/*
 * Cogl
 *
 * An object oriented GL/GLES Abstraction/Utility Layer
 *
 * Copyright (C) 2010 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/>.
 *
 *
 *
 * Authors:
 *   Neil Roberts <neil@linux.intel.com>
 */

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

#include "cogl-pipeline-private.h"
#include "cogl-pipeline-opengl-private.h"

#ifdef COGL_PIPELINE_PROGEND_GLSL

#include "cogl.h"
#include "cogl-internal.h"
#include "cogl-context.h"
#include "cogl-handle.h"
#include "cogl-program-private.h"
#include "cogl-pipeline-fragend-glsl-private.h"
#include "cogl-pipeline-vertend-glsl-private.h"

#ifndef HAVE_COGL_GLES2

#define glCreateProgram      ctx->drv.pf_glCreateProgram
#define glAttachShader       ctx->drv.pf_glAttachShader
#define glUseProgram         ctx->drv.pf_glUseProgram
#define glLinkProgram        ctx->drv.pf_glLinkProgram
#define glDeleteProgram      ctx->drv.pf_glDeleteProgram
#define glGetProgramInfoLog  ctx->drv.pf_glGetProgramInfoLog
#define glGetProgramiv       ctx->drv.pf_glGetProgramiv
#define glGetUniformLocation ctx->drv.pf_glGetUniformLocation
#define glUniform1i          ctx->drv.pf_glUniform1i
#define glUniform1f          ctx->drv.pf_glUniform1f
#define glUniform4fv         ctx->drv.pf_glUniform4fv

#endif /* HAVE_COGL_GLES2 */

const CoglPipelineProgend _cogl_pipeline_glsl_progend;

typedef struct _UnitState
{
  unsigned int dirty_combine_constant:1;

  GLint combine_constant_uniform;
} UnitState;

typedef struct
{
  unsigned int ref_count;

  /* Age that the user program had last time we generated a GL
     program. If it's different then we need to relink the program */
  unsigned int user_program_age;

  GLuint program;

  /* To allow writing shaders that are portable between GLES 2 and
   * OpenGL Cogl prepends a number of boilerplate #defines and
   * declarations to user shaders. One of those declarations is an
   * array of texture coordinate varyings, but to know how to emit the
   * declaration we need to know how many texture coordinate
   * attributes are in use.  The boilerplate also needs to be changed
   * if this increases. */
  int n_tex_coord_attribs;

#ifdef HAVE_COGL_GLES2
  /* Under GLES2 the alpha test is implemented in the shader. We need
     a uniform for the reference value */
  gboolean dirty_alpha_test_reference;
  GLint alpha_test_reference_uniform;

  gboolean dirty_point_size;
  GLint point_size_uniform;

  /* Under GLES2 we can't use the builtin functions to set attribute
     pointers such as the vertex position. Instead the vertex
     attribute code needs to query the attribute numbers from the
     progend backend */
  int position_attribute_location;
  int color_attribute_location;
  int normal_attribute_location;
  int tex_coord0_attribute_location;
  /* We only allocate this array if more than one tex coord attribute
     is requested because most pipelines will only use one layer */
  GArray *tex_coord_attribute_locations;
#endif

  /* We need to track the last pipeline that the program was used with
   * so know if we need to update all of the uniforms */
  CoglPipeline *last_used_for_pipeline;

  UnitState *unit_state;
} CoglPipelineProgendPrivate;

static CoglUserDataKey glsl_priv_key;

static void
delete_program (GLuint program)
{
#ifdef HAVE_COGL_GLES2
  /* This hack can go away once this GLSL backend replaces the GLES2
     wrapper */
  _cogl_gles2_clear_cache_for_program (program);
#else
  _COGL_GET_CONTEXT (ctx, NO_RETVAL);
#endif

