'''Test model IO with pickle.'''
import pickle
import numpy as np
import subprocess
import os
import sys
import json
import pytest
import xgboost as xgb
from xgboost import XGBClassifier

sys.path.append("tests/python")
import testing as tm

model_path = './model.pkl'


def build_dataset():
    N = 10
    x = np.linspace(0, N*N, N*N)
    x = x.reshape((N, N))
    y = np.linspace(0, N, N)
    return x, y


def save_pickle(bst, path):
    with open(path, 'wb') as fd:
        pickle.dump(bst, fd)


def load_pickle(path):
    with open(path, 'rb') as fd:
        bst = pickle.load(fd)
    return bst


class TestPickling:
    args_template = [
        "pytest",
        "--verbose",
        "-s",
        "--fulltrace"]

    def run_pickling(self, bst) -> None:
        save_pickle(bst, model_path)
        args = [
            "pytest", "--verbose", "-s", "--fulltrace",
            "./tests/python-gpu/load_pickle.py::TestLoadPickle::test_load_pkl"
        ]
        command = ''
        for arg in args:
            command += arg
            command += ' '

        cuda_environment = {'CUDA_VISIBLE_DEVICES': '-1'}
        env = os.environ.copy()
        # Passing new_environment directly to `env' argument results
        # in failure on Windows:
        #    Fatal Python error: _Py_HashRandomization_Init: failed to
        #    get random numbers to initialize Python
        env.update(cuda_environment)

        # Load model in a CPU only environment.
        status = subprocess.call(command, env=env, shell=True)
        assert status == 0
        os.remove(model_path)

    @pytest.mark.skipif(**tm.no_sklearn())
    def test_pickling(self):
        x, y = build_dataset()
        train_x = xgb.DMatrix(x, label=y)

        param = {'tree_method': 'gpu_hist', "gpu_id": 0}
        bst = xgb.train(param, train_x)
        self.run_pickling(bst)

        bst = xgb.XGBRegressor(**param).fit(x, y)
        self.run_pickling(bst)

        param = {"booster": "gblinear", "updater": "gpu_coord_descent", "gpu_id": 0}
        bst = xgb.train(param, train_x)
        self.run_pickling(bst)

        bst = xgb.XGBRegressor(**param).fit(x, y)
        self.run_pickling(bst)

    @pytest.mark.mgpu
    def test_wrap_gpu_id(self):
        X, y = build_dataset()
        dtrain = xgb.DMatrix(X, y)

        bst = xgb.train({'tree_method': 'gpu_hist',
                         'gpu_id': 1},
                        dtrain, num_boost_round=6)

        model_path = 'model.pkl'
        save_pickle(bst, model_path)
        cuda_environment = {'CUDA_VISIBLE_DEVICES': '0'}
        env = os.environ.copy()
        env.update(cuda_environment)
        args = self.args_template.copy()
        args.append(
            "./tests/python-gpu/"
            "load_pickle.py::TestLoadPickle::test_wrap_gpu_id"
        )
        status = subprocess.call(args, env=env)
        assert status == 0
        os.remove(model_path)

    def test_pickled_predictor(self):
        x, y = build_dataset()
        train_x = xgb.DMatrix(x, label=y)

        param = {'tree_method': 'gpu_hist',
                 'verbosity': 1, 'predictor': 'gpu_predictor'}
        bst = xgb.train(param, train_x)
        config = json.loads(bst.save_config())
        assert config['learner']['gradient_booster']['gbtree_train_param'][
            'predictor'] == 'gpu_predictor'

        save_pickle(bst, model_path)

        args = self.args_template.copy()
        args.append(
            "./tests/python-gpu/"
            "load_pickle.py::TestLoadPickle::test_predictor_type_is_auto")

        cuda_environment = {'CUDA_VISIBLE_DEVICES': '-1'}
        env = os.environ.copy()
        env.update(cuda_environment)

        # Load model in a CPU only environment.
        status = subprocess.call(args, env=env)
        assert status == 0

        args = self.args_template.copy()
        args.append(
            "./tests/python-gpu/"
            "load_pickle.py::TestLoadPickle::test_predictor_type_is_gpu")

        # Load in environment that has GPU.
        env = os.environ.copy()
        assert 'CUDA_VISIBLE_DEVICES' not in env.keys()
        status = subprocess.call(args, env=env)
        assert status == 0

        os.remove(model_path)

    def test_predict_sklearn_pickle(self):
        x, y = build_dataset()

        kwargs = {'tree_method': 'gpu_hist',
                  'predictor': 'gpu_predictor',
                  'objective': 'binary:logistic',
                  'n_estimators': 10}

        model = XGBClassifier(**kwargs)
        model.fit(x, y)

        save_pickle(model, "model.pkl")
        del model

        # load model
        model: xgb.XGBClassifier = load_pickle("model.pkl")
        os.remove("model.pkl")

        gpu_pred = model.predict(x, output_margin=True)

        # Switch to CPU predictor
        bst = model.get_booster()
        bst.set_param({'predictor': 'cpu_predictor'})
        cpu_pred = model.predict(x, output_margin=True)
        np.testing.assert_allclose(cpu_pred, gpu_pred, rtol=1e-5)

    def test_training_on_cpu_only_env(self):
        cuda_environment = {'CUDA_VISIBLE_DEVICES': '-1'}
        env = os.environ.copy()
        env.update(cuda_environment)
        args = self.args_template.copy()
        args.append(
            "./tests/python-gpu/"
            "load_pickle.py::TestLoadPickle::test_training_on_cpu_only_env")
        status = subprocess.call(args, env=env)
        assert status == 0
