#include "config.h"

#include "gskgldeviceprivate.h"

#include "gskdebugprivate.h"
#include "gskgpushaderopprivate.h"
#include "gskglbufferprivate.h"
#include "gskglimageprivate.h"

#include "gdk/gdkdisplayprivate.h"
#include "gdk/gdkglcontextprivate.h"

#include <glib/gi18n-lib.h>

struct _GskGLDevice
{
  GskGpuDevice parent_instance;

  GHashTable *gl_programs;
  const char *version_string;
  GdkGLAPI api;

  guint sampler_ids[GSK_GPU_SAMPLER_N_SAMPLERS];
};

struct _GskGLDeviceClass
{
  GskGpuDeviceClass parent_class;
};

typedef struct _GLProgramKey GLProgramKey;

struct _GLProgramKey
{
  const GskGpuShaderOpClass *op_class;
  GskGpuShaderClip clip;
  guint n_external_textures;
};

G_DEFINE_TYPE (GskGLDevice, gsk_gl_device, GSK_TYPE_GPU_DEVICE)

static guint
gl_program_key_hash (gconstpointer data)
{
  const GLProgramKey *key = data;

  return GPOINTER_TO_UINT (key->op_class) ^
         key->clip ^
         (key->n_external_textures << 24);
}

static gboolean
gl_program_key_equal (gconstpointer a,
                      gconstpointer b)
{
  const GLProgramKey *keya = a;
  const GLProgramKey *keyb = b;

  return keya->op_class == keyb->op_class &&
         keya->clip == keyb->clip && 
         keya->n_external_textures == keyb->n_external_textures;
}

static GskGpuImage *
gsk_gl_device_create_offscreen_image (GskGpuDevice   *device,
                                      gboolean        with_mipmap,
                                      GdkMemoryDepth  depth,
                                      gsize           width,
                                      gsize           height)
{
  GskGLDevice *self = GSK_GL_DEVICE (device);

  return gsk_gl_image_new (self,
                           gdk_memory_depth_get_format (depth),
                           GSK_GPU_IMAGE_RENDERABLE | GSK_GPU_IMAGE_FILTERABLE,
                           width,
                           height);
}

static GskGpuImage *
gsk_gl_device_create_upload_image (GskGpuDevice    *device,
                                   gboolean         with_mipmap,
                                   GdkMemoryFormat  format,
                                   gsize            width,
                                   gsize            height)
{
  GskGLDevice *self = GSK_GL_DEVICE (device);

  return gsk_gl_image_new (self,
                           format,
                           0,
                           width,
                           height);
}

static GskGpuImage *
gsk_gl_device_create_download_image (GskGpuDevice   *device,
                                     GdkMemoryDepth  depth,
                                     gsize           width,
                                     gsize           height)
{
  GskGLDevice *self = GSK_GL_DEVICE (device);

  return gsk_gl_image_new (self,
                           gdk_memory_depth_get_format (depth),
                           GSK_GPU_IMAGE_RENDERABLE,
                           width,
                           height);
}

static GskGpuImage *
gsk_gl_device_create_atlas_image (GskGpuDevice *device,
                                  gsize         width,
                                  gsize         height)
{
  GskGLDevice *self = GSK_GL_DEVICE (device);

  return gsk_gl_image_new (self,
                           GDK_MEMORY_R8G8B8A8_PREMULTIPLIED,
                           GSK_GPU_IMAGE_RENDERABLE,
                           width,
                           height);
}

static void
gsk_gl_device_finalize (GObject *object)
{
  GskGLDevice *self = GSK_GL_DEVICE (object);
  GskGpuDevice *device = GSK_GPU_DEVICE (self);

  g_object_steal_data (G_OBJECT (gsk_gpu_device_get_display (device)), "-gsk-gl-device");

  gdk_gl_context_make_current (gdk_display_get_gl_context (gsk_gpu_device_get_display (device)));

  g_hash_table_unref (self->gl_programs);
  glDeleteSamplers (G_N_ELEMENTS (self->sampler_ids), self->sampler_ids);

