/**

 * $Id$

 *

 * VMU volume (ie block device) support

 *

 * Copyright (c) 2009 Nathan Keynes.

 *

 * This program is free software; you can redistribute it and/or modify

 * it under the terms of the GNU General Public License as published by

 * the Free Software Foundation; either version 2 of the License, or

 * (at your option) any later version.

 *

 * This program is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

 * GNU General Public License for more details.

 */

#include <glib/gmem.h>

#include <glib/gstrfuncs.h>

#include <string.h>

#include <unistd.h>

#include <stdio.h>

#include <fcntl.h>

#include <errno.h>

#include "vmu/vmuvol.h"

#include "dream.h"

#include "lxpaths.h"

#define VMU_MAX_PARTITIONS 256

#define VMU_MAX_BLOCKS 65536 /* Actually slightly less than this, but it'll do */

typedef struct vmu_partition {

    struct vmu_volume_metadata metadata;

    uint32_t block_count;

    char *blocks;

} *vmu_partition_t;

struct vmu_volume {

    const gchar *display_name;

    vmu_partnum_t part_count;

    gboolean dirty;

    struct vmu_partition part[0];

};

/* On-VMU structures, courtesy of Marcus Comstedt */ 

struct vmu_superblock {

    char magic[16];

    uint8_t colour_flag;

    uint8_t bgra[4];

    uint8_t pad1[27];

    char timestamp[8];

    char pad2[8];

    char unknown[6];

    uint16_t fat_block;

    uint16_t fat_size;

    uint16_t dir_block;

    uint16_t dir_size;

    uint16_t icon_shape;

    uint16_t user_size;

    /* remainder unknown */

};

struct vmu_direntry {

    uint8_t filetype;

    uint8_t copy_flag;

    uint16_t blkno;

    char filename[12];

    char timestamp[8];

    uint16_t blksize; /* Size in blocks*/

    uint16_t hdroff; /* Header offset in blocks */

    char pad[4];

};

#define MD(vmu,ptno) ((vmu)->part[ptno].metadata)

#define VMU_BLOCK(vmu,ptno,blkno) (&(vmu)->part[ptno].blocks[(blkno)*VMU_BLOCK_SIZE])

#define VMU_FAT_ENTRY(vmu,pt,ent)  ((uint16_t *)VMU_BLOCK(vmu, pt, (MD(vmu,pt).fat_block - ((ent)>>8))))[(ent)&0xFF]

#define FAT_EMPTY 0xFFFC

#define FAT_EOF   0xFFFA

static const struct vmu_volume_metadata default_metadata = { 255, 255, 254, 1, 253, 13, 0, 200, 31, 0, 128 };

vmu_volume_t vmu_volume_new_default( const gchar *display_name )

{

    vmu_volume_t vol = g_malloc0( sizeof(struct vmu_volume) + sizeof(struct vmu_partition) );

    vol->part_count = 1;

    vol->dirty = FALSE;

    memcpy( &vol->part[0].metadata, &default_metadata, sizeof(struct vmu_volume_metadata) );

    vol->part[0].block_count = VMU_DEFAULT_VOL_BLOCKS;

    vol->part[0].blocks = g_malloc0( VMU_DEFAULT_VOL_BLOCKS * VMU_BLOCK_SIZE );

    vol->display_name = display_name == NULL ? NULL : g_strdup(display_name);

    vmu_volume_format( vol, 0, TRUE );

    return vol;

}

void vmu_volume_destroy( vmu_volume_t vol )

{

    int i;

    if( vol == NULL )

        return;

    for( i=0; i<vol->part_count; i++ ) {

        g_free( vol->part[i].blocks );

        vol->part[i].blocks = NULL;

    }

    if( vol->display_name ) {

        g_free( (char *)vol->display_name );

        vol->display_name = NULL;

    }

    g_free(vol);

}

void vmu_volume_format( vmu_volume_t vol, vmu_partnum_t pt, gboolean quick )

{

    if( pt >= vol->part_count ) {

        return;

    }

    if( !quick ) {

        /* Wipe it completely first */

        memset( vol->part[pt].blocks, 0, (vol->part[pt].block_count) * VMU_BLOCK_SIZE );

    }

    struct vmu_volume_metadata *meta = &vol->part[pt].metadata;

    unsigned int fatblkno = meta->fat_block;

    unsigned int dirblkno = meta->dir_block;

    /* Write superblock */

    struct vmu_superblock *super = (struct vmu_superblock *)VMU_BLOCK(vol,pt, meta->super_block);

    memset( super->magic, 0x55, 16 );

    memset( &super->colour_flag, 0, 240 ); /* Blank the rest for now */

    super->fat_block = meta->fat_block;

    super->fat_size = meta->fat_size;

    super->dir_block = meta->dir_block;

    super->user_size = meta->user_size;

