// NOTE: get useful debug messages from opengl
// 	https://www.khronos.org/opengl/wiki/Debug_Output

#include <GL/glew.h>

#include "shader.h"


void dumpShader(GLuint prog_id);
void openglDebugCallback(GLenum source,
	GLenum type,
	GLuint id,
	GLenum severity,
	GLsizei length,
	const GLchar* message,
	const void* userParam);


#ifdef GL_DEBUG_IMPLEMENTATION

const char*
glEnumToString(GLenum e)
{
	switch (e) {
		case GL_FLOAT_MAT4: return "GL_FLOAT_MAT4";
		case GL_FLOAT_VEC3: return "GL_FLOAT_VEC3";
		case GL_FLOAT_VEC4: return "GL_FLOAT_VEC4";

		case GL_BYTE: return "GL_BYTE";
		case GL_UNSIGNED_BYTE: return "GL_UNSIGNED_BYTE";
		case GL_SHORT: return "GL_SHORT";
		case GL_UNSIGNED_SHORT: return "GL_UNSIGNED_SHORT";
		case GL_INT: return "GL_INT";
		case GL_UNSIGNED_INT: return "GL_UNSIGNED_INT";
		case GL_FLOAT: return "GL_FLOAT";
		case GL_DOUBLE: return "GL_DOUBLE";

		case GL_ARRAY_BUFFER: return "GL_ARRAY_BUFFER";
		case GL_ELEMENT_ARRAY_BUFFER: return "GL_ELEMENT_ARRAY_BUFFER";
		case GL_UNIFORM_BUFFER: return "GL_UNIFORM_BUFFER";
		case GL_TEXTURE_BUFFER: return "GL_TEXTURE_BUFFER";

		case GL_DEBUG_TYPE_ERROR: return "GL_DEBUG_TYPE_ERROR";
		case GL_DEBUG_TYPE_DEPRECATED_BEHAVIOR:
			return "GL_DEBUG_TYPE_DEPRECATED_BEHAVIOR";
		case GL_DEBUG_TYPE_UNDEFINED_BEHAVIOR:
			return "GL_DEBUG_TYPE_UNDEFINED_BEHAVIOR";
		case GL_DEBUG_TYPE_PORTABILITY: return "GL_DEBUG_TYPE_PORTABILITY";
		case GL_DEBUG_TYPE_PERFORMANCE: return "GL_DEBUG_TYPE_PERFORMANCE";
		case GL_DEBUG_TYPE_MARKER: return "GL_DEBUG_TYPE_MARKER";
		case GL_DEBUG_TYPE_PUSH_GROUP: return "GL_DEBUG_TYPE_PUSH_GROUP";
		case GL_DEBUG_TYPE_POP_GROUP: return "GL_DEBUG_TYPE_POP_GROUP";
		case GL_DEBUG_TYPE_OTHER: return "GL_DEBUG_TYPE_OTHER";

		case GL_DEBUG_SEVERITY_HIGH: return "GL_DEBUG_SEVERITY_HIGH";
		case GL_DEBUG_SEVERITY_MEDIUM: return "GL_DEBUG_SEVERITY_MEDIUM";
		case GL_DEBUG_SEVERITY_LOW: return "GL_DEBUG_SEVERITY_LOW";
		case GL_DEBUG_SEVERITY_NOTIFICATION:
			return "GL_DEBUG_SEVERITY_NOTIFICATION";

		default: return "???";
	}
}

void
openglDebugCallback(GLenum source,
	GLenum type,
	GLuint id,
	GLenum severity,
	GLsizei length,
	const GLchar* message,
	const void* userParam)
{
	// NOTE: filter out notification about using video memory for buffer object
	if (id == 131185)
		return;

	std::cout << "message id: " << id << ", "
		<< ((type == GL_DEBUG_TYPE_ERROR) ? "Error" : "Debug")
		<< (type == GL_DEBUG_TYPE_ERROR ? "** GL Error **" : "")
		<< ", type: " << glEnumToString(type)
		<< ", severity: " << glEnumToString(severity)
		<< ", message: " << message << "\n";
}

void
dumpShader(GLuint prog_id)
{
	printf("------------------------\n");
	printf("%s(), dumping shader info, program id: %d\n",
			__FUNCTION__, prog_id);

	GLint active_uniforms;
	GLint active_uniform_blocks;
	GLint active_attribs;

	// NOTE: unused uniforms/attributes get optimized away
	//	https://www.khronos.org/opengl/wiki/Program_Introspection#Attributes
	glGetProgramiv(prog_id, GL_ACTIVE_UNIFORMS, &active_uniforms);
	glGetProgramiv(prog_id, GL_ACTIVE_UNIFORM_BLOCKS, &active_uniform_blocks);
	glGetProgramiv(prog_id, GL_ACTIVE_ATTRIBUTES, &active_attribs);

	printf("active uniforms: %d\n", active_uniforms);
	printf("active uniform blocks: %d\n", active_uniform_blocks);
	printf("active attributes: %d\n", active_attribs);

	GLchar uni_name[256];
	GLsizei length;
	GLint size;
	GLenum type;

	for (int i = 0; i < active_uniforms; i++) {
		glGetActiveUniform(prog_id, i, sizeof(uni_name),
							&length, &size, &type, uni_name);
		printf("uniform idx: %d, type: %s, name: %s \n",
				i, glEnumToString(type), uni_name);
	}

	for (int i = 0; i < active_attribs; i++) {
		glGetActiveAttrib(prog_id, i, sizeof(uni_name),
							&length, &size, &type, uni_name);
		printf("attribute idx: %d, type: %s, name: %s \n",
				i, glEnumToString(type), uni_name);
	}

	printf("------------------------\n");
}

#endif // ifdef GL_DEBUG_IMPLEMENTATION