  G_OBJECT_CLASS (gsk_gl_device_parent_class)->finalize (object);
}

static void
gsk_gl_device_class_init (GskGLDeviceClass *klass)
{
  GskGpuDeviceClass *gpu_device_class = GSK_GPU_DEVICE_CLASS (klass);
  GObjectClass *object_class = G_OBJECT_CLASS (klass);

  gpu_device_class->create_offscreen_image = gsk_gl_device_create_offscreen_image;
  gpu_device_class->create_atlas_image = gsk_gl_device_create_atlas_image;
  gpu_device_class->create_upload_image = gsk_gl_device_create_upload_image;
  gpu_device_class->create_download_image = gsk_gl_device_create_download_image;

  object_class->finalize = gsk_gl_device_finalize;
}

static void
free_gl_program (gpointer program)
{
  glDeleteProgram (GPOINTER_TO_UINT (program));
}

static void
gsk_gl_device_init (GskGLDevice *self)
{
  self->gl_programs = g_hash_table_new_full (gl_program_key_hash, gl_program_key_equal, g_free, free_gl_program);
}

static void
gsk_gl_device_setup_samplers (GskGLDevice *self)
{
  struct {
    GLuint min_filter;
    GLuint mag_filter;
    GLuint wrap;
  } sampler_flags[GSK_GPU_SAMPLER_N_SAMPLERS] = {
    [GSK_GPU_SAMPLER_DEFAULT] = {
      .min_filter = GL_LINEAR,
      .mag_filter = GL_LINEAR,
      .wrap = GL_CLAMP_TO_EDGE,
    },
    [GSK_GPU_SAMPLER_TRANSPARENT] = {
      .min_filter = GL_LINEAR,
      .mag_filter = GL_LINEAR,
      .wrap = GL_CLAMP_TO_BORDER,
    },
    [GSK_GPU_SAMPLER_REPEAT] = {
      .min_filter = GL_LINEAR,
      .mag_filter = GL_LINEAR,
      .wrap = GL_REPEAT,
    },
    [GSK_GPU_SAMPLER_NEAREST] = {
      .min_filter = GL_NEAREST,
      .mag_filter = GL_NEAREST,
      .wrap = GL_CLAMP_TO_EDGE,
    },
    [GSK_GPU_SAMPLER_MIPMAP_DEFAULT] = {
      .min_filter = GL_LINEAR_MIPMAP_LINEAR,
      .mag_filter = GL_LINEAR,
      .wrap = GL_CLAMP_TO_EDGE,
    }
  };
  guint i;

  glGenSamplers (G_N_ELEMENTS (self->sampler_ids), self->sampler_ids);

  for (i = 0; i < G_N_ELEMENTS (self->sampler_ids); i++)
    {
      glSamplerParameteri (self->sampler_ids[i], GL_TEXTURE_MIN_FILTER, sampler_flags[i].min_filter);
      glSamplerParameteri (self->sampler_ids[i], GL_TEXTURE_MAG_FILTER, sampler_flags[i].mag_filter);
      glSamplerParameteri (self->sampler_ids[i], GL_TEXTURE_WRAP_S, sampler_flags[i].wrap);
      glSamplerParameteri (self->sampler_ids[i], GL_TEXTURE_WRAP_T, sampler_flags[i].wrap);
    }
}

GskGpuDevice *
gsk_gl_device_get_for_display (GdkDisplay  *display,
                               GError     **error)
{
  GskGLDevice *self;
  GdkGLContext *context;
  GLint max_texture_size;

  self = g_object_get_data (G_OBJECT (display), "-gsk-gl-device");
  if (self)
    return GSK_GPU_DEVICE (g_object_ref (self));

  if (!gdk_display_prepare_gl (display, error))
    return NULL;

  context = gdk_display_get_gl_context (display);

  /* GLES 2 is not supported */
  if (!gdk_gl_context_check_version (context, "3.0", "3.0"))
    {
      g_set_error (error, GDK_GL_ERROR, GDK_GL_ERROR_NOT_AVAILABLE,
                   _("OpenGL ES 2.0 is not supported by this renderer."));
      return NULL;
    }

  self = g_object_new (GSK_TYPE_GL_DEVICE, NULL);

  gdk_gl_context_make_current (context);

  glGetIntegerv (GL_MAX_TEXTURE_SIZE, &max_texture_size);
  gsk_gpu_device_setup (GSK_GPU_DEVICE (self), display, max_texture_size);

  self->version_string = gdk_gl_context_get_glsl_version_string (context);
  self->api = gdk_gl_context_get_api (context);
  gsk_gl_device_setup_samplers (self);

