#!/usr/bin/env python

import importlib
import logging
import operator
import os
import sys
from functools import reduce

from theano import tensor

from blocks import roles
from blocks.algorithms import AdaDelta, CompositeRule, GradientDescent, RemoveNotFinite, StepRule
from blocks.extensions import Printing, FinishAfter
from blocks.extensions.monitoring import DataStreamMonitoring, TrainingDataMonitoring
from blocks.extensions.plot import Plot
from blocks.extensions.saveload import LoadFromDump, Dump
from blocks.dump import MainLoopDumpManager
from blocks.filter import VariableFilter
from blocks.graph import ComputationGraph, apply_dropout, apply_noise
from blocks.main_loop import MainLoop
from blocks.model import Model


logger = logging.getLogger(__name__)


class ElementwiseRemoveNotFinite(StepRule):
    """A step rule that replaces non-finite coefficients by zeros.

    Replaces non-finite elements (such as ``inf`` or ``NaN``) in a step
    (the parameter update of a single shared variable)
    with a scaled version of the parameters being updated instead.

    Parameters
    ----------
    scaler : float, optional
        The scaling applied to the parameter in case the step contains
        non-finite elements. Defaults to 0.1.

    Notes
    -----
    This trick was originally used in the GroundHog_ framework.

    .. _GroundHog: https://github.com/lisa-groundhog/GroundHog

    """
    def __init__(self, scaler=0.1):
        self.scaler = scaler

    def compute_step(self, param, previous_step):
        not_finite = tensor.isnan(previous_step) + tensor.isinf(previous_step)
        step = tensor.switch(not_finite, self.scaler * param, previous_step)

        return step, []

class CustomDumpManager(MainLoopDumpManager):
    def dump(self, main_loop):
        """Dumps the main loop to the root folder.
        See :mod:`blocks.dump`.
        Overwrites the old data if present.
        """
        if not os.path.exists(self.folder):
            os.mkdir(self.folder)
        self.dump_parameters(main_loop)
        self.dump_log(main_loop)

    def load(self):
        return (self.load_parameters(), self.load_log())

    def load_to(self, main_loop):
        """Loads the dump from the root folder into the main loop."""
        parameters, log = self.load()
        main_loop.model.set_param_values(parameters)
        main_loop.log = log

if __name__ == "__main__":
    if len(sys.argv) != 2:
        print >> sys.stderr, 'Usage: %s config' % sys.argv[0]
        sys.exit(1)
    model_name = sys.argv[1]
    config = importlib.import_module('.%s' % model_name, 'config')

    logger.info('# Configuration: %s' % config.__name__)
    for key in dir(config):
        if not key.startswith('__') and isinstance(getattr(config, key), (int, str, list, tuple)):
            logger.info('    %20s %s' % (key, str(getattr(config, key))))

    model = config.Model(config)
    model.initialize()

    stream = config.Stream(config)
    inputs = stream.inputs()
    req_vars = model.cost.inputs

    train_stream = stream.train(req_vars)
    valid_stream = stream.valid(req_vars)

    cost = model.cost(**inputs)
    cg = ComputationGraph(cost)
    monitored = set([cost] + VariableFilter(roles=[roles.COST])(cg.variables))

    if hasattr(config, 'dropout') and config.dropout < 1.0:
        cg = apply_dropout(cg, config.dropout_inputs(cg), config.dropout)
    if hasattr(config, 'noise') and config.noise > 0.0:
        cg = apply_noise(cg, config.noise_inputs(cg), config.noise)
    cost = cg.outputs[0]
    cg = Model(cost)

    logger.info('# Parameter shapes:')
    parameters_size = 0
    for key, value in cg.get_params().iteritems():
        logger.info('    %20s %s' % (value.get_value().shape, key))
        parameters_size += reduce(operator.mul, value.get_value().shape, 1)
    logger.info('Total number of parameters: %d in %d matrices' % (parameters_size, len(cg.get_params())))

    params = cg.parameters
    algorithm = GradientDescent(
        cost=cost,
        step_rule=CompositeRule([
                ElementwiseRemoveNotFinite(),
                AdaDelta(),
                #Momentum(learning_rate=config.learning_rate, momentum=config.momentum),
            ]),
        params=params)
    
    plot_vars = [['valid_' + x.name for x in monitored]]
    logger.info('Plotted variables: %s' % str(plot_vars))

    dump_path = os.path.join('model_data', model_name)
    logger.info('Dump path: %s' % dump_path)

    load_dump_ext = LoadFromDump(dump_path)
    dump_ext = Dump(dump_path, every_n_batches=1000)
    load_dump_ext.manager = CustomDumpManager(dump_path)
    dump_ext.manager = CustomDumpManager(dump_path)

    extensions=[TrainingDataMonitoring(monitored, prefix='train', every_n_batches=1000),
                DataStreamMonitoring(monitored, valid_stream,
                                     prefix='valid',
                                     every_n_batches=1000),
                Printing(every_n_batches=1000),
                Plot(model_name, channels=plot_vars, every_n_batches=500),
                load_dump_ext,
                dump_ext 
                ]

    main_loop = MainLoop(
        model=cg,
        data_stream=train_stream,
        algorithm=algorithm,
        extensions=extensions)
    main_loop.run()
    main_loop.profile.report()