"""
Conversion service.

Hardcoded to manage only conversion to PDF, to text and to image series.

Includes result caching (on filesystem).

Assumes poppler-utils and LibreOffice are installed.

TODO: rename Converter into ConversionService ?
"""
from __future__ import print_function
from __future__ import division
from __future__ import absolute_import

import glob
import hashlib
import shutil
import logging
from tempfile import mkstemp
import traceback
from abc import ABCMeta, abstractmethod
from pathlib import Path
from magic import Magic
import os
import subprocess
import threading
from base64 import encodestring, decodestring
from xmlrpclib import ServerProxy
import mimetypes
import re
import cStringIO as StringIO
from contextlib import contextmanager

from PIL import Image
from PIL.ExifTags import TAGS

from abilian.services.image import resize, FIT


logger = logging.getLogger(__name__)

# For some reason, twill includes a broken version of subprocess.
assert not 'twill' in subprocess.__file__

# Hack for Mac OS + homebrew
os.environ['PATH'] += ":/usr/local/bin"

TMP_DIR = "tmp"
CACHE_DIR = "cache"


def get_tmp_dir():
  return converter.TMP_DIR


class ConversionError(Exception):
  pass


class Cache(object):

  CACHE_DIR = None

  def _path(self, key):
    """ file path for `key`"""
    return self.CACHE_DIR / "{}.blob".format(key)

  def __contains__(self, key):
    return self._path(key).exists()

  def get(self, key):
    if key in self:
      value = self._path(key).open('rb').read()
      if key.startswith("txt:"):
        value = unicode(value, encoding="utf8")
      return value
    else:
      return None

  __getitem__ = get

  def set(self, key, value):
    # if not os.path.exists(self.CACHE_DIR):
    #   os.mkdir(CACHE_DIR)
    fd = self._path(key).open("wb")
    if key.startswith("txt:"):
      fd.write(value.encode("utf8"))
    else:
      fd.write(value)
    fd.close()

  __setitem__ = set

  def clear(self):
    pass


class Converter(object):
  def __init__(self):
    self.handlers = []
    self.cache = Cache()

  def init_app(self, app):
    self.init_work_dirs(
      cache_dir=Path(app.instance_path, CACHE_DIR),
      tmp_dir=Path(app.instance_path, TMP_DIR),
    )

    app.extensions['conversion'] = self

    for handler in self.handlers:
      handler.init_app(app)

  def init_work_dirs(self, cache_dir, tmp_dir):
    self.TMP_DIR = Path(tmp_dir)
    self.CACHE_DIR = Path(cache_dir)
    self.cache.CACHE_DIR = self.CACHE_DIR

    if not self.TMP_DIR.exists():
      self.TMP_DIR.mkdir()
    if not self.CACHE_DIR.exists():
      self.CACHE_DIR.mkdir()

  def clear(self):
    self.cache.clear()
    for d in (self.TMP_DIR, self.CACHE_DIR):
      shutil.rmtree(bytes(d))
      d.mkdir()

  def register_handler(self, handler):
    self.handlers.append(handler)

  # TODO: refactor, pass a "File" or "Document" or "Blob" object
  def to_pdf(self, digest, blob, mime_type):
    cache_key = "pdf:" + digest
    pdf = self.cache.get(cache_key)
    if pdf:
      return pdf

    for handler in self.handlers:
      if handler.accept(mime_type, "application/pdf"):
        pdf = handler.convert(blob)
        self.cache[cache_key] = pdf
        return pdf
    raise ConversionError("No handler found to convert from %s to PDF" % mime_type)

  def to_text(self, digest, blob, mime_type):
    """Converts a file to plain text.

    Useful for full-text indexing. Returns an unicode string.
    """
    # Special case, for now (XXX).
    if mime_type.startswith("image/"):
      return u""

    cache_key = "txt:" + digest

    text = self.cache.get(cache_key)
    if text:
      return text

    # Direct conversion possible
    for handler in self.handlers:
      if handler.accept(mime_type, "text/plain"):
        text = handler.convert(blob)
        self.cache[cache_key] = text
        return text

    # Use PDF as a pivot format
    pdf = self.to_pdf(digest, blob, mime_type)
    for handler in self.handlers:
      if handler.accept("application/pdf", "text/plain"):
        text = handler.convert(pdf)
        self.cache[cache_key] = text
        return text

    raise ConversionError()

  def has_image(self, digest, mime_type, index, size=500):
    """ Tell if there is a preview image
    """
    cache_key = "img:%s:%s:%s" % (index, size, digest)
    return mime_type.startswith("image/") or cache_key in self.cache

  def get_image(self, digest, blob, mime_type, index, size=500):
    """ Return an image for the given content, only if it already exists in the
    image cache
    """
    # Special case, for now (XXX).
    if mime_type.startswith("image/"):
      return ""

    cache_key = "img:%s:%s:%s" % (index, size, digest)
    return self.cache.get(cache_key)

  def to_image(self, digest, blob, mime_type, index, size=500):
    """
    Converts a file to a list of images. Returns image at the given index.
    """
    # Special case, for now (XXX).
    if mime_type.startswith("image/"):
      return ""

    cache_key = "img:%s:%s:%s" % (index, size, digest)
    converted = self.cache.get(cache_key)
    if converted:
      return converted

    # Direct conversion possible
    for handler in self.handlers:
      if handler.accept(mime_type, "image/jpeg"):
        converted_images = handler.convert(blob, size=size)
        for i in range(0, len(converted_images)):
          converted = converted_images[i]
          self.cache["img:%s:%s:%s" % (i, size, digest)] = converted
        return converted_images[index]

    # Use PDF as a pivot format
    pdf = self.to_pdf(digest, blob, mime_type)
    for handler in self.handlers:
      if handler.accept("application/pdf", "image/jpeg"):
        converted_images = handler.convert(pdf, size=size)
        for i in range(0, len(converted_images)):
          converted = converted_images[i]
          self.cache["img:%s:%s:%s" % (i, size, digest)] = converted
        return converted_images[index]

    raise ConversionError()

  def get_metadata(self, digest, content, mime_type):
    """Gets a dictionary representing the metadata embedded in the given content."""

    # XXX: ad-hoc for now, refactor later
    if mime_type.startswith("image/"):
      img = Image.open(StringIO.StringIO(content))
      ret = {}
      if not hasattr(img, '_getexif'):
        return {}
      info = img._getexif()
      if not info:
        return {}
      for tag, value in info.items():
        decoded = TAGS.get(tag, tag)
        ret["EXIF:" + str(decoded)] = value
      return ret
    else:
      if mime_type != "application/pdf":
        content = self.to_pdf(digest, content, mime_type)

      with make_temp_file(content) as in_fn:
        output = subprocess.check_output(['pdfinfo', in_fn])

      ret = {}
      for line in output.split("\n"):
        if ":" in line:
          key, value = line.strip().split(":", 1)
          ret["PDF:" + key] = unicode(value.strip(), errors="replace")

      return ret

  @staticmethod
  def digest(blob):
    assert isinstance(blob, basestring)
    if type(blob) == str:
      digest = hashlib.md5(blob).hexdigest()
    else:
      digest = hashlib.md5(blob.encode("utf8")).hexdigest()
    return digest


class Handler(object):
  __metaclass__ = ABCMeta

  accepts_mime_types = []
  produces_mime_types = []

  def __init__(self, *args, **kwargs):
    self.log = logger.getChild(self.__class__.__name__)

  def init_app(self, app):
    pass

  @property
  def TMP_DIR(self):
    return get_tmp_dir()

  @property
  def mime_sniffer(self):
    return Magic(mime=True)

  @property
  def encoding_sniffer(self):
    return Magic(mime_encoding=True)

  def accept(self, source_mime_type, target_mime_type):
    """Generic matcher based on patterns."""

    match_source = False
    match_target = False

    for pat in self.accepts_mime_types:
      if re.match("^%s$" % pat, source_mime_type):
        match_source = True
        break

    for pat in self.produces_mime_types:
      if re.match("^%s$" % pat, target_mime_type):
        match_target = True
        break

    return match_source and match_target

  @abstractmethod
  def convert(self, key, **kw):
    pass


class PdfToTextHandler(Handler):
  accepts_mime_types = ['application/pdf']
  produces_mime_types = ['text/plain']

  def convert(self, blob, **kw):
    with make_temp_file(blob) as in_fn, make_temp_file() as out_fn:
      try:
        subprocess.check_call(['pdftotext', in_fn, out_fn])
      except Exception as e:
        raise ConversionError(e)

      converted = open(out_fn).read()
      encoding = self.encoding_sniffer.from_file(out_fn)

    if encoding in ("binary", None):
      encoding = "ascii"
    try:
      converted_unicode = unicode(converted, encoding, errors="ignore")
    except:
      traceback.print_exc()
      converted_unicode = unicode(converted, errors="ignore")

    return converted_unicode


class AbiwordTextHandler(Handler):
  accepts_mime_types = ['application/msword']
  produces_mime_types = ['text/plain']