  g_object_set_data (G_OBJECT (display), "-gsk-gl-device", self);

  return GSK_GPU_DEVICE (self);
}

static char *
prepend_line_numbers (char *code)
{
  GString *s;
  char *p;
  int line;

  s = g_string_new ("");
  p = code;
  line = 1;
  while (*p)
    {
      char *end = strchr (p, '\n');
      if (end)
        end = end + 1; /* Include newline */
      else
        end = p + strlen (p);

      g_string_append_printf (s, "%3d| ", line++);
      g_string_append_len (s, p, end - p);

      p = end;
    }

  g_free (code);

  return g_string_free (s, FALSE);
}

static gboolean
gsk_gl_device_check_shader_error (int      shader_id,
                                  GError **error)
{
  GLint status;
  GLint log_len;
  GLint code_len;
  char *log;
  char *code;

  glGetShaderiv (shader_id, GL_COMPILE_STATUS, &status);

  if G_LIKELY (status == GL_TRUE)
    return TRUE;

  glGetShaderiv (shader_id, GL_INFO_LOG_LENGTH, &log_len);
  log = g_malloc0 (log_len + 1);
  glGetShaderInfoLog (shader_id, log_len, NULL, log);

  glGetShaderiv (shader_id, GL_SHADER_SOURCE_LENGTH, &code_len);
  code = g_malloc0 (code_len + 1);
  glGetShaderSource (shader_id, code_len, NULL, code);

  code = prepend_line_numbers (code);

  g_set_error (error,
               GDK_GL_ERROR,
               GDK_GL_ERROR_COMPILATION_FAILED,
               "Compilation failure in shader.\n"
               "Source Code:\n"
               "%s\n"
               "\n"
               "Error Message:\n"
               "%s\n"
               "\n",
               code,
               log);

  g_free (code);
  g_free (log);

  return FALSE;
}

static void
print_shader_info (const char *prefix,
                   GLuint      shader_id,
                   const char *name)
{
  if (GSK_DEBUG_CHECK (SHADERS))
    {
      int code_len;

      glGetShaderiv (shader_id, GL_SHADER_SOURCE_LENGTH, &code_len);

      if (code_len > 0)
        {
          char *code;

          code = g_malloc0 (code_len + 1);
          glGetShaderSource (shader_id, code_len, NULL, code);

          code = prepend_line_numbers (code);

          g_message ("%s %d, %s:\n%s",
                     prefix, shader_id,
                     name ? name : "unnamed",
                     code);
          g_free (code);
        }
    }
}

static GLuint
gsk_gl_device_load_shader (GskGLDevice      *self,
                           const char       *program_name,
                           GLenum            shader_type,
                           GskGpuShaderClip  clip,
                           guint             n_external_textures,
                           GError          **error)
{
  GString *preamble;
  char *resource_name;
  GBytes *bytes;
  GLuint shader_id;

  preamble = g_string_new (NULL);

  g_string_append (preamble, self->version_string);
  g_string_append (preamble, "\n");
  if (self->api == GDK_GL_API_GLES)
    {
      if (n_external_textures > 0)
        {
          g_string_append (preamble, "#extension GL_OES_EGL_image_external_essl3 : require\n");
          g_string_append (preamble, "#extension GL_OES_EGL_image_external : require\n");
        }
      g_string_append (preamble, "#define GSK_GLES 1\n");
      g_assert (3 * n_external_textures <= 16);
    }
  else
    {
      g_assert (n_external_textures == 0);
    }

  g_string_append_printf (preamble, "#define N_TEXTURES %u\n", 16 - 3 * n_external_textures);
  g_string_append_printf (preamble, "#define N_EXTERNAL_TEXTURES %u\n", n_external_textures);

  switch (shader_type)
    {
      case GL_VERTEX_SHADER:
        g_string_append (preamble, "#define GSK_VERTEX_SHADER 1\n");
        break;

      case GL_FRAGMENT_SHADER:
        g_string_append (preamble, "#define GSK_FRAGMENT_SHADER 1\n");
        break;

