/*
 * VDF support routines for PhysicsFS.
 *
 * This driver handles Gothic I/II VDF archives.
 * This format (but not this driver) was designed by Piranha Bytes for
 *  use wih the ZenGin engine.
 *
 * This file was written by Francesco Bertolaccini, based on the UNPK archiver
 *  by Ryan C. Gordon and the works of degenerated1123 and Nico Bendlin.
 */

#define __PHYSICSFS_INTERNAL__
#include "physfs_internal.h"

#if PHYSFS_SUPPORTS_VDF

#include <time.h>

#define VDF_COMMENT_LENGTH 256
#define VDF_SIGNATURE_LENGTH 16
#define VDF_ENTRY_NAME_LENGTH 64

static const char* VDF_SIGNATURE_G1 = "PSVDSC_V2.00\r\n\r\n";
static const char* VDF_SIGNATURE_G2 = "PSVDSC_V2.00\n\r\n\r";


static inline int readui32(PHYSFS_Io *io, PHYSFS_uint32 *val)
{
    PHYSFS_uint32 v;
    BAIL_IF_ERRPASS(!__PHYSFS_readAll(io, &v, sizeof (v)), 0);
    *val = PHYSFS_swapULE32(v);
    return 1;
} /* readui32 */


static PHYSFS_sint64 vdfDosTimeToEpoch(const PHYSFS_uint32 dostime)
{
    /* VDF stores timestamps as 32bit DOS dates: the seconds are counted in
       2-seconds intervals and the years are counted since 1 Jan. 1980 */
    struct tm t;
    memset(&t, '\0', sizeof (t));
    t.tm_year = ((int) ((dostime >> 25) & 0x7F)) + 80; /* 1980 to 1900 */
    t.tm_mon = ((int) ((dostime >> 21) & 0xF)) - 1;  /* 1-12 to 0-11 */
    t.tm_mday = (int) ((dostime >> 16) & 0x1F);
    t.tm_hour = (int) ((dostime >> 11) & 0x1F);
    t.tm_min = (int) ((dostime >> 5) & 0x3F);
    t.tm_sec = ((int) ((dostime >> 0) & 0x1F)) * 2;  /* 2 seconds to 1. */
    return (PHYSFS_sint64) mktime(&t);
} /* vdfDosTimeToEpoch */


static int vdfLoadEntries(PHYSFS_Io *io, const PHYSFS_uint32 count,
                          const PHYSFS_sint64 ts, void *arc)
{
    PHYSFS_uint32 i;

    for (i = 0; i < count; i++)
    {
        char name[VDF_ENTRY_NAME_LENGTH + 1];
        int namei;
        PHYSFS_uint32 jump, size, type, attr;

        BAIL_IF_ERRPASS(!__PHYSFS_readAll(io, name, sizeof (name) - 1), 0);
        BAIL_IF_ERRPASS(!readui32(io, &jump), 0);
        BAIL_IF_ERRPASS(!readui32(io, &size), 0);
        BAIL_IF_ERRPASS(!readui32(io, &type), 0);
        BAIL_IF_ERRPASS(!readui32(io, &attr), 0);

        /* Trim whitespace off the end of the filename */
        name[VDF_ENTRY_NAME_LENGTH] = '\0';  /* always null-terminated. */
        for (namei = VDF_ENTRY_NAME_LENGTH - 1; namei >= 0; namei--)
        {
            if (name[namei] == ' ')
                name[namei] = '\0';
            else
                break;
        } /* for */

        BAIL_IF(!name[0], PHYSFS_ERR_CORRUPT, 0);

        /* !!! FIXME: we assume the filenames are low-ASCII; if they use
           any high-ASCII chars, they will be invalid UTF-8. */

        BAIL_IF_ERRPASS(!UNPK_addEntry(arc, name, 0, ts, ts, jump, size), 0);
    } /* for */

    return 1;
} /* vdfLoadEntries */


static void *VDF_openArchive(PHYSFS_Io *io, const char *name, int forWriting)
{
    PHYSFS_uint8 ignore[16];
    PHYSFS_uint8 sig[VDF_SIGNATURE_LENGTH];
    PHYSFS_uint32 count, timestamp, version, dataSize, rootCatOffset;
    void *unpkarc;

    assert(io != NULL); /* shouldn't ever happen. */
    
    BAIL_IF(forWriting, PHYSFS_ERR_READ_ONLY, NULL);

    /* skip the 256-byte comment field. */
    BAIL_IF_ERRPASS(!io->seek(io, VDF_COMMENT_LENGTH), NULL);

    BAIL_IF_ERRPASS(!__PHYSFS_readAll(io, sig, sizeof (sig)), NULL);
    BAIL_IF_ERRPASS(!readui32(io, &count), NULL);
    BAIL_IF_ERRPASS(!__PHYSFS_readAll(io, ignore, 4), NULL);  /* numFiles */
    BAIL_IF_ERRPASS(!readui32(io, &timestamp), NULL);
    BAIL_IF_ERRPASS(!readui32(io, &dataSize), NULL);  /* dataSize */
    BAIL_IF_ERRPASS(!readui32(io, &rootCatOffset), NULL);  /* rootCatOff */
    BAIL_IF_ERRPASS(!readui32(io, &version), NULL);

    BAIL_IF(version != 0x50, PHYSFS_ERR_UNSUPPORTED, NULL);

    if ((memcmp(sig, VDF_SIGNATURE_G1, VDF_SIGNATURE_LENGTH) != 0) &&
        (memcmp(sig, VDF_SIGNATURE_G2, VDF_SIGNATURE_LENGTH) != 0))
    {
        BAIL(PHYSFS_ERR_UNSUPPORTED, NULL);
    } /* if */

    BAIL_IF_ERRPASS(!io->seek(io, rootCatOffset), NULL);

    unpkarc = UNPK_openArchive(io);
    BAIL_IF_ERRPASS(!unpkarc, NULL);

    if (!vdfLoadEntries(io, count, vdfDosTimeToEpoch(timestamp), unpkarc))
    {
        UNPK_abandonArchive(unpkarc);
        return NULL;
    } /* if */

    return unpkarc;
} /* VDF_openArchive */


const PHYSFS_Archiver __PHYSFS_Archiver_VDF =
{
    CURRENT_PHYSFS_ARCHIVER_API_VERSION,
    {
        "VDF",
        "Gothic I/II engine format",
        "Francesco Bertolaccini <bertolaccinifrancesco@gmail.com>",
        "https://github.com/frabert",
        0,  /* supportsSymlinks */
    },
    VDF_openArchive,
    UNPK_enumerateFiles,
    UNPK_openRead,
    UNPK_openWrite,
    UNPK_openAppend,
    UNPK_remove,
    UNPK_mkdir,
    UNPK_stat,
    UNPK_closeArchive
};

#endif /* defined PHYSFS_SUPPORTS_VDF */

/* end of archiver_vdf.c ... */