/*
 * Copyright 2001-2017, Axel Dörfler, axeld@pinc-software.de.
 * Copyright 2020, Shubham Bhagat, shubhambhagat111@yahoo.com
 * All rights reserved. Distributed under the terms of the MIT License.
 */


#include "system_dependencies.h"
#include "Directory.h"
#include "Inode.h"
#include "ShortAttribute.h"
#include "Symlink.h"
#include "Volume.h"

#include <file_systems/fs_ops_support.h>


#define XFS_IO_SIZE     65536

struct identify_cookie {
        XfsSuperBlock super_block;
};

//      #pragma mark - Scanning


static float
xfs_identify_partition(int fd, partition_data *partition, void **_cookie)
{
        XfsSuperBlock superBlock;
        status_t status = Volume::Identify(fd, &superBlock);
        if (status != B_OK)
                return -1;

        identify_cookie* cookie = new identify_cookie;
        memcpy(&cookie->super_block, &superBlock, sizeof(XfsSuperBlock));
        *_cookie = cookie;

        return 0.8f;
}


static status_t
xfs_scan_partition(int fd, partition_data *partition, void *_cookie)
{
        identify_cookie* cookie = (identify_cookie*)_cookie;

        partition->status = B_PARTITION_VALID;
        partition->flags |= B_PARTITION_FILE_SYSTEM;
        partition->content_size = cookie->super_block.TotalBlocks() * cookie->super_block.BlockSize();
        partition->block_size = cookie->super_block.BlockSize();
        partition->content_name = strdup(cookie->super_block.Name());
        if (partition->content_name == NULL)
                return B_NO_MEMORY;

        return B_OK;
}


static void
xfs_free_identify_partition_cookie(partition_data *partition, void *_cookie)
{
        delete (identify_cookie*)_cookie;
}


//      #pragma mark -


static status_t
xfs_mount(fs_volume *_volume, const char *device, uint32 flags,
        const char *args, ino_t *_rootID)
{
        TRACE("xfs_mount(): Trying to mount\n");

        Volume *volume = new (std::nothrow) Volume(_volume);
        if (volume == NULL)
                return B_NO_MEMORY;

        _volume->private_volume = volume;
        _volume->ops = &gxfsVolumeOps;

        status_t status = volume->Mount(device, flags);
        if (status != B_OK) {
                ERROR("Failed mounting the volume. Error: %s\n", strerror(status));
                delete volume;
                _volume->private_volume = NULL;
                return status;
        }

        *_rootID = volume->Root();
        return B_OK;
}


static status_t
xfs_unmount(fs_volume *_volume)
{
        Volume* volume = (Volume*) _volume->private_volume;

        status_t status = volume->Unmount();
        delete volume;
        TRACE("xfs_unmount(): Deleted volume");
        return status;
}


static status_t
xfs_read_fs_info(fs_volume *_volume, struct fs_info *info)
{
        TRACE("XFS_READ_FS_INFO:\n");
        Volume* volume = (Volume*)_volume->private_volume;

        info->flags = B_FS_IS_READONLY
                                        | B_FS_HAS_ATTR | B_FS_IS_PERSISTENT;

        info->io_size = XFS_IO_SIZE;
        info->block_size = volume->SuperBlock().BlockSize();
        info->total_blocks = volume->SuperBlock().TotalBlocks();
        info->free_blocks = volume->SuperBlock().FreeBlocks();

        // Volume name
        strlcpy(info->volume_name, volume->Name(), sizeof(info->volume_name));

        // Filesystem name
        if(volume->IsVersion5())
                strlcpy(info->fsh_name, "xfs V5", sizeof(info->fsh_name));
        else
                strlcpy(info->fsh_name, "xfs V4", sizeof(info->fsh_name));

        return B_OK;
}


//      #pragma mark -


static status_t
xfs_get_vnode(fs_volume *_volume, ino_t id, fs_vnode *_node, int *_type,
        uint32 *_flags, bool reenter)
{
        TRACE("XFS_GET_VNODE:\n");
        Volume* volume = (Volume*)_volume->private_volume;

        Inode* inode = new(std::nothrow) Inode(volume, id);
        if (inode == NULL)
                return B_NO_MEMORY;

        status_t status = inode->Init();
        if (status != B_OK) {
                delete inode;
                ERROR("get_vnode: InitCheck() failed. Error: %s\n", strerror(status));
                return B_NO_INIT;
        }

        _node->private_node = inode;
        _node->ops = &gxfsVnodeOps;
        *_type = inode->Mode();
        *_flags = 0;
        TRACE("(%ld)\n", inode->ID());
        return B_OK;
}


static status_t
xfs_put_vnode(fs_volume *_volume, fs_vnode *_node, bool reenter)
{
        TRACE("XFS_PUT_VNODE:\n");
        delete (Inode*)_node->private_node;
        return B_OK;
}


static bool
xfs_can_page(fs_volume *_volume, fs_vnode *_node, void *_cookie)
{
        return B_NOT_SUPPORTED;
}


static status_t
xfs_read_pages(fs_volume *_volume, fs_vnode *_node, void *_cookie,
        off_t pos, const iovec *vecs, size_t count, size_t *_numBytes)
{
        return B_NOT_SUPPORTED;
}


static status_t
xfs_io(fs_volume *_volume, fs_vnode *_node, void *_cookie,
        io_request *request)
{
        return B_NOT_SUPPORTED;
}


static status_t
xfs_get_file_map(fs_volume *_volume, fs_vnode *_node, off_t offset,
        size_t size, struct file_io_vec *vecs, size_t *_count)
{
        return B_NOT_SUPPORTED;
}


//      #pragma mark -


static status_t
xfs_lookup(fs_volume *_volume, fs_vnode *_directory, const char *name,
        ino_t *_vnodeID)
{
        TRACE("XFS_LOOKUP: %p (%s)\n", name, name);
        Volume* volume = (Volume*)_volume->private_volume;
        Inode* directory = (Inode*)_directory->private_node;

        if (!directory->IsDirectory())
                return B_NOT_A_DIRECTORY;

        status_t status = directory->CheckPermissions(X_OK);
        if (status < B_OK)
                return status;

        DirectoryIterator* iterator = DirectoryIterator::Init(directory);
        if (iterator == NULL)
                return B_BAD_VALUE;

        status = iterator->Lookup(name, strlen(name), (xfs_ino_t*)_vnodeID);
        if (status != B_OK) {
                delete iterator;
                return status;
        }

        TRACE("XFS_LOOKUP: ID: (%ld)\n", *_vnodeID);
        status = get_vnode(volume->FSVolume(), *_vnodeID, NULL);
        TRACE("get_vnode status: (%d)\n", status);
        return status;
}


static status_t
xfs_ioctl(fs_volume *_volume, fs_vnode *_node, void *_cookie, uint32 cmd,
        void *buffer, size_t bufferLength)
{
        return B_NOT_SUPPORTED;
}


static status_t
xfs_read_stat(fs_volume *_volume, fs_vnode *_node, struct stat *stat)
{
        Inode* inode = (Inode*)_node->private_node;
        TRACE("XFS_READ_STAT: id: (%ld)\n", inode->ID());
        stat->st_dev = inode->GetVolume()->ID();
        stat->st_ino = inode->ID();
        stat->st_nlink = 1;
        stat->st_blksize = XFS_IO_SIZE;

        stat->st_uid = inode->UserId();
        stat->st_gid = inode->GroupId();
        stat->st_mode = inode->Mode();
        stat->st_type = 0;      // TODO

        stat->st_size = inode->Size();
        stat->st_blocks = inode->BlockCount();

        inode->GetAccessTime(stat->st_atim);
        inode->GetModificationTime(stat->st_mtim);
        inode->GetChangeTime(stat->st_ctim);

        // Only version 3 Inodes has creation time
        if(inode->Version() == 3)
                inode->GetCreationTime(stat->st_crtim);
        else
                inode->GetChangeTime(stat->st_crtim);

        return B_OK;
}


static status_t
xfs_open(fs_volume * /*_volume*/, fs_vnode *_node, int openMode,
        void **_cookie)
{
        TRACE("XFS_OPEN:\n");
        Inode* inode = (Inode*)_node->private_node;

        // opening a directory read-only is allowed, although you can't read
        // any data from it.
        if (inode->IsDirectory() && (openMode & O_RWMASK) != 0)
                return B_IS_A_DIRECTORY;

        status_t status =  inode->CheckPermissions(open_mode_to_access(openMode));
        if (status != B_OK)
                return status;

        // Prepare the cookie
        file_cookie* cookie = new(std::nothrow) file_cookie;
        if (cookie == NULL)
                return B_NO_MEMORY;
        ObjectDeleter<file_cookie> cookieDeleter(cookie);

        cookie->open_mode = openMode & XFS_OPEN_MODE_USER_MASK;
        cookie->last_size = inode->Size();
        cookie->last_notification = system_time();

        cookieDeleter.Detach();
        *_cookie = cookie;

        return B_OK;
}


static status_t
xfs_read(fs_volume *_volume, fs_vnode *_node, void *_cookie, off_t pos,
        void *buffer, size_t *_length)
{
        TRACE("Inode::ReadAt: pos:(%ld), *length:(%ld)\n", pos, *_length);
        Inode* inode = (Inode*)_node->private_node;

        if (!inode->IsFile()) {
                *_length = 0;
                return inode->IsDirectory() ? B_IS_A_DIRECTORY : B_BAD_VALUE;
        }

        return inode->ReadAt(pos, (uint8*)buffer, _length);
}


static status_t
xfs_close(fs_volume *_volume, fs_vnode *_node, void *_cookie)
{
        return B_OK;
}


static status_t
xfs_free_cookie(fs_volume *_volume, fs_vnode *_node, void *_cookie)
{
        TRACE("XFS_FREE_COOKIE:\n");
        file_cookie* cookie = (file_cookie*)_cookie;
        Volume* volume = (Volume*)_volume->private_volume;
        Inode* inode = (Inode*)_node->private_node;

        if (inode->Size() != cookie->last_size)
                notify_stat_changed(volume->ID(), -1, inode->ID(), B_STAT_SIZE);

        delete cookie;
        return B_OK;
}


static status_t
xfs_access(fs_volume *_volume, fs_vnode *_node, int accessMode)
{
        Inode* inode = (Inode*)_node->private_node;
        return inode->CheckPermissions(accessMode);
}


static status_t
xfs_read_link(fs_volume *_volume, fs_vnode *_node, char *buffer,
        size_t *_bufferSize)
{
        TRACE("XFS_READ_SYMLINK\n");

        Inode* inode = (Inode*)_node->private_node;

        if (!inode->IsSymLink())
                return B_BAD_VALUE;

        Symlink symlink(inode);

        status_t result = symlink.ReadLink(0, buffer, _bufferSize);

        return result;
}


status_t
xfs_unlink(fs_volume *_volume, fs_vnode *_directory, const char *name)
{
        return B_NOT_SUPPORTED;
}


//      #pragma mark - Directory functions


static status_t
xfs_create_dir(fs_volume *_volume, fs_vnode *_directory, const char *name,
        int mode)
{
        return B_NOT_SUPPORTED;
}


static status_t
xfs_remove_dir(fs_volume *_volume, fs_vnode *_directory, const char *name)
{
        return B_NOT_SUPPORTED;
}


static status_t
xfs_open_dir(fs_volume * /*_volume*/, fs_vnode *_node, void **_cookie)
{
        Inode* inode = (Inode*)_node->private_node;
        TRACE("XFS_OPEN_DIR: (%ld)\n", inode->ID());

        status_t status = inode->CheckPermissions(R_OK);
        if (status < B_OK)
                return status;

        if (!inode->IsDirectory())
                return B_NOT_A_DIRECTORY;

        DirectoryIterator* iterator = DirectoryIterator::Init(inode);
        if (iterator == NULL)
                return B_BAD_VALUE;

        *_cookie = iterator;
        return status;
}


static status_t
xfs_read_dir(fs_volume *_volume, fs_vnode *_node, void *_cookie,
        struct dirent *buffer, size_t bufferSize, uint32 *_num)
{
        TRACE("XFS_READ_DIR\n");
        DirectoryIterator* iterator = (DirectoryIterator*)_cookie;
        Volume* volume = (Volume*)_volume->private_volume;

        uint32 maxCount = *_num;
        uint32 count = 0;

        while (count < maxCount && (bufferSize > sizeof(struct dirent))) {
                size_t length = bufferSize - sizeof(struct dirent);
                xfs_ino_t ino;

                status_t status = iterator->GetNext(buffer->d_name, &length, &ino);
                if (status == B_ENTRY_NOT_FOUND)
                        break;
                if (status == B_BUFFER_OVERFLOW) {
                        if (count == 0)
                                return status;
                        break;
                }
                if (status != B_OK)
                        return status;

                buffer->d_dev = volume->ID();
                buffer->d_ino = ino;

                buffer = next_dirent(buffer, length, bufferSize);
                count++;
        }

        *_num = count;
        TRACE("Count: (%d)\n", count);
        return B_OK;
}


static status_t
xfs_rewind_dir(fs_volume * /*_volume*/, fs_vnode * /*node*/, void *_cookie)
{
        DirectoryIterator* iterator = (DirectoryIterator*)_cookie;
        return iterator->Rewind();
}


static status_t
xfs_close_dir(fs_volume * /*_volume*/, fs_vnode * /*node*/,
        void * /*_cookie*/)
{
        return B_OK;
}


static status_t
xfs_free_dir_cookie(fs_volume *_volume, fs_vnode *_node, void *_cookie)
{
        delete (DirectoryIterator*)_cookie;
        return B_OK;
}


static status_t
xfs_open_attr_dir(fs_volume *_volume, fs_vnode *_node, void **_cookie)
{
        Inode* inode = (Inode*)_node->private_node;
        TRACE("%s()\n", __FUNCTION__);

        Attribute* iterator = Attribute::Init(inode);
        if (iterator == NULL)
                return B_BAD_VALUE;

        *_cookie = iterator;
        return B_OK;
}


static status_t
xfs_close_attr_dir(fs_volume *_volume, fs_vnode *_node, void *cookie)
{
        TRACE("%s()\n", __FUNCTION__);
        return B_OK;
}


static status_t
xfs_free_attr_dir_cookie(fs_volume *_volume, fs_vnode *_node, void *_cookie)
{
        delete (Attribute*)_cookie;
        return B_OK;
}


static status_t
xfs_read_attr_dir(fs_volume *_volume, fs_vnode *_node,
        void *_cookie, struct dirent *dirent, size_t bufferSize, uint32 *_num)
{
        TRACE("%s()\n", __FUNCTION__);
        Attribute* iterator = (Attribute*)_cookie;

        size_t length = bufferSize;
        status_t status = iterator->GetNext(dirent->d_name, &length);
        if (status == B_ENTRY_NOT_FOUND) {
                *_num = 0;
                return B_OK;
        }

        if (status != B_OK)
                return status;

        Volume* volume = (Volume*)_volume->private_volume;
        Inode* inode = (Inode*)_node->private_node;
        dirent->d_dev = volume->ID();
        dirent->d_ino = inode->ID();
        dirent->d_reclen = offsetof(struct dirent, d_name) + length + 1;
        *_num = 1;

        return B_OK;
}


static status_t
xfs_rewind_attr_dir(fs_volume *_volume, fs_vnode *_node, void *_cookie)
{
        return B_NOT_SUPPORTED;
}


/* attribute operations */
static status_t
xfs_create_attr(fs_volume *_volume, fs_vnode *_node,
        const char *name, uint32 type, int openMode, void **_cookie)
{
        return B_NOT_SUPPORTED;
}


static status_t
xfs_open_attr(fs_volume *_volume, fs_vnode *_node, const char *name,
        int openMode, void **_cookie)
{
        TRACE("%s()\n", __FUNCTION__);

        status_t status;

        Inode* inode = (Inode*)_node->private_node;

        status = inode->CheckPermissions(open_mode_to_access(openMode));
        if (status < B_OK)
                return status;

        Attribute* attribute = Attribute::Init(inode);

        if (attribute == NULL)
                return B_BAD_VALUE;

        status = attribute->Open(name, openMode, (attr_cookie**)_cookie);
        delete attribute;

        return status;
}


static status_t
xfs_close_attr(fs_volume *_volume, fs_vnode *_node,
        void *cookie)
{
        return B_OK;
}


static status_t
xfs_free_attr_cookie(fs_volume *_volume, fs_vnode *_node, void *cookie)
{
        delete (attr_cookie*)cookie;
        return B_OK;
}


static status_t
xfs_read_attr(fs_volume *_volume, fs_vnode *_node, void *_cookie,
        off_t pos, void *buffer, size_t *_length)
{
        TRACE("%s()\n", __FUNCTION__);

        attr_cookie* cookie = (attr_cookie*)_cookie;
        Inode* inode = (Inode*)_node->private_node;

        Attribute* attribute = Attribute::Init(inode);

        if (attribute == NULL)
                return B_BAD_VALUE;

        status_t status = attribute->Read(cookie, pos, (uint8*)buffer, _length);
        delete attribute;

        return status;
}


static status_t
xfs_write_attr(fs_volume *_volume, fs_vnode *_node, void *cookie,
        off_t pos, const void *buffer, size_t *length)
{
        return B_NOT_SUPPORTED;
}


static status_t
xfs_read_attr_stat(fs_volume *_volume, fs_vnode *_node,
        void *_cookie, struct stat *stat)
{
        TRACE("%s()\n", __FUNCTION__);

        attr_cookie* cookie = (attr_cookie*)_cookie;
        Inode* inode = (Inode*)_node->private_node;

        Attribute* attribute = Attribute::Init(inode);

        if (attribute == NULL)
                return B_BAD_VALUE;

        status_t status = attribute->Stat(cookie, *stat);
        delete attribute;

        return status;
}


static status_t
xfs_write_attr_stat(fs_volume *_volume, fs_vnode *_node,
        void *cookie, const struct stat *stat, int statMask)
{
        return B_NOT_SUPPORTED;
}


static status_t
xfs_rename_attr(fs_volume *_volume, fs_vnode *fromVnode,
        const char *fromName, fs_vnode *toVnode, const char *toName)
{
        return B_NOT_SUPPORTED;
}


static status_t
xfs_remove_attr(fs_volume *_volume, fs_vnode *vnode,
        const char *name)
{
        return B_NOT_SUPPORTED;
}


static uint32
xfs_get_supported_operations(partition_data *partition, uint32 mask)
{
        return B_NOT_SUPPORTED;
}


static status_t
xfs_initialize(int fd, partition_id partitionID, const char *name,
        const char *parameterString, off_t partitionSize, disk_job_id job)
{
        return B_NOT_SUPPORTED;
}


static status_t
xfs_uninitialize(int fd, partition_id partitionID, off_t partitionSize,
        uint32 blockSize, disk_job_id job)
{
        return B_NOT_SUPPORTED;
}


//      #pragma mark -


static status_t
xfs_std_ops(int32 op, ...)
{
        switch (op)
        {
        case B_MODULE_INIT:
#ifdef XFS_DEBUGGER_COMMANDS
                // Perform nothing at the moment
                // add_debugger_commands();
#endif
                return B_OK;
        case B_MODULE_UNINIT:
#ifdef XFS_DEBUGGER_COMMANDS
                // Perform nothing at the moment
                // remove_debugger_commands();
#endif
                return B_OK;

        default:
                return B_ERROR;
        }
}


fs_volume_ops gxfsVolumeOps = {
        &xfs_unmount,
        &xfs_read_fs_info,
        NULL,                           // write_fs_info()
        NULL,                           // fs_sync,
        &xfs_get_vnode,
};


fs_vnode_ops gxfsVnodeOps = {
        /* vnode operations */
        &xfs_lookup,
        NULL,                           // xfs_get_vnode_name- optional, and we can't do better
                                                // than the fallback implementation, so leave as NULL.
        &xfs_put_vnode,
        NULL,                           // xfs_remove_vnode,

        /* VM file access */
        &xfs_can_page,
        &xfs_read_pages,
        NULL,                           // xfs_write_pages,

        &xfs_io,                        // io()
        NULL,                           // cancel_io()

        &xfs_get_file_map,

        &xfs_ioctl,
        NULL,
        NULL,                           // fs_select
        NULL,                           // fs_deselect
        NULL,                           // fs_fsync,

        &xfs_read_link,
        NULL,                           // fs_create_symlink,

        NULL,                           // fs_link,
        &xfs_unlink,
        NULL,                           // fs_rename,

        &xfs_access,
        &xfs_read_stat,
        NULL,                           // fs_write_stat,
        NULL,                           // fs_preallocate

        /* file operations */
        NULL,                           // fs_create,
        &xfs_open,
        &xfs_close,
        &xfs_free_cookie,
        &xfs_read,
        NULL,                           // fs_write,

        /* directory operations */
        &xfs_create_dir,
        &xfs_remove_dir,
        &xfs_open_dir,
        &xfs_close_dir,
        &xfs_free_dir_cookie,
        &xfs_read_dir,
        &xfs_rewind_dir,

        /* attribute directory operations */
        &xfs_open_attr_dir,
        &xfs_close_attr_dir,
        &xfs_free_attr_dir_cookie,
        &xfs_read_attr_dir,
        &xfs_rewind_attr_dir,

        /* attribute operations */
        &xfs_create_attr,
        &xfs_open_attr,
        &xfs_close_attr,
        &xfs_free_attr_cookie,
        &xfs_read_attr,
        &xfs_write_attr,
        &xfs_read_attr_stat,
        &xfs_write_attr_stat,
        &xfs_rename_attr,
        &xfs_remove_attr,
};


static
file_system_module_info sxfsFileSystem = {
        {
                "file_systems/xfs" B_CURRENT_FS_API_VERSION,
                0,
                xfs_std_ops,
        },

        "xfs",                          // short_name
        "XFS File System",      // pretty_name

        // DDM flags
        0 |B_DISK_SYSTEM_SUPPORTS_INITIALIZING |B_DISK_SYSTEM_SUPPORTS_CONTENT_NAME
        //      | B_DISK_SYSTEM_SUPPORTS_WRITING
        ,

        // scanning
        xfs_identify_partition,
        xfs_scan_partition,
        xfs_free_identify_partition_cookie,
        NULL,                           // free_partition_content_cookie()

        &xfs_mount,

        /* capability querying operations */
        &xfs_get_supported_operations,

        NULL,                           // validate_resize
        NULL,                           // validate_move
        NULL,                           // validate_set_content_name
        NULL,                           // validate_set_content_parameters
        NULL,                           // validate_initialize,

        /* shadow partition modification */
        NULL,                           // shadow_changed

        /* writing */
        NULL,                           // defragment
        NULL,                           // repair
        NULL,                           // resize
        NULL,                           // move
        NULL,                           // set_content_name
        NULL,                           // set_content_parameters
        xfs_initialize,
        xfs_uninitialize};


module_info *modules[] = {
        (module_info *)&sxfsFileSystem,
        NULL,
};