      default:
        g_assert_not_reached ();
        return 0;
    }

  switch (clip)
  {
    case GSK_GPU_SHADER_CLIP_NONE:
      g_string_append (preamble, "#define GSK_SHADER_CLIP GSK_GPU_SHADER_CLIP_NONE\n");
      break;
    case GSK_GPU_SHADER_CLIP_RECT:
      g_string_append (preamble, "#define GSK_SHADER_CLIP GSK_GPU_SHADER_CLIP_RECT\n");
      break;
    case GSK_GPU_SHADER_CLIP_ROUNDED:
      g_string_append (preamble, "#define GSK_SHADER_CLIP GSK_GPU_SHADER_CLIP_ROUNDED\n");
      break;
    default:
      g_assert_not_reached ();
      break;
  }

  resource_name = g_strconcat ("/org/gtk/libgsk/shaders/gl/", program_name, ".glsl", NULL);
  bytes = g_resources_lookup_data (resource_name, 0, error);
  g_free (resource_name);
  if (bytes == NULL)
    return 0;

  shader_id = glCreateShader (shader_type);

  glShaderSource (shader_id,
                  2,
                  (const char *[]) {
                    preamble->str,
                    g_bytes_get_data (bytes, NULL),
                  },
                  NULL);

  g_bytes_unref (bytes);
  g_string_free (preamble, TRUE);

  glCompileShader (shader_id);

  print_shader_info (shader_type == GL_FRAGMENT_SHADER ? "fragment" : "vertex", shader_id, program_name);

  if (!gsk_gl_device_check_shader_error (shader_id, error))
    {
      glDeleteShader (shader_id);
      return 0;
    }

  return shader_id;
}

static GLuint
gsk_gl_device_load_program (GskGLDevice      *self,
                            const char       *program_name,
                            GskGpuShaderClip  clip,
                            guint             n_external_textures,
                            GError          **error)
{
  GLuint vertex_shader_id, fragment_shader_id, program_id;
  GLint link_status;

  vertex_shader_id = gsk_gl_device_load_shader (self, program_name, GL_VERTEX_SHADER, clip, n_external_textures, error);
  if (vertex_shader_id == 0)
    return 0;

  fragment_shader_id = gsk_gl_device_load_shader (self, program_name, GL_FRAGMENT_SHADER, clip, n_external_textures, error);
  if (fragment_shader_id == 0)
    return 0;

  program_id = glCreateProgram ();

  glAttachShader (program_id, vertex_shader_id);
  glAttachShader (program_id, fragment_shader_id);

  glLinkProgram (program_id);

  glGetProgramiv (program_id, GL_LINK_STATUS, &link_status);

  glDetachShader (program_id, vertex_shader_id);
  glDeleteShader (vertex_shader_id);
  glDetachShader (program_id, fragment_shader_id);
  glDeleteShader (fragment_shader_id);

  if (link_status == GL_FALSE)
    {
      char *buffer = NULL;
      int log_len = 0;

      glGetProgramiv (program_id, GL_INFO_LOG_LENGTH, &log_len);

      if (log_len > 0)
        {
          /* log_len includes NULL */
          buffer = g_malloc0 (log_len);
          glGetProgramInfoLog (program_id, log_len, NULL, buffer);
        }

      g_set_error (error,
                   GDK_GL_ERROR,
                   GDK_GL_ERROR_LINK_FAILED,
                   "Linking failure in shader: %s",
                   buffer ? buffer : "");

      g_free (buffer);

      glDeleteProgram (program_id);

      return 0;
    }

  return program_id;
}

void
gsk_gl_device_use_program (GskGLDevice               *self,
                           const GskGpuShaderOpClass *op_class,
                           GskGpuShaderClip           clip,
                           guint                      n_external_textures)
{
  GError *error = NULL;
  GLuint program_id;
  GLProgramKey key = {
    .op_class = op_class,
    .clip = clip,
    .n_external_textures = n_external_textures
  };
  guint i, n_textures;

  program_id = GPOINTER_TO_UINT (g_hash_table_lookup (self->gl_programs, &key));
  if (program_id)
    {
      glUseProgram (program_id);
      return;
    }

  program_id = gsk_gl_device_load_program (self, op_class->shader_name, clip, n_external_textures, &error);
  if (program_id == 0)
    {
      g_critical ("Failed to load shader program: %s", error->message);
      g_clear_error (&error);
      return;
    }
  
  g_hash_table_insert (self->gl_programs, g_memdup (&key, sizeof (GLProgramKey)), GUINT_TO_POINTER (program_id));

  glUseProgram (program_id);

  n_textures = 16 - 3 * n_external_textures;

  for (i = 0; i < n_external_textures; i++)
    {
      char *name = g_strdup_printf ("external_textures[%u]", i);
      glUniform1i (glGetUniformLocation (program_id, name), n_textures + 3 * i);
      g_free (name);
    }

  for (i = 0; i < n_textures; i++)
    {
      char *name = g_strdup_printf ("textures[%u]", i);
      glUniform1i (glGetUniformLocation (program_id, name), i);
      g_free (name);
    }
}

