"""
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
* PS backend: latex w/ psfrag, dvips, and Ghostscript 8.51
  (older versions do not work properly)

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 = self.texmanager.get_rgba(s, size=12, dpi=80, rgb=(1,0,0))

To enable tex rendering of all text in your matplotlib figure, set
text.usetex in your matplotlibrc file (http://matplotlib.sf.net/matplotlibrc)
or include these two lines in your script::

  from matplotlib import rc
  rc('text', usetex=True)

"""

import copy, glob, os, shutil, sys, warnings

try:
    from hashlib import md5
except ImportError:
    from md5 import md5 #Deprecated in 2.5

import distutils.version
import numpy as np
import matplotlib as mpl
from matplotlib import rcParams
from matplotlib._png import read_png

DEBUG = False

if sys.platform.startswith('win'): cmd_split = '&'
else: cmd_split = ';'

def dvipng_hack_alpha():
    stdin, stdout = os.popen4('dvipng -version')
    for line in stdout:
        if line.startswith('dvipng '):
            version = line.split()[-1]
            mpl.verbose.report('Found dvipng version %s'% version,
                'helpful')
            version = distutils.version.LooseVersion(version)
            return version < distutils.version.LooseVersion('1.6')
    raise RuntimeError('Could not obtain dvipng version')



class TexManager:

    """
    Convert strings to dvi files using TeX, caching the results to a
    working dir
    """

    oldpath = mpl.get_home()
    if oldpath is None: oldpath = mpl.get_data_path()
    oldcache = os.path.join(oldpath, '.tex.cache')

    configdir = mpl.get_configdir()
    texcache = os.path.join(configdir, 'tex.cache')

    if os.path.exists(oldcache):
        print >> sys.stderr, """\
WARNING: found a TeX cache dir in the deprecated location "%s".
  Moving it to the new default location "%s"."""%(oldcache, texcache)
        shutil.move(oldcache, texcache)
    if not os.path.exists(texcache):
        os.mkdir(texcache)

    _dvipng_hack_alpha = dvipng_hack_alpha()

    # mappable cache of
    rgba_arrayd = {}
    grey_arrayd = {}
    postscriptd = {}
    pscnt = 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', )\
                     + tuple(['font.'+n for n in ('family', ) + font_families])

    def __init__(self):

        if not os.path.isdir(self.texcache):
            os.mkdir(self.texcache)
        ff = rcParams['font.family'].lower()
        if ff in self.font_families:
            self.font_family = ff
        else:
            mpl.verbose.report('The %s font family is not compatible with LaTeX. serif will be used by default.' % ff, 'helpful')
            self.font_family = 'serif'

        fontconfig = [self.font_family]
        for font_family, font_family_attr in \
            [(ff, ff.replace('-', '_')) for ff in self.font_families]:
            for font in rcParams['font.'+font_family]:
                if font.lower() in self.font_info:
                    found_font = self.font_info[font.lower()]
                    setattr(self, font_family_attr,
                            self.font_info[font.lower()])
                    if DEBUG:
                        print 'family: %s, font: %s, info: %s'%(font_family,
                                    font, self.font_info[font.lower()])
                    break
                else:
                    if DEBUG: print '$s font is not compatible with usetex'
            else:
                mpl.verbose.report('No LaTeX-compatible font found for the %s font family in rcParams. Using default.' % ff, 'helpful')
                setattr(self, font_family_attr, self.font_info[font_family])
            fontconfig.append(getattr(self, font_family_attr)[0])
        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])
        while r'\usepackage{type1cm}' in cmd:
            cmd.remove(r'\usepackage{type1cm}')
        cmd = '\n'.join(cmd)
        self._font_preamble = '\n'.join([r'\usepackage{type1cm}', cmd,
                                         r'\usepackage{textcomp}'])

    def get_basefile(self, tex, fontsize, dpi=None):
        """
        returns 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 '')])
        # make sure hash is consistent for all strings, regardless of encoding:
        bytes = unicode(s).encode('utf-8')
        return os.path.join(self.texcache, md5(bytes).hexdigest())

    def get_font_config(self):
        """Reinitializes self if relevant rcParams on have changed."""
        if self._rc_cache is None:
            self._rc_cache = dict([(k,None) for k in self._rc_cache_keys])
        changed = [par for par in self._rc_cache_keys if rcParams[par] != \
                   self._rc_cache[par]]
        if changed:
            if DEBUG: print 'DEBUG following keys changed:', changed
            for k in changed:
                if DEBUG:
                    print '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])
            if DEBUG: print 'DEBUG RE-INIT\nold fontconfig:', self._fontconfig
            self.__init__()
        if DEBUG: print 'DEBUG fontconfig:', self._fontconfig
        return self._fontconfig

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

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

    def _get_shell_cmd(self, *args):
        """
        On windows, changing directories can be complicated by the presence of
        multiple drives. get_shell_cmd deals with this issue.
        """
        if sys.platform == 'win32':
            command = ['%s'% os.path.splitdrive(self.texcache)[0]]
        else:
            command = []
        command.extend(args)
        return ' && '.join(command)

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

        returns the file name
        """
        basefile = self.get_basefile(tex, fontsize)
        texfile = '%s.tex'%basefile
        fh = file(texfile, 'w')
        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 = """\usepackage{ucs}
\usepackage[utf8x]{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)
        if rcParams['text.latex.unicode']:
            fh.write(s.encode('utf8'))
        else:
            try:
                fh.write(s)
            except UnicodeEncodeError, err:
                mpl.verbose.report("You are using unicode and latex, but have "
                            "not enabled the matplotlib 'text.latex.unicode' "
                            "rcParam.", 'helpful')
                raise

        fh.close()

        return texfile

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

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

        if DEBUG or not os.path.exists(dvifile):
            texfile = self.make_tex(tex, fontsize)
            outfile = basefile+'.output'
            command = self._get_shell_cmd('cd "%s"'% self.texcache,
                            'latex -interaction=nonstopmode %s > "%s"'\
                            %(os.path.split(texfile)[-1], outfile))
            mpl.verbose.report(command, 'debug')
            exit_status = os.system(command)
            try:
                fh = file(outfile)
                report = fh.read()
                fh.close()
            except IOError:
                report = 'No latex error report available.'
            if exit_status:
                raise RuntimeError(('LaTeX was not able to process the following \
string:\n%s\nHere is the full report generated by LaTeX: \n\n'% repr(tex)) + report)
            else: mpl.verbose.report(report, 'debug')
            for fname in glob.glob(basefile+'*'):
                if fname.endswith('dvi'): pass
                elif fname.endswith('tex'): pass
                else:
                    try: os.remove(fname)
                    except OSError: pass

        return dvifile

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

        returns the filename
        """
        basefile = self.get_basefile(tex, fontsize, dpi)
        pngfile = '%s.png'% basefile

        # see get_rgba for a discussion of the background
        if DEBUG or not os.path.exists(pngfile):
            dvifile = self.make_dvi(tex, fontsize)
            outfile = basefile+'.output'
            command = self._get_shell_cmd('cd "%s"' % self.texcache,
                        'dvipng -bg Transparent -D %s -T tight -o \
                        "%s" "%s" > "%s"'%(dpi, os.path.split(pngfile)[-1],
                        os.path.split(dvifile)[-1], outfile))
            mpl.verbose.report(command, 'debug')
            exit_status = os.system(command)
            try:
                fh = file(outfile)
                report = fh.read()
                fh.close()
            except IOError:
                report = 'No dvipng error report available.'
            if exit_status:
                raise RuntimeError('dvipng was not able to \
process the flowing file:\n%s\nHere is the full report generated by dvipng: \
\n\n'% dvifile + report)
            else: mpl.verbose.report(report, 'debug')
            try: os.remove(outfile)
            except OSError: pass

        return pngfile

    def make_ps(self, tex, fontsize):
        """
        generates a postscript file containing latex's rendering of tex string

        returns the file name
        """
        basefile = self.get_basefile(tex, fontsize)
        psfile = '%s.epsf'% basefile

        if DEBUG or not os.path.exists(psfile):
            dvifile = self.make_dvi(tex, fontsize)
            outfile = basefile+'.output'
            command = self._get_shell_cmd('cd "%s"'% self.texcache,
                        'dvips -q -E -o "%s" "%s" > "%s"'\
                        %(os.path.split(psfile)[-1],
                          os.path.split(dvifile)[-1], outfile))
            mpl.verbose.report(command, 'debug')
            exit_status = os.system(command)
            fh = file(outfile)
            if exit_status:
                raise RuntimeError('dvipng was not able to \
process the flowing file:\n%s\nHere is the full report generated by dvipng: \
\n\n'% dvifile + fh.read())
            else: mpl.verbose.report(fh.read(), 'debug')
            fh.close()
            os.remove(outfile)

        return psfile

    def get_ps_bbox(self, tex, fontsize):
        """
        returns a list containing the postscript bounding box for latex's
        rendering of the tex string
        """
        psfile = self.make_ps(tex, fontsize)
        ps = file(psfile)
        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):
        """returns 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 = read_png(os.path.join(self.texcache, pngfile))

            if rcParams['text.dvipnghack'] is not None:
                hack = rcParams['text.dvipnghack']
            else:
                hack = self._dvipng_hack_alpha

            if hack:
                # hack the alpha channel
                # dvipng assumed a constant background, whereas we want to
                # overlay these rasters with antialiasing over arbitrary
                # backgrounds that may have other figure elements under them.
                # When you set dvipng -bg Transparent, it actually makes the
                # alpha channel 1 and does the background compositing and
                # antialiasing itself and puts the blended data in the rgb
                # channels.  So what we do is extract the alpha information
                # from the red channel, which is a blend of the default dvipng
                # background (white) and foreground (black).  So the amount of
                # red (or green or blue for that matter since white and black
                # blend to a grayscale) is the alpha intensity.  Once we
                # extract the correct alpha information, we assign it to the
                # alpha channel properly and let the users pick their rgb.  In
                # this way, we can overlay tex strings on arbitrary
                # backgrounds with antialiasing
                #
                # red = alpha*red_foreground + (1-alpha)*red_background
                #
                # Since the foreground is black (0) and the background is
                # white (1) this reduces to red = 1-alpha or alpha = 1-red
                #alpha = npy.sqrt(1-X[:,:,0]) # should this be sqrt here?
                alpha = 1-X[:,:,0]
            else:
                alpha = X[:,:,-1]

            self.grey_arrayd[key] = alpha
        return alpha


    def get_rgba(self, tex, fontsize=None, dpi=None, rgb=(0,0,0)):
        """
        Returns 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.zeros((alpha.shape[0], alpha.shape[1], 4), np.float)

            Z[:,:,0] = r
            Z[:,:,1] = g
            Z[:,:,2] = b
            Z[:,:,3] = alpha
            self.rgba_arrayd[key] = Z

        return Z
