#ifndef ACCENT_H
#define ACCENT_H
#include <stdint.h>
#include <string.h>
#include <sys/mman.h>
#include <sys/stat.h>
#include <fcntl.h>

#define SHMNAME "/breathing_color_shm"
#define SHM_MAGIC 0xBEEFCAFEu
#define SHM_VERSION 1u

typedef struct {
    uint32_t magic;
    uint32_t version;
    volatile uint32_t seq;
    char color[8];
} ColorShm;

static inline ColorShm *
mapaccent(void)
{
    int fd;
    ColorShm *blk;
    if ((fd = shm_open(SHMNAME, O_RDONLY, 0)) < 0)
        return NULL;
    blk = mmap(NULL, sizeof(ColorShm), PROT_READ, MAP_SHARED, fd, 0);
    close(fd);
    if (blk == MAP_FAILED)
        return NULL;
    if (blk->magic != SHM_MAGIC || blk->version != SHM_VERSION) {
        munmap(blk, sizeof(ColorShm));
        return NULL;
    }
    return blk;
}

static inline int
readaccent(ColorShm **blk, char out[8])
{
    uint32_t s1, s2;
    if (!*blk && !(*blk = mapaccent()))
        return 0;
    do {
        s1 = (*blk)->seq;
        memcpy(out, (*blk)->color, 8);
        s2 = (*blk)->seq;
    } while (s1 != s2);
    return out[0] == '#';
}

#endif /* ACCENT_H */