GLuint
gsk_gl_device_get_sampler_id (GskGLDevice   *self,
                              GskGpuSampler  sampler)
{
  g_return_val_if_fail (sampler < G_N_ELEMENTS (self->sampler_ids), 0);

  return self->sampler_ids[sampler];
}

static gboolean
gsk_gl_device_get_format_flags (GskGLDevice      *self,
                                GdkGLContext     *context,
                                GdkMemoryFormat   format,
                                GskGpuImageFlags *out_flags)
{
  GdkGLMemoryFlags gl_flags;

  *out_flags = 0;
  gl_flags = gdk_gl_context_get_format_flags (context, format);

  if (!(gl_flags & GDK_GL_FORMAT_USABLE))
    return FALSE;

  if (gl_flags & GDK_GL_FORMAT_RENDERABLE)
    *out_flags |= GSK_GPU_IMAGE_RENDERABLE;
  else if (gdk_gl_context_get_use_es (context))
    *out_flags |= GSK_GPU_IMAGE_NO_BLIT;
  if (gl_flags & GDK_GL_FORMAT_FILTERABLE)
    *out_flags |= GSK_GPU_IMAGE_FILTERABLE;
  if ((gl_flags & (GDK_GL_FORMAT_RENDERABLE | GDK_GL_FORMAT_FILTERABLE)) == (GDK_GL_FORMAT_RENDERABLE | GDK_GL_FORMAT_FILTERABLE))
    *out_flags |= GSK_GPU_IMAGE_CAN_MIPMAP;

  if (gdk_memory_format_alpha (format) == GDK_MEMORY_ALPHA_STRAIGHT)
    *out_flags |= GSK_GPU_IMAGE_STRAIGHT_ALPHA;

  return TRUE;
}

void
gsk_gl_device_find_gl_format (GskGLDevice      *self,
                              GdkMemoryFormat   format,
                              GskGpuImageFlags  required_flags,
                              GdkMemoryFormat  *out_format,
                              GskGpuImageFlags *out_flags,
                              GLint            *out_gl_internal_format,
                              GLenum           *out_gl_format,
                              GLenum           *out_gl_type,
                              GLint             out_swizzle[4])
{
  GdkGLContext *context = gdk_gl_context_get_current ();
  GskGpuImageFlags flags;
  GdkMemoryFormat alt_format;
  const GdkMemoryFormat *fallbacks;
  gsize i;

  /* First, try the actual format */
  if (gsk_gl_device_get_format_flags (self, context, format, &flags) &&
      ((flags & required_flags) == required_flags))
    {
      *out_format = format;
      *out_flags = flags;
      gdk_memory_format_gl_format (format,
                                   out_gl_internal_format,
                                   out_gl_format,
                                   out_gl_type,
                                   out_swizzle);
      return;
    }

  /* Second, try the potential RGBA format */
  if (gdk_memory_format_gl_rgba_format (format,
                                        &alt_format,
                                        out_gl_internal_format,
                                        out_gl_format,
                                        out_gl_type,
                                        out_swizzle) &&
      gsk_gl_device_get_format_flags (self, context, alt_format, &flags) &&
      ((flags & required_flags) == required_flags))
    {
      *out_format = format;
      *out_flags = flags;
      return;
    }

  /* Next, try the fallbacks */
  fallbacks = gdk_memory_format_get_fallbacks (format);
  for (i = 0; fallbacks[i] != -1; i++)
    {
      if (gsk_gl_device_get_format_flags (self, context, fallbacks[i], &flags) &&
          ((flags & required_flags) == required_flags))
        {
          *out_format = fallbacks[i];
          *out_flags = flags;
          gdk_memory_format_gl_format (fallbacks[i],
                                       out_gl_internal_format,
                                       out_gl_format,
                                       out_gl_type,
                                       out_swizzle);
          return;
        }
    }

  /* fallbacks will always fallback to a supported format */
  g_assert_not_reached ();
}