"""
Copyright 2020 The Magma Authors.

This source code is licensed under the BSD-style license found in the
LICENSE file in the root directory of this source tree.

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.
"""

import json
from collections import namedtuple
from typing import Any, Optional, Union

from lte.protos.mconfig import mconfigs_pb2
from common.misc_utils import get_ip_from_if
from configuration.exceptions import LoadConfigError
from configuration.service_configs import load_enb_config, load_common_config
from configuration.mconfig_managers import load_service_mconfig_as_json
from data_models.data_model import DataModel
from data_models.data_model_parameters import ParameterName
from device_config.enodeb_config_postprocessor import (
    EnodebConfigurationPostProcessor,
)
from device_config.enodeb_configuration import EnodebConfiguration
from exceptions import ConfigurationError
from logger import EnodebdLogger as logger
from lte_utils import (
    DuplexMode,
    map_earfcndl_to_band_earfcnul_mode,
    map_earfcndl_to_duplex_mode,
)

# LTE constants
DEFAULT_S1_PORT = 36412
# This is a known working value for supported eNB devices.
# Cell Identity is a 28 bit number, but not all values are supported.
DEFAULT_CELL_IDENTITY = 138777000

SingleEnodebConfig = namedtuple(
    'SingleEnodebConfig',
    [
        'earfcndl', 'subframe_assignment',
        'special_subframe_pattern',
        'pci', 'plmnid_list', 'tac',
        'bandwidth_mhz', 'cell_id',
        'allow_enodeb_transmit',
        'mme_address', 'mme_port',
    ],
)


def config_assert(condition: bool, message: str = None) -> None:
    """ To be used in place of 'assert' so that ConfigurationError is raised
        for all config-related exceptions. """
    if not condition:
        raise ConfigurationError(message)


def build_desired_config(
        mconfig: Any,
        service_config: Any,
        device_config: EnodebConfiguration,
        data_model: DataModel,
        post_processor: EnodebConfigurationPostProcessor,
) -> EnodebConfiguration:
    """
    Factory for initializing DESIRED data model configuration.

    When working with the configuration of an eNodeB, we track the
    current state of configuration for that device, as well as what
    configuration we want to set on the device.
    Args:
        mconfig: Managed configuration, eNodeB protobuf message
        service_config:
    Returns:
        Desired data model configuration for the device
    """

    print("DEVICE CFG: ", device_config)

    cfg_desired = EnodebConfiguration(data_model)

    # Determine configuration parameters
    _set_management_server(cfg_desired)

    # Attempt to load device configuration from YANG before service mconfig
    enb_config = _get_enb_yang_config(device_config) or \
                 _get_enb_config(mconfig, device_config)

    _set_earfcn_freq_band_mode(
        device_config, cfg_desired, data_model,
        enb_config.earfcndl,
    )
    if enb_config.subframe_assignment is not None:
        _set_tdd_subframe_config(
            device_config, cfg_desired,
            enb_config.subframe_assignment,
            enb_config.special_subframe_pattern,
        )
    _set_pci(cfg_desired, enb_config.pci)
    _set_plmnids_tac(cfg_desired, enb_config.plmnid_list, enb_config.tac)
    _set_bandwidth(cfg_desired, data_model, enb_config.bandwidth_mhz)
    _set_cell_id(cfg_desired, enb_config.cell_id)
    _set_perf_mgmt(
        cfg_desired,
        get_ip_from_if(service_config['tr069']['interface']),
        service_config['tr069']['perf_mgmt_port'],
    )
    _set_misc_static_params(device_config, cfg_desired, data_model)
    if enb_config.mme_address is not None and enb_config.mme_port is not None:
        _set_s1_connection(
            cfg_desired,
            enb_config.mme_address,
            enb_config.mme_port,
        )
    else:
        _set_s1_connection(
            cfg_desired, get_ip_from_if(service_config['s1_interface']),
        )

    # Enable LTE if we should
    cfg_desired.set_parameter(
        ParameterName.ADMIN_STATE,
        enb_config.allow_enodeb_transmit,
    )

    post_processor.postprocess(mconfig, service_config, cfg_desired)
    return cfg_desired


def _get_enb_yang_config(
        device_config: EnodebConfiguration,
) -> Optional[SingleEnodebConfig]:
    """"
    Proof of concept configuration function to load eNB configs from YANG
    data model. Attempts to load configuration from YANG for the eNodeB if
    an entry exists with a matching serial number.
    Args:
        device_config: eNodeB device configuration
    Returns:
        None or a SingleEnodebConfig from YANG with matching serial number
    """
    enb = []
    mme_list = []
    mme_address = None
    mme_port = None
    try:
        enb_serial = \
            device_config.get_parameter(ParameterName.SERIAL_NUMBER)
        config = json.loads(
            load_service_mconfig_as_json('yang').get('value', '{}'),
        )