    /* Write file allocation tables */

    int i,j;

    for( j=0; j<meta->fat_size; j++ ) {

        uint16_t *fat = (uint16_t *)VMU_BLOCK(vol,pt,fatblkno-j); 

        for( i=0; i<256; i++ ) {

            fat[i] = FAT_EMPTY;

        }

    }

    /* Fill in the system allocations in the FAT */

    for( i=0; i<meta->fat_size-1; i++ ) {

        VMU_FAT_ENTRY(vol,pt,fatblkno-i) = fatblkno-i-1;

    }

    VMU_FAT_ENTRY(vol,pt,fatblkno - i) = FAT_EOF;

    for( i=0; i<meta->dir_size-1; i++ ) {

        VMU_FAT_ENTRY(vol,pt,dirblkno-i) = dirblkno-i-1;

    }

    VMU_FAT_ENTRY(vol,pt,dirblkno-i) = FAT_EOF;

    /* If quick-format, blank the directory. Otherwise it's already been done */

    if( quick ) {

        memset( VMU_BLOCK(vol,pt,dirblkno-meta->dir_size+1),

                0, meta->dir_size * VMU_BLOCK_SIZE );

    }

}

/*************************** File load/save ********************************/

/**

 * Current file has 1 META chunk for all volume metadata, followed by a

 * DATA chunk for each partition's block data. The META chunk is required to

 * occur before any DATA blocks.

 * Unknown chunks are skipped to allow for forwards compatibility if/when

 * we add the VMU runtime side of things

 */

struct vmu_file_header {

    char magic[16];

    uint32_t version;

    uint32_t head_len;

    uint32_t part_count;

    uint32_t display_name_len;

    char display_name[0];

};

struct vmu_chunk_header {

    char name[4];

    uint32_t length;

};

gboolean vmu_volume_save( const gchar *filename, vmu_volume_t vol, gboolean create_only )

{

    struct vmu_file_header head;

    struct vmu_chunk_header chunk;

    int i;

    gchar *tempfile = get_filename_at(filename, ".XXXXXXXX.vmu");

    int fd = mkstemps( tempfile, 4 );

    if( fd == -1 ) {

        g_free(tempfile);

        return FALSE;

    }

    FILE *f = fdopen( fd, "w+" );

    /* File header */

    memcpy( head.magic, VMU_FILE_MAGIC, 16 );

    head.version = VMU_FILE_VERSION;

    head.part_count = vol->part_count;

    head.display_name_len = vol->display_name == NULL ? 0 : (strlen(vol->display_name)+1);

    head.head_len = sizeof(head) + head.display_name_len;

    fwrite( &head, sizeof(head), 1, f );

    if( vol->display_name != NULL ) {

        fwrite( vol->display_name, head.display_name_len, 1, f );

    }

    /* METAdata chunk */

    memcpy( chunk.name, "META", 4 );

    chunk.length = sizeof(struct vmu_volume_metadata) * vol->part_count;

    fwrite( &chunk, sizeof(chunk), 1, f );

    for( i=0; i < vol->part_count; i++ ) {

        fwrite( &vol->part[i].metadata, sizeof(struct vmu_volume_metadata), 1, f );

    }

    /* partition DATA chunks */

    for( i=0; i< vol->part_count; i++ ) {

        memcpy( chunk.name, "DATA", 4 );

        chunk.length = 0;

        if( fwrite( &chunk, sizeof(chunk), 1, f ) != 1 ) goto cleanup;

        long posn = ftell(f);

        if( fwrite( &vol->part[i].block_count, sizeof(vol->part[i].block_count), 1, f ) != 1 ) goto cleanup;

        fwrite_gzip( vol->part[i].blocks, vol->part[i].block_count, VMU_BLOCK_SIZE, f );

        long end = ftell(f);

        fseek( f, posn - sizeof(chunk.length), SEEK_SET );

        chunk.length = end-posn;

        if( fwrite( &chunk.length, sizeof(chunk.length), 1, f ) != 1 ) goto cleanup;

        fseek( f, end, SEEK_SET );

    }

    fclose(f);

    if( rename(tempfile, filename) != 0 )

        goto cleanup;

    /* All good */

    vol->dirty = FALSE;

    g_free(tempfile);

    return TRUE;

cleanup:

    fclose(f);

    unlink(tempfile);

    g_free(tempfile);

    return FALSE;

}

vmu_volume_t vmu_volume_load( const gchar *filename )

{

    struct vmu_file_header head;

    struct vmu_chunk_header chunk;

    vmu_volume_t vol;

    int i;

    FILE *f = fopen( filename, "ro" );

    if( f == NULL ) {

        ERROR( "Unable to open VMU file '%s': %s", filename, strerror(errno) );

        return FALSE;

