#include <rgl.h>

#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/mman.h>

#define crashErrno() RGL_CRASH(strerror(errno))
#define assertErrno(cond) RGL_ASSERT(cond, strerror(errno))

void BufferAlloc(RGL_Buffer *buf) {
  unsigned int size = buf->width * buf->height * 4;

  buf->data = mmap(NULL, size, PROT_READ | PROT_WRITE,
                   MAP_PRIVATE | MAP_ANONYMOUS, 0, 0);
  assertErrno(buf->data != MAP_FAILED);
}

void BufferDestroy(RGL_Buffer *buf) {
  unsigned int size = buf->width * buf->height * 4;
  if (munmap(buf->data, size) < 0) {
    crashErrno();
  }
}

void ArenaInit(RGL_Arena *arena, unsigned int capacity) {
  if (capacity) {
    arena->capacity = capacity;
  } else {
    arena->capacity = 4096;
  }

  arena->data = mmap(0, arena->capacity, PROT_READ | PROT_WRITE,
                     MAP_PRIVATE | MAP_ANONYMOUS, 0, 0);
  if (arena->data == MAP_FAILED) {
    crashErrno();
  }

  arena->size = 0;
}

void ArenaDestroy(RGL_Arena *arena) {
  if (munmap(arena->data, arena->capacity) < 0) {
    crashErrno();
  }
}

int WritePPM(RGL_Buffer buf, const char *filename) {
  int i;
  FILE *f = fopen(filename, "wb");
  RGL_ASSERT(f, "failed to open file");

  fprintf(f, "P6\n%d %d\n255\n", buf.width, buf.height);

  for (i = 0; i < buf.width * buf.height; ++i) {
    unsigned int pixel = buf.data[i];

    unsigned char r = (pixel >> 16) & 0xFF;
    unsigned char g = (pixel >> 8) & 0xFF;
    unsigned char b = pixel & 0xFF;

    fputc(r, f);
    fputc(g, f);
    fputc(b, f);
  }

  fclose(f);
  return 0;
}