#!/usr/bin/env python3
# -*- coding: utf-8 -*-
# @Author: Jean-Luc Auge
# @Date:   2018-02-02 14:06:55

from numpy import zeros, array
from gnpy.core.elements import Transceiver, Edfa
from gnpy.core.utils import automatic_fmax, lin2db, db2lin, merge_amplifier_restrictions
from gnpy.core.info import create_input_spectral_information, ReferenceCarrier
from gnpy.core.network import build_network
from gnpy.tools.json_io import load_network, load_equipment
from pathlib import Path
import pytest

TEST_DIR = Path(__file__).parent
DATA_DIR = TEST_DIR / 'data'
test_network = DATA_DIR / 'test_network.json'
eqpt_library = DATA_DIR / 'eqpt_config.json'

# TODO in elements.py code: pytests doesn't pass with 1 channel: interpolate fail


@pytest.fixture(
    params=[(96, 0.05e12), (60, 0.075e12), (45, 0.1e12), (2, 0.1e12)],
    ids=['50GHz spacing', '75GHz spacing', '100GHz spacing', '2 channels'])
def nch_and_spacing(request):
    """parametrize channel count vs channel spacing (Hz)"""
    yield request.param


@pytest.fixture()
def bw():
    """parametrize signal bandwidth (Hz)"""
    return 45e9


@pytest.fixture()
def setup_edfa_variable_gain():
    """init edfa class by reading test_network.json file
    remove all gain and nf ripple"""
    equipment = load_equipment(eqpt_library)
    network = load_network(test_network, equipment)
    build_network(network, equipment, 0, 20)
    edfa = [n for n in network.nodes() if isinstance(n, Edfa)][0]
    edfa.gain_ripple = zeros(96)
    edfa.interpol_nf_ripple = zeros(96)
    yield edfa


@pytest.fixture()
def setup_edfa_fixed_gain():
    """init edfa class by reading the 2nd edfa in test_network.json file"""
    equipment = load_equipment(eqpt_library)
    network = load_network(test_network, equipment)
    build_network(network, equipment, 0, 20)
    edfa = [n for n in network.nodes() if isinstance(n, Edfa)][1]
    yield edfa


@pytest.fixture()
def setup_trx():
    """init transceiver class to access snr and osnr calculations"""
    equipment = load_equipment(eqpt_library)
    network = load_network(test_network, equipment)
    build_network(network, equipment, 0, 20)
    trx = [n for n in network.nodes() if isinstance(n, Transceiver)][0]
    return trx


@pytest.fixture()
def si(nch_and_spacing, bw):
    """parametrize a channel comb with nb_channel, spacing and signal bw"""
    nb_channel, spacing = nch_and_spacing
    f_min = 191.3e12
    f_max = automatic_fmax(f_min, spacing, nb_channel)
    return create_input_spectral_information(f_min=f_min, f_max=f_max, roll_off=0.15, baud_rate=bw, power=1e-3,
                                             spacing=spacing, tx_osnr=40.0,
                                             ref_carrier=ReferenceCarrier(baud_rate=32e9, slot_width=50e9))


@pytest.mark.parametrize("gain, nf_expected", [(10, 15), (15, 10), (25, 5.8)])
def test_variable_gain_nf(gain, nf_expected, setup_edfa_variable_gain, si):
    """=> unitary test for variable gain model Edfa._calc_nf() (and Edfa.interpol_params)"""
    edfa = setup_edfa_variable_gain
    si.signal /= db2lin(gain)
    si.nli /= db2lin(gain)
    si.ase /= db2lin(gain)
    edfa.operational.gain_target = gain
    si.pref = si.pref._replace(p_span0=0, p_spani=-gain)
    edfa.interpol_params(si)
    result = edfa.nf
    assert pytest.approx(nf_expected, abs=0.01) == result[0]


