#!/usr/bin/env python

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

import cdec
import aligner
import decoder
import util

# Dummy input token that is unlikely to appear in normalized data (but no fatal errors if it does)
LIKELY_OOV = '(OOV)'

logger = logging.getLogger('rt')

class RealtimeDecoder:
    '''Do not use directly unless you know what you're doing.  Use RealtimeTranslator.'''

    def __init__(self, configdir, tmpdir):

        cdec_root = os.path.dirname(os.path.dirname(os.path.dirname(os.path.abspath(__file__))))

        self.tmp = tmpdir
        os.mkdir(self.tmp)

        # 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, force=False):
        logger.info('Closing decoder and removing {}'.format(self.tmp))
        self.decoder.close(force)
        self.ref_fifo.close()
        shutil.rmtree(self.tmp)

class RealtimeTranslator:
    '''Main entry point into API: serves translations to any number of concurrent users'''

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

        # name -> (method, set of possible nargs)
        self.COMMANDS = {
                'TR': (self.translate, set((1,))),
                'LEARN': (self.learn, set((2,))),
                'SAVE': (self.save_state, set((0, 1))),
                'LOAD': (self.load_state, set((0, 1))),
                'DROP': (self.drop_ctx, set((0,))),
                'LIST': (self.list_ctx, set((0,))),
                }
        
        cdec_root = os.path.dirname(os.path.dirname(os.path.dirname(os.path.abspath(__file__))))

        ### Single instance for all contexts

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

        # Normalization
        self.norm = norm
        if self.norm:
            self.tokenizer = util.popen_io([os.path.join(cdec_root, 'corpus', 'tokenize-anything.sh'), '-u'])
            self.tokenizer_lock = util.FIFOLock()
            self.detokenizer = util.popen_io([os.path.join(cdec_root, 'corpus', 'untok.pl')])
            self.detokenizer_lock = util.FIFOLock()

        # 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 = cdec.configobj.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.cache_size = cache_size

        ### One instance per context

        self.ctx_names = set()
        # All context-dependent operations are atomic
        self.ctx_locks = collections.defaultdict(util.FIFOLock)
        # ctx -> list of (source, target, alignment)
        self.ctx_data = {}

        # Grammar extractor is not threadsafe
        self.extractor_lock = util.FIFOLock()
        # ctx -> deque of file
        self.grammar_files = {}
        # ctx -> dict of {sentence: file}
        self.grammar_dict = {}

        self.decoders = {}

    def __enter__(self):
        return self

    def __exit__(self, ex_type, ex_value, ex_traceback):
        # Force shutdown on exception
        self.close(ex_type is not None)

    def close(self, force=False):
        '''Cleanup'''
        if force:
            logger.info('Forced shutdown: stopping immediately')
        for ctx_name in list(self.ctx_names):
            self.drop_ctx(ctx_name, force)
        logger.info('Closing processes')
        self.aligner.close(force)
        if self.norm:
            if not force:
                self.tokenizer_lock.acquire()
                self.detokenizer_lock.acquire()
            self.tokenizer.stdin.close()
            self.tokenizer.wait()
            self.detokenizer.stdin.close()
            self.detokenizer.wait()
            if not force:
                self.tokenizer_lock.release()
                self.detokenizer_lock.release()
        logger.info('Deleting {}'.format(self.tmp))
        shutil.rmtree(self.tmp)

    def lazy_ctx(self, ctx_name):
        '''Initialize a context (inc starting a new decoder) if needed.
        NOT threadsafe, acquire ctx_name lock before calling.'''
        if ctx_name in self.ctx_names:
            return
        logger.info('({}) New context'.format(ctx_name))
        self.ctx_names.add(ctx_name)
        self.ctx_data[ctx_name] = []
        self.grammar_files[ctx_name] = collections.deque()
        self.grammar_dict[ctx_name] = {}
        tmpdir = os.path.join(self.tmp, 'decoder.{}'.format(ctx_name))
        self.decoders[ctx_name] = RealtimeDecoder(self.config, tmpdir)

    def drop_ctx(self, ctx_name=None, force=False):
        '''Delete a context (inc stopping the decoder)
        Threadsafe and FIFO unless forced.'''
        lock = self.ctx_locks[ctx_name]
        if not force:
            lock.acquire()
        if ctx_name not in self.ctx_names:
            logger.info('({}) No context found, no action taken'.format(ctx_name))
            if not force:
                lock.release()
            return
        logger.info('({}) Dropping context'.format(ctx_name))
        self.ctx_names.remove(ctx_name)
        self.ctx_data.pop(ctx_name)
        self.extractor.drop_ctx(ctx_name)
        self.grammar_files.pop(ctx_name)
        self.grammar_dict.pop(ctx_name)
        self.decoders.pop(ctx_name).close(force)
        self.ctx_locks.pop(ctx_name)
        if not force:
            lock.release()

