#
# Copyright (C) 2022 Soleta Networks <info@soleta.eu>
#
# This program is free software: you can redistribute it and/or modify it under
# the terms of the GNU Affero General Public License as published by the
# Free Software Foundation; either version 3 of the License, or
# (at your option) any later version.

import os
import logging
import shlex
import subprocess
import json
from src.log import OgError

import fdisk


class ogPartitionData:
    def __init__(self, parttype, fstype, padev, size, partno):
        self.parttype = parttype
        self.fstype = fstype
        self.padev = padev
        self.size = size
        self.partno = partno

class ogDiskData:
    def __init__(self, nsectors, sector_size, label_name):
        self.nsectors = nsectors
        self.sector_size = sector_size
        self.label_name = label_name

def get_partition_data(device):
    res = []
    try:
        cxt = fdisk.Context(device=device, details=True)
    except Exception as e:
        raise OgError(f'Partition query error: {e}') from e

    for i, p in enumerate(cxt.partitions):
        pd = ogPartitionData(
            parttype = cxt.partition_to_string(p, fdisk.FDISK_FIELD_TYPEID),
            fstype = cxt.partition_to_string(p, fdisk.FDISK_FIELD_FSTYPE),
            padev = cxt.partition_to_string(p, fdisk.FDISK_FIELD_DEVICE),
            size = cxt.partition_to_string(p, fdisk.FDISK_FIELD_SIZE),
            partno = p.partno)
        res.append(pd)
    return res

def get_disk_data(device):
    try:
        cxt = fdisk.Context(device=device, details=True)
    except Exception as e:
        raise OgError(f'Partition query error: {e}') from e
    return ogDiskData(
            nsectors = cxt.nsectors,
            sector_size = cxt.sector_size,
            label_name = cxt.label.name if cxt.label else "")

def get_disks():
    """
    Walks /sys/block/ and returns files starting with 'sd',
    'nvme' or 'vd'
    """
    return sorted([ dev for dev in os.listdir('/sys/block/')
                    if dev.startswith('sd')
                    or dev.startswith('nvme')
                    or dev.startswith('vd')])


def get_partition_device(disknum, partnum):
    """
    Returns the device path, given a disk and partition number
    """
    disk_index = disknum - 1
    if disk_index < 0 or disk_index >= len(get_disks()):
        raise OgError(f'Invalid disk number {disknum}, {len(get_disks())} disks available.')

    disk = get_disks()[disk_index]
    cxt = fdisk.Context(f'/dev/{disk}')

    for pa in cxt.partitions:
        if pa.partno == partnum - 1:
            return cxt.partition_to_string(pa, fdisk.FDISK_FIELD_DEVICE)

    raise OgError(f'No such partition with disk index {disknum} and partition index {partnum}')


def get_efi_partition(disknum, enforce_gpt):
    """
    Look for an EFI System Partition at the n-th disk. If disknum is invalid an
    exception is thrown.
    If enforce_gpt is set to True the ESP will be ignored in a MBR partition
    scheme.

    Returns tuple with:
        - Device name containing the ESP
        - /dev/{device} string
        - Partition number (starting at 1)
    """
    disk_index = disknum - 1
    if disk_index < 0 or disk_index >= len(get_disks()):
        raise OgError(f'Invalid disk number {disknum} when trying to find EFI partition, {len(get_disks())} disks available.')

    disk = get_disks()[disk_index]
    cxt = fdisk.Context(f'/dev/{disk}')

    if enforce_gpt and cxt.label == fdisk.FDISK_DISKLABEL_DOS:
        raise OgError(f'Windows EFI partition requires GPT partition scheme, but /dev/{disk} has DOS partition scheme')

    logging.info('Searching EFI partition...')
    for pa in cxt.partitions:
        if pa.type.name == 'EFI System':
            logging.info(f'EFI partition found at /dev/{disk}')
            return cxt.partition_to_string(pa, fdisk.FDISK_FIELD_DEVICE), f'/dev/{disk}', pa.partno + 1
    raise OgError(f'Cannot find EFI partition at /dev/{disk}')


def get_partition_id(disk_index, part_index):
    device = get_partition_device(disk_index, part_index)
    cmd = f'blkid -s PARTUUID -o value {device}'
    proc = subprocess.run(shlex.split(cmd),
                          stdout=subprocess.PIPE,
                          encoding='utf-8')
    if proc.returncode != 0:
            raise OgError(f'failed to query partition UUID for {device}')
    return proc.stdout.strip()


def get_disk_id(disk_index):
    disk = get_disks()[disk_index - 1]
    disk_path = f'/dev/{disk}'
    cmd = f'blkid -s PTUUID -o value {disk_path}'
    proc = subprocess.run(shlex.split(cmd),
                          stdout=subprocess.PIPE,
                          encoding='utf-8')
    if proc.returncode != 0:
            raise OgError(f'failed to query disk UUID for {disk_path}')
    return proc.stdout.strip()


def get_filesystem_id(disk_index, part_index):
    device = get_partition_device(disk_index, part_index)
    cmd = f'blkid -s UUID -o value {device}'
    proc = subprocess.run(shlex.split(cmd),
                          stdout=subprocess.PIPE,
                          encoding='utf-8')
    if proc.returncode != 0:
            raise OgError(f'failed to query filesystem UUID for {device}')
    return proc.stdout.strip()


def get_sector_size(disk):
    disk_index = disk - 1

    if disk_index < 0 or disk_index >= len(get_disks()):
        raise OgError(f'Invalid disk number {disk} when trying to find ESP, {len(get_disks())} disks available.')

    device_name = get_disks()[disk_index]
    file_path = f'/sys/class/block/{device_name}/queue/hw_sector_size'

    try:
        with open(file_path, 'r') as f:
            data = f.read().strip()
    except OSError as e:
        raise OgError(f'Error while trying to read {file_path}: {e}') from e
    return int(data)


def get_partition_start_offset(disk, partition):
    disk_name = get_disks()[disk - 1]
    disk_path = f'/dev/{disk_name}'
    part_number = partition - 1

    cmd = f'sfdisk -J {disk_path}'
    proc = subprocess.run(shlex.split(cmd), capture_output=True, text=True)

    if proc.returncode != 0:
        raise OgError(f'Failed to query sfdisk')

    try:
        part_data_json = json.loads(proc.stdout)
    except json.JSONDecodeError as e:
        raise OgError(f'Invalid sfdisk output: {e}') from e

    try:
        part_data = part_data_json['partitiontable']['partitions']
        start_offset = part_data[part_number]['start']
    except KeyError as e:
        raise OgError(f'Error while trying to parse sfdisk: {e}') from e

    return start_offset