#!/usr/bin/env python

import argparse
import collections
import logging
import os
import shutil
import sys
import subprocess
import tempfile
import time

from cdec.configobj import ConfigObj
import cdec.sa

import aligner
import decoder
import util

class RealtimeDecoder:

    def __init__(self, configdir, tmpdir='/tmp', cache_size=5):

        # Temporary work dir
        self.tmp = tempfile.mkdtemp(dir=tmpdir, prefix='realtime.')
        logging.info('Using temp dir {}'.format(self.tmp))

        # Word aligner
        fwd_params = os.path.join(configdir, 'a.fwd_params')
        fwd_err = os.path.join(configdir, 'a.fwd_err')
        rev_params = os.path.join(configdir, 'a.rev_params')
        rev_err = os.path.join(configdir, 'a.rev_err')
        self.aligner = aligner.ForceAligner(fwd_params, fwd_err, rev_params, rev_err)

        # Grammar extractor
        sa_config = ConfigObj(os.path.join(configdir, 'sa.ini'), unrepr=True)
        sa_config.filename = os.path.join(self.tmp, 'sa.ini')
        util.sa_ini_for_realtime(sa_config, os.path.abspath(configdir))
        sa_config.write()
        self.extractor = cdec.sa.GrammarExtractor(sa_config.filename, online=True)
        self.grammar_files = collections.deque()
        self.grammar_dict = {}
        self.cache_size = cache_size

        # HPYPLM reference stream
        ref_fifo_file = os.path.join(self.tmp, 'ref.fifo')
        os.mkfifo(ref_fifo_file)
        self.ref_fifo = open(ref_fifo_file, 'w+')
        # Start with empty line (do not learn prior to first input)
        self.ref_fifo.write('\n')
        self.ref_fifo.flush()

        # Decoder
        decoder_config = [[f.strip() for f in line.split('=')] for line in open(os.path.join(configdir, 'cdec.ini'))]
        util.cdec_ini_for_realtime(decoder_config, os.path.abspath(configdir), ref_fifo_file)
        decoder_config_file = os.path.join(self.tmp, 'cdec.ini')
        with open(decoder_config_file, 'w') as output:
            for (k, v) in decoder_config:
                output.write('{}={}\n'.format(k, v))
        decoder_weights = os.path.join(configdir, 'weights.final')
        self.decoder = decoder.MIRADecoder(decoder_config_file, decoder_weights)

    def close(self):
        logging.info('Closing processes')
        self.aligner.close()
        self.decoder.close()
        self.ref_fifo.close()
        logging.info('Deleting {}'.format(self.tmp))
        shutil.rmtree(self.tmp)

    def grammar(self, sentence):
        grammar_file = self.grammar_dict.get(sentence, None)
        # Cache hit
        if grammar_file:
            logging.info('Grammar cache hit')
            return grammar_file
        # Extract and cache
        grammar_file = tempfile.mkstemp(dir=self.tmp, prefix='grammar.')[1]
        with open(grammar_file, 'w') as output:
            for rule in self.extractor.grammar(sentence):
                output.write(str(rule) + '\n')
        if len(self.grammar_files) == self.cache_size:
            rm_sent = self.grammar_files.popleft()
            # If not already removed by learn method
            if rm_sent in self.grammar_dict:
                rm_grammar = self.grammar_dict.pop(rm_sent)
                os.remove(rm_grammar)
        self.grammar_files.append(sentence)
        self.grammar_dict[sentence] = grammar_file
        return grammar_file
        
    def decode(self, sentence):
        grammar_file = self.grammar(sentence)
        start_time = time.time()
        hyp = self.decoder.decode(sentence, grammar_file)
        # Empty reference: HPYPLM does not learn prior to next translation
        self.ref_fifo.write('\n')
        self.ref_fifo.flush()
        stop_time = time.time()
        logging.info('Translation time: {} seconds'.format(stop_time - start_time))
        return hyp

    def learn(self, source, target):
        # MIRA update before adding data to grammar extractor
        grammar_file = self.grammar(source)
        mira_log = self.decoder.update(source, grammar_file, target)
        logging.info('MIRA: {}'.format(mira_log))
        # Add aligned sentence pair to grammar extractor
        alignment = self.aligner.align(source, target)
        logging.info('Adding instance: {} ||| {} ||| {}'.format(source, target, alignment))
        self.extractor.add_instance(source, target, alignment)
        # Clear (old) cached grammar
        rm_grammar = self.grammar_dict.pop(source)
        os.remove(rm_grammar)
        # Add to HPYPLM by writing to fifo (read on next translation)
        logging.info('Adding to HPYPLM: {}'.format(target))
        self.ref_fifo.write('{}\n'.format(target))
        self.ref_fifo.flush()