-- Optional parser that creates a flat DOM from parsing
--[=====================================================================[
v0.7 Copyright © 2013-2014 Gavin Kistner <!@phrogz.net>; MIT Licensed
See http://github.com/Phrogz/SLAXML for details.
--]=====================================================================]
SLAXML = {
	VERSION = "0.7",
	_call = {
		pi = function(target,content)
			print(string.format("<?%s %s?>",target,content))
		end,
		comment = function(content)
			print(string.format("<!-- %s -->",content))
		end,
		startElement = function(name,nsURI,nsPrefix)
			                 io.write("<")
			if nsPrefix then io.write(nsPrefix,":") end
			                 io.write(name)
			if nsURI    then io.write(" (ns='",nsURI,"')") end
			                 print(">")
		end,
		attribute = function(name,value,nsURI,nsPrefix)
			                 io.write('  ')
			if nsPrefix then io.write(nsPrefix,":") end
			                 io.write(name,'=',string.format('%q',value))
			if nsURI    then io.write(" (ns='",nsURI,"')") end
			                 io.write("\n")
		end,
		text = function(text)
			print(string.format("  text: %q",text))
		end,
		closeElement = function(name,nsURI,nsPrefix)
			print(string.format("</%s>",name))
		end,
	}
}

function SLAXML:parser(callbacks)
	return { _call=callbacks or self._call, parse=SLAXML.parse }
end

function SLAXML:parse(xml, fileName, options)
	if not options then options = { stripWhitespace=false } end

	-- Cache references for maximum speed
	local find, sub, gsub, char, push, pop, concat = string.find, string.sub, string.gsub, string.char, table.insert, table.remove, table.concat
	local first, last, match1, match2, match3, pos2, nsURI
	local unpack = unpack or table.unpack
	local pos = 1
	local state = "text"
	local textStart = 1
	local currentElement={}
	local currentAttributes={}
	local currentAttributeCt -- manually track length since the table is re-used
	local nsStack = {}
	local anyElement = false

	local utf8markers = { {0x7FF,192}, {0xFFFF,224}, {0x1FFFFF,240} }
	local function utf8(decimal) -- convert unicode code point to utf-8 encoded character string
		if decimal<128 then return char(decimal) end
		local charbytes = {}
		for bytes,vals in ipairs(utf8markers) do
			if decimal<=vals[1] then
				for b=bytes+1,2,-1 do
					local mod = decimal%64
					decimal = (decimal-mod)/64
					charbytes[b] = char(128+mod)
				end
				charbytes[1] = char(vals[2]+decimal)
				return concat(charbytes)
			end
		end
	end
	local entityMap  = { ["lt"]="<", ["gt"]=">", ["amp"]="&", ["quot"]='"', ["apos"]="'" }
	local entitySwap = function(orig,n,s) return entityMap[s] or n=="#" and utf8(tonumber('0'..s)) or orig end  
	local function unescape(str) return gsub( str, '(&(#?)([%d%a]+);)', entitySwap ) end

	local function finishText()
		if first>textStart and self._call.text then
			local text = sub(xml,textStart,first-1)
			if options.stripWhitespace then
				text = gsub(text,'^%s+','')
				text = gsub(text,'%s+$','')
				if #text==0 then text=nil end
			end
			if text then self._call.text(unescape(text)) end
		end
	end

	local function findPI()
		first, last, match1, match2 = find( xml, '^<%?([:%a_][:%w_.-]*) ?(.-)%?>', pos )
		if first then
			finishText()
			if self._call.pi then self._call.pi(match1,match2) end
			pos = last+1
			textStart = pos
			return true
		end
	end

	local function findComment()
		first, last, match1 = find( xml, '^<!%-%-(.-)%-%->', pos )
		if first then
			finishText()
			if self._call.comment then self._call.comment(match1) end
			pos = last+1
			textStart = pos
			return true
		end
	end

	local function nsForPrefix(prefix)
		if prefix=='xml' then return 'http://www.w3.org/XML/1998/namespace' end -- http://www.w3.org/TR/xml-names/#ns-decl
		for i=#nsStack,1,-1 do if nsStack[i][prefix] then return nsStack[i][prefix] end end
		error(("Cannot find namespace for prefix %s"):format(prefix))
	end

	local function startElement()
		anyElement = true
		first, last, match1 = find( xml, '^<([%a_][%w_.-]*)', pos )
		if first then
			currentElement[2] = nil -- reset the nsURI, since this table is re-used
			currentElement[3] = nil -- reset the nsPrefix, since this table is re-used
			finishText()
			pos = last+1
			first,last,match2 = find(xml, '^:([%a_][%w_.-]*)', pos )
			if first then
				currentElement[1] = match2
				currentElement[3] = match1 -- Save the prefix for later resolution
				match1 = match2
				pos = last+1
			else
				currentElement[1] = match1
				for i=#nsStack,1,-1 do if nsStack[i]['!'] then currentElement[2] = nsStack[i]['!']; break end end
			end
			currentAttributeCt = 0
			push(nsStack,{})
			return true
		end
	end

