#include "fsctl/fugue/dirent.h"
#include "fsctl/fugue/cluster.h"
#include "fsctl/fugue/bits/fat.h"

//---
// Internals
//---

/* _fugue_dirent_checksum() : Fugue checksum handling */
static uint8_t _fugue_dirent_checksum(uintptr_t directory)
{
    uint8_t *block;
    uint8_t checksum;
    int a;
    int b;

    checksum = 0;
    block = (void *)directory;
    for (int i = 0 ; i < 11 ; ++i)
    {
        checksum = checksum & 0xff;
        a = checksum / 2;
        b = checksum * 128;
        checksum = a | b;
        checksum = checksum + block[i];
    }
    checksum = checksum & 0xff;
    return checksum;
}

//---
// Public
//---

/* fugue_dirent_dir_fetch() : fetch the current dir blob and walk to next */
void *fugue_dirent_dir_fetch(fugue_dir_t *dirent)
{
    void *dir;

    dir = (void*)dirent->current_dir_addr;
    if (dir == NULL)
        return NULL;

    dirent->current_dir_addr += 32;
    if (dirent->current_dir_addr < dirent->cluster_addr_end)
        return dir;

    dirent->cluster_addr_start = fugue_cluster_find_next(
        &dirent->_private.fs,
        dirent->cluster_idx
    );
    dirent->cluster_addr_end = dirent->cluster_addr_start;
    if (dirent->cluster_addr_start != 0x00000000)
        dirent->cluster_addr_end += dirent->_private.fs.props.cluster_size;
    return dir;
}

/* fugue_dirent_name_fetch() : fetch fragment */
int fugue_dirent_name_fetch(fugue_dir_t *dirent, fugue_file_t *file, void *dir)
{
    struct fugue_fat_dir_name *lfn;

    lfn = (void *)dir;

    //---
    // check directory block validity
    //---

    if (lfn->DIR_Attr != FUGUE_DIR_ATTR_LFN)
        return -1;
    if (lfn->DIR_Type != 0x00)
        return -2;
    if (lfn->DIR_FstClus != 0x0000)
        return -3;
    //TODO : check Secquence validity
    if (lfn->checksum != _fugue_dirent_checksum(dirent->current_dir_addr))
        return -5;

    //---
    // Dump name fragment
    //---

    //TODO: dump
    return -1;
}