/*
 *
 * Copyright 2023 Oleg Borodin  <borodin@unix7.org>
 *
 */

#include <stdlib.h>
#include <string.h>
#include <stdio.h>
#include <fcntl.h>

#include <rcache.h>


#define CACHE_INITCAPA 512

rcache_t* rcache_init(rcache_t * cache, int fd) {
    cache->data = malloc(CACHE_INITCAPA);
    if (cache->data == NULL) {
        return NULL;
    }
    cache->wpos = 0;
    cache->rpos = 0;
    cache->capa = CACHE_INITCAPA;
    cache->fd = fd;
    return cache;
}

#define BUFFER_SIZE 1024

char rcache_getc(rcache_t * cache) {
    size_t unread = cache->wpos - cache->rpos;

    if (unread == 0) {
        char* buffer[BUFFER_SIZE];
        size_t rsize = read(cache->fd, buffer, sizeof(buffer));

        if (rsize == 0) {
            return EOF;
        }
        if ((cache->wpos + rsize) > cache->capa) {
            size_t newcapa = cache->capa * 2 + rsize;
            uint8_t* newdata = realloc(cache->data, (size_t)newcapa);

            if (newdata == NULL) {
                return (ssize_t) - 1;
            }
            cache->data = newdata;
            cache->capa = newcapa;
        }
        memcpy(&(cache->data[cache->wpos]), buffer, (size_t)rsize);
        cache->wpos += rsize;
    }
    return (char)cache->data[cache->rpos++];
}


void rcache_destroy(rcache_t * cache) {
    if (cache != NULL) {
        free(cache->data);
    }
}