r"""
This module supports embedded TeX expressions in matplotlib via dvipng
and dvips for the raster and postscript backends.  The tex and
dvipng/dvips information is cached in ~/.matplotlib/tex.cache for reuse between
sessions

Requirements:

* latex
* \*Agg backends: dvipng>=1.6
* PS backend: psfrag, dvips, and Ghostscript>=8.60

Backends:

* \*Agg
* PS
* PDF

For raster output, you can get RGBA numpy arrays from TeX expressions
as follows::

  texmanager = TexManager()
  s = ('\TeX\ is Number '
       '$\displaystyle\sum_{n=1}^\infty\frac{-e^{i\pi}}{2^n}$!')
  Z = texmanager.get_rgba(s, fontsize=12, dpi=80, rgb=(1,0,0))

To enable tex rendering of all text in your matplotlib figure, set
:rc:`text.usetex` to True.
"""

import copy
import glob
import hashlib
import logging
import os
from pathlib import Path
import re
import subprocess

import numpy as np

import matplotlib as mpl
from matplotlib import _png, cbook, dviread, rcParams

_log = logging.getLogger(__name__)


class TexManager(object):
    """
    Convert strings to dvi files using TeX, caching the results to a directory.
    """

    cachedir = mpl.get_cachedir()
    if cachedir is not None:
        texcache = os.path.join(cachedir, 'tex.cache')
        Path(texcache).mkdir(parents=True, exist_ok=True)
    else:
        # Should only happen in a restricted environment (such as Google App
        # Engine). Deal with this gracefully by not creating a cache directory.
        texcache = None

    # Caches.
    rgba_arrayd = {}
    grey_arrayd = {}
    postscriptd = property(mpl.cbook.deprecated("2.2")(lambda self: {}))
    pscnt = property(mpl.cbook.deprecated("2.2")(lambda self: 0))

    serif = ('cmr', '')
    sans_serif = ('cmss', '')
    monospace = ('cmtt', '')
    cursive = ('pzc', r'\usepackage{chancery}')
    font_family = 'serif'
    font_families = ('serif', 'sans-serif', 'cursive', 'monospace')

    font_info = {
        'new century schoolbook': ('pnc', r'\renewcommand{\rmdefault}{pnc}'),
        'bookman': ('pbk', r'\renewcommand{\rmdefault}{pbk}'),
        'times': ('ptm', r'\usepackage{mathptmx}'),
        'palatino': ('ppl', r'\usepackage{mathpazo}'),
        'zapf chancery': ('pzc', r'\usepackage{chancery}'),
        'cursive': ('pzc', r'\usepackage{chancery}'),
        'charter': ('pch', r'\usepackage{charter}'),
        'serif': ('cmr', ''),
        'sans-serif': ('cmss', ''),
        'helvetica': ('phv', r'\usepackage{helvet}'),
        'avant garde': ('pag', r'\usepackage{avant}'),
        'courier': ('pcr', r'\usepackage{courier}'),
        'monospace': ('cmtt', ''),
        'computer modern roman': ('cmr', ''),
        'computer modern sans serif': ('cmss', ''),
        'computer modern typewriter': ('cmtt', '')}

    _rc_cache = None
    _rc_cache_keys = (
        ('text.latex.preamble', 'text.latex.unicode', 'text.latex.preview',
         'font.family') + tuple('font.' + n for n in font_families))

    def __init__(self):

        if self.texcache is None:
            raise RuntimeError('Cannot create TexManager, as there is no '
                               'cache directory available')

        Path(self.texcache).mkdir(parents=True, exist_ok=True)
        ff = rcParams['font.family']
        if len(ff) == 1 and ff[0].lower() in self.font_families:
            self.font_family = ff[0].lower()
        elif isinstance(ff, str) and ff.lower() in self.font_families:
            self.font_family = ff.lower()
        else:
            _log.info('font.family must be one of (%s) when text.usetex is '
                      'True. serif will be used by default.',
                      ', '.join(self.font_families))
            self.font_family = 'serif'

