#!/usr/bin/python
# Copyright (C) 2014 Codethink Limited
#
# 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; version 2 of the License.
#
# 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.
#
# You should have received a copy of the GNU General Public License along
# with this program; if not, write to the Free Software Foundation, Inc.,
# 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.


'''A Baserock installer.'''



import morphlib
import ConfigParser
import os
import re
import sys
import json
import subprocess
import tempfile
import errno
import time

class BaserockInstaller():

    config_file = '/etc/install.conf'
    to_mount = (
        ('/proc', 'proc', 'none'),
        ('/sys', 'sysfs', 'none'),

    )

    def run(self):
        try:
            print "Baserock installation script begins..."
            mounted = self.do_mounts(self.to_mount)

            rawdisk_path = morphlib.extensions._get_morph_extension_filename(
                               'rawdisk', '.write')

            disk_dest, rootfs = self.check_and_read_config(self.config_file)
            self.validate_install_values(disk_dest, rootfs)

            deployment_config=self.get_deployment_config(rootfs)

            self.compute_install_command(rawdisk_path,
                     deployment_config, rootfs, disk_dest)

            self.do_unmounts(mounted)
            self.finish_and_reboot()
        except BaseException, e:
            print "Something failed, opening shell..."
            print "Once you have finished, use `reboot -f`"
            os.execl('/bin/sh', 'sh')

    def validate_install_values(self, disk_dest, rootfs):
        if not self.is_device(disk_dest):
           print "ERROR: Not deploying to a device"
           raise BaseException
        if not os.path.exists(disk_dest):
           print "ERROR: The device %s doesn't exist." % disk_dest
           raise BaseException
        if not self.is_baserock_rootfs(rootfs):
           print "ERROR: The rootfs %s is not a baserock rootfs." % rootfs
           raise BaseException

    def is_baserock_rootfs(self, rootfs):
        if os.path.isdir(os.path.join(rootfs, 'baserock')):
            return True
        return False

    def compute_install_command(self, rawdisk_path, deployment_config,
                              rootfs, disk_dest):
        fd, script = tempfile.mkstemp()
        with os.fdopen(fd, 'w') as fp:
            fp.write('#!/bin/sh\n')
            fp.write('env ')
            for name in deployment_config:
                if deployment_config[name] is not None:
                    fp.write('%s="%s" ' % (name, deployment_config[name]))
            fp.write("%s %s %s\n" % (rawdisk_path, rootfs, disk_dest))
        self.install_system(script)
        os.remove(script)

    def finish_and_reboot(self):
        os.system("sync")
        print "Rebooting in 5 seconds..."
        time.sleep(5)
        os.system("reboot -f")

    def do_mounts(self, to_mount):
        mounted = []
        for mount_point, mount_type, source in to_mount:
            print 'Mounting %s in %s' % (source, mount_point)
            if not os.path.exists(mount_point):
                os.makedirs(mount_point)
            if self.mount( source, mount_point, mount_type) == 0:
                mounted.append(mount_point)
        return mounted

    def mount(self, partition, mount_point, fstype):
        return subprocess.call(['mount', partition, mount_point, '-t', fstype])

    def do_unmounts(self, to_unmount):
        for path in reversed(to_unmount):
            print 'Unmounting %s' % path
            try:
                subprocess.check_call(['umount', path])
            except:
                print 'WARNING: Failed to `umount %s`' % path

    def check_and_read_config(self, config_file):
        print "Reading configuration from %s..." % config_file
        config = ConfigParser.RawConfigParser()
        config.read(config_file)
        keys = ('device', 'rootfs')

        device, rootfs = (self.read_option(config, 'install', key)
                             for key in keys)
        return device, rootfs

    def read_option(self, config, section, option):
        try:
            value = config.get(section, option)
        except:
            value = raw_input("Option '%s.%s' missing, please enter a value: "
                                %  (section, option))
        print "Option '%s.%s' with value '%s" % (section, option, value)
        return value

    def get_deployment_config(self, rootfs):
        print "Reading deployment.meta of the system to install..."
        try:
            meta = open(os.path.join(rootfs, 'baserock/deployment.meta'))
        except IOError as e:
            if e.errno != errno.ENOENT:
                raise
            print "Failed to read deployment.meta, it will be empty"
            deployment_config = {}
        else:
            deployment_config = json.load(meta).get('configuration', {})
            meta.close()
            print "################ Environment #################"
            for key in deployment_config:
                print "# %s: %s" % (key, deployment_config[key])
            print "##############################################"
        return deployment_config


    def install_system(self, install_script):
        run_script = "sh %s" % install_script
        subprocess.check_call(run_script, shell=True)

    def is_device(self, location):
        try:
            st = os.stat(location)
            return stat.S_ISBLK(st.st_mode)
        except OSError as e:
            if e.errno == errno.ENOENT:
                return False
            raise

        dev_regex = re.compile("^/dev/((sd|vd|mmcblk|hd)[a-z0-9]+)$")
        if dev_regex.match(location):
            return True
        return False


BaserockInstaller().run()