#!/usr/bin/env python

# RaidGuessFS, a FUSE pseudo-filesystem to guess RAID parameters of a damaged device
# Copyright (C) 2015 Ludovic Pouzenc <ludovic@pouzenc.fr>
#
# This file is part of RaidGuessFS.
#
# RaidGuessFS 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 3 of the License, or
# (at your option) any later version.
#
# RaidGuessFS 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.
#
# You should have received a copy of the GNU General Public License
# along with RaidGuessFS. If not, see <http://www.gnu.org/licenses/>

import os, sys, logging

class MyDisks():
    """Auxiliary class, managing disk layer"""

    def __init__(self, *args, **kwargs):
        self.disks = []
        self.disk_paths = []
        self.disk_count = 0
        self.disks_size = [0]
        self.max_disks = 16

    def get_disk_count(self):
        return self.disk_count

    def set_disks_path(self,disk_path_list):
        """Set the list of real filepath to disks or images and (re)open them"""
        self.disk_paths = disk_path_list

    def set_disk_count(self,new_disk_count):
        """Update the number of attached disks on the fly"""
        self.disk_count = min(new_disk_count,self.max_disks)
        logging.info("MyDisks.set_disk_count(%d) : setting disk_count to %d" % (new_disk_count, self.disk_count))

    def open_disks(self):
        """(re)open all disks"""
        logging.debug("Enter open_disks()")
        for fd in self.disks:
            try:
                fd.close()
            except:
                pass
        self.disks = [ None for d in range(self.disk_count) ]
        self.disks_size = [ 0 for d in range(self.disk_count) ]

        for d in range(self.disk_count):
            path = self.disk_paths[d]
            logging.debug("Try to open disk #%2d"%d)
            try:
                self.disks[d] = open(path, "r")
                self.disks_size[d] = os.lstat(path).st_size
                logging.debug("Opened disk #%2d"%d)
            except IOError as e:
                logging.error("Can't open disk #%2d ('%s') : %s"%(d, path, e.strerror))
                self.disks_size[d] = 0
            except:
                logging.error("Can't open disk #%2d ('%s') : unhandled exception"%(d, path))
                self.disks_size[d] = 0
        logging.debug("Exit. open_disks()")

    def read(self,disk_no,offset,size):
        self.disks[disk_no].seek(offset)
        return self.disks[disk_no].read(size)