Unpredictable string mutator

// I got so carried away with this thing [http://pastebin.com/EJjVBgwT] that I lost track of what is even going on.
#include <stdio.h>
#include <string.h>

void modify_buffer(char *buffer){
    int i = 1,
        j = 2,
        k = 57;
    char min = ' ',
         max = 'z',
         range = (max - min) - 1;

    while(*buffer){
        *buffer += ++i * strlen(buffer);
        *buffer -= min;
        *buffer += (j * 7) % k;
        *buffer %= range;
        *buffer += min;
        j += strlen(buffer) % 2 == 0 ? 1 : 3;
        k -= k % 3 == 0 ? 1 : 4;
        k += k % 2 == 0 ? 5 : 1;

        while(*buffer < min || *buffer > max)
            *buffer += k;

        buffer++;
    }
}

void parse_args(char **argv, char *buffer){
    while(*argv){
        strncpy(buffer, *argv, 1000);
        modify_buffer(buffer);
        printf("%s ", buffer);
        argv++;
    }

    printf("\n");
}

int main(int argc, char **argv){
    char buffer[1000] = "ABCDEFG";

    if(argv[1]){
        parse_args(argv + 1, buffer);
    } else {
        modify_buffer(buffer);
        printf("%s\n", buffer);
    }

    return 0;
}