  GE (glDeleteProgram (program));
}

static CoglPipelineProgendPrivate *
get_glsl_priv (CoglPipeline *pipeline)
{
  return cogl_object_get_user_data (COGL_OBJECT (pipeline), &glsl_priv_key);
}

#ifdef HAVE_COGL_GLES2

#define ATTRIBUTE_LOCATION_UNKNOWN -2

/* Under GLES2 the vertex attribute API needs to query the attribute
   numbers because it can't used the fixed function API to set the
   builtin attributes. We cache the attributes here because the
   progend knows when the program is changed so it can clear the
   cache. This should always be called after the pipeline is flushed
   so they can assert that the gl program is valid */

int
_cogl_pipeline_progend_glsl_get_position_attribute (CoglPipeline *pipeline)
{
  CoglPipelineProgendPrivate *priv = get_glsl_priv (pipeline);

  g_return_val_if_fail (priv != NULL, -1);
  g_return_val_if_fail (priv->program != 0, -1);

  if (priv->position_attribute_location == ATTRIBUTE_LOCATION_UNKNOWN)
    GE_RET( priv->position_attribute_location,
            glGetAttribLocation (priv->program, "cogl_position_in") );

  return priv->position_attribute_location;
}

int
_cogl_pipeline_progend_glsl_get_color_attribute (CoglPipeline *pipeline)
{
  CoglPipelineProgendPrivate *priv = get_glsl_priv (pipeline);

  g_return_val_if_fail (priv != NULL, -1);
  g_return_val_if_fail (priv->program != 0, -1);

  if (priv->color_attribute_location == ATTRIBUTE_LOCATION_UNKNOWN)
    GE_RET( priv->color_attribute_location,
            glGetAttribLocation (priv->program, "cogl_color_in") );

  return priv->color_attribute_location;
}

int
_cogl_pipeline_progend_glsl_get_normal_attribute (CoglPipeline *pipeline)
{
  CoglPipelineProgendPrivate *priv = get_glsl_priv (pipeline);

  g_return_val_if_fail (priv != NULL, -1);
  g_return_val_if_fail (priv->program != 0, -1);

  if (priv->normal_attribute_location == ATTRIBUTE_LOCATION_UNKNOWN)
    GE_RET( priv->normal_attribute_location,
            glGetAttribLocation (priv->program, "cogl_normal_in") );

  return priv->normal_attribute_location;
}

int
_cogl_pipeline_progend_glsl_get_tex_coord_attribute (CoglPipeline *pipeline,
                                                     int unit)
{
  CoglPipelineProgendPrivate *priv = get_glsl_priv (pipeline);

  g_return_val_if_fail (priv != NULL, -1);
  g_return_val_if_fail (priv->program != 0, -1);

  if (unit == 0)
    {
      if (priv->tex_coord0_attribute_location == ATTRIBUTE_LOCATION_UNKNOWN)
        GE_RET( priv->tex_coord0_attribute_location,
                glGetAttribLocation (priv->program, "cogl_tex_coord0_in") );

      return priv->tex_coord0_attribute_location;
    }
  else
    {
      char *name = g_strdup_printf ("cogl_tex_coord%i_in", unit);
      int *locations;

      if (priv->tex_coord_attribute_locations == NULL)
        priv->tex_coord_attribute_locations = g_array_new (FALSE, FALSE,
                                                           sizeof (int));
      if (priv->tex_coord_attribute_locations->len <= unit - 1)
        {
          int i = priv->tex_coord_attribute_locations->len;
          g_array_set_size (priv->tex_coord_attribute_locations, unit);
          for (; i < unit; i++)
            g_array_index (priv->tex_coord_attribute_locations, int, i) =
              ATTRIBUTE_LOCATION_UNKNOWN;
        }

      locations = &g_array_index (priv->tex_coord_attribute_locations, int, 0);

      if (locations[unit - 1] == ATTRIBUTE_LOCATION_UNKNOWN)
        GE_RET( locations[unit - 1],
                glGetAttribLocation (priv->program, name) );

