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

#include "scheme.h"

#include "../any_log.h"

char *str_replace(char *orig, char *rep, char *with) {
    char *result; // the return string
    char *ins;    // the next insert point
    char *tmp;    // varies
    int len_rep;  // length of rep (the string to remove)
    int len_with; // length of with (the string to replace rep with)
    int len_front; // distance between rep and end of last rep
    int count;    // number of replacements

    // sanity checks and initialization
    if (!orig || !rep)
        return NULL;
    len_rep = strlen(rep);
    if (len_rep == 0)
        return NULL; // empty rep causes infinite loop during count
    if (!with)
        with = "";
    len_with = strlen(with);

    // count the number of replacements needed
    ins = orig;
    for (count = 0; (tmp = strstr(ins, rep)); ++count) {
        ins = tmp + len_rep;
    }

    tmp = result = malloc(strlen(orig) + (len_with - len_rep) * count + 1);

    if (!result)
        return NULL;

    // first time through the loop, all the variable are set correctly
    // from here on,
    //    tmp points to the end of the result string
    //    ins points to the next occurrence of rep in orig
    //    orig points to the remainder of orig after "end of rep"
    while (count--) {
        ins = strstr(orig, rep);
        len_front = ins - orig;
        tmp = strncpy(tmp, orig, len_front) + len_front;
        tmp = strcpy(tmp, with) + len_with;
        orig += len_front + len_rep; // move to next "end of rep"
    }
    strcpy(tmp, orig);
    return result;
}

static void block_ram_update(block_t *block)
{
    FILE *meminfo = fopen("/proc/meminfo", "rb");
    assert(meminfo != NULL);

    uintmax_t total, unused, buffers, cached;
    assert(5 == fscanf(meminfo,
                       "MemTotal: %ju kB\n"
                       "MemFree: %ju kB\n"
                       "MemAvailable: %ju kB\n"
                       "Buffers: %ju kB\n"
                       "Cached: %ju kB\n",
                       &total, &unused, &buffers, &buffers, &cached));

    int usage = 100 * (total - unused - buffers - cached) / total;
    fclose(meminfo);

    free(block->text.text);

    char str[100];
    sprintf(str, "%d", usage);

    block->text.text = str_replace(block->state, "%{ram}", str);
    assert(block->text.text != NULL);
}

static void block_ram_finalize(block_t *block)
{
    free(block->state);
}

static bool block_ram_validate(block_t *block, const block_scheme_t *scheme)
{
    block->state = block->text.text;
    block->text.text = NULL;

    if (block->state == NULL) {
        log_error("Block '%s' requires key '%s'", block->label, "text");
        return false;
    }

    if (strstr(block->state, "%{ram}") != NULL)
        log_warn("Block '%s' does not have a ram format", block->label);

    return true;
}

const block_scheme_t block_ram_scheme = {
    .name = "ram",
    .block = {
        .type = BLOCK_TEXT,
        .update_interval = {
            .tv_sec = 1,
            .tv_nsec = 0,
        },
        .update_cb = block_ram_update,
        .finalize_cb = block_ram_finalize,
    },
    .size = sizeof(char *),
    .entries = NULL,
    .validate = block_ram_validate,
};