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''' Unit tests for Gluon Estimator '''

import sys
import unittest
import warnings
import pytest

import mxnet as mx
from mxnet import gluon
from mxnet.gluon import nn
from mxnet.gluon.contrib.estimator import *
from mxnet.gluon.contrib.estimator.event_handler import *

mx.npx.reset_np()

def _get_test_network(params=None):
    net = nn.Sequential()
    net.add(nn.Dense(4, activation='relu', flatten=False))
    net.share_parameters(params)
    return net

def _get_test_data():
    batch_size = 4
    in_data = mx.np.random.uniform(size=(10, 3))
    out_data = mx.np.random.uniform(size=(10, 4))
    # Input dataloader
    dataset = gluon.data.dataset.ArrayDataset(in_data, out_data)
    dataloader = gluon.data.DataLoader(dataset, batch_size=batch_size)
    dataiter = mx.io.NDArrayIter(data=in_data, label=out_data, batch_size=batch_size)
    return dataloader, dataiter


@mx.util.use_np
def test_fit():
    ''' test estimator with different train data types '''
    net = _get_test_network()
    dataloader, dataiter = _get_test_data()
    num_epochs = 1
    device = mx.cpu()
    loss = gluon.loss.L2Loss()
    acc = mx.gluon.metric.Accuracy()
    net.initialize(device=device)
    trainer = gluon.Trainer(net.collect_params(), 'sgd', {'learning_rate': 0.001})
    est = Estimator(net=net,
                    loss=loss,
                    train_metrics=acc,
                    trainer=trainer,
                    device=device)

    est.fit(train_data=dataloader,
            epochs=num_epochs)

    with pytest.raises(ValueError):
        est.fit(train_data=dataiter,
                epochs=num_epochs)

    # Input NDArray
    with pytest.raises(ValueError):
        est.fit(train_data=[mx.np.ones(shape=(10, 3))],
                epochs=num_epochs)


@mx.util.use_np
def test_validation():
    ''' test different validation data types'''
    net = _get_test_network()
    dataloader, dataiter = _get_test_data()
    num_epochs = 1
    device = mx.cpu()
    loss = gluon.loss.L2Loss()
    acc = mx.gluon.metric.Accuracy()
    val_loss = gluon.loss.L1Loss()
    net.initialize(device=device)
    trainer = gluon.Trainer(net.collect_params(), 'sgd', {'learning_rate': 0.001})
    est = Estimator(net=net,
                    loss=loss,
                    train_metrics=acc,
                    trainer=trainer,
                    device=device,
                    val_loss=val_loss)
    # Input dataloader
    est.fit(train_data=dataloader,
            val_data=dataloader,
            epochs=num_epochs)

    # using validation handler
    train_metrics = est.train_metrics
    val_metrics = est.val_metrics
    validation_handler = ValidationHandler(val_data=dataloader, eval_fn=est.evaluate)

    with pytest.raises(ValueError):
        est.fit(train_data=dataiter,
                val_data=dataiter,
                epochs=num_epochs)
    # Input NDArray
    with pytest.raises(ValueError):
        est.fit(train_data=[mx.np.ones(shape=(10, 3))],
                val_data=[mx.np.ones(shape=(10, 3))],
                epochs=num_epochs)


@mx.util.use_np
def test_initializer():
    ''' test with no initializer, inconsistent initializer '''
    net = _get_test_network()
    train_data, _ = _get_test_data()
    num_epochs = 1
    device = mx.cpu()

    loss = gluon.loss.L2Loss()
    acc = mx.gluon.metric.Accuracy()
    # no initializer
    est = Estimator(net=net,
                    loss=loss,
                    train_metrics=acc,
                    device=device)
    est.fit(train_data=train_data,
            epochs=num_epochs)

    # different initializer for net and estimator
    net = _get_test_network()
    net.initialize(mx.init.Xavier(), device=device)
    trainer = gluon.Trainer(net.collect_params(), 'sgd', {'learning_rate': 0.001})
    # catch reinit warning
    with warnings.catch_warnings(record=True) as w:
        est = Estimator(net=net,
                        loss=loss,
                        train_metrics=acc,
                        initializer=mx.init.MSRAPrelu(),
                        trainer=trainer,
                        device=device)
        assert 'Network already fully initialized' in str(w[-1].message)
    # net partially initialized, fine tuning use case
    net = gluon.model_zoo.vision.resnet18_v1(pretrained=False, device=device)
    net.features.initialize(device=device)
    net.features(mx.np.zeros((1, 3, 224, 224)))
    net.output = gluon.nn.Dense(10) #last layer not initialized
    est = Estimator(net, loss=loss, train_metrics=acc, device=device)
    dataset =  gluon.data.ArrayDataset(mx.np.zeros((10, 3, 224, 224)), mx.np.zeros((10, 10)))
    train_data = gluon.data.DataLoader(dataset=dataset, batch_size=5)
    est.fit(train_data=train_data,
            epochs=num_epochs)