    }

    if( fread( &head, sizeof(head), 1, f ) != 1 ||

        memcmp(head.magic, VMU_FILE_MAGIC, 16) != 0 ||

        head.part_count > VMU_MAX_PARTITIONS || 

        head.head_len < (sizeof(head) + head.display_name_len) )  {

        fclose(f);

        ERROR( "Unable to load VMU '%s': bad file header", filename );

        return NULL;

    }

    vol = (vmu_volume_t)g_malloc0( sizeof(struct vmu_volume) + sizeof(struct vmu_partition)*head.part_count );

    vol->part_count = head.part_count;

    vol->dirty = FALSE;

    if( head.display_name_len != 0 ) {

        vol->display_name = g_malloc( head.display_name_len );

        fread( (char *)vol->display_name, head.display_name_len, 1, f );

    }

    fseek( f, head.head_len, SEEK_SET );

    gboolean have_meta = FALSE;

    int next_part = 0;

    while( !feof(f) && fread( &chunk, sizeof(chunk), 1, f ) == 1 ) {

        if( memcmp( &chunk.name, "META", 4 ) == 0 ) {

            if( have_meta || chunk.length != head.part_count * sizeof(struct vmu_volume_metadata) ) {

                vmu_volume_destroy(vol);

                fclose(f);

                ERROR( "Unable to load VMU '%s': bad metadata size (expected %d but was %d)", filename,

                       head.part_count * sizeof(struct vmu_volume_metadata), chunk.length );

                return NULL;

            }

            for( i=0; i<head.part_count; i++ ) {

                fread( &vol->part[i].metadata, sizeof(struct vmu_volume_metadata), 1, f );

            }

            have_meta = TRUE;

        } else if( memcmp( &chunk.name, "DATA", 4 ) == 0 ) {

            uint32_t block_count;

            fread( &block_count, sizeof(block_count), 1, f );

            if( next_part >= vol->part_count || block_count >= VMU_MAX_BLOCKS ) {

                // Too many partitions / blocks

                vmu_volume_destroy(vol);

                fclose(f);

                ERROR( "Unable to load VMU '%s': too large (%d/%d)", filename, next_part, block_count );

                return NULL;

            }

            vol->part[next_part].block_count = block_count;

            vol->part[next_part].blocks = g_malloc(block_count*VMU_BLOCK_SIZE);

            fread_gzip(vol->part[next_part].blocks, VMU_BLOCK_SIZE, block_count, f );

            next_part++;

        } else {

            // else skip unknown block

            fseek( f, SEEK_CUR, chunk.length );

            WARN( "Unexpected VMU data chunk: '%4.4s'", chunk.name );

        }

    }

    fclose(f);

    if( !have_meta || next_part != vol->part_count ) {

        vmu_volume_destroy( vol );

        return NULL;

    }

    return vol;

}

/*************************** Accessing data ********************************/

const char *vmu_volume_get_display_name( vmu_volume_t vol ) 

{

    return vol->display_name;

}

void vmu_volume_set_display_name( vmu_volume_t vol, const gchar *name )

{

    if( vol->display_name != NULL ) {

        g_free( (char *)vol->display_name );

    }

    if( name == NULL ) {

        vol->display_name = NULL;

    } else {

        vol->display_name = g_strdup(name);

    }

}

gboolean vmu_volume_is_dirty( vmu_volume_t vol )

{

    return vol->dirty;

}

gboolean vmu_volume_read_block( vmu_volume_t vol, vmu_partnum_t pt, unsigned int block, unsigned char *out )

{

    if( pt >= vol->part_count || block >= vol->part[pt].block_count ) {

        return FALSE;

    }

    memcpy( out, VMU_BLOCK(vol,pt,block), VMU_BLOCK_SIZE );

    return TRUE;

}

gboolean vmu_volume_write_block( vmu_volume_t vol, vmu_partnum_t pt, unsigned int block, unsigned char *in )

{

    if( pt >= vol->part_count || block >= vol->part[pt].block_count ) {

        return FALSE;

    }

    memcpy( VMU_BLOCK(vol,pt,block), in, VMU_BLOCK_SIZE );

    vol->dirty = TRUE;

}

gboolean vmu_volume_write_phase( vmu_volume_t vol, vmu_partnum_t pt, unsigned int block, unsigned int phase, unsigned char *in )

{

    if( pt >= vol->part_count || block >= vol->part[pt].block_count || phase >= 4 ) {

        return FALSE;

    }

    memcpy( VMU_BLOCK(vol,pt,block) + (phase*128), in, VMU_BLOCK_SIZE/4 );

    vol->dirty = TRUE;

}

const struct vmu_volume_metadata *vmu_volume_get_metadata( vmu_volume_t vol, vmu_partnum_t partition )

{

    if( partition >= vol->part_count ) {

        return NULL;

    } else {

        return &vol->part[partition].metadata;

    }

}