// enums with a specified width are a clang C extension & available in C++11
#if defined __clang__ || __cplusplus >= 201103L
#define ENUM_U8 typedef enum : u8 
#define ENUM_U8_END(name) name
#define ENUM_U16 typedef enum : u16
#define ENUM_U16_END(name) name
#else
#define ENUM_U8 enum
#define ENUM_U8_END(name) ; typedef u8 name
#define ENUM_U16 enum
#define ENUM_U16_END(name) ; typedef u16 name
#endif


#ifdef __GNUC__
#define maybe_unused __attribute__((unused))
#else
#define maybe_unused
#endif

typedef void (APIENTRY *GLAttachShader)(GLuint program, GLuint shader);
typedef void (APIENTRY *GLCompileShader)(GLuint shader);
typedef GLuint (APIENTRY *GLCreateProgram)(void);
typedef GLuint (APIENTRY *GLCreateShader)(GLenum shaderType);
typedef void (APIENTRY *GLDeleteProgram)(GLuint program);
typedef void (APIENTRY *GLDeleteShader)(GLuint shader);
typedef GLint (APIENTRY *GLGetAttribLocation)(GLuint program, const char *name);
typedef void (APIENTRY *GLGetProgramInfoLog)(GLuint program, GLsizei maxLength, GLsizei *length, char *infoLog);
typedef void (APIENTRY *GLGetProgramiv)(GLuint program, GLenum pname, GLint *params);
typedef void (APIENTRY *GLGetShaderInfoLog)(GLuint shader, GLsizei maxLength, GLsizei *length, char *infoLog);
typedef void (APIENTRY *GLGetShaderiv)(GLuint shader, GLenum pname, GLint *params);
typedef GLint (APIENTRY *GLGetUniformLocation)(GLuint program, char const *name);
typedef void (APIENTRY *GLLinkProgram)(GLuint program);
typedef void (APIENTRY *GLShaderSource)(GLuint shader, GLsizei count, const char *const *string, const GLint *length);
typedef void (APIENTRY *GLUniform1f)(GLint location, GLfloat v0);
typedef void (APIENTRY *GLUniform2f)(GLint location, GLfloat v0, GLfloat v1);
typedef void (APIENTRY *GLUniform3f)(GLint location, GLfloat v0, GLfloat v1, GLfloat v2);
typedef void (APIENTRY *GLUniform4f)(GLint location, GLfloat v0, GLfloat v1, GLfloat v2, GLfloat v3);
typedef void (APIENTRY *GLUniform1i)(GLint location, GLint v0);
typedef void (APIENTRY *GLUniform2i)(GLint location, GLint v0, GLint v1);
typedef void (APIENTRY *GLUniform3i)(GLint location, GLint v0, GLint v1, GLint v2);
typedef void (APIENTRY *GLUniform4i)(GLint location, GLint v0, GLint v1, GLint v2, GLint v3);
typedef void (APIENTRY *GLUniformMatrix4fv)(GLint location, GLsizei count, GLboolean transpose, const GLfloat *value);
typedef void (APIENTRY *GLUseProgram)(GLuint program);
typedef void (APIENTRY *GLVertexAttrib1f)(GLuint index, GLfloat v0);
typedef void (APIENTRY *GLVertexAttrib2f)(GLuint index, GLfloat v0, GLfloat v1);
typedef void (APIENTRY *GLVertexAttrib3f)(GLuint index, GLfloat v0, GLfloat v1, GLfloat v2);
typedef void (APIENTRY *GLVertexAttrib4f)(GLuint index, GLfloat v0, GLfloat v1, GLfloat v2, GLfloat v3);

typedef struct {
	GLAttachShader AttachShader;
	GLCompileShader CompileShader;
	GLCreateProgram CreateProgram;
	GLCreateShader CreateShader;
	GLDeleteProgram DeleteProgram;
	GLDeleteShader DeleteShader;
	GLGetAttribLocation GetAttribLocation;
	GLGetProgramInfoLog GetProgramInfoLog;
	GLGetProgramiv GetProgramiv;
	GLGetShaderInfoLog GetShaderInfoLog;
	GLGetShaderiv GetShaderiv;
	GLGetUniformLocation GetUniformLocation;
	GLLinkProgram LinkProgram;
	GLShaderSource ShaderSource;
	GLUniform1f Uniform1f;
	GLUniform2f Uniform2f;
	GLUniform3f Uniform3f;
	GLUniform4f Uniform4f;
	GLUniform1i Uniform1i;
	GLUniform2i Uniform2i;
	GLUniform3i Uniform3i;
	GLUniform4i Uniform4i;
	GLUniformMatrix4fv UniformMatrix4fv;
	GLUseProgram UseProgram;
	GLVertexAttrib1f VertexAttrib1f;
	GLVertexAttrib2f VertexAttrib2f;
	GLVertexAttrib3f VertexAttrib3f;
	GLVertexAttrib4f VertexAttrib4f;
} GL;

typedef struct {
	GLuint program;
#if DEBUG
	char vertex_filename[32];
	char fragment_filename[32];
	struct timespec last_modified;
#endif
} ShaderBase;

typedef GLuint VertexAttributeLocation;
typedef GLint UniformLocation;

typedef struct {
	ShaderBase base;
	VertexAttributeLocation vertex_p1, vertex_p2;
	UniformLocation uniform_thickness;
} ShaderPlatform;

typedef struct {
	v2 center;
	float size;
	float angle;
} Platform;

typedef struct {
	bool initialized;
	i32 win_width, win_height; // width,height of window

	GL gl; // gl functions
	ShaderPlatform shader_platform;

	u32 nplatforms;
	Platform platforms[1000];

	u32 tmp_mem_used; // this is not measured in bytes, but in MaxAligns 
#define TMP_MEM_BYTES (4L<<20)
	MaxAlign tmp_mem[TMP_MEM_BYTES / sizeof(MaxAlign)];
#if DEBUG
	u32 magic_number;
	#define MAGIC_NUMBER 0x1234ACAB
#endif
} State;