@mx.util.use_np
def test_trainer():
    ''' test with no trainer and invalid trainer '''
    net = _get_test_network()
    train_data, _ = _get_test_data()
    num_epochs = 1
    device = mx.cpu()

    loss = gluon.loss.L2Loss()
    acc = mx.gluon.metric.Accuracy()
    net.initialize(device=device)
    # input no trainer
    with warnings.catch_warnings(record=True) as w:
        est = Estimator(net=net,
                        loss=loss,
                        train_metrics=acc,
                        device=device)
        assert 'No trainer specified' in str(w[-1].message)
    est.fit(train_data=train_data,
            epochs=num_epochs)

    # input invalid trainer
    trainer = 'sgd'
    with pytest.raises(ValueError):
        est = Estimator(net=net,
                        loss=loss,
                        train_metrics=acc,
                        trainer=trainer,
                        device=device)


@mx.util.use_np
def test_metric():
    ''' test with no metric, list of metrics, invalid metric '''
    net = _get_test_network()
    train_data, _ = _get_test_data()
    num_epochs = 1
    device = mx.cpu()

    loss = gluon.loss.L2Loss()
    net.initialize(device=device)
    trainer = gluon.Trainer(net.collect_params(), 'sgd', {'learning_rate': 0.001})
    # input no metric
    est = Estimator(net=net,
                    loss=loss,
                    trainer=trainer,
                    device=device)
    est.fit(train_data=train_data,
            epochs=num_epochs)
    # input list of metrics
    metrics = [mx.gluon.metric.Accuracy(), mx.gluon.metric.Accuracy()]
    est = Estimator(net=net,
                    loss=loss,
                    train_metrics=metrics,
                    trainer=trainer,
                    device=device)
    est.fit(train_data=train_data,
            epochs=num_epochs)
    # input invalid metric
    with pytest.raises(ValueError):
        est = Estimator(net=net,
                        loss=loss,
                        train_metrics='acc',
                        trainer=trainer,
                        device=device)
    # test default metric
    loss = gluon.loss.SoftmaxCrossEntropyLoss()
    est = Estimator(net=net,
                    loss=loss,
                    trainer=trainer,
                    device=device)
    assert isinstance(est.train_metrics[0], mx.gluon.metric.Accuracy)


@mx.util.use_np
def test_loss():
    ''' test with invalid loss '''
    net = _get_test_network()
    device = mx.cpu()
    acc = mx.gluon.metric.Accuracy()
    net.initialize(device=device)
    trainer = gluon.Trainer(net.collect_params(), 'sgd', {'learning_rate': 0.001})
    # input invalid loss
    with pytest.raises(ValueError):
        est = Estimator(net=net,
                        loss='mse',
                        train_metrics=acc,
                        trainer=trainer,
                        device=device)


@mx.util.use_np
def test_device():
    ''' test with no device, list of device, invalid device '''
    net = _get_test_network()
    loss = gluon.loss.L2Loss()
    metrics = mx.gluon.metric.Accuracy()
    # input no device
    est = Estimator(net=net,
                    loss=loss,
                    train_metrics=metrics)
    # input list of device
    gpus = mx.device.num_gpus()
    device = [mx.gpu(i) for i in range(gpus)] if gpus > 0 else [mx.cpu()]
    net = _get_test_network()
    est = Estimator(net=net,
                    loss=loss,
                    train_metrics=metrics,
                    device=device)
    # input invalid device
    with pytest.raises(ValueError):
        est = Estimator(net=net,
                        loss=loss,
                        train_metrics=metrics,
                        device='cpu')

    with pytest.raises(AssertionError):
        est = Estimator(net=net,
                        loss=loss,
                        train_metrics=metrics,
                        device=[mx.gpu(0), mx.gpu(100)])


@mx.util.use_np
def test_categorize_handlers():
    class CustomHandler1(TrainBegin):

        def train_begin(self):
            print("custom train begin")

    class CustomHandler2(EpochBegin, BatchBegin, TrainEnd):

        def epoch_begin(self):
            print("custom epoch begin")

        def batch_begin(self):
            print("custom batch begin")

        def train_end(self):
            print("custom train end")

    class CustomHandler3(EpochBegin, BatchBegin, BatchEnd, TrainEnd):

        def epoch_begin(self):
            print("custom epoch begin")

        def batch_begin(self):
            print("custom batch begin")

        def batch_end(self):
            print("custom batch end")

        def train_end(self):
            print("custom train end")

    net = nn.Sequential()
    net.add(nn.Dense(10))
    loss = gluon.loss.SoftmaxCrossEntropyLoss()
    est = Estimator(net, loss=loss)
    event_handlers = [CustomHandler1(), CustomHandler2(), CustomHandler3()]
    train_begin, epoch_begin, batch_begin, \
    batch_end, epoch_end, train_end = est._categorize_handlers(event_handlers)
    assert len(train_begin) == 1
    assert len(epoch_begin) == 2
    assert len(batch_begin) == 2
    assert len(batch_end) == 1
    assert len(train_end) == 2


