#! /usr/bin/env python

################################################
# Convert each figchild picture to a PDF file. #
#                                              #
# Author: Scott Pakin <scott.clsl@pakin.org>   #
################################################

import concurrent.futures
import os
import re
import subprocess
import sys


def kpsewhich(fname):
    'Find a filename in the TeX tree.'
    proc = subprocess.run(['kpsewhich', fname], capture_output=True,
                          check=True, encoding='utf-8')
    return proc.stdout.strip()


# Extract all commands defined by figchild.sty and the package description.
desc = None
commands = []
newcmd_re = re.compile(r'^\\newcommand{\\(fc\w+)\}')
desc_re = re.compile(r'\\ProvidesPackage\{figchild\}\[(.*?)\]')
sty = kpsewhich('figchild.sty')
with open(sty) as r:
    for ln in r:
        # Extract the package description.
        if desc is None:
            match = desc_re.search(ln)
            if match is not None:
                desc = match[1]

        # Extract a command.
        match = newcmd_re.search(ln)
        if match is None:
            continue
        if match[1] != 'fcAlligatorB':   # Undocumented and broken
            commands.append(match[1])
commands.sort(key=lambda s: s.lower())

# Create a fakefigchild.sty file.
with open('fakefigchild.sty', 'w') as w:
    w.write('''\
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% This is a generated file.  DO NOT EDIT. %
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

''')
    w.write('''\
\\NeedsTeXFormat{LaTeX2e}
\\ProvidesPackage{fakefigchild}[%s]
\\RequirePackage{graphicx}

''' % desc)
    for cmd in commands:
        ht = 20
        if cmd == 'fcPencil':
            # Special case for \fcPencil, which is abnormally wide and short.
            ht = 5
        w.write('\\DeclareRobustCommand{\\%s}{%%\n' % cmd)
        w.write('  \\includegraphics[height=%dpt,keepaspectratio]'
                '{figchild/%s}%%\n' % (ht, cmd))
        w.write('}\n')
    w.write('\n')
    w.write('\\endinput\n')

# Create and switch to a figchild subdirectory.
try:
    os.mkdir('figchild')
except FileExistsError:
    pass
os.chdir('figchild')

# For speed, dump a LaTeX format file with figchild preloaded.
with open('preloaded.tex', 'w') as w:
    w.write(r'''
\documentclass{minimal}
\usepackage[a2paper,landscape]{geometry}
\usepackage{figchild}
\usepackage{graphicx}
\begin{document}
\end{document}
'''[1:])
subprocess.run([
    'pdflatex',
    '--ini',
    '&pdflatex',
    'mylatex.ltx',
    'preloaded.tex'
],
    check=True)


def run_and_return_output(cmd_line):
    'Run a command line and return its combined stdout + stderr.'
    stdout = 'RUN: ' + ' '.join(cmd_line) + '\n'
    proc = subprocess.run(cmd_line, check=True,
                          stdout=subprocess.PIPE, stderr=subprocess.STDOUT)
    stdout += proc.stdout.decode('utf-8')
    return stdout


def generate_graphic(cmd):
    'Generate a PDF file for a given figchild command.'
    stdout = f'*** PROCESSING {cmd} ***\n\n'

    # Create a LaTeX file.
    stdout += f'CREATE: {cmd}.tex\n'
    div = 48
    if cmd == 'fcPencil':
        # Special case for \fcPencil, which is abnormally wide and short.
        div = 12
    with open(cmd + '.tex', 'w') as w:
        w.write(r'''
\documentclass{minimal}
\begin{document}

\newsavebox{\fig}
\savebox{\fig}{\%s{1}{black}{1}}
\newlength{\figheight}
\settoheight{\figheight}{\usebox{\fig}}

\makeatletter
\edef\figscale{\expandafter\strip@pt\dimexpr\figheight / %d\relax}
\makeatother

\%s{1}{black}{\figscale}
\end{document}
'''[1:] % (cmd, div, cmd))

    # Compile the LaTeX file to PDF.
    stdout += run_and_return_output(['pdflatex', '&mylatex', cmd + '.tex'])

    # Crop the PDF file.
    stdout += run_and_return_output(['pdfcrop', cmd + '.pdf'])

    # Overwrite the original PDF file with the cropped version.
    stdout += f'RUN: mv {cmd}-crop.pdf {cmd}.pdf\n'
    os.rename(f'{cmd}-crop.pdf', f'{cmd}.pdf')

    # Output the buffered output.
    stdout += '\n'
    print(stdout)


# Concurrently process all figures.
with concurrent.futures.ProcessPoolExecutor() as executor:
    executor.map(generate_graphic, commands)