uprof_init (NULL, NULL);
  _cogl_uprof_init ();
#endif

  /* Allocate context memory */
  context = g_malloc (sizeof (CoglContext));

  /* XXX: Gross hack!
   * Currently everything in Cogl just assumes there is a default
   * context which it can access via _COGL_GET_CONTEXT() including
   * code used to construct a CoglContext. Until all of that code
   * has been updated to take an explicit context argument we have
   * to immediately make our pointer the default context.
   */
  _context = context;

  /* Init default values */
  context->feature_flags = 0;

  context->texture_types = NULL;
  context->buffer_types = NULL;

  context->rectangle_state = COGL_WINSYS_RECTANGLE_STATE_UNKNOWN;

  _cogl_bitmask_init (&context->winsys_features);

  if (!display)
    display = cogl_display_new (NULL, NULL);
  else
    cogl_object_ref (display);

  if (!cogl_display_setup (display, error))
    {
      cogl_object_unref (display);
      g_free (context);
      return NULL;
    }

  context->display = display;

#ifdef COGL_HAS_FULL_WINSYS
  if (!_cogl_winsys_context_init (context, error))
    {
      cogl_object_unref (display);
      g_free (context);
      return NULL;
    }
#else
  /* In this case Clutter is still responsible for creating a GL
   * context. */
  context->stub_winsys = TRUE;
  if (!_cogl_gl_check_version (error))
    {
      g_free (context);
      return NULL;
    }
  _cogl_gl_update_features (context);
#ifdef COGL_HAS_XLIB_SUPPORT
  _cogl_xlib_query_damage_extension ();
#endif
#endif

  /* Initialise the driver specific state */
  _cogl_init_feature_overrides (context);

  _cogl_pipeline_init_default_pipeline ();
  _cogl_pipeline_init_default_layers ();
  _cogl_pipeline_init_state_hash_functions ();
  _cogl_pipeline_init_layer_state_hash_functions ();

  context->enable_flags = 0;

  context->enable_backface_culling = FALSE;
  context->flushed_front_winding = COGL_FRONT_WINDING_COUNTER_CLOCKWISE;

  cogl_matrix_init_identity (&context->identity_matrix);
  cogl_matrix_init_identity (&context->y_flip_matrix);
  cogl_matrix_scale (&context->y_flip_matrix, 1, -1, 1);

  context->flushed_matrix_mode = COGL_MATRIX_MODELVIEW;

  context->texture_units =
    g_array_new (FALSE, FALSE, sizeof (CoglTextureUnit));

  /* See cogl-pipeline.c for more details about why we leave texture unit 1
   * active by default... */
  context->active_texture_unit = 1;
  GE (glActiveTexture (GL_TEXTURE1));

  context->legacy_fog_state.enabled = FALSE;

  context->opaque_color_pipeline = cogl_pipeline_new ();
  context->blended_color_pipeline = cogl_pipeline_new ();
  context->texture_pipeline = cogl_pipeline_new ();
  context->codegen_header_buffer = g_string_new ("");
  context->codegen_source_buffer = g_string_new ("");
  context->source_stack = NULL;

  context->legacy_state_set = 0;

  context->default_gl_texture_2d_tex = COGL_INVALID_HANDLE;
  context->default_gl_texture_rect_tex = COGL_INVALID_HANDLE;

  context->framebuffers = NULL;

  context->journal_flush_attributes_array =
    g_array_new (TRUE, FALSE, sizeof (CoglAttribute *));
  context->journal_clip_bounds = NULL;

  context->polygon_vertices = g_array_new (FALSE, FALSE, sizeof (float));

  context->current_pipeline = NULL;
  context->current_pipeline_changes_since_flush = 0;
  context->current_pipeline_skip_gl_color = FALSE;

  context->pipeline0_nodes =
    g_array_sized_new (FALSE, FALSE, sizeof (CoglHandle), 20);
  context->pipeline1_nodes =
    g_array_sized_new (FALSE, FALSE, sizeof (CoglHandle), 20);

  _cogl_bitmask_init (&context->arrays_enabled);
  _cogl_bitmask_init (&context->temp_bitmask);
  _cogl_bitmask_init (&context->arrays_to_change);

  context->max_texture_units = -1;
  context->max_texture_image_units = -1;
  context->max_activateable_texture_units = -1;

  context->current_program = COGL_INVALID_HANDLE;

  context->current_fragment_program_type = COGL_PIPELINE_PROGRAM_TYPE_FIXED;
  context->current_vertex_program_type = COGL_PIPELINE_PROGRAM_TYPE_FIXED;
  context->current_gl_program = 0;

  context->gl_blend_enable_cache = FALSE;

  context->depth_test_enabled_cache = FALSE;
  context->depth_test_function_cache = COGL_DEPTH_TEST_FUNCTION_LESS;
  context->depth_writing_enabled_cache = TRUE;
  context->depth_range_near_cache = 0;
  context->depth_range_far_cache = 1;

  context->point_size_cache = 1.0f;

  context->legacy_depth_test_enabled = FALSE;

#ifdef HAVE_COGL_GL
  _context->arbfp_cache = g_hash_table_new (_cogl_pipeline_fragend_arbfp_hash,
                                            _cogl_pipeline_fragend_arbfp_equal);
#endif

  for (i = 0; i < COGL_BUFFER_BIND_TARGET_COUNT; i++)
    context->current_buffer[i] = NULL;

  context->framebuffer_stack = _cogl_create_framebuffer_stack ();

  /* XXX: In this case the Clutter backend is still responsible for
   * the OpenGL binding API and for creating onscreen framebuffers and
   * so we have to add a dummy framebuffer to represent the backend
   * owned window... */
  if (context->stub_winsys)
    {
      CoglOnscreen *window = _cogl_onscreen_new ();
      cogl_set_framebuffer (COGL_FRAMEBUFFER (window));
      cogl_object_unref (COGL_FRAMEBUFFER (window));
    }

  _context->current_clip_stack_valid = FALSE;

  context->dirty_bound_framebuffer = TRUE;
  context->dirty_gl_viewport = TRUE;

  context->current_path = cogl2_path_new ();
  context->stencil_pipeline = cogl_pipeline_new ();

  context->in_begin_gl_block = FALSE;

  context->quad_buffer_indices_byte = COGL_INVALID_HANDLE;
  context->quad_buffer_indices = COGL_INVALID_HANDLE;
  context->quad_buffer_indices_len = 0;

  context->rectangle_byte_indices = NULL;
  context->rectangle_short_indices = NULL;
  context->rectangle_short_indices_len = 0;

  context->texture_download_pipeline = COGL_INVALID_HANDLE;
  context->blit_texture_pipeline = COGL_INVALID_HANDLE;

#ifndef HAVE_COGL_GLES2
  /* The default for GL_ALPHA_TEST is to always pass which is equivalent to
   * the test being disabled therefore we assume that for all drivers there
   * will be no performance impact if we always leave the test enabled which
   * makes things a bit simpler for us. Under GLES2 the alpha test is
   * implemented in the fragment shader so there is no enable for it
   */
  GE (glEnable (GL_ALPHA_TEST));
#endif

#ifdef HAVE_COGL_GLES2
  _context->flushed_modelview_stack = NULL;
  _context->flushed_projection_stack = NULL;
#endif

  /* Create default textures used for fall backs */
  context->default_gl_texture_2d_tex =
    cogl_texture_new_from_data (1, /* width */
                                1, /* height */
                                COGL_TEXTURE_NO_SLICING,
                                COGL_PIXEL_FORMAT_RGBA_8888_PRE, /* data format */
                                /* internal format */
                                COGL_PIXEL_FORMAT_RGBA_8888_PRE,
                                0, /* auto calc row stride */
                                default_texture_data);
  context->default_gl_texture_rect_tex =
    cogl_texture_new_from_data (1, /* width */
                                1, /* height */
                                COGL_TEXTURE_NO_SLICING,
                                COGL_PIXEL_FORMAT_RGBA_8888_PRE, /* data format */
                                /* internal format */
                                COGL_PIXEL_FORMAT_RGBA_8888_PRE,
                                0, /* auto calc row stride */
                                default_texture_data);

  cogl_push_source (context->opaque_color_pipeline);
  _cogl_pipeline_flush_gl_state (context->opaque_color_pipeline, FALSE, 0);
  _cogl_enable (enable_flags);
  _cogl_flush_face_winding ();

  context->atlases = NULL;