@mx.util.use_np
def test_default_handlers():
    net = _get_test_network()
    train_data, _ = _get_test_data()

    num_epochs = 1
    device = mx.cpu()

    net.initialize(device=device)
    trainer = gluon.Trainer(net.collect_params(), 'sgd', {'learning_rate': 0.001})

    train_acc = mx.gluon.metric.RMSE()
    loss = gluon.loss.L2Loss()

    est = Estimator(net=net,
                    loss=loss,
                    train_metrics=train_acc,
                    trainer=trainer,
                    device=device)
    # no handler(all default handlers), no warning
    with warnings.catch_warnings(record=True) as w:
        est.fit(train_data=train_data, epochs=num_epochs)

    # handler with prepared loss and metrics
    # use mix of default and user defined handlers
    train_metrics = est.train_metrics
    val_metrics = est.val_metrics
    logging = LoggingHandler(metrics=train_metrics)
    est.fit(train_data=train_data, epochs=num_epochs, event_handlers=[logging])

    # handler with all user defined metrics
    # use mix of default and user defined handlers
    metric = MetricHandler(metrics=[train_acc])
    logging = LoggingHandler(metrics=[train_acc])
    est.fit(train_data=train_data, epochs=num_epochs, event_handlers=[metric, logging])

    # handler with mixed metrics, some handler use metrics prepared by estimator
    # some handler use metrics user prepared
    logging = LoggingHandler(metrics=[mx.gluon.metric.RMSE("val acc")])
    with pytest.raises(ValueError):
        est.fit(train_data=train_data, epochs=num_epochs, event_handlers=[logging])

    # test handler order
    train_metrics = est.train_metrics
    val_metrics = est.val_metrics
    early_stopping = EarlyStoppingHandler(monitor=val_metrics[0])
    handlers = est._prepare_default_handlers(val_data=None, event_handlers=[early_stopping])
    assert len(handlers) == 5
    assert isinstance(handlers[0], GradientUpdateHandler)
    assert isinstance(handlers[1], MetricHandler)
    assert isinstance(handlers[4], LoggingHandler)

@mx.util.use_np
def test_val_net():
    ''' test estimator with different training and validation networks '''
    net = _get_test_network()
    val_net = _get_test_network(params=net.collect_params())
    dataloader, dataiter = _get_test_data()
    num_epochs = 1
    device = mx.cpu()
    loss = gluon.loss.L2Loss()
    val_loss = gluon.loss.L2Loss()
    acc = mx.gluon.metric.Accuracy()
    net.initialize(device=device)
    trainer = gluon.Trainer(net.collect_params(), 'sgd', {'learning_rate': 0.001})
    est = Estimator(net=net,
                    loss=loss,
                    train_metrics=acc,
                    trainer=trainer,
                    device=device,
                    val_loss=val_loss,
                    val_net=val_net)

    est.fit(train_data=dataloader,
            val_data=dataloader,
            epochs=num_epochs)

    ''' test partial weight sharing of two resnets '''
    net = gluon.model_zoo.vision.resnet18_v1(pretrained=False, device=device)
    net.output = gluon.nn.Dense(10)
    val_net = gluon.model_zoo.vision.resnet18_v1(pretrained=False, device=device)
    val_net.output = net.output
    dataset = gluon.data.ArrayDataset(mx.np.zeros((10, 3, 224, 224)), mx.np.zeros((10, 10)))
    dataloader = gluon.data.DataLoader(dataset=dataset, batch_size=5)
    net.initialize(device=device)
    val_net.initialize(device=device)
    trainer = gluon.Trainer(net.collect_params(), 'sgd', {'learning_rate': 0.001})
    est = Estimator(net=net,
                    loss=loss,
                    train_metrics=acc,
                    trainer=trainer,
                    device=device,
                    val_loss=val_loss,
                    val_net=val_net)

    est.fit(train_data=dataloader,
            val_data=dataloader,
            epochs=num_epochs)

@mx.util.use_np
def test_val_handlers():
    net = _get_test_network()
    train_data, _ = _get_test_data()
    val_data, _ = _get_test_data()

    num_epochs = 1
    device = mx.cpu()
    net.initialize(device=device)
    trainer = gluon.Trainer(net.collect_params(), 'sgd', {'learning_rate': 0.001})

    train_acc = mx.gluon.metric.RMSE()
    loss = gluon.loss.L2Loss()

    est = Estimator(net=net,
                    loss=loss,
                    train_metrics=train_acc,
                    trainer=trainer,
                    device=device)

    with warnings.catch_warnings(record=True) as w:
        est.fit(train_data=train_data, epochs=num_epochs)
        est.evaluate(val_data=val_data)

    logging = LoggingHandler(log_interval=1, metrics=est.val_metrics)
    est.evaluate(val_data=val_data, event_handlers=[logging])