import sys

import os

import codecs

from dbtexmf.dblatex.texcodec import LatexCodec

from fsencoder import FontSpecEncoder

class XetexCodec(LatexCodec):

    def __init__(self, fontconfig="", pre="", post=""):

        # Use the default TeX escapes, and encoding method

        LatexCodec.__init__(self, input_encoding="utf8",

                            output_encoding="utf8")

        # XeTeX font manager

        if not(fontconfig):

            fontconfig = os.getenv("DBLATEX_FONTSPEC_FILE", "xefont.xml")

        # If not proper fontconfig, fallback to default behaviour

        try:

            self._fontmgr = FontSpecEncoder(fontconfig)

        except:

            self._fontmgr = None

            return

        # Ignore the special characters \1 and \2 used as specific

        # substitution characters

        self._fontmgr.ignorechars("\1\2\r")

    def clear_errors(self):

        pass

    def get_errors(self):

        pass

    def decode(self, text):

        return self._decode(text)[0]

    def encode(self, text):

        # If no font manager, behaves as the default latex codec

        if not(self._fontmgr):

            return LatexCodec.encode(self, text)

        # Preliminary backslash substitution

        text = text.replace("\\", "\2")

        # Consider that each text sequence is in his own tex group

        self._fontmgr.reset()

        # Handle fonts for this Unicode string. We build a list of

        # strings, where each string is handled by a new font

        switchfonts = []

        for c in text:

            font, char = self._fontmgr.encode(c)

            # A new font, or empty switchfont list

            if font or not(switchfonts):

                sf = [font, char]

                switchfonts.append(sf)

            else:

            # No new font, so extend the current string

                sf[1] += char

        # Merge each part, after escaping each string

        text = ""

        for sf in switchfonts:

            sf[1] = self._texescape(sf[1])

            text += "".join(sf)

        # Encode for string output

        text = self._encode(text)[0]

        # Things are done, substitute the '\'

        text = text.replace("\2", r"\textbackslash{}")

        return "{" + text + "}"