        fontconfig = [self.font_family]
        for font_family in self.font_families:
            font_family_attr = font_family.replace('-', '_')
            for font in rcParams['font.' + font_family]:
                if font.lower() in self.font_info:
                    setattr(self, font_family_attr,
                            self.font_info[font.lower()])
                    _log.debug('family: %s, font: %s, info: %s',
                               font_family, font, self.font_info[font.lower()])
                    break
                else:
                    _log.debug('%s font is not compatible with usetex.',
                               font_family)
            else:
                _log.info('No LaTeX-compatible font found for the %s font '
                          'family in rcParams. Using default.', font_family)
                setattr(self, font_family_attr, self.font_info[font_family])
            fontconfig.append(getattr(self, font_family_attr)[0])
        # Add a hash of the latex preamble to self._fontconfig so that the
        # correct png is selected for strings rendered with same font and dpi
        # even if the latex preamble changes within the session
        preamble_bytes = self.get_custom_preamble().encode('utf-8')
        fontconfig.append(hashlib.md5(preamble_bytes).hexdigest())
        self._fontconfig = ''.join(fontconfig)

        # The following packages and commands need to be included in the latex
        # file's preamble:
        cmd = [self.serif[1], self.sans_serif[1], self.monospace[1]]
        if self.font_family == 'cursive':
            cmd.append(self.cursive[1])
        self._font_preamble = '\n'.join(
            [r'\usepackage{type1cm}'] + cmd + [r'\usepackage{textcomp}'])

    def get_basefile(self, tex, fontsize, dpi=None):
        """
        Return a filename based on a hash of the string, fontsize, and dpi.
        """
        s = ''.join([tex, self.get_font_config(), '%f' % fontsize,
                     self.get_custom_preamble(), str(dpi or '')])
        return os.path.join(
            self.texcache, hashlib.md5(s.encode('utf-8')).hexdigest())

    def get_font_config(self):
        """Reinitializes self if relevant rcParams on have changed."""
        if self._rc_cache is None:
            self._rc_cache = dict.fromkeys(self._rc_cache_keys)
        changed = [par for par in self._rc_cache_keys
                   if rcParams[par] != self._rc_cache[par]]
        if changed:
            _log.debug('following keys changed: %s', changed)
            for k in changed:
                _log.debug('%-20s: %-10s -> %-10s',
                           k, self._rc_cache[k], rcParams[k])
                # deepcopy may not be necessary, but feels more future-proof
                self._rc_cache[k] = copy.deepcopy(rcParams[k])
            _log.debug('RE-INIT\nold fontconfig: %s', self._fontconfig)
            self.__init__()
        _log.debug('fontconfig: %s', self._fontconfig)
        return self._fontconfig

    def get_font_preamble(self):
        """
        Return a string containing font configuration for the tex preamble.
        """
        return self._font_preamble

    def get_custom_preamble(self):
        """Return a string containing user additions to the tex preamble."""
        return '\n'.join(rcParams['text.latex.preamble'])

    def make_tex(self, tex, fontsize):
        """
        Generate a tex file to render the tex string at a specific font size.

        Return the file name.
        """
        basefile = self.get_basefile(tex, fontsize)
        texfile = '%s.tex' % basefile
        custom_preamble = self.get_custom_preamble()
        fontcmd = {'sans-serif': r'{\sffamily %s}',
                   'monospace': r'{\ttfamily %s}'}.get(self.font_family,
                                                       r'{\rmfamily %s}')
        tex = fontcmd % tex

        if rcParams['text.latex.unicode']:
            unicode_preamble = r"""
\usepackage[utf8]{inputenc}"""
        else:
            unicode_preamble = ''

        s = r"""
\documentclass{article}
%s
%s
%s
\usepackage[papersize={72in,72in},body={70in,70in},margin={1in,1in}]{geometry}
\pagestyle{empty}
\begin{document}
\fontsize{%f}{%f}%s
\end{document}
""" % (self._font_preamble, unicode_preamble, custom_preamble,
       fontsize, fontsize * 1.25, tex)
        with open(texfile, 'wb') as fh:
            if rcParams['text.latex.unicode']:
                fh.write(s.encode('utf8'))
            else:
                try:
                    fh.write(s.encode('ascii'))
                except UnicodeEncodeError as err:
                    _log.info("You are using unicode and latex, but have not "
                              "enabled the 'text.latex.unicode' rcParam.")
                    raise

        return texfile

    _re_vbox = re.compile(
        r"MatplotlibBox:\(([\d.]+)pt\+([\d.]+)pt\)x([\d.]+)pt")

    def make_tex_preview(self, tex, fontsize):
        """
        Generate a tex file to render the tex string at a specific font size.