      g_free (name);

      return locations[unit - 1];
    }
}

static void
clear_attribute_cache (CoglPipelineProgendPrivate *priv)
{
  priv->position_attribute_location = ATTRIBUTE_LOCATION_UNKNOWN;
  priv->color_attribute_location = ATTRIBUTE_LOCATION_UNKNOWN;
  priv->normal_attribute_location = ATTRIBUTE_LOCATION_UNKNOWN;
  priv->tex_coord0_attribute_location = ATTRIBUTE_LOCATION_UNKNOWN;
  if (priv->tex_coord_attribute_locations)
    {
      g_array_free (priv->tex_coord_attribute_locations, TRUE);
      priv->tex_coord_attribute_locations = NULL;
    }
}

#endif /* HAVE_COGL_GLES2 */

static void
destroy_glsl_priv (void *user_data)
{
  CoglPipelineProgendPrivate *priv = user_data;

  if (--priv->ref_count == 0)
    {
#ifdef HAVE_COGL_GLES2
      clear_attribute_cache (priv);
#endif

      if (priv->program)
        delete_program (priv->program);

      g_free (priv->unit_state);

      g_slice_free (CoglPipelineProgendPrivate, priv);
    }
}

static void
set_glsl_priv (CoglPipeline *pipeline, CoglPipelineProgendPrivate *priv)
{
  cogl_object_set_user_data (COGL_OBJECT (pipeline),
                             &glsl_priv_key,
                             priv,
                             destroy_glsl_priv);
}

static void
dirty_glsl_program_state (CoglPipeline *pipeline)
{
  cogl_object_set_user_data (COGL_OBJECT (pipeline),
                             &glsl_priv_key,
                             NULL,
                             destroy_glsl_priv);
}

static void
link_program (GLint gl_program)
{
  /* On GLES2 we'll let the backend link the program. This hack can go
     away once this backend replaces the GLES2 wrapper */
#ifndef HAVE_COGL_GLES2

  GLint link_status;

  _COGL_GET_CONTEXT (ctx, NO_RETVAL);

  GE( glLinkProgram (gl_program) );

  GE( glGetProgramiv (gl_program, GL_LINK_STATUS, &link_status) );

  if (!link_status)
    {
      GLint log_length;
      GLsizei out_log_length;
      char *log;

      GE( glGetProgramiv (gl_program, GL_INFO_LOG_LENGTH, &log_length) );

      log = g_malloc (log_length);

      GE( glGetProgramInfoLog (gl_program, log_length,
                               &out_log_length, log) );

      g_warning ("Failed to link GLSL program:\n%.*s\n",
                 log_length, log);

      g_free (log);
    }

#endif /* HAVE_COGL_GLES2 */
}

typedef struct
{
  int unit;
  GLuint gl_program;
  gboolean update_all;
  CoglPipelineProgendPrivate *priv;
} UpdateUniformsState;

static gboolean
get_uniform_cb (CoglPipeline *pipeline,
                int layer_index,
                void *user_data)
{
  UpdateUniformsState *state = user_data;
  CoglPipelineProgendPrivate *priv = state->priv;
  UnitState *unit_state = &priv->unit_state[state->unit];
  GLint uniform_location;

  _COGL_GET_CONTEXT (ctx, FALSE);

  /* We can reuse the source buffer to create the uniform name because
     the program has now been linked */
  g_string_set_size (ctx->codegen_source_buffer, 0);
  g_string_append_printf (ctx->codegen_source_buffer,
                          "_cogl_sampler_%i", state->unit);

  GE_RET( uniform_location,
          glGetUniformLocation (state->gl_program,
                                ctx->codegen_source_buffer->str) );