	local function findAttribute()
		first, last, match1 = find( xml, '^%s+([:%a_][:%w_.-]*)%s*=%s*', pos )
		if first then
			pos2 = last+1
			first, last, match2 = find( xml, '^"([^<"]*)"', pos2 ) -- FIXME: disallow non-entity ampersands
			if first then
				pos = last+1
				match2 = unescape(match2)
			else
				first, last, match2 = find( xml, "^'([^<']*)'", pos2 ) -- FIXME: disallow non-entity ampersands
				if first then
					pos = last+1
					match2 = unescape(match2)
				end
			end
		end
		if match1 and match2 then
			local currentAttribute = {match1,match2}
			local prefix,name = string.match(match1,'^([^:]+):([^:]+)$')
			if prefix then
				if prefix=='xmlns' then
					nsStack[#nsStack][name] = match2
				else
					currentAttribute[1] = name
					currentAttribute[4] = prefix
				end
			else
				if match1=='xmlns' then
					nsStack[#nsStack]['!'] = match2
					currentElement[2]      = match2
				end
			end
			currentAttributeCt = currentAttributeCt + 1
			currentAttributes[currentAttributeCt] = currentAttribute
			return true
		end
	end

	local function findCDATA()
		first, last, match1 = find( xml, '^<!%[CDATA%[(.-)%]%]>', pos )
		if first then
			finishText()
			if self._call.text then self._call.text(match1) end
			pos = last+1
			textStart = pos
			return true
		end
	end

	local function closeElement()
		first, last, match1 = find( xml, '^%s*(/?)>', pos )
		if first then
			state = "text"
			pos = last+1
			textStart = pos

			-- Resolve namespace prefixes AFTER all new/redefined prefixes have been parsed
			if currentElement[3] then currentElement[2] = nsForPrefix(currentElement[3])    end
			if self._call.startElement then self._call.startElement(unpack(currentElement)) end
			if self._call.attribute then
				for i=1,currentAttributeCt do
					if currentAttributes[i][4] then currentAttributes[i][3] = nsForPrefix(currentAttributes[i][4]) end
					self._call.attribute(unpack(currentAttributes[i]))
				end
			end

			if match1=="/" then
				pop(nsStack)
				if self._call.closeElement then self._call.closeElement(unpack(currentElement)) end
			end
			return true
		end
	end

	local function findElementClose()
		first, last, match1, match2 = find( xml, '^</([%a_][%w_.-]*)%s*>', pos )
		if first then
			nsURI = nil
			for i=#nsStack,1,-1 do if nsStack[i]['!'] then nsURI = nsStack[i]['!']; break end end
		else
			first, last, match2, match1 = find( xml, '^</([%a_][%w_.-]*):([%a_][%w_.-]*)%s*>', pos )
			if first then nsURI = nsForPrefix(match2) end
		end
		if first then
			finishText()
			if self._call.closeElement then self._call.closeElement(match1,nsURI) end
			pos = last+1
			textStart = pos
			pop(nsStack)
			return true
		end
	end

	while pos<#xml do
		if state=="text" then
			if not (findPI() or findComment() or findCDATA() or findElementClose()) then		
				if startElement() then
					state = "attributes"
				else
					first, last = find( xml, '^[^<]+', pos )
					pos = (first and last or pos) + 1
				end
			end
		elseif state=="attributes" then
			if not findAttribute() then
				if not closeElement() then
					print("\n[ERROR] " .. fileName .. " is broken! Please put in online validator and fix!\n")
					break
				end
			end
		end
	end

	-- if not anyElement then error("Parsing did not discover any elements") end
	-- if #nsStack > 0 then print("Parsing could not find closing to attribute. Please put in online validator and fix!\nTo figure out what Pattern/VCF is broken look at the last loaded, the one after that is broken.\n\n") end
end

function SLAXML:dom(xml, filename, opts)
	if not opts then opts={} end
	local rich = not opts.simple
	local push, pop = table.insert, table.remove
	local stack = {}
	local doc = { type="document", name="#doc", kids={} }
	local current = doc
	local builder = SLAXML:parser{
		startElement = function(name,nsURI)
			local el = { type="element", name=name, kids={}, el=rich and {} or nil, attr={}, nsURI=nsURI, parent=rich and current or nil }
			if current==doc then
				if doc.root then error(("Encountered element '%s' when the document already has a root '%s' element"):format(name,doc.root.name)) end
				doc.root = el
			end
			push(current.kids,el)
			if current.el then push(current.el,el) end
			current = el
			push(stack,el)
		end,
		attribute = function(name,value,nsURI)
			if not current or current.type~="element" then error(("Encountered an attribute %s=%s but I wasn't inside an element"):format(name,value)) end
			local attr = {type='attribute',name=name,nