# -*- coding: utf-8 -*-
# Copyright: Damien Elmes <anki@ichi2.net>
# License: GNU AGPL, version 3 or later; http://www.gnu.org/licenses/agpl.html

import re, tempfile, os, sys, shutil, cgi, subprocess
from anki.utils import checksum, call
from anki.hooks import addHook
from htmlentitydefs import entitydefs
from anki.lang import _

latexCmd = ["latex", "-interaction=nonstopmode"]
latexDviPngCmd = ["dvipng", "-D", "200", "-T", "tight"]
build = True # if off, use existing media but don't create new
regexps = {
    "standard": re.compile(r"\[latex\](.+?)\[/latex\]", re.DOTALL | re.IGNORECASE),
    "expression": re.compile(r"\[\$\](.+?)\[/\$\]", re.DOTALL | re.IGNORECASE),
    "math": re.compile(r"\[\$\$\](.+?)\[/\$\$\]", re.DOTALL | re.IGNORECASE),
    }

tmpdir = tempfile.mkdtemp(prefix="anki")

# add standard tex install location to osx
if sys.platform == "darwin":
    os.environ['PATH'] += ":/usr/texbin"

def stripLatex(text):
    for match in regexps['standard'].finditer(text):
        text = text.replace(match.group(), "")
    for match in regexps['expression'].finditer(text):
        text = text.replace(match.group(), "")
    for match in regexps['math'].finditer(text):
        text = text.replace(match.group(), "")
    return text

def mungeQA(html, type, fields, model, gname, data, deck):
    "Convert TEXT with embedded latex tags to image links."
    for match in regexps['standard'].finditer(html):
        html = html.replace(match.group(), _imgLink(deck, match.group(1)))
    for match in regexps['expression'].finditer(html):
        html = html.replace(match.group(), _imgLink(
            deck, "$" + match.group(1) + "$"))
    for match in regexps['math'].finditer(html):
        html = html.replace(match.group(), _imgLink(
            deck,
            "\\begin{displaymath}" + match.group(1) + "\\end{displaymath}"))
    return html

def _imgLink(deck, latex):
    "Return an img link for LATEX, creating if necesssary."
    txt = _latexFromHtml(deck, latex)
    fname = "latex-%s.png" % checksum(txt)
    link = '<img src="%s">' % fname
    if os.path.exists(fname):
        return link
    elif not build:
        return "[latex]"+latex+"[/latex]"
    else:
        err = _buildImg(deck, txt, fname)
        if err:
            return err
        else:
            return link

def _latexFromHtml(deck, latex):
    "Convert entities, fix newlines, and convert to utf8."
    for match in re.compile("&([a-z]+);", re.IGNORECASE).finditer(latex):
        if match.group(1) in entitydefs:
            latex = latex.replace(match.group(), entitydefs[match.group(1)])
    latex = re.sub("<br( /)?>", "\n", latex)
    latex = latex.encode("utf-8")
    return latex

def _buildImg(deck, latex, fname):
    # add header/footer
    latex = (deck.conf["latexPre"] + "\n" +
             latex + "\n" +
             deck.conf["latexPost"])
    # write into a temp file
    log = open(os.path.join(tmpdir, "latex_log.txt"), "w+")
    texpath = os.path.join(tmpdir, "tmp.tex")
    texfile = file(texpath, "w")
    texfile.write(latex)
    texfile.close()
    # make sure we have a valid mediaDir
    mdir = deck.media.dir(create=True)
    oldcwd = os.getcwd()
    try:
        # generate dvi
        os.chdir(tmpdir)
        if call(latexCmd + ["tmp.tex"], stdout=log, stderr=log):
            return _errMsg("latex")
        # and png
        if call(latexDviPngCmd + ["tmp.dvi", "-o", "tmp.png"],
                stdout=log, stderr=log):
            return _errMsg("dvipng")
        # add to media
        shutil.copy2(os.path.join(tmpdir, "tmp.png"),
                     os.path.join(mdir, fname))
        return
    finally:
        os.chdir(oldcwd)

def _errMsg(type):
    msg = (_("Error executing %s.") % type) + "<br>"
    try:
        log = open(os.path.join(tmpdir, "latex_log.txt")).read()
        if not log:
            raise Exception()
        msg += "<small><pre>" + cgi.escape(log) + "</pre></small>"
    except:
        msg += _("Have you installed latex and dvipng?")
        pass
    return msg

# setup q/a filter
addHook("mungeQA", mungeQA)