#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>  // This gives us sized types
#include <stdbool.h>
#include <assert.h>

#define NB_NODES 4

bool add_file(uint64_t* inodes, int file_size, char name[7]) {
    // We only have 7 bits for the file size, so it can't be bigger
    if (file_size > 0x7f || file_size < 0) {
        return false;
    }

    for (int i = 0; i < NB_NODES; i++) {
        bool is_taken = ((inodes[i] >> (7*8)) & 0x8) > 0;

        if (!is_taken) {
            // Set highest bit
            inodes[i] = ((uint64_t) file_size | 0x80) << (7*8);

            // Set name byte by byte
            for (int ii = 0; ii < 7; ii++) {
                inodes[i] |= (((uint64_t) name[ii]) & 0xff) << (ii*8);
            }
            return true;
        }
    }

    return false;
}

void printd_inodes(uint64_t* inodes) {
    printf("Debug with name: ");

    for (int i = 0; i < NB_NODES; i++) {
        for (int ii = 0; ii < 7; ii++) {
            // Get character out
            printf("%c", (uint8_t) ((inodes[i] >> (ii*8)) & 0xff));
        }

        printf(" %02x", (uint8_t) (inodes[i] >> (7*8)));

        if (i == NB_NODES - 1) {
            printf("\n");
        } else {
            printf(" ");
        }
    }
}

int main(void) {
    // Use bottom 8 bits for file size (7 bits) and occupied indicator (1 bit)
    // Use top 56 bits for 7 character name
    uint64_t* inodes = calloc(NB_NODES, sizeof(uint64_t));

    printd_inodes(inodes);

    add_file(inodes, 8, "one\0\0\0");
    printd_inodes(inodes);

    add_file(inodes, 12, "two\0\0\0");
    printd_inodes(inodes);

    assert(add_file(inodes, 121, "another"));
    printd_inodes(inodes);

    add_file(inodes, 127, "four\0\0");
    printd_inodes(inodes);

    FILE* f = fopen("bits.out", "wb");
    fwrite(inodes, sizeof(uint64_t), NB_NODES, f);
    fclose(f);

    free(inodes);
}