        enb.extend(
            filter(
                lambda entry: entry['serial'] == enb_serial,
                config.get('cellular', {}).get('enodeb', []),
            ),
        )
    except (ValueError, KeyError, LoadConfigError):
        return None
    if len(enb) == 0:
        return None
    enb_config = enb[0].get('config', {})
    mme_list.extend(enb_config.get('mme', []))
    if len(mme_list) > 0:
        mme_address = mme_list[0].get('host')
        mme_port = mme_list[0].get('port')
    single_enodeb_config = SingleEnodebConfig(
        earfcndl=enb_config.get('earfcndl'),
        subframe_assignment=enb_config.get('subframe_assignment'),
        special_subframe_pattern=enb_config.get('special_subframe_pattern'),
        pci=enb_config.get('pci'),
        plmnid_list=",".join(enb_config.get('plmnid', [])),
        tac=enb_config.get('tac'),
        bandwidth_mhz=enb_config.get('bandwidth_mhz'),
        cell_id=enb_config.get('cell_id'),
        allow_enodeb_transmit=enb_config.get('transmit_enabled'),
        mme_address=mme_address,
        mme_port=mme_port,
    )
    return single_enodeb_config


def _get_enb_config(
        mconfig: mconfigs_pb2.EnodebD,
        device_config: EnodebConfiguration,
) -> SingleEnodebConfig:

    # The eNodeB parameters to be generated with default value,
    # It will load from eNB configs based on serial number or default value
    # The params is a nested list which contains 2 format of parameter names.
    # The first parameter is the name of eNB / ACS configuration in
    #   magma_configs/serial_number/ and magma_configs/acs_common.yml
    # The second parameter is the name of gateway configuration in 
    #   override_configs/gateway.mconfig
    params = [
        ["earfcndl", "earfcndl"],
        ["subframeAssignment", "subframe_assignment"],
        ["special_subframe_pattern", "special_subframe_pattern"],
        ["pci", "pci"],
        ["plmnidList", "plmnid_list"],
        ["tac", "tac"],
        ["bandwidthMhz", "bandwidth_mhz"],
        ["allowEnodebTransmit", "allow_enodeb_transmit"]
    ]
    
    extend_params = ["cell_id", "mme_address", "mme_port"]

    params_dict = dict()

    common_config = load_common_config()
    enb_configs = load_enb_config()
    enb_serial = device_config.get_parameter(ParameterName.SERIAL_NUMBER)
    enb_config = enb_configs.get(enb_serial, dict())

    for param in params:
        params_dict[param[1]] = enb_config.get(param[0], 
            common_config.get(param[0], mconfig.__getattribute__(param[1]))
        )

    for param in extend_params:
        params_dict[param] = enb_config.get(param, common_config.get(param, None))

    return SingleEnodebConfig(**params_dict)


def _set_pci(
        cfg: EnodebConfiguration,
        pci: Any,
) -> None:
    """
    Set the following parameters:
     - PCI
    """
    if pci not in range(0, 504 + 1):
        raise ConfigurationError('Invalid PCI (%d)' % pci)
    cfg.set_parameter(ParameterName.PCI, pci)


def _set_bandwidth(
        cfg: EnodebConfiguration,
        data_model: DataModel,
        bandwidth_mhz: Any,
) -> None:
    """
    Set the following parameters:
     - DL bandwidth
     - UL bandwidth
    """
    _set_param_if_present(
        cfg, data_model, ParameterName.DL_BANDWIDTH,
        bandwidth_mhz,
    )
    _set_param_if_present(
        cfg, data_model, ParameterName.UL_BANDWIDTH,
        bandwidth_mhz,
    )


def _set_cell_id(
        cfg: EnodebConfiguration,
        cell_id: int,
) -> None:
    config_assert(
        cell_id in range(0, 268435456),
        'Cell Identity should be from 0 - (2^28 - 1)',
    )
    cfg.set_parameter(ParameterName.CELL_ID, cell_id)


def _set_tdd_subframe_config(
        device_cfg: EnodebConfiguration,
        cfg: EnodebConfiguration,
        subframe_assignment: Any,
        special_subframe_pattern: Any,
) -> None:
    """
    Set the following parameters:
     - Subframe assignment
     - Special subframe pattern
    """
    # Don't try to set if this is not TDD mode
    if (
        device_cfg.has_parameter(ParameterName.DUPLEX_MODE_CAPABILITY)
            and device_cfg.get_parameter(ParameterName.DUPLEX_MODE_CAPABILITY)
            != 'TDDMode'
    ):
        return