@pytest.mark.parametrize("gain, nf_expected", [(15, 10), (20, 5), (25, 5)])
def test_fixed_gain_nf(gain, nf_expected, setup_edfa_fixed_gain, si):
    """=> unitary test for fixed gain model Edfa._calc_nf() (and Edfa.interpol_params)"""
    edfa = setup_edfa_fixed_gain
    si.signal /= db2lin(gain)
    si.nli /= db2lin(gain)
    si.ase /= db2lin(gain)
    edfa.operational.gain_target = gain
    si.pref = si.pref._replace(p_span0=0, p_spani=-gain)
    edfa.interpol_params(si)
    assert pytest.approx(nf_expected, abs=0.01) == edfa.nf[0]


def test_si(si, nch_and_spacing):
    """basic total power check of the channel comb generation"""
    nb_channel = nch_and_spacing[0]
    p_tot = sum(si.signal + si.ase + si.nli)
    expected_p_tot = si.signal[0] * nb_channel
    assert pytest.approx(expected_p_tot, abs=0.01) == p_tot


@pytest.mark.parametrize("gain", [17, 19, 21, 23])
def test_compare_nf_models(gain, setup_edfa_variable_gain, si):
    """compare the 2 amplifier models (polynomial and estimated from nf_min and max)
     => nf_model vs nf_poly_fit for intermediate gain values:
     between gain_min and gain_flatmax some discrepancy is expected but target < 0.5dB
     => unitary test for Edfa._calc_nf (and Edfa.interpol_params)"""
    edfa = setup_edfa_variable_gain
    si.signal /= db2lin(gain)
    si.nli /= db2lin(gain)
    si.ase /= db2lin(gain)
    edfa.operational.gain_target = gain
    # edfa is variable gain type
    si.pref = si.pref._replace(p_span0=0, p_spani=-gain)
    edfa.interpol_params(si)
    nf_model = edfa.nf[0]

    # change edfa type variety to a polynomial
    el_config = {
        "uid": "Edfa1",
        "operational": {
            "gain_target": gain,
            "tilt_target": 0
        },
        "metadata": {
            "location": {
                "region": "",
                "latitude": 2,
                "longitude": 0
            }
        }
    }
    equipment = load_equipment(eqpt_library)
    extra_params = equipment['Edfa']['CienaDB_medium_gain']
    temp = el_config.setdefault('params', {})
    temp = merge_amplifier_restrictions(temp, extra_params.__dict__)
    el_config['params'] = temp
    edfa = Edfa(**el_config)

    # edfa is variable gain type
    edfa.interpol_params(si)
    nf_poly = edfa.nf[0]
    print(nf_poly, nf_model)
    assert pytest.approx(nf_model, abs=0.5) == nf_poly


@pytest.mark.parametrize("gain", [13, 15, 17, 19, 21, 23, 25, 27])
def test_ase_noise(gain, si, setup_trx, bw):
    """testing 3 different ways of calculating osnr:
    1-pin-edfa.nf+58 vs
    2-pout/pase afet propagate
    3-Transceiver osnr_ase_01nm
    => unitary test for Edfa.noise_profile (Edfa.interpol_params, Edfa.propagate)"""
    equipment = load_equipment(eqpt_library)
    network = load_network(test_network, equipment)
    edfa = next(n for n in network.nodes() if n.uid == 'Edfa1')
    span = next(n for n in network.nodes() if n.uid == 'Span1')
    # update span1 and Edfa1 according to new gain before building network
    # updating span 1  avoids to overload amp
    span.params.length = gain * 1e3 / 0.2
    edfa.operational.gain_target = gain
    build_network(network, equipment, 0, 20)
    edfa.gain_ripple = zeros(96)
    edfa.interpol_nf_ripple = zeros(96)
    # propagate in span1 to have si with the correct power level
    si = span(si)
    print(span)

    si.pref = si.pref._replace(p_span0=0, p_spani=-gain)
    edfa.interpol_params(si)
    nf = edfa.nf
    print('nf', nf)
    pin = lin2db((si.signal[0] + si.ase[0] + si.nli[0]) * 1e3)
    osnr_expected = pin - nf[0] + 58

    si = edfa(si)
    print(edfa)
    osnr = lin2db(si.signal[0] / si.ase[0]) - lin2db(12.5e9 / bw)
    assert pytest.approx(osnr_expected, abs=0.01) == osnr

    trx = setup_trx
    si = trx(si)
    osnr = trx.osnr_ase_01nm[0]
    assert pytest.approx(osnr_expected, abs=0.01) == osnr