# SPDX-License-Identifier:      GPL-2.0+
#
# Copyright (c) 2018, Linaro Limited
# Author: Takahiro Akashi <takahiro.akashi@linaro.org>

"""Helper functions for dealing with filesystems"""

import re
import os
import shutil
from subprocess import call, check_call, check_output, CalledProcessError
from subprocess import DEVNULL
import tempfile

# size_gran (int): Size granularity of file system image in bytes
SIZE_GRAN = 1 << 20


class FsHelper:
    """Creating a filesystem containing test files

    Usage:
        with FsHelper(ubman.config, 'ext4', 10, 'mmc1') as fsh:
            # create files in the self.srcdir directory
            fsh.mk_fs()
            # Now use the filesystem

        # The filesystem and srcdir are erased after the 'with' statement.

        It is also possible to use an existing srcdir:

            with FsHelper(ubman.config, 'fat32', 10, 'usb2') as fsh:
                fsh.srcdir = src_dir
                fsh.mk_fs()
                ...

    Properties:
        fs_img (str): Filename for the filesystem image
    """
    def __init__(self, config, fs_type, size_mb, prefix):
        """Set up a new object

        Args:
            config (u_boot_config): U-Boot configuration
            fs_type (str): File system type: one of ext2, ext3, ext4, vfat,
                fat12, fat16, fat32, exfat, fs_generic (which means vfat)
            size_mb (int): Size of file system in MB
            prefix (str): Prefix string of volume's file name
        """
        if fs_type not in ['fat12', 'fat16', 'fat32', 'vfat',
                          'ext2', 'ext3', 'ext4',
                          'exfat', 'fs_generic']:
            raise ValueError(f"Unsupported filesystem type '{fs_type}'")

        self.config = config
        self.fs_type = fs_type
        self.size_mb = size_mb
        self.prefix = prefix
        self.quiet = True
        self.fs_img = None
        self.tmpdir = None
        self.srcdir = None
        self._do_cleanup = False

    def mk_fs(self):
        """Make a new filesystem and copy in the files"""
        self.setup()
        self._do_cleanup = True
        self.fs_img = mk_fs(self.config, self.fs_type, self.size_mb << 20,
                            self.prefix, self.srcdir, quiet=self.quiet)

    def setup(self):
        """Set up the srcdir ready to receive files"""
        if not self.srcdir:
            if self.config:
                self.srcdir = os.path.join(self.config.persistent_data_dir,
                                           f'{self.prefix}.{self.fs_type}.tmp')
                if os.path.exists(self.srcdir):
                    shutil.rmtree(self.srcdir)
                os.mkdir(self.srcdir)
            else:
                self.tmpdir = tempfile.TemporaryDirectory('fs_helper')
                self.srcdir = self.tmpdir.name

    def cleanup(self):
        """Remove created image"""
        if self.tmpdir:
            self.tmpdir.cleanup()
        if self._do_cleanup:
            os.remove(self.fs_img)

    def __enter__(self):
        self.setup()
        return self

    def __exit__(self, extype, value, traceback):
        self.cleanup()


def mk_fs(config, fs_type, size, prefix, src_dir=None, fs_img=None, quiet=False):
    """Create a file system volume

    Args:
        config (u_boot_config): U-Boot configuration
        fs_type (str): File system type, e.g. 'ext4'
        size (int): Size of file system in bytes
        prefix (str): Prefix string of volume's file name
        src_dir (str): Root directory to use, or None for none
        fs_img (str or None): Leaf filename for image, or None to use a
            default name. The image is always placed under
            persistent_data_dir.
        quiet (bool): Suppress non-error output

    Raises:
        CalledProcessError: if any error occurs when creating the filesystem
    """
    if not fs_img:
        fs_img = f'{prefix}.{fs_type}.img'
    fs_img = os.path.join(config.persistent_data_dir, fs_img)

    if fs_type == 'fat12':
        mkfs_opt = '-F 12'
    elif fs_type == 'fat16':
        mkfs_opt = '-F 16'
    elif fs_type == 'fat32':
        mkfs_opt = '-F 32'
    else:
        mkfs_opt = ''

    if fs_type == 'exfat':
        fs_lnxtype = 'exfat'
    elif re.match('fat', fs_type) or fs_type == 'fs_generic':
        fs_lnxtype = 'vfat'
    else:
        fs_lnxtype = fs_type

    if src_dir:
        if fs_lnxtype == 'ext4':
            mkfs_opt = mkfs_opt + ' -d ' + src_dir
        elif fs_lnxtype != 'vfat' and fs_lnxtype != 'exfat':
            raise ValueError(f'src_dir not implemented for fs {fs_lnxtype}')

    count = (size + SIZE_GRAN - 1) // SIZE_GRAN

    # Some distributions do not add /sbin to the default PATH, where mkfs lives
    if '/sbin' not in os.environ["PATH"].split(os.pathsep):
        os.environ["PATH"] += os.pathsep + '/sbin'

    try:
        check_call(f'rm -f {fs_img}', shell=True)
        check_call(f'truncate -s $(( {SIZE_GRAN} * {count} )) {fs_img}',
                   shell=True)
        check_call(f'mkfs.{fs_lnxtype} {mkfs_opt} {fs_img}', shell=True,
                   stdout=DEVNULL if quiet else None)
        if fs_type == 'ext4':
            sb_content = check_output(f'tune2fs -l {fs_img}',
                                      shell=True).decode()
            if 'metadata_csum' in sb_content:
                check_call(f'tune2fs -O ^metadata_csum {fs_img}', shell=True)
        elif fs_lnxtype == 'vfat' and src_dir:
            flags = f"-smpQ{'' if quiet else 'v'}"
            check_call(f'mcopy -i {fs_img} {flags} {src_dir}/* ::/',
                       shell=True)
        elif fs_lnxtype == 'exfat' and src_dir:
            check_call(f'fattools cp {src_dir}/* {fs_img}', shell=True)
        return fs_img
    except CalledProcessError:
        call(f'rm -f {fs_img}', shell=True)
        raise

def setup_image(ubman, devnum, part_type, img_size=20, second_part=False,
                basename='mmc'):
    """Create a disk image with one or two partitions

    Args:
        ubman (ConsoleBase): Console to use
        devnum (int): Device number to use, e.g. 1
        part_type (int): Partition type, e.g. 0xc for FAT32
        img_size (int): Image size in MiB
        second_part (bool): True to contain a small second partition
        basename (str): Base name to use in the filename, e.g. 'mmc'

    Returns:
        tuple:
            str: Filename of MMC image
            str: Directory name of scratch directory
    """
    fname = os.path.join(ubman.config.source_dir, f'{basename}{devnum}.img')
    mnt = os.path.join(ubman.config.persistent_data_dir, 'scratch')

    spec = f'type={part_type:x}, size={img_size - 2}M, start=1M, bootable'
    if second_part:
        spec += '\ntype=c'

    try:
        check_call(f'mkdir -p {mnt}', shell=True)
        check_call(f'qemu-img create {fname} {img_size}M', shell=True)
        check_call(f'printf "{spec}" | sfdisk {fname}', shell=True)
    except CalledProcessError:
        call(f'rm -f {fname}', shell=True)
        raise

    return fname, mnt

# Just for trying out
if __name__ == "__main__":
    import collections

    CNF= collections.namedtuple('config', 'persistent_data_dir')

    mk_fs(CNF('.'), 'ext4', 0x1000000, 'pref')