  /* We can set the uniform immediately because the samplers are the
     unit index not the texture object number so it will never
     change. Unfortunately GL won't let us use a constant instead of a
     uniform */
  if (uniform_location != -1)
    GE( glUniform1i (uniform_location, state->unit) );

  g_string_set_size (ctx->codegen_source_buffer, 0);
  g_string_append_printf (ctx->codegen_source_buffer,
                          "_cogl_layer_constant_%i", state->unit);

  GE_RET( uniform_location,
          glGetUniformLocation (state->gl_program,
                                ctx->codegen_source_buffer->str) );

  unit_state->combine_constant_uniform = uniform_location;

  state->unit++;

  return TRUE;
}

static gboolean
update_constants_cb (CoglPipeline *pipeline,
                     int layer_index,
                     void *user_data)
{
  UpdateUniformsState *state = user_data;
  CoglPipelineProgendPrivate *priv = state->priv;
  UnitState *unit_state = &priv->unit_state[state->unit++];

  _COGL_GET_CONTEXT (ctx, FALSE);

  if (unit_state->combine_constant_uniform != -1 &&
      (state->update_all || unit_state->dirty_combine_constant))
    {
      float constant[4];
      _cogl_pipeline_get_layer_combine_constant (pipeline,
                                                 layer_index,
                                                 constant);
      GE (glUniform4fv (unit_state->combine_constant_uniform,
                        1, constant));
      unit_state->dirty_combine_constant = FALSE;
    }
  return TRUE;
}

#ifdef HAVE_COGL_GLES2

static void
update_alpha_test_reference (CoglPipeline *pipeline,
                             GLuint gl_program,
                             CoglPipelineProgendPrivate *priv)
{
  float alpha_reference;

  if (priv->dirty_alpha_test_reference &&
      priv->alpha_test_reference_uniform != -1)
    {
      alpha_reference = cogl_pipeline_get_alpha_test_reference (pipeline);

      GE( glUniform1f (priv->alpha_test_reference_uniform,
                       alpha_reference) );

      priv->dirty_alpha_test_reference = FALSE;
    }
}

static void
update_point_size (CoglPipeline *pipeline,
                   GLuint gl_program,
                   CoglPipelineProgendPrivate *priv)
{
  if (priv->dirty_point_size && priv->point_size_uniform != -1)
    {
      float point_size = cogl_pipeline_get_point_size (pipeline);

      GE( glUniform1f (priv->point_size_uniform, point_size) );

      priv->dirty_point_size = FALSE;
    }
}

#endif /* HAVE_COGL_GLES2 */

static void
_cogl_pipeline_progend_glsl_end (CoglPipeline *pipeline,
                                 unsigned long pipelines_difference,
                                 int n_tex_coord_attribs)
{
  CoglPipelineProgendPrivate *priv;
  GLuint gl_program;
  gboolean program_changed = FALSE;
  UpdateUniformsState state;
  CoglProgram *user_program;

  _COGL_GET_CONTEXT (ctx, NO_RETVAL);

  /* If neither of the glsl fragend or vertends are used then we don't
     need to do anything */
  if (pipeline->fragend != COGL_PIPELINE_FRAGEND_GLSL &&
      pipeline->vertend != COGL_PIPELINE_VERTEND_GLSL)
    return;

  priv = get_glsl_priv (pipeline);

  user_program = cogl_pipeline_get_user_program (pipeline);

  if (priv == NULL)
    {
      CoglPipeline *authority;

      /* Get the authority for anything affecting program state. This
         should include both fragment codegen state and vertex codegen
         state */
      authority = _cogl_pipeline_find_equivalent_parent
        (pipeline,
         (COGL_PIPELINE_STATE_AFFECTS_VERTEX_CODEGEN |
          COGL_PIPELINE_STATE_AFFECTS_FRAGMENT_CODEGEN) &
         ~COGL_PIPELINE_STATE_LAYERS,
         COGL_PIPELINE_LAYER_STATE_AFFECTS_FRAGMENT_CODEGEN |
         COGL_PIPELINE_LAYER_STATE_AFFECTS_VERTEX_CODEGEN,
         COGL_PIPELINE_FIND_EQUIVALENT_COMPARE_TEXTURE_TARGET);

