"""
Replace Latex math mode/\\begin{}\\end{} blocks with html img tag
after rendering

$Id: ReplaceInlineLatex.py,v 1.11 2001/09/07 14:21:16 rsbowman Exp $

TODO:
    use \\ref{shit} to make reference to equations.  Convert \\ref{shit} to the
    appropriate (number): add negative match to latexPattern for \\ref, do a
        s/// after generating an equation with a \\label.
    Separate vertical alignment characters & into a new
        \\end{equation}\\begin{equation} and then render the separate images in
        a table to acheive vertical alignment.

"""

import re, os
from DocumentTemplate.html_quote import html_quote
from util import fileNameFor, imagesPath, workingDir, getPngSize, runCommand, log
from string import strip, join, replace

# This will fail on nested blocks \begin{array} \begin{array}...\end{array} \end{array} 
# It is necessary for this to be all one regex (unfortunately) so that we do
# not pick up equations inside \begin{latex}...\end{latex}, rather only the
# outer delimiters.
latexPattern = r'(?<!\\)(?:\\\\)*(!?\$\$(?:[^\$\\]|\\[^\$\\]|\\\$|\\\\)*?\$\$|!?\$(?:[^\$\\]|\\[^\$\\]|\\\$|\\\\)*?\$|!?\\\((?:[^\\]|\\[^\)]|\\\\)*?\\\)|!?(?:\\begin{ *([^}]+?) *}.*?\\end{ *\2 *}|\\\[(?:[^\\]|\\[^\]]|\\\\)*?\\\]))'

latexRemoveDelim = r'^(?:(\$\$|\$(?!\$))|\\\(|\\begin{[^}]*}|\\\[)(.*)(?:\\\]|\\end{[^}]*}|\\\)|\1)$'

errorMessage = """\n<hr/><font size="-1" color="red">
Some or all expressions may not have rendered properly,
because Latex returned the following error:<br/><pre>%s</pre></font>"""

reConsts = re.MULTILINE+re.DOTALL
def findLatexCode(text,
                  findLatex=re.compile(latexPattern,
                                        reConsts).findall,
                  ):
    codeList = map(lambda x: x[0], findLatex(text))
    return codeList

def replaceInlineLatex(body, charheightpx, alignfudge, resfudge, latexTemplate=None):
    from latexWrapper import renderNonexistingImages

    renumbered   = re.compile(r'[ \t]*\\begin{ *(math|equation|eqnarray) *}')
    reunnumbered = re.compile(r'[ \t]*(\\begin{ *((math|equation|eqnarray)\*|table|tabular|displaymath|array|latex) *}|\\\[)')
    body = strip(body)
    latexCodeList = findLatexCode(body)
    newlatexCodeList = []
    eqnum = 0
    for code in latexCodeList:
        if code[0]=='!': 
# We need to identify if we're inside a '' block or an example:: block here.
            newcode = re.compile('^!', re.MULTILINE).sub('', code)
            # change the dollar sign so that the replace below does not hit
            # this code again (in the case of the same code appearing twice,
            # once escaped, once not)
            #newcode = re.compile('\$', re.MULTILINE).sub('&#36;', newcode, 2)
            # prevent stx from mangling asterisks
            #newcode = re.compile('\*', re.MULTILINE).sub('&#42;', newcode) 
            # and this will hide \(\), \[\], \begin...\end, including any
            # equations that may be hiding inside a \begin{latex}..\end{latex}
            newcode = re.compile(r'\\\[', re.MULTILINE).sub('\\![', newcode)
            #newcode = re.compile(r'\\', re.MULTILINE).sub('&#92;', newcode)
            body = replace(body, code, newcode, 1)
            continue
        else:
            newlatexCodeList.append(code)
        oldcode = code
        renummatch = renumbered.match(code)
        if renummatch:
            eqnum = eqnum + 1
            code = renumbered.sub('\\\\begin{\\1*}\n\\label{eq%d}' %(eqnum), code, 1)
            kind = renummatch.group(1)
            code = re.compile('\\\\end{ *%s *}' %(kind)).sub('\\\\end{%s*}' %(kind), code, 1)
            code = renumbered.sub('\\\\begin{\\1*}\n\\label{eq%d}' %(eqnum), code, 1)
# FIXME we really shouldn't do this...it will recreate block equations with different numbers.
            newlatexCodeList[newlatexCodeList.index(oldcode)] = code
# FIXME This will also replace any escaped code :(
            body = replace(body, oldcode, code, 1)
    errors = renderNonexistingImages(newlatexCodeList, charheightpx, alignfudge, resfudge,
                                     latexTemplate=latexTemplate)
    
    if not errors:
        for code in newlatexCodeList:
            labelmatch = re.compile('\\\\label{eq(\\d+)}').search(code, 1)
            commentedcode = re.compile('^', re.MULTILINE).sub('!', html_quote(code))
# "--" inside a comment screws up browsers.  But in LaTeX math mode "--" and "- -" are equivalent.
            commentedcode = re.compile('--', re.MULTILINE).sub('- -', commentedcode)
            if labelmatch:
                eqnum = labelmatch.group(1)
                imageTag = '<a name="eq%s">' %(eqnum)                                 \
                    + '<table width="100%"><tr><td align="center" width="95%">'       \
                    + getImageFor(code, charheightpx)                                 \
                    + '</td><td align="right">(%s)</td></tr></table></a>' %(eqnum)
            elif reunnumbered.match(code):
                imageTag = '<a name="unnumbered">'                                    \
                    + '<table width="100%"><tr><td align="center" width="95%">'       \
                    + getImageFor(code, charheightpx)                                 \
                    + '</td><td width="5%" align="right">&nbsp;</td></tr></table></a>'
            else:
                imageTag = getImageFor(code, charheightpx)
            body = replace(body, code, imageTag, 1)

# We try to match the > and < (or ^/$) from the preceeding and trailing tags,
# so as not to catch the alt="..." from a latex equation
# FIXME this is slow.  Use something like perl's m/\G/g to iterate over (n)
        for i in range(1,int(eqnum)+1):
            body = re.compile(r'((?:>|^)(?:[^<]*\s|))\( *(?:[Ee][Qq]\.)?\s*(%d) *\)([^>]*(?:<|$))' %(i)).sub(r'\1<a href="#eq\2">(\2)</a>\3', body)

    else:
        body = "<pre>" + body + "</pre>" + errorMessage %(errors)

    # Handle escaping of latex
    body = re.compile(r'(?<!\\)((?:\\\\)*)\\\$', re.MULTILINE).sub(r'\1$', body)
    body = re.compile(r'\\\\', re.MULTILINE).sub(r'\\', body)
    return body

def getImageFor(latexCode, charheightpx):    
    preamble, postamble = '', ''
    width, height = '', '' 
    imageFile = fileNameFor(latexCode, charheightpx, '.png')
    imageUrl = imagesPath + imageFile
    width, height = getPngSize(os.path.join(workingDir, imageFile))
    src = html_quote(re.match(latexRemoveDelim, latexCode, re.MULTILINE|re.DOTALL).group(2))
    src = re.sub(r'\n\n+', '\n', src) # FIXME collapse blank lines or they will
    # be interpreted as stx paragraphs -- this is an stx bug since they are
    # inside a tag.
    return '%s<img alt="%s" class="equation" src="%s" width="%s" height="%s"/>%s' %(preamble,
                                                            src,
                                                            imageUrl,
                                                            width,
                                                            height,
                                                            postamble)