    def list_ctx(self, ctx_name=None):
        '''Return a string of active contexts'''
        return 'ctx_name ||| {}'.format(' '.join(sorted(str(ctx_name) for ctx_name in self.ctx_names)))

    def grammar(self, sentence, ctx_name=None):
        '''Extract a sentence-level grammar on demand (or return cached)
        Threadsafe wrt extractor but NOT decoder.  Acquire ctx_name lock
        before calling.'''
        self.extractor_lock.acquire()
        self.lazy_ctx(ctx_name)
        grammar_dict = self.grammar_dict[ctx_name]
        grammar_file = grammar_dict.get(sentence, None)
        # Cache hit
        if grammar_file:
            logger.info('({}) Grammar cache hit: {}'.format(ctx_name, grammar_file))
            self.extractor_lock.release()
            return grammar_file
        # Extract and cache
        (fid, grammar_file) = tempfile.mkstemp(dir=self.decoders[ctx_name].tmp, prefix='grammar.')
        os.close(fid)
        with open(grammar_file, 'w') as output:
            for rule in self.extractor.grammar(sentence, ctx_name):
                output.write('{}\n'.format(str(rule)))
        grammar_files = self.grammar_files[ctx_name]
        if len(grammar_files) == self.cache_size:
            rm_sent = grammar_files.popleft()
            # If not already removed by learn method
            if rm_sent in grammar_dict:
                rm_grammar = grammar_dict.pop(rm_sent)
                os.remove(rm_grammar)
        grammar_files.append(sentence)
        grammar_dict[sentence] = grammar_file
        self.extractor_lock.release()
        return grammar_file
        
    def translate(self, sentence, ctx_name=None):
        '''Decode a sentence (inc extracting a grammar if needed)
        Threadsafe, FIFO'''
        lock = self.ctx_locks[ctx_name]
        lock.acquire()
        self.lazy_ctx(ctx_name)
        # Empty in, empty out
        if sentence.strip() == '':
            lock.release()
            return ''
        if self.norm:
            sentence = self.tokenize(sentence)
            logger.info('({}) Normalized input: {}'.format(ctx_name, sentence))
        grammar_file = self.grammar(sentence, ctx_name)
        decoder = self.decoders[ctx_name]
        start_time = time.time()
        hyp = decoder.decoder.decode(sentence, grammar_file)
        stop_time = time.time()
        logger.info('({}) Translation time: {} seconds'.format(ctx_name, stop_time - start_time))
        # Empty reference: HPYPLM does not learn prior to next translation
        decoder.ref_fifo.write('\n')
        decoder.ref_fifo.flush()
        if self.norm:
            logger.info('({}) Normalized translation: {}'.format(ctx_name, hyp))
            hyp = self.detokenize(hyp)
        lock.release()
        return hyp

    def tokenize(self, line):
        self.tokenizer_lock.acquire()
        self.tokenizer.stdin.write('{}\n'.format(line))
        tok_line = self.tokenizer.stdout.readline().strip()
        self.tokenizer_lock.release()
        return tok_line

    def detokenize(self, line):
        self.detokenizer_lock.acquire()
        self.detokenizer.stdin.write('{}\n'.format(line))
        detok_line = self.detokenizer.stdout.readline().strip()
        self.detokenizer_lock.release()
        return detok_line

    def command_line(self, line, ctx_name=None):
        # COMMAND [ctx_name] ||| arg1 [||| arg2 ...]
        args = [f.strip() for f in line.split('|||')]
        if args[-1] == '':
            args = args[:-1]
        if len(args) > 0:
            cmd_name = args[0].split()
            # ctx_name provided
            if len(cmd_name) == 2:
                (cmd_name, ctx_name) = cmd_name
            # ctx_name default/passed
            else:
                cmd_name = cmd_name[0]
            (command, nargs) = self.COMMANDS.get(cmd_name, (None, None))
            if command and len(args[1:]) in nargs:
                logger.info('({}) {} ||| {}'.format(ctx_name, cmd_name, ' ||| '.join(args[1:])))
                return command(*args[1:], ctx_name=ctx_name)
        logger.info('ERROR: command: {}'.format(' ||| '.join(args)))
        