  def convert(self, blob, **kw):
    tmp_dir = self.TMP_DIR
    cur_dir = os.getcwd()
    with make_temp_file(blob, suffix=".doc") as in_fn,\
         make_temp_file(suffix='.txt') as out_fn:
      try:
        os.chdir(str(tmp_dir))
        subprocess.check_call(
          ['abiword',
           '--to', os.path.basename(out_fn),
          os.path.basename(in_fn)])
      except Exception as e:
        raise ConversionError(e)
      finally:
        os.chdir(cur_dir)

      converted = open(out_fn).read()
      encoding = self.encoding_sniffer.from_file(out_fn)

    if encoding in ("binary", None):
      encoding = "ascii"
    try:
      converted_unicode = unicode(converted, encoding, errors="ignore")
    except:
      traceback.print_exc()
      converted_unicode = unicode(converted, errors="ignore")

    return converted_unicode


class AbiwordPDFHandler(Handler):
  accepts_mime_types = ['application/msword',
                        'application/vnd.oasis.opendocument.text',
                        'text/rtf',]
  produces_mime_types = ['application/pdf']

  def convert(self, blob, **kw):
    cur_dir = os.getcwd()
    with make_temp_file(blob, suffix=".doc") as in_fn,\
         make_temp_file(suffix='.pdf') as out_fn:
      try:
        os.chdir(bytes(self.TMP_DIR))
        subprocess.check_call(
          ['abiword',
           '--to', os.path.basename(out_fn),
          os.path.basename(in_fn)])
      except Exception as e:
        raise ConversionError(e)
      finally:
        os.chdir(cur_dir)

      converted = open(out_fn).read()
      return converted


class ImageMagickHandler(Handler):
  accepts_mime_types = ['image/.*']
  produces_mime_types = ['application/pdf']

  def convert(self, blob, **kw):
    with make_temp_file(blob) as in_fn, make_temp_file() as out_fn:
      try:
        subprocess.check_call(['convert', in_fn, "pdf:" + out_fn])
        converted = open(out_fn).read()
        return converted
      except Exception as e:
        raise ConversionError(e)


class PdfToPpmHandler(Handler):
  accepts_mime_types = ['application/pdf']
  produces_mime_types = ['image/jpeg']

  def convert(self, blob, size=500):
    """Size is the maximum horizontal size."""
    l = []
    with make_temp_file(blob) as in_fn, make_temp_file() as out_fn:
      try:
        subprocess.check_call(['pdftoppm', '-jpeg', in_fn, out_fn])
        l = glob.glob("%s-*.jpg" % out_fn)
        l.sort()

        converted_images = []
        for fn in l:
          converted = resize(open(fn).read(), size, size, mode=FIT)
          converted_images.append(converted)

        return converted_images
      except Exception as e:
        raise ConversionError(e)
      finally:
        for fn in l:
          try:
            os.remove(fn)
          except OSError:
            pass


class UnoconvPdfHandler(Handler):
  """Handles conversion from office documents (MS-Office, OOo) to PDF.

  Uses unoconv.
  """

  # TODO: add more if needed.
  accepts_mime_types = ['application/vnd.oasis.*',
                        'application/msword',
                        'application/mspowerpoint',
                        'application/vnd.ms-powerpoint',
                        'application/vnd.ms-excel',
                        'application/ms-excel',
                        'application/vnd.openxmlformats-officedocument.*',
                        'text/rtf']
  produces_mime_types = ['application/pdf']
  run_timeout = 60
  _process = None
  unoconv = 'unoconv'

  def init_app(self, app):
    unoconv = app.config.get('UNOCONV_LOCATION')
    found = False
    execute_ok = False

    if unoconv:
      found = os.path.isfile(unoconv)
      if found:
        # make absolute path: avoid errors when running with different CWD
        unoconv = os.path.abspath(unoconv)
        execute_ok = os.access(unoconv, os.X_OK)
        if not execute_ok:
          self.log.warning('Not allowed to execute "{}", fallback to '
                           '"unoconv"'.format(unoconv))
      else:
        self.log.warning('Cannot find "{}", fallback to "unoconv"'
                         ''.format(unoconv))
    if (not unoconv or not found or not execute_ok):
      unoconv = 'unoconv'

    self.unoconv = unoconv

  @property
  def unoconv_version(self):
    # Hack for my Mac, FIXME later
    if os.path.exists("/Applications/LibreOffice.app/Contents/program/python"):
      cmd = ['/Applications/LibreOffice.app/Contents/program/python',
             '/usr/local/bin/unoconv', '--version']
    else:
      cmd = [self.unoconv, '--version']

    process = subprocess.Popen(cmd, stdout=subprocess.PIPE)
    out, err = process.communicate()
    return out

  def convert(self, blob, **kw):
    """
    Unoconv converter called.
    """
    timeout = self.run_timeout
    with make_temp_file(blob) as in_fn,\
        make_temp_file(prefix='tmp-unoconv-', suffix=".pdf") as out_fn:

      # Hack for my Mac, FIXME later
      if os.path.exists("/Applications/LibreOffice.app/Contents/program/python"):
        cmd = ['/Applications/LibreOffice.app/Contents/program/python',
               '/usr/local/bin/unoconv', '-f', 'pdf', '-o', out_fn, in_fn]
      else:
        cmd = [self.unoconv, '-f', 'pdf', '-o', out_fn, in_fn]

      def run_uno():
        try:
          self._process = subprocess.Popen(cmd,
                                           close_fds=True,
                                           cwd=bytes(self.TMP_DIR))
          self._process.communicate()
        except Exception as e:
          logger.error('run_uno error: %s', bytes(e), exc_info=True)
          raise ConversionError(e)

      run_thread = threading.Thread(target=run_uno)
      run_thread.start()
      run_thread.join(timeout)

      try:
        if run_thread.is_alive():
          # timeout reached
          self._process.terminate()
          if self._process.poll() is not None:
            try:
              self._process.kill()
            except OSError:
              logger.warning("Failed to kill process {}".format(self._process))

          self._process = None
          raise ConversionError("Conversion timeout ({})".format(timeout))

        converted = open(out_fn).read()
        return converted
      finally:
        self._process = None


class CloudoooPdfHandler(Handler):
  """Handles conversion from OOo to PDF.

  Highly inefficient since file are serialized in base64 over HTTP.

  Deactivated because it's so hard to set up.

  FIXME: needs cleanup, or removal.
  """

  accepts_mime_types = [r'application/.*']
  produces_mime_types = ['application/pdf']

  # Hardcoded for now
  SERVER_URL = "http://localhost:8011"

  pivot_format_map = {
    "doc": "odt",
    "docx": "odt",
    "xls": "ods",
    "xlsx": "ods",
    "ppt": "odp",
    "pptx": "odp",
    }

  def convert(self, key):
    in_fn = "data/%s.blob" % key
    in_mime_type = open("data/%s.mime" % key).read()
    file_extension = mimetypes.guess_extension(in_mime_type).strip(".")

    data = encodestring(open(in_fn).read())
    proxy = ServerProxy(self.SERVER_URL, allow_none=True)

    if in_mime_type.startswith("application/vnd.oasis.opendocument"):
      data = proxy.convertFile(data, file_extension, 'pdf')
    else:
      pivot_format = self.pivot_format_map[file_extension]
      data = proxy.convertFile(data, file_extension, pivot_format)
      data = proxy.convertFile(data, pivot_format, 'pdf')

    converted = decodestring(data)
    new_key = hashlib.md5(converted).hexdigest()
    with open("data/%s.blob" % new_key, "wcb") as fd:
      fd.write(converted)
    return new_key


class WvwareTextHandler(Handler):
  accepts_mime_types = ['application/msword']
  produces_mime_types = ['text/plain']

  def convert(self, blob, **kw):

    with make_temp_file(blob) as in_fn, make_temp_file() as out_fn:
      try:
        subprocess.check_call(['wvText', in_fn, out_fn])
      except Exception as e:
        raise ConversionError(e)

      converted = open(out_fn).read()

      encoding = self.encoding_sniffer.from_file(out_fn)
      if encoding in ("binary", None):
        encoding = "ascii"
      try:
        converted_unicode = unicode(converted, encoding, errors="ignore")
      except:
        traceback.print_exc()
        converted_unicode = unicode(converted, errors="ignore")

      return converted_unicode

# Utils
@contextmanager
def make_temp_file(blob=None, prefix='tmp', suffix="", tmp_dir=None):
  if tmp_dir is None:
    tmp_dir = get_tmp_dir()

  fd, filename = mkstemp(dir=str(tmp_dir), prefix=prefix, suffix=suffix)
  if blob is not None:
    fd = os.fdopen(fd, 'wb')
    fd.write(blob)
    fd.close()
  else:
    os.close(fd)

  yield filename
  try:
    os.remove(filename)
  except OSError:
    pass


# Singleton, yuck!
converter = Converter()
converter.register_handler(PdfToTextHandler())
converter.register_handler(PdfToPpmHandler())
converter.register_handler(ImageMagickHandler())

_unoconv_handler = UnoconvPdfHandler()
converter.register_handler(_unoconv_handler)

#converter.register_handler(AbiwordPDFHandler())
#converter.register_handler(AbiwordTextHandler())


# Needs to be rewriten
#converter.register_handler(CloudoooPdfHandler())