    config_assert(
        subframe_assignment in range(0, 6 + 1),
        'Invalid TDD subframe assignment (%d)' % subframe_assignment,
    )
    config_assert(
        special_subframe_pattern in range(0, 9 + 1),
        'Invalid TDD special subframe pattern (%d)'
        % special_subframe_pattern,
    )

    cfg.set_parameter(
        ParameterName.SUBFRAME_ASSIGNMENT,
        subframe_assignment,
    )
    cfg.set_parameter(
        ParameterName.SPECIAL_SUBFRAME_PATTERN,
        special_subframe_pattern,
    )


def _set_management_server(cfg: EnodebConfiguration) -> None:
    """
    Set the following parameters:
     - Periodic inform enable
     - Periodic inform interval (hard-coded)
    """
    cfg.set_parameter(ParameterName.PERIODIC_INFORM_ENABLE, True)
    # In seconds
    cfg.set_parameter(ParameterName.PERIODIC_INFORM_INTERVAL, 5)


def _set_s1_connection(
        cfg: EnodebConfiguration,
        mme_ip: Any,
        mme_port: Any = DEFAULT_S1_PORT,
) -> None:
    """
    Set the following parameters:
     - MME IP
     - MME port (defalts to 36412 as per TR-196 recommendation)
    """
    config_assert(type(mme_ip) == str, 'Invalid MME IP type')
    config_assert(type(mme_port) == int, 'Invalid MME Port type')
    cfg.set_parameter(ParameterName.MME_IP, mme_ip)
    cfg.set_parameter(ParameterName.MME_PORT, mme_port)


def _set_perf_mgmt(
        cfg: EnodebConfiguration,
        perf_mgmt_ip: str,
        perf_mgmt_port: int,
) -> None:
    """
    Set the following parameters:
     - Perf mgmt enable
     - Perf mgmt upload interval
     - Perf mgmt upload URL
    """
    cfg.set_parameter(ParameterName.PERF_MGMT_ENABLE, True)
    # Upload interval supported values (in secs):
    # [60, 300, 900, 1800, 3600]
    # Note: eNodeB crashes have been experienced with 60-sec interval.
    # Hence using 300sec
    cfg.set_parameter(
        ParameterName.PERF_MGMT_UPLOAD_INTERVAL,
        300,
    )
    cfg.set_parameter(
        ParameterName.PERF_MGMT_UPLOAD_URL,
        'http://%s:%d/' % (perf_mgmt_ip, perf_mgmt_port),
    )


def _set_misc_static_params(
        device_cfg: EnodebConfiguration,
        cfg: EnodebConfiguration,
        data_model: DataModel,
) -> None:
    """
    Set the following parameters:
     - Local gateway enable
     - GPS enable
    """
    _set_param_if_present(
        cfg, data_model, ParameterName.LOCAL_GATEWAY_ENABLE,
        0,
    )
    _set_param_if_present(cfg, data_model, ParameterName.GPS_ENABLE, True)
    # For BaiCells eNodeBs, IPSec enable may be either integer or bool.
    # Set to false/0 depending on the current type
    if data_model.is_parameter_present(ParameterName.IP_SEC_ENABLE):
        try:
            int(device_cfg.get_parameter(ParameterName.IP_SEC_ENABLE))
            cfg.set_parameter(ParameterName.IP_SEC_ENABLE, value=0)
        except ValueError:
            cfg.set_parameter(ParameterName.IP_SEC_ENABLE, value=False)

    _set_param_if_present(cfg, data_model, ParameterName.CELL_RESERVED, False)
    _set_param_if_present(
        cfg, data_model, ParameterName.MME_POOL_ENABLE,
        False,
    )


def _set_plmnids_tac(
        cfg: EnodebConfiguration,
        plmnids: Union[int, str],
        tac: Any,
) -> None:
    """
    Set the following parameters:
     - PLMNID list (including all child parameters)

    Input 'plmnids' is comma-separated list of PLMNIDs
    """
    # Convert int PLMNID to string
    if type(plmnids) == int:
        plmnid_str = str(plmnids)
    else:
        config_assert(type(plmnids) == str, 'PLMNID must be string')
        plmnid_str = plmnids

    # Multiple PLMNIDs will be supported using comma-separated list.
    # Currently, just one supported
    for char in plmnid_str:
        config_assert(
            char in '0123456789, ',
            'Unhandled character (%s) in PLMNID' % char,
        )
    plmnid_list = plmnid_str.split(',')

    # TODO - add support for multiple PLMNIDs
    config_assert(
        len(plmnid_list) == 1,
        'Exactly one PLMNID must be configured',
    )

    # Validate PLMNIDs
    plmnid_list[0] = plmnid_list[0].strip()
    config_assert(
        len(plmnid_list[0]) <= 6,
        'PLMNID must be length <=6 (%s)' % plmnid_list[0],
    )

    # We just need one PLMN element in the config. Delete all others.
    for i in range(1, 2):  # data_model.get_num_plmns() + 1):
        object_name = ParameterName.PLMN_N % i
        enable_plmn = i == 1
        cfg.add_object(object_name)
        cfg.set_parameter_for_object(
            ParameterName.PLMN_N_ENABLE % i,
            enable_plmn,
            object_name,
        )
        if enable_plmn:
            cfg.set_parameter_for_object(
                ParameterName.PLMN_N_CELL_RESERVED % i,
                False, object_name,
            )
            cfg.set_parameter_for_object(
                ParameterName.PLMN_N_PRIMARY % i,
                enable_plmn,
                object_name,
            )
            cfg.set_parameter_for_object(
                ParameterName.PLMN_N_PLMNID % i,
                plmnid_list[i - 1],
                object_name,
            )
    cfg.set_parameter(ParameterName.TAC, tac)


def _set_earfcn_freq_band_mode(
        device_cfg: EnodebConfiguration,
        cfg: EnodebConfiguration,
        data_model: DataModel,
        earfcndl: int,
) -> None:
    """
    Set the following parameters:
     - EARFCNDL
     - EARFCNUL
     - Band
    """
    # Note: validation of EARFCNDL done by mapping function. If invalid
    # EARFCN, raise ConfigurationError
    try:
        band, duplex_mode, earfcnul = map_earfcndl_to_band_earfcnul_mode(
            earfcndl,
        )
    except ValueError as err:
        raise ConfigurationError(err)

    # Verify capabilities
    if device_cfg.has_parameter(ParameterName.DUPLEX_MODE_CAPABILITY):
        duplex_capability = \
            device_cfg.get_parameter(ParameterName.DUPLEX_MODE_CAPABILITY)
        if duplex_mode == DuplexMode.TDD and duplex_capability != 'TDDMode':
            raise ConfigurationError((
                'eNodeB duplex mode capability is <{0}>, '
                'but earfcndl is <{1}>, giving duplex '
                'mode <{2}> instead'
            ).format(
                duplex_capability, str(earfcndl), str(duplex_mode),
            ))
        elif duplex_mode == DuplexMode.FDD and duplex_capability != 'FDDMode':
            raise ConfigurationError((
                'eNodeB duplex mode capability is <{0}>, '
                'but earfcndl is <{1}>, giving duplex '
                'mode <{2}> instead'
            ).format(
                duplex_capability, str(earfcndl), str(duplex_mode),
            ))
        elif duplex_mode not in {DuplexMode.TDD, DuplexMode.FDD}:
            raise ConfigurationError(
                'Invalid duplex mode (%s)' % str(duplex_mode),
            )

    if device_cfg.has_parameter(ParameterName.BAND_CAPABILITY):
        # Baicells indicated that they no longer use the band capability list,
        # so it may not be populated correctly
        band_capability_list = device_cfg.get_parameter(
            ParameterName.BAND_CAPABILITY,
        )
        band_capabilities = band_capability_list.split(',')
        if str(band) not in band_capabilities:
            logger.warning(
                'Band %d not in capabilities list (%s). Continuing'
                ' with config because capabilities list may not be'
                ' correct', band, band_capabilities,
            )
    cfg.set_parameter(ParameterName.EARFCNDL, earfcndl)
    if duplex_mode == DuplexMode.FDD:
        _set_param_if_present(
            cfg, data_model, ParameterName.EARFCNUL,
            earfcnul,
        )
    else:
        logger.debug('Not setting EARFCNUL - duplex mode is not FDD')

    _set_param_if_present(cfg, data_model, ParameterName.BAND, band)

    if duplex_mode == DuplexMode.TDD:
        logger.debug('Set EARFCNDL=%d, Band=%d', earfcndl, band)
    elif duplex_mode == DuplexMode.FDD:
        logger.debug(
            'Set EARFCNDL=%d, EARFCNUL=%d, Band=%d',
            earfcndl, earfcnul, band,
        )


def _set_param_if_present(
        cfg: EnodebConfiguration,
        data_model: DataModel,
        param: ParameterName,
        value: Any,
) -> None:
    if data_model.is_parameter_present(param):
        cfg.set_parameter(param, value)