      priv = get_glsl_priv (authority);

      if (priv == NULL)
        {
          priv = g_slice_new (CoglPipelineProgendPrivate);
          priv->ref_count = 1;
          priv->program = 0;
          priv->n_tex_coord_attribs = 0;
          priv->unit_state = g_new (UnitState,
                                    cogl_pipeline_get_n_layers (pipeline));
#ifdef HAVE_COGL_GLES2
          priv->tex_coord_attribute_locations = NULL;
#endif
          set_glsl_priv (authority, priv);
        }

      if (authority != pipeline)
        {
          priv->ref_count++;
          set_glsl_priv (pipeline, priv);
        }
    }

  /* If the program has changed since the last link then we do
   * need to relink
   *
   * Also if the number of texture coordinate attributes in use has
   * increased, then delete the program so we can prepend a new
   * _cogl_tex_coord[] varying array declaration. */
  if (priv->program && user_program &&
      (user_program->age != priv->user_program_age ||
       n_tex_coord_attribs > priv->n_tex_coord_attribs))
    {
      delete_program (priv->program);
      priv->program = 0;
    }

  if (priv->program == 0)
    {
      GLuint backend_shader;
      GSList *l;

      GE_RET( priv->program, glCreateProgram () );

      /* Attach all of the shader from the user program */
      if (user_program)
        {
          if (priv->n_tex_coord_attribs > n_tex_coord_attribs)
            n_tex_coord_attribs = priv->n_tex_coord_attribs;

#ifdef HAVE_COGL_GLES2
          /* Find the largest count of texture coordinate attributes
           * associated with each of the shaders so we can ensure a consistent
           * _cogl_tex_coord[] array declaration across all of the shaders.*/
          if (user_program)
            for (l = user_program->attached_shaders; l; l = l->next)
              {
                CoglShader *shader = l->data;
                n_tex_coord_attribs = MAX (shader->n_tex_coord_attribs,
                                           n_tex_coord_attribs);
              }
#endif

          for (l = user_program->attached_shaders; l; l = l->next)
            {
              CoglShader *shader = l->data;

              _cogl_shader_compile_real (shader, n_tex_coord_attribs);

              g_assert (shader->language == COGL_SHADER_LANGUAGE_GLSL);

              GE( glAttachShader (priv->program,
                                  shader->gl_handle) );
            }

          priv->user_program_age = user_program->age;
        }

      /* Attach any shaders from the GLSL backends */
      if (pipeline->fragend == COGL_PIPELINE_FRAGEND_GLSL &&
          (backend_shader = _cogl_pipeline_fragend_glsl_get_shader (pipeline)))
        GE( glAttachShader (priv->program, backend_shader) );
      if (pipeline->vertend == COGL_PIPELINE_VERTEND_GLSL &&
          (backend_shader = _cogl_pipeline_vertend_glsl_get_shader (pipeline)))
        GE( glAttachShader (priv->program, backend_shader) );

      link_program (priv->program);

      program_changed = TRUE;

      priv->n_tex_coord_attribs = n_tex_coord_attribs;
    }

  gl_program = priv->program;

#ifdef HAVE_COGL_GLES2
  /* This function is a massive hack to get the GLES2 backend to
     work. It should only be neccessary until we move the GLSL vertex
     shader generation into a vertend instead of the GLES2 driver
     backend */
  _cogl_gles2_use_program (gl_program);
#else
  if (pipeline->fragend == COGL_PIPELINE_FRAGEND_GLSL)
    _cogl_use_fragment_program (gl_program, COGL_PIPELINE_PROGRAM_TYPE_GLSL);
  if (pipeline->vertend == COGL_PIPELINE_VERTEND_GLSL)
    _cogl_use_vertex_program (gl_program, COGL_PIPELINE_PROGRAM_TYPE_GLSL);
#endif

  state.unit = 0;
  state.gl_program = gl_program;
  state.priv = priv;

  if (program_changed)
    cogl_pipeline_foreach_layer (pipeline,
                                 get_uniform_cb,
                                 &state);

  state.unit = 0;
  state.update_all = (program_changed ||
                      priv->last_used_for_pipeline != pipeline);

  cogl_pipeline_foreach_layer (pipeline,
                               update_constants_cb,
                               &state);

#ifdef HAVE_COGL_GLES2
  if (program_changed)
    {
      clear_attribute_cache (priv);

      GE_RET( priv->alpha_test_reference_uniform,
              glGetUniformLocation (gl_program,
                                    "_cogl_alpha_test_ref") );

      GE_RET( priv->point_size_uniform,
              glGetUniformLocation (gl_program,
                                    "cogl_point_size_in") );
    }
  if (program_changed ||
      priv->last_used_for_pipeline != pipeline)
    {
      priv->dirty_alpha_test_reference = TRUE;
      priv->dirty_point_size = TRUE;
    }

  update_alpha_test_reference (pipeline, gl_program, priv);
  update_point_size (pipeline, gl_program, priv);
#endif

  if (user_program)
    _cogl_program_flush_uniforms (user_program,
                                  gl_program,
                                  program_changed);

  /* We need to track the last pipeline that the program was used with
   * so know if we need to update all of the uniforms */
  priv->last_used_for_pipeline = pipeline;
}

static void
_cogl_pipeline_progend_glsl_pre_change_notify (CoglPipeline *pipeline,
                                               CoglPipelineState change,
                                               const CoglColor *new_color)
{
  if ((change & COGL_PIPELINE_STATE_AFFECTS_FRAGMENT_CODEGEN))
    dirty_glsl_program_state (pipeline);
#ifdef HAVE_COGL_GLES2
  else if ((change & COGL_PIPELINE_STATE_ALPHA_FUNC_REFERENCE))
    {
      CoglPipelineProgendPrivate *priv = get_glsl_priv (pipeline);
      if (priv)
        priv->dirty_alpha_test_reference = TRUE;
    }
  else if ((change & COGL_PIPELINE_STATE_POINT_SIZE))
    {
      CoglPipelineProgendPrivate *priv = get_glsl_priv (pipeline);
      if (priv)
        priv->dirty_point_size = TRUE;
    }
#endif /* HAVE_COGL_GLES2 */
}

/* NB: layers are considered immutable once they have any dependants
 * so although multiple pipelines can end up depending on a single
 * static layer, we can guarantee that if a layer is being *changed*
 * then it can only have one pipeline depending on it.
 *
 * XXX: Don't forget this is *pre* change, we can't read the new value
 * yet!
 */
static void
_cogl_pipeline_progend_glsl_layer_pre_change_notify (
                                                CoglPipeline *owner,
                                                CoglPipelineLayer *layer,
                                                CoglPipelineLayerState change)
{
  if ((change & COGL_PIPELINE_LAYER_STATE_AFFECTS_FRAGMENT_CODEGEN))
    {
      dirty_glsl_program_state (owner);
      return;
    }

  if (change & COGL_PIPELINE_LAYER_STATE_COMBINE_CONSTANT)
    {
      CoglPipelineProgendPrivate *priv = get_glsl_priv (owner);
      if (priv)
        {
          int unit_index = _cogl_pipeline_layer_get_unit_index (layer);
          priv->unit_state[unit_index].dirty_combine_constant = TRUE;
        }
    }
}

const CoglPipelineProgend _cogl_pipeline_glsl_progend =
  {
    _cogl_pipeline_progend_glsl_end,
    _cogl_pipeline_progend_glsl_pre_change_notify,
    _cogl_pipeline_progend_glsl_layer_pre_change_notify
  };

#endif /* COGL_PIPELINE_PROGEND_GLSL */