# Copyright 2018 Microsoft Corporation
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
#
# Requires Python 2.6+ and Openssl 1.0+
#

"""
Provision handler
"""

import os
import os.path
import re
import time

from datetime import datetime

import azurelinuxagent.common.conf as conf
import azurelinuxagent.common.logger as logger
import azurelinuxagent.common.utils.shellutil as shellutil
import azurelinuxagent.common.utils.fileutil as fileutil

from azurelinuxagent.common.future import ustr
from azurelinuxagent.common.event import add_event, WALAEventOperation, \
    elapsed_milliseconds
from azurelinuxagent.common.exception import ProvisionError, ProtocolError, \
    OSUtilError
from azurelinuxagent.common.osutil import get_osutil
from azurelinuxagent.common.protocol.restapi import ProvisionStatus
from azurelinuxagent.common.protocol.util import get_protocol_util
from azurelinuxagent.common.version import AGENT_NAME
from azurelinuxagent.pa.provision.cloudinitdetect import cloud_init_is_enabled

CUSTOM_DATA_FILE = "CustomData"
CLOUD_INIT_PATTERN = b".*/bin/cloud-init.*"
CLOUD_INIT_REGEX = re.compile(CLOUD_INIT_PATTERN)

PROVISIONED_FILE = 'provisioned'


class ProvisionHandler(object):
    def __init__(self):
        self.osutil = get_osutil()
        self.protocol_util = get_protocol_util()

    def run(self):
        if not conf.get_provision_enabled():
            logger.info("Provisioning is disabled, skipping.")
            self.write_provisioned()
            self.report_ready()
            return

        try:
            utc_start = datetime.utcnow()
            thumbprint = None  # pylint: disable=W0612

            if self.check_provisioned_file():
                logger.info("Provisioning already completed, skipping.")
                return

            logger.info("Running default provisioning handler")

            if cloud_init_is_enabled():
                raise ProvisionError("cloud-init appears to be installed and enabled, "
                                        "this is not expected, cannot continue")

            logger.info("Copying ovf-env.xml")
            ovf_env = self.protocol_util.copy_ovf_env()

            self.protocol_util.get_protocol()  # Trigger protocol detection
            self.report_not_ready("Provisioning", "Starting")
            logger.info("Starting provisioning")

            self.provision(ovf_env)

            thumbprint = self.reg_ssh_host_key()
            self.osutil.restart_ssh_service()

            self.write_provisioned()

            self.report_event("Provisioning succeeded ({0}s)".format(self._get_uptime_seconds()),
                is_success=True,
                duration=elapsed_milliseconds(utc_start))

            self.handle_provision_guest_agent(ovf_env.provision_guest_agent)

            self.report_ready()
            logger.info("Provisioning complete")

        except (ProtocolError, ProvisionError) as e:
            msg = "Provisioning failed: {0} ({1}s)".format(ustr(e), self._get_uptime_seconds())
            logger.error(msg)
            self.report_not_ready("ProvisioningFailed", ustr(e))
            self.report_event(msg, is_success=False)
            return

    @staticmethod
    def _get_uptime_seconds():
        try:
            with open('/proc/uptime') as fh:
                uptime, _ = fh.readline().split()
                return uptime
        except:  # pylint: disable=W0702
            return 0

    def reg_ssh_host_key(self):
        keypair_type = conf.get_ssh_host_keypair_type()
        if conf.get_regenerate_ssh_host_key():
            fileutil.rm_files(conf.get_ssh_key_glob())
            if conf.get_ssh_host_keypair_mode() == "auto":
                # pylint: disable=W0105
                '''
                The -A option generates all supported key types.
                This is supported since OpenSSH 5.9 (2011).
                '''
                # pylint: enable=W0105
                shellutil.run("ssh-keygen -A")
            else:
                keygen_cmd = "ssh-keygen -N '' -t {0} -f {1}"
                shellutil.run(keygen_cmd.
                              format(keypair_type,
                                     conf.get_ssh_key_private_path()))
        return self.get_ssh_host_key_thumbprint()

    def get_ssh_host_key_thumbprint(self, chk_err=True):
        cmd = "ssh-keygen -lf {0}".format(conf.get_ssh_key_public_path())
        ret = shellutil.run_get_output(cmd, chk_err=chk_err)
        if ret[0] == 0:
            return ret[1].rstrip().split()[1].replace(':', '')
        else:
            raise ProvisionError(("Failed to generate ssh host key: "
                                  "ret={0}, out= {1}").format(ret[0], ret[1]))

    @staticmethod
    def provisioned_file_path():
        return os.path.join(conf.get_lib_dir(), PROVISIONED_FILE)

    @staticmethod
    def is_provisioned():
        """
        A VM is considered provisioned *anytime* the provisioning
        sentinel file exists and not provisioned *anytime* the file
        is absent.
        """
        return os.path.isfile(ProvisionHandler.provisioned_file_path())

    def check_provisioned_file(self):
        """
        If the VM was provisioned using an agent that did not record
        the VM unique identifier, the provisioning file will be re-written
        to include the identifier.

        A warning is logged *if* the VM unique identifier has changed
        since VM was provisioned.