        It uses the preview.sty to determine the dimension (width, height,
        descent) of the output.

        Return the file name.
        """
        basefile = self.get_basefile(tex, fontsize)
        texfile = '%s.tex' % basefile
        custom_preamble = self.get_custom_preamble()
        fontcmd = {'sans-serif': r'{\sffamily %s}',
                   'monospace': r'{\ttfamily %s}'}.get(self.font_family,
                                                       r'{\rmfamily %s}')
        tex = fontcmd % tex

        if rcParams['text.latex.unicode']:
            unicode_preamble = r"""
\usepackage[utf8]{inputenc}"""
        else:
            unicode_preamble = ''

        # newbox, setbox, immediate, etc. are used to find the box
        # extent of the rendered text.

        s = r"""
\documentclass{article}
%s
%s
%s
\usepackage[active,showbox,tightpage]{preview}
\usepackage[papersize={72in,72in},body={70in,70in},margin={1in,1in}]{geometry}

%% we override the default showbox as it is treated as an error and makes
%% the exit status not zero
\def\showbox#1%%
{\immediate\write16{MatplotlibBox:(\the\ht#1+\the\dp#1)x\the\wd#1}}

\begin{document}
\begin{preview}
{\fontsize{%f}{%f}%s}
\end{preview}
\end{document}
""" % (self._font_preamble, unicode_preamble, custom_preamble,
       fontsize, fontsize * 1.25, tex)
        with open(texfile, 'wb') as fh:
            if rcParams['text.latex.unicode']:
                fh.write(s.encode('utf8'))
            else:
                try:
                    fh.write(s.encode('ascii'))
                except UnicodeEncodeError as err:
                    _log.info("You are using unicode and latex, but have not "
                              "enabled the 'text.latex.unicode' rcParam.")
                    raise

        return texfile

    def _run_checked_subprocess(self, command, tex):
        _log.debug(command)
        try:
            report = subprocess.check_output(command,
                                             cwd=self.texcache,
                                             stderr=subprocess.STDOUT)
        except subprocess.CalledProcessError as exc:
            raise RuntimeError(
                '{prog} was not able to process the following string:\n'
                '{tex!r}\n\n'
                'Here is the full report generated by {prog}:\n'
                '{exc}\n\n'.format(
                    prog=command[0],
                    tex=tex.encode('unicode_escape'),
                    exc=exc.output.decode('utf-8')))
        _log.debug(report)
        return report

    def make_dvi(self, tex, fontsize):
        """
        Generate a dvi file containing latex's layout of tex string.

        Return the file name.
        """

        if rcParams['text.latex.preview']:
            return self.make_dvi_preview(tex, fontsize)

        basefile = self.get_basefile(tex, fontsize)
        dvifile = '%s.dvi' % basefile
        if not os.path.exists(dvifile):
            texfile = self.make_tex(tex, fontsize)
            with cbook._lock_path(texfile):
                self._run_checked_subprocess(
                    ["latex", "-interaction=nonstopmode", "--halt-on-error",
                     texfile], tex)
            for fname in glob.glob(basefile + '*'):
                if not fname.endswith(('dvi', 'tex')):
                    try:
                        os.remove(fname)
                    except OSError:
                        pass

        return dvifile

    def make_dvi_preview(self, tex, fontsize):
        """
        Generate a dvi file containing latex's layout of tex string.

        It calls make_tex_preview() method and store the size information
        (width, height, descent) in a separate file.

        Return the file name.
        """
        basefile = self.get_basefile(tex, fontsize)
        dvifile = '%s.dvi' % basefile
        baselinefile = '%s.baseline' % basefile

        if not os.path.exists(dvifile) or not os.path.exists(baselinefile):
            texfile = self.make_tex_preview(tex, fontsize)
            report = self._run_checked_subprocess(
                ["latex", "-interaction=nonstopmode", "--halt-on-error",
                 texfile], tex)

            # find the box extent information in the latex output
            # file and store them in ".baseline" file
            m = TexManager._re_vbox.search(report.decode("utf-8"))
            with open(basefile + '.baseline', "w") as fh:
                fh.write(" ".join(m.groups()))

            for fname in glob.glob(basefile + '*'):
                if not fname.endswith(('dvi', 'tex', 'baseline')):
                    try:
                        os.remove(fname)
                    except OSError:
                        pass

        return dvifile

    def make_png(self, tex, fontsize, dpi):
        """
        Generate a png file containing latex's rendering of tex string.

        Return the file name.
        """
        basefile = self.get_basefile(tex, fontsize, dpi)
        pngfile = '%s.png' % basefile
        # see get_rgba for a discussion of the background
        if not os.path.exists(pngfile):
            dvifile = self.make_dvi(tex, fontsize)
            self._run_checked_subprocess(
                ["dvipng", "-bg", "Transparent", "-D", str(dpi),
                 "-T", "tight", "-o", pngfile, dvifile], tex)
        return pngfile

    @mpl.cbook.deprecated("2.2")
    def make_ps(self, tex, fontsize):
        """
        Generate a postscript file containing latex's rendering of tex string.

        Return the file name.
        """
        basefile = self.get_basefile(tex, fontsize)
        psfile = '%s.epsf' % basefile
        if not os.path.exists(psfile):
            dvifile = self.make_dvi(tex, fontsize)
            self._run_checked_subprocess(
                ["dvips", "-q", "-E", "-o", psfile, dvifile], tex)
        return psfile

    @mpl.cbook.deprecated("2.2")
    def get_ps_bbox(self, tex, fontsize):
        """
        Return a list of PS bboxes for latex's rendering of the tex string.
        """
        psfile = self.make_ps(tex, fontsize)
        with open(psfile) as ps:
            for line in ps:
                if line.startswith('%%BoundingBox:'):
                    return [int(val) for val in line.split()[1:]]
        raise RuntimeError('Could not parse %s' % psfile)

    def get_grey(self, tex, fontsize=None, dpi=None):
        """Return the alpha channel."""
        key = tex, self.get_font_config(), fontsize, dpi
        alpha = self.grey_arrayd.get(key)
        if alpha is None:
            pngfile = self.make_png(tex, fontsize, dpi)
            X = _png.read_png(os.path.join(self.texcache, pngfile))
            self.grey_arrayd[key] = alpha = X[:, :, -1]
        return alpha

    def get_rgba(self, tex, fontsize=None, dpi=None, rgb=(0, 0, 0)):
        """Return latex's rendering of the tex string as an rgba array."""
        if not fontsize:
            fontsize = rcParams['font.size']
        if not dpi:
            dpi = rcParams['savefig.dpi']
        r, g, b = rgb
        key = tex, self.get_font_config(), fontsize, dpi, tuple(rgb)
        Z = self.rgba_arrayd.get(key)

        if Z is None:
            alpha = self.get_grey(tex, fontsize, dpi)
            Z = np.dstack([r, g, b, alpha])
            self.rgba_arrayd[key] = Z

        return Z

    def get_text_width_height_descent(self, tex, fontsize, renderer=None):
        """Return width, height and descent of the text."""
        if tex.strip() == '':
            return 0, 0, 0

        dpi_fraction = renderer.points_to_pixels(1.) if renderer else 1

        if rcParams['text.latex.preview']:
            # use preview.sty
            basefile = self.get_basefile(tex, fontsize)
            baselinefile = '%s.baseline' % basefile

            if not os.path.exists(baselinefile):
                dvifile = self.make_dvi_preview(tex, fontsize)

            with open(baselinefile) as fh:
                l = fh.read().split()
            height, depth, width = [float(l1) * dpi_fraction for l1 in l]
            return width, height + depth, depth

        else:
            # use dviread. It sometimes returns a wrong descent.
            dvifile = self.make_dvi(tex, fontsize)
            with dviread.Dvi(dvifile, 72 * dpi_fraction) as dvi:
                page = next(iter(dvi))
            # A total height (including the descent) needs to be returned.
            return page.width, page.height + page.descent, page.descent