    def learn(self, source, target, ctx_name=None):
        '''Learn from training instance (inc extracting grammar if needed)
        Threadsafe, FIFO'''
        lock = self.ctx_locks[ctx_name]
        lock.acquire()
        self.lazy_ctx(ctx_name)
        if '' in (source.strip(), target.strip()):
            logger.info('({}) ERROR: empty source or target: {} ||| {}'.format(ctx_name, source, target))
            lock.release()
            return
        if self.norm:
            source = self.tokenize(source)
            target = self.tokenize(target)
        # Align instance
        alignment = self.aligner.align(source, target)
        grammar_file = self.grammar(source, ctx_name)
        # MIRA update before adding data to grammar extractor
        decoder = self.decoders[ctx_name]
        mira_log = decoder.decoder.update(source, grammar_file, target)
        logger.info('({}) MIRA HBF: {}'.format(ctx_name, mira_log))
        # Add to HPYPLM by writing to fifo (read on next translation)
        logger.info('({}) Adding to HPYPLM: {}'.format(ctx_name, target))
        decoder.ref_fifo.write('{}\n'.format(target))
        decoder.ref_fifo.flush()
        # Store incremental data for save/load
        self.ctx_data[ctx_name].append((source, target, alignment))
        # Add aligned sentence pair to grammar extractor
        logger.info('({}) Adding to bitext: {} ||| {} ||| {}'.format(ctx_name, source, target, alignment))
        self.extractor.add_instance(source, target, alignment, ctx_name)
        # Clear (old) cached grammar
        rm_grammar = self.grammar_dict[ctx_name].pop(source)
        os.remove(rm_grammar)
        lock.release()

    def save_state(self, file_or_stringio=None, ctx_name=None):
        '''Write state (several lines terminated by EOF line) to file, buffer, or stdout'''
        lock = self.ctx_locks[ctx_name]
        lock.acquire()
        self.lazy_ctx(ctx_name)
        ctx_data = self.ctx_data[ctx_name]
        # Filename, StringIO or None (stdout)
        if file_or_stringio:
            if isinstance(file_or_stringio, StringIO.StringIO):
                out = file_or_stringio
            else:
                out = open(file_or_stringio, 'w')
        else:
            out = sys.stdout
        logger.info('({}) Saving state with {} sentences'.format(ctx_name, len(ctx_data)))
        out.write('{}\n'.format(self.decoders[ctx_name].decoder.get_weights()))
        for (source, target, alignment) in ctx_data:
            out.write('{} ||| {} ||| {}\n'.format(source, target, alignment))
        out.write('EOF\n')
        # Close if file
        if file_or_stringio and not isinstance(file_or_stringio, StringIO.StringIO):
            out.close()
        lock.release()

    def load_state(self, file_or_stringio=None, ctx_name=None):
        '''Load state (several lines terminated by EOF line) from file, buffer, or stdin.
        Restarts context on any error.'''
        lock = self.ctx_locks[ctx_name]
        lock.acquire() 
        self.lazy_ctx(ctx_name)
        ctx_data = self.ctx_data[ctx_name]
        decoder = self.decoders[ctx_name]
        # Filename, StringIO, or None (stdin)
        if file_or_stringio:
            if isinstance(file_or_stringio, StringIO.StringIO):
                input = file_or_stringio
            else:
                input = open(file_or_stringio)
        else:
            input = sys.stdin
        # Non-initial load error
        if ctx_data:
            logger.info('({}) ERROR: Incremental data has already been added to context'.format(ctx_name))
            logger.info('  State can only be loaded to a new context.')
            lock.release()
            return
        # Many things can go wrong if bad state data is given
        try:
            # MIRA weights
            line = input.readline().strip()
            # Throws exception if bad line
            decoder.decoder.set_weights(line)
            logger.info('({}) Loading state...'.format(ctx_name))
            start_time = time.time()
            # Lines source ||| target ||| alignment
            while True:
                line = input.readline()
                if not line:
                    raise Exception('End of file before EOF line')
                line = line.strip()
                if line == 'EOF':
                    break
                (source, target, alignment) = line.split(' ||| ')
                ctx_data.append((source, target, alignment))
                # Extractor
                self.extractor.add_instance(source, target, alignment, ctx_name)
                # HPYPLM
                hyp = decoder.decoder.decode(LIKELY_OOV)
                decoder.ref_fifo.write('{}\n'.format(target))
                decoder.ref_fifo.flush()
            stop_time = time.time()
            logger.info('({}) Loaded state with {} sentences in {} seconds'.format(ctx_name, len(ctx_data), stop_time - start_time))
            lock.release()
        # Recover from bad load attempt by restarting context.
        # Guaranteed not to cause data loss since only a new context can load state.
        except:
            logger.info('({}) ERROR: could not load state, restarting context'.format(ctx_name))
            # ctx_name is already owned and needs to be restarted before other blocking threads use
            self.drop_ctx(ctx_name, force=True)
            self.lazy_ctx(ctx_name)
            lock.release()