  _context->buffer_map_fallback_array = g_byte_array_new ();
  _context->buffer_map_fallback_in_use = FALSE;

  /* As far as I can tell, GL_POINT_SPRITE doesn't have any effect
     unless GL_COORD_REPLACE is enabled for an individual
     layer. Therefore it seems like it should be ok to just leave it
     enabled all the time instead of having to have a set property on
     each pipeline to track whether any layers have point sprite
     coords enabled. We don't need to do this for GLES2 because point
     sprites are handled using a builtin varying in the shader. */
#ifndef HAVE_COGL_GLES2
  if (cogl_features_available (COGL_FEATURE_POINT_SPRITE))
    GE (glEnable (GL_POINT_SPRITE));
#endif

  return _cogl_context_object_new (context);
}

static void
_cogl_context_free (CoglContext *context)
{
  _cogl_winsys_context_deinit (context);

  _cogl_destroy_texture_units ();

  _cogl_free_framebuffer_stack (context->framebuffer_stack);

  if (context->current_path)
    cogl_handle_unref (context->current_path);

  if (context->default_gl_texture_2d_tex)
    cogl_handle_unref (context->default_gl_texture_2d_tex);
  if (context->default_gl_texture_rect_tex)
    cogl_handle_unref (context->default_gl_texture_rect_tex);

  if (context->opaque_color_pipeline)
    cogl_handle_unref (context->opaque_color_pipeline);
  if (context->blended_color_pipeline)
    cogl_handle_unref (context->blended_color_pipeline);
  if (context->texture_pipeline)
    cogl_handle_unref (context->texture_pipeline);

  if (context->blit_texture_pipeline)
    cogl_handle_unref (context->blit_texture_pipeline);

  if (context->journal_flush_attributes_array)
    g_array_free (context->journal_flush_attributes_array, TRUE);
  if (context->journal_clip_bounds)
    g_array_free (context->journal_clip_bounds, TRUE);

  if (context->polygon_vertices)
    g_array_free (context->polygon_vertices, TRUE);

  if (context->quad_buffer_indices_byte)
    cogl_handle_unref (context->quad_buffer_indices_byte);
  if (context->quad_buffer_indices)
    cogl_handle_unref (context->quad_buffer_indices);

  if (context->rectangle_byte_indices)
    cogl_object_unref (context->rectangle_byte_indices);
  if (context->rectangle_short_indices)
    cogl_object_unref (context->rectangle_short_indices);

  if (context->default_pipeline)
    cogl_handle_unref (context->default_pipeline);

  if (context->dummy_layer_dependant)
    cogl_handle_unref (context->dummy_layer_dependant);
  if (context->default_layer_n)
    cogl_handle_unref (context->default_layer_n);
  if (context->default_layer_0)
    cogl_handle_unref (context->default_layer_0);

  if (context->current_clip_stack_valid)
    _cogl_clip_stack_unref (context->current_clip_stack);

  g_slist_free (context->atlases);

  _cogl_bitmask_destroy (&context->arrays_enabled);
  _cogl_bitmask_destroy (&context->temp_bitmask);
  _cogl_bitmask_destroy (&context->arrays_to_change);

  g_slist_free (context->texture_types);
  g_slist_free (context->buffer_types);

#ifdef HAVE_COGL_GLES2
  if (_context->flushed_modelview_stack)
    cogl_object_unref (_context->flushed_modelview_stack);
  if (_context->flushed_projection_stack)
    cogl_object_unref (_context->flushed_projection_stack);
#endif

#ifdef HAVE_COGL_GL
  g_hash_table_unref (context->arbfp_cache);
#endif

  g_byte_array_free (context->buffer_map_fallback_array, TRUE);

  _cogl_bitmask_destroy (&context->winsys_features);

  cogl_object_unref (context->display);

  g_free (context);
}

CoglContext *
_cogl_context_get_default (void)
{
  GError *error = NULL;
  /* Create if doesn't exist yet */
  if (_context == NULL)
    {
      _context = cogl_context_new (NULL, &error);
      if (!_context)
        {
          g_warning ("Failed to create default context: %s",
                     error->message);
          g_error_free (error);
        }
    }

  return _context;
}

void
cogl_set_default_context (CoglContext *context)
{
  cogl_object_ref (context);

  if (_context)
    cogl_object_unref (_context);
  _context = context;
}