#include "memory.h"

#include <stdlib.h>
#include <string.h>
#include <stdio.h>
#include <stdbool.h>
#include <inttypes.h>
#include <tgmath.h>

#define FILE_MEMINFO_PATH "/proc/meminfo"

#define VALUE_SIZE 32

struct memory {
    FILE * memfd;
    char value[VALUE_SIZE];
};

struct memory_info {
    unsigned long total;
    unsigned long avaliable;
    unsigned short found;
};

struct memory *
memory_new()
{
    struct memory * m = malloc(sizeof(struct memory));

    m->memfd = fopen(FILE_MEMINFO_PATH, "r");

    return m;
}

void
memory_free(struct memory * m)
{
    free(m);
}

static char *
find_mem_value(char * line, const char * key)
{
    size_t klen = strlen(key);
    if(strncmp(line, key, klen) == 0) {
        return line + klen;
    }
    return NULL;
}

void
memory_update(struct memory * m)
{
    const unsigned short lsize = 512;
    char line[lsize];
    char * val;

    bool found_total = false, found_available = false;
    unsigned long total = 0, available = 0;

    unsigned short percent = 0;

    rewind(m->memfd);
    fflush(m->memfd);

    while((!found_total || !found_available) && !feof(m->memfd)) {
        fgets(line, lsize, m->memfd);

        val = find_mem_value(line, "MemTotal: ");
        if(!found_total && val != NULL) {
            found_total = true;
            total = strtoul(val, NULL, 10);
        }

        val = find_mem_value(line, "MemAvailable: ");
        if(!found_available && val != NULL) {
            found_available = true;
            available = strtoul(val, NULL, 10);
        }
    }

    percent = round((100.0f / total) * (total - available));

    snprintf(m->value, VALUE_SIZE, "\uf538% 4d%%", percent);
}

const char *
memory_get_val(struct memory * m)
{
    return m->value;
}