        Returns False if the VM has not been provisioned.
        """
        if not ProvisionHandler.is_provisioned():
            return False

        s = fileutil.read_file(ProvisionHandler.provisioned_file_path()).strip()
        if not self.osutil.is_current_instance_id(s):
            if len(s) > 0:
                msg = "VM is provisioned, but the VM unique identifier has changed. This indicates the VM may be " \
                      "created from an image that was not properly deprovisioned or generalized, which can result in " \
                      "unexpected behavior from the guest agent -- clearing cached state"
                logger.warn(msg)
                self.report_event(msg)
                from azurelinuxagent.pa.deprovision \
                    import get_deprovision_handler
                deprovision_handler = get_deprovision_handler()
                deprovision_handler.run_changed_unique_id()

            self.write_provisioned()
            self.report_ready()

        return True

    def write_provisioned(self):
        fileutil.write_file(
            ProvisionHandler.provisioned_file_path(),
            get_osutil().get_instance_id())

    @staticmethod
    def write_agent_disabled():
        logger.warn("Disabling guest agent in accordance with ovf-env.xml")
        fileutil.write_file(conf.get_disable_agent_file_path(), '')

    def handle_provision_guest_agent(self, provision_guest_agent):
        self.report_event(message=provision_guest_agent,
                          is_success=True,
                          duration=0,
                          operation=WALAEventOperation.ProvisionGuestAgent)
        if provision_guest_agent and provision_guest_agent.lower() == 'false':
            self.write_agent_disabled()

    def provision(self, ovfenv):
        logger.info("Handle ovf-env.xml.")
        try:
            logger.info("Set hostname [{0}]".format(ovfenv.hostname))
            self.osutil.set_hostname(ovfenv.hostname)

            logger.info("Publish hostname [{0}]".format(ovfenv.hostname))
            self.osutil.publish_hostname(ovfenv.hostname)

            self.config_user_account(ovfenv)

            self.save_customdata(ovfenv)

            if conf.get_delete_root_password():
                self.osutil.del_root_password()

        except OSUtilError as e:
            raise ProvisionError("Failed to provision: {0}".format(ustr(e)))

    def config_user_account(self, ovfenv):
        logger.info("Create user account if not exists")
        self.osutil.useradd(ovfenv.username)

        if ovfenv.user_password is not None:
            logger.info("Set user password.")
            crypt_id = conf.get_password_cryptid()
            salt_len = conf.get_password_crypt_salt_len()
            self.osutil.chpasswd(ovfenv.username, ovfenv.user_password,
                                 crypt_id=crypt_id, salt_len=salt_len)

        logger.info("Configure sudoer")
        self.osutil.conf_sudoer(ovfenv.username,
                                nopasswd=ovfenv.user_password is None)

        logger.info("Configure sshd")
        self.osutil.conf_sshd(ovfenv.disable_ssh_password_auth)

        self.deploy_ssh_pubkeys(ovfenv)
        self.deploy_ssh_keypairs(ovfenv)

    def save_customdata(self, ovfenv):
        customdata = ovfenv.customdata
        if customdata is None:
            return

        lib_dir = conf.get_lib_dir()
        if conf.get_decode_customdata() or conf.get_execute_customdata():
            logger.info("Decode custom data")
            customdata = self.osutil.decode_customdata(customdata)

        logger.info("Save custom data")
        customdata_file = os.path.join(lib_dir, CUSTOM_DATA_FILE)
        fileutil.write_file(customdata_file, customdata)

        if conf.get_execute_customdata():
            start = time.time()
            logger.info("Execute custom data")
            os.chmod(customdata_file, 0o700)
            shellutil.run(customdata_file)
            add_event(name=AGENT_NAME,
                        duration=int(time.time() - start),
                        is_success=True,
                        op=WALAEventOperation.CustomData)

    def deploy_ssh_pubkeys(self, ovfenv):
        for pubkey in ovfenv.ssh_pubkeys:
            logger.info("Deploy ssh public key.")
            self.osutil.deploy_ssh_pubkey(ovfenv.username, pubkey)

    def deploy_ssh_keypairs(self, ovfenv):
        for keypair in ovfenv.ssh_keypairs:
            logger.info("Deploy ssh key pairs.")
            self.osutil.deploy_ssh_keypair(ovfenv.username, keypair)

    def report_event(self, message, is_success=False, duration=0,
                     operation=WALAEventOperation.Provision):
        add_event(name=AGENT_NAME,
                    message=message,
                    duration=duration,
                    is_success=is_success,
                    op=operation)

    def report_not_ready(self, sub_status, description):
        status = ProvisionStatus(status="NotReady", subStatus=sub_status,
                                 description=description)
        try:
            protocol = self.protocol_util.get_protocol()
            protocol.report_provision_status(status)
        except ProtocolError as e:
            logger.error("Reporting NotReady failed: {0}", e)
            self.report_event(ustr(e))

    def report_ready(self):
        status = ProvisionStatus(status="Ready")
        try:
            protocol = self.protocol_util.get_protocol()
            protocol.report_provision_status(status)
        except ProtocolError as e:
            logger.error("Reporting Ready failed: {0}", e)
            self.report_event(ustr(e))