#ifndef RGL_H
#define RGL_H

#ifdef RGL_DEBUG

static char *ERROR_MESSAGE;

#define RGL_CRASH(text)                                                        \
  do {                                                                         \
    ERROR_MESSAGE = text;                                                      \
    __builtin_trap();                                                          \
  } while (0)

#define RGL_ASSERT(cond, text)                                                 \
  if (!(cond)) {                                                               \
    RGL_CRASH(text);                                                           \
  }

#else

#define RGL_CRASH(text)
#define RGL_ASSERT(cond, text)

#endif

static int RGL_ABS(int n) {
  return n < 0 ? -n : n;
}

/* Memory */

typedef struct {
  unsigned int size;
  unsigned int capacity;

  unsigned char *data;
} RGL_Arena;

void *RGL_ArenaAlloc(RGL_Arena *arena, unsigned int size);

unsigned int RGL_ArenaCheckpoint(RGL_Arena *arena);

void RGL_ArenaRollback(RGL_Arena *arena, unsigned int checkpoint);

void RGL_ArenaReset(RGL_Arena *arena);

/* Math */

typedef unsigned int RGL_Fixed;

#define RGL_SUBPIXEL_SHIFT 8
#define RGL_SUBPIXEL_SCALE 256
#define RGL_SUBPIXEL_MASK 255

static RGL_Fixed RGL_GetFixedI(int x) {
  return (RGL_Fixed)(x << RGL_SUBPIXEL_SHIFT);
}

static RGL_Fixed RGL_GetFixedF(float x) {
  return (RGL_Fixed)(x * RGL_SUBPIXEL_SCALE);
}

static RGL_Fixed RGL_GetFixedD(double x) {
  return (RGL_Fixed)(x * RGL_SUBPIXEL_SCALE);
}

static int RGL_FixedToInt(RGL_Fixed x) {
  return x >> RGL_SUBPIXEL_SHIFT;
}

static RGL_Fixed RGL_FixedMul(RGL_Fixed a, RGL_Fixed b) {
  return (RGL_Fixed)(((long int)a * b) >> RGL_SUBPIXEL_SHIFT);
}

/* Graphics */

typedef unsigned int RGL_Color;

#define RGL_COLOR(a, r, g, b)                                                  \
  ((RGL_Color)((a << 24) | (r << 16) | (g << 8) | b))

typedef struct {
  unsigned int width, height;
  unsigned int *data;
} RGL_Buffer;

typedef struct {
  RGL_Color color;
  unsigned int x, y, width, height;
} RGL_Rectangle;

typedef struct {
  RGL_Fixed x, y;
} RGL_Point;

typedef enum { PathStroke, PathFill } RGL_PathVerb;

typedef struct {
  RGL_PathVerb verb;
  unsigned int size;
  RGL_Color color;
} RGL_PathHeader;

typedef enum {
  Rect,
  Path,
} RGL_CommandType;

typedef struct {
  RGL_CommandType type;
  union {
    RGL_Rectangle rect;
    RGL_PathHeader path;
  } data;
} RGL_Command;

typedef struct {
  RGL_Arena arena;
  unsigned int size;

  RGL_Command *commands;
} RGL_CommandQueue;

typedef struct {
  RGL_Color color;
  RGL_CommandQueue queue;

  RGL_Command *current;
} RGL_Context;

void RGL_Rect(RGL_Context *ctx, unsigned int x, unsigned int y,
              unsigned int width, unsigned int height);

void RGL_BeginPath(RGL_Context *ctx, RGL_PathVerb verb);

void RGL_PathMoveTo(RGL_Context *ctx, int x, int y);

void RGL_EndPath(RGL_Context *ctx);

void RGL_DrawRect(RGL_Buffer *buf, RGL_Command *cmd);

void RGL_DrawStroke(RGL_Buffer *buf, RGL_PathHeader *path, RGL_Point *points);

void RGL_DrawPath(RGL_Buffer *buf, RGL_PathHeader *path, RGL_Point *points);

void RGL_Draw(RGL_Context *ctx, RGL_Buffer *buf);

#endif