#!/usr/bin/env python3

'''
Application for splitting groups from one SVG file into separate files

Usage:
python3 vector_layer_split.py infile format outdir

Usage Example:
python3 vector_layer_split.py vector_source.svg tw ../src/art/vector/layers/
'''

import lxml.etree as etree
from lxml.etree import XMLParser, parse

import sys
import os
import copy
import re
import normalize_svg

input_file = sys.argv[1]
output_format = sys.argv[2]
output_directory = sys.argv[3]

if not os.path.exists(output_directory):
    os.makedirs(output_directory)

ns = {
    'svg': 'http://www.w3.org/2000/svg',
    'inkscape': 'http://www.inkscape.org/namespaces/inkscape',
    'sodipodi': "http://sodipodi.sourceforge.net/DTD/sodipodi-0.dtd",
}

p = XMLParser(huge_tree=True)
tree = parse(input_file, parser=p)
#tree = etree.parse(input_file)
normalize_svg.fix(tree)

# prepare output template
template = copy.deepcopy(tree)
root = template.getroot()

# remove all svg root attributes except document size
for a in root.attrib:
    if (a != "viewBox"):
        del root.attrib[a]

# add placeholder for CSS class (needed for workaround for non HTML 5.1 compliant browser)
if output_format == 'tw':
    root.attrib["class"] = "'+_art_display_class+'"

# remove all content, including metadata
# for twine output, style definitions are removed, too
defs = None
for e in root:
    if (e.tag == etree.QName(ns['svg'], 'defs')):
        defs = e
    if (e.tag == etree.QName(ns['svg'], 'g') or
            e.tag == etree.QName(ns['svg'], 'metadata') or
            e.tag == etree.QName(ns['svg'], 'defs') or
            e.tag == etree.QName(ns['sodipodi'], 'namedview') or
            (output_format == 'tw' and e.tag == etree.QName(ns['svg'], 'style'))
    ):
        root.remove(e)
# template preparation finished

# prepare regex for later use
regex_xmlns = re.compile(' xmlns[^ ]+', )
regex_space = re.compile('[>][ ]+[<]', )
regex_transformValue = re.compile('(?<=transformVariableName=")[^"]*', )
regex_transformVar = re.compile('transformVariableName="[^"]*"', )
regex_transformAttr = re.compile('transform="[^"]*"', )
# find all groups
layers = tree.xpath('//svg:g', namespaces=ns)
for layer in layers:
    i = layer.get('id')
    if (  # disregard non-content groups
            i.endswith("_") or  # manually suppressed with underscore
            i.startswith("XMLID") or  # Illustrator generated group
            i.startswith("g")  # Inkscape generated group
    ):
        continue
    # create new canvas
    output = copy.deepcopy(template)
    # copy all shapes into template
    canvas = output.getroot()
    for e in layer:
        canvas.append(e)
    # represent template as SVG (binary string)
    svg = etree.tostring(output, pretty_print=False)
    # poor man's conditional defs insertion
    # TODO: extract only referenced defs (filters, gradients, ...)
    # TODO: detect necessity by traversing the elements. do not stupidly search in the string representation
    if ("filter:" in svg.decode('utf-8')):
        # it seems there is a filter referenced in the generated SVG, re-insert defs from main document
        canvas.insert(0, defs)
        # re-generate output
        svg = etree.tostring(output, pretty_print=False)
    elif ("clip-path=" in svg.decode('utf-8')):
        # it seems there is a clip path referenced in the generated SVG, re-insert defs from main document
        canvas.insert(0, defs)
        # re-generate output
        svg = etree.tostring(output, pretty_print=False)

    if (output_format == 'tw'):
        # remove unnecessary attributes
        # TODO: never generate unnecessary attributes in the first place
        svg = svg.decode('utf-8')
        svg = regex_xmlns.sub('', svg)
        svg = svg.replace(' inkscape:connector-curvature="0"', '')  # this just saves space
        svg = svg.replace('\n', '').replace('\r', '')  # print cannot be multi-line
        svg = regex_space.sub('><', svg)  # remove indentaion
        svg = svg.replace('svg:', '')  # svg namespace was removed

        transformGroups = regex_transformVar.findall(svg)

        if (len(transformGroups) > 0):
            svg = regex_transformAttr.sub('', svg)
            for transformGroup in transformGroups:
                transformValue = regex_transformValue.search(transformGroup)
                if (transformValue is not None):
                    svg = svg.replace(transformGroup, ' transform="\'+' + transformValue.group() + '+\'" ')  # internal groups are used for scaling

        svg = svg.encode('utf-8')

    # save SVG string to file
    i = layer.get('id')
    output_path = os.path.join(output_directory, i + '.' + output_format)
    with open(output_path, 'wb') as f:
        if (output_format == 'svg'):
            # Header for normal SVG (XML)
            f.write('<?xml version="1.0" encoding="UTF-8" standalone="no"?>\n'.encode("utf-8"))
            f.write(svg)
        elif (output_format == 'tw'):
            # Header for SVG in Twine file (SugarCube print statement)
            f.write((':: Art_Vector_Revamp_%s [nobr]\n\n' % (i)).encode("utf-8"))
            f.write("<<print '<html>".encode("utf-8"))
            f.write(svg)
            f.write("</html>' >>".encode("utf-8"))
