Anki/pylib/anki/latex.py

# Copyright: Ankitects Pty Ltd and contributors
# License: GNU AGPL, version 3 or later; http://www.gnu.org/licenses/agpl.html

from __future__ import annotations

import html
import os
import re
from dataclasses import dataclass
from typing import Any, List, Optional, Tuple

import anki
from anki import hooks
from anki.models import NoteType
from anki.rsbackend import TR, pb
from anki.template import TemplateRenderContext, TemplateRenderOutput
from anki.utils import call, isMac, namedtmp, tmpdir

pngCommands = [
    ["latex", "-interaction=nonstopmode", "tmp.tex"],
    ["dvipng", "-D", "200", "-T", "tight", "tmp.dvi", "-o", "tmp.png"],
]

svgCommands = [
    ["latex", "-interaction=nonstopmode", "tmp.tex"],
    ["dvisvgm", "--no-fonts", "--exact", "-Z", "2", "tmp.dvi", "-o", "tmp.svg"],
]

build = True  # if off, use existing media but don't create new

# add standard tex install location to osx
if isMac:
    os.environ["PATH"] += ":/usr/texbin:/Library/TeX/texbin"


@dataclass
class ExtractedLatex:
    filename: str
    latex_body: str


@dataclass
class ExtractedLatexOutput:
    html: str
    latex: List[ExtractedLatex]

    @staticmethod
    def from_proto(proto: pb.ExtractLatexOut) -> ExtractedLatexOutput:
        return ExtractedLatexOutput(
            html=proto.text,
            latex=[
                ExtractedLatex(filename=l.filename, latex_body=l.latex_body)
                for l in proto.latex
            ],
        )


def on_card_did_render(
    output: TemplateRenderOutput, ctx: TemplateRenderContext
) -> None:
    output.question_text = render_latex(
        output.question_text, ctx.note_type(), ctx.col()
    )
    output.answer_text = render_latex(output.answer_text, ctx.note_type(), ctx.col())


def render_latex(html: str, model: NoteType, col: anki.collection.Collection) -> str:
    "Convert embedded latex tags in text to image links."
    html, err = render_latex_returning_errors(html, model, col)
    if err:
        html += "\n".join(err)
    return html


def render_latex_returning_errors(
    html: str,
    model: NoteType,
    col: anki.collection.Collection,
    expand_clozes: bool = False,
) -> Tuple[str, List[str]]:
    """Returns (text, errors).

    errors will be non-empty if LaTeX failed to render."""
    svg = model.get("latexsvg", False)
    header = model["latexPre"]
    footer = model["latexPost"]

    proto = col.backend.extract_latex(text=html, svg=svg, expand_clozes=expand_clozes)
    out = ExtractedLatexOutput.from_proto(proto)
    errors = []
    html = out.html

    for latex in out.latex:
        # don't need to render?
        if not build or col.media.have(latex.filename):
            continue

        err = _save_latex_image(col, latex, header, footer, svg)
        if err is not None:
            errors.append(err)

    return html, errors


def _save_latex_image(
    col: anki.collection.Collection,
    extracted: ExtractedLatex,
    header: str,
    footer: str,
    svg: bool,
) -> Optional[str]:
    # add header/footer
    latex = header + "\n" + extracted.latex_body + "\n" + footer
    # it's only really secure if run in a jail, but these are the most common
    tmplatex = latex.replace("\\includegraphics", "")
    for bad in (
        "\\write18",
        "\\readline",
        "\\input",
        "\\include",
        "\\catcode",
        "\\openout",
        "\\write",
        "\\loop",
        "\\def",
        "\\shipout",
    ):
        # don't mind if the sequence is only part of a command
        bad_re = "\\" + bad + "[^a-zA-Z]"
        if re.search(bad_re, tmplatex):
            return col.tr(TR.MEDIA_FOR_SECURITY_REASONS_IS_NOT, val=bad)

    # commands to use
    if svg:
        latexCmds = svgCommands
        ext = "svg"
    else:
        latexCmds = pngCommands
        ext = "png"

    # write into a temp file
    log = open(namedtmp("latex_log.txt"), "w")
    texpath = namedtmp("tmp.tex")
    texfile = open(texpath, "w", encoding="utf8")
    texfile.write(latex)
    texfile.close()
    oldcwd = os.getcwd()
    png_or_svg = namedtmp("tmp.%s" % ext)
    try:
        # generate png/svg
        os.chdir(tmpdir())
        for latexCmd in latexCmds:
            if call(latexCmd, stdout=log, stderr=log):
                return _errMsg(col, latexCmd[0], texpath)
        # add to media
        with open(png_or_svg, "rb") as file:
            data = file.read()
        col.media.write_data(extracted.filename, data)
        os.unlink(png_or_svg)
        return None
    finally:
        os.chdir(oldcwd)
        log.close()


def _errMsg(col: anki.collection.Collection, type: str, texpath: str) -> Any:
    msg = col.tr(TR.MEDIA_ERROR_EXECUTING, val=type) + "<br>"
    msg += col.tr(TR.MEDIA_GENERATED_FILE, val=texpath) + "<br>"
    try:
        with open(namedtmp("latex_log.txt", rm=False)) as f:
            log = f.read()
        if not log:
            raise Exception()
        msg += "<small><pre>" + html.escape(log) + "</pre></small>"
    except:
        msg += col.tr(TR.MEDIA_HAVE_YOU_INSTALLED_LATEX_AND_DVIPNGDVISVGM)
    return msg


hooks.card_did_render.append(on_card_did_render)