import inkex
from inkex import bezier
from inkex.command import inkscape_command

# (X)HTML stuff:
ESCAPE=str.maketrans({'&':'&amp;','<':'&lt;','>':'&gt;'})
def quotedval(val):
	quote="'" if val.count('"')>val.count("'") else '"'
	return quote+val.translate(ESCAPE).translate({ord(quote):f'&#{ord(quote)}'})+quote
def htmlval(val):
	if val=='': return ''
	elif not any(i in val for i in ' \t\r\n\f"\'=`'):
		return '='+val.translate(ESCAPE)
	else:
		return '='+quotedval(val)

AREA_ATTRS={
	'href':lambda a:a.get('href',a.get('{http://www.w3.org/1999/xlink}href')),
	'alt':lambda a:a.get('{http://www.w3.org/1999/xlink}title')
} # TODO target
SHAPE_MARKUP = {
	'HTML': lambda shape, coords, href, alt:
		f"<area shape={shape} coords={','.join(str(c) for c in sum(coords,start=[]))}"
		+(f' href{htmlval(href)}' if href is not None else '')
		+(f' alt{htmlval(alt)}' if alt is not None else '')+">\n",
	'XHTML': lambda shape, coords, href, alt:
		f"<area shape=\"{shape}\" coords=\"{','.join(str(c) for c in sum(coords,start=[]))}\""
		+(f" href={quotedval(href)}" if href is not None else '')
		+(f' alt={quotedval(alt)}' if alt is not None else '')+"/>\n",
	'mod_imagemap': lambda shape, coords, href, alt:
		f"{shape} {href if href is not None else 'nocontent'} {' '.join(f'{i[0]},{i[1]}' for i in coords)}"
		+(f" \"{alt.translate({34:'&#34;'})}\"" if alt is not None else '')+'\n'
} # if we ever implement `circ` we gotta handle it specially
CSS_LINK_INDEX='-computer-viatrix-inx-imagemap-linkindex'

# "rectifiable" as in "can be made into a rect"
def rectifiable(coords):
	if len(coords)!=4: return False
	else: return (coords[0][0]==coords[1][0] and coords[1][1]==coords[2][1] and coords[2][0]==coords[3][0] and coords[3][1]==coords[0][1] ) \
		or (coords[0][1]==coords[1][1] and coords[1][0]==coords[2][0] and coords[2][1]==coords[3][1] and coords[0][0]==coords[3][0])
def rectify(coords):
	return [[min(coords[0][0],coords[2][0]),min(coords[0][1],coords[2][1])],[max(coords[0][0],coords[2][0]),max(coords[0][1],coords[2][1])]]

class ImageMap(inkex.OutputExtension):
	def add_arguments(self,pars):
		pars.add_argument("--maptype")
	def save(self,stream):
		assert self.options.maptype in {"HTML","XHTML","mod_imagemap"}
		shapemarkup=SHAPE_MARKUP[self.options.maptype]
		
		viewBox=self.svg.get_viewbox()
		wscale=self.svg.viewport_width/viewBox[2] if viewBox[2]!=0 else 1
		hscale=self.svg.viewport_height/viewBox[3] if viewBox[3]!=0 else 1
		
		# preprocess shapes for our purposes.
		# after this, the shapes within the image must: look the same as before (barring colour/alpha), not be clones, have no stroke, not intersect, and be visually unaffected by `fill-rule`.
		# TODO pay attention to clip-path
		links=[]
		for a in self.svg.iterdescendants('{http://www.w3.org/2000/svg}a'):
			# save link attributes because they get removed when flattening
			link={attr:AREA_ATTRS[attr](a) for attr in AREA_ATTRS.keys()}
			for el in a.iterdescendants(): # CSS is preserved when flattening (for paths)
				if not isinstance(el,inkex.ShapeElement): continue
				style=el.effective_style()
				style[CSS_LINK_INDEX]=f'" {CSS_LINK_INDEX}-{len(links)} "'
			links += [link]
		command=\
			';'.join(f'select-clear;select-by-selector:[style~="{CSS_LINK_INDEX}-{i}"];object-stroke-to-path;path-union;object-set-attribute:style,{CSS_LINK_INDEX}:" {CSS_LINK_INDEX}-{i} "' for i in range(len(links))) \
			+';select-all;path-flatten;path-split'
			# (we re-set the existing style attribute in case it got unset on non-paths)
		newbytes=inkscape_command(self.svg,actions=command)
		self.svg=self.load(newbytes).getroot()
		
		seen=set()
		for el in self.svg.iterdescendants():
			if not isinstance(el,inkex.ShapeElement): continue
			linkindex=el.cascaded_style().get(CSS_LINK_INDEX)
			if linkindex is None: continue
			linkindex=int(linkindex[len(CSS_LINK_INDEX)+3:-2])
			link=links[linkindex]
			href=link['href']
			alt=link['alt'] if int(linkindex) not in seen else None
			shapes=[]
			path=el.get_path().to_superpath()
			bezier.cspsubdiv(path,0.5)
			for subpath in path:
				coords=[[round((c[0][0]-viewBox[0])*wscale),round((c[0][1]-viewBox[1])*hscale)] for c in subpath]
				i=0
				while i<len(coords):
					if coords[i]==coords[(i+1)%len(coords)]: coords.pop(i)
					else: i+=1
				if rectifiable(coords): shapes.append(shapemarkup('rect',rectify(coords),href,alt))
				elif len(coords)>=3: shapes.append(shapemarkup('poly',coords,href,alt))
				href=None # because subsequent subpaths must be enclaves
				alt=None
			seen.add(linkindex)
			stream.write(bytes(''.join(reversed(shapes)),'utf-8'))

if __name__ == "__main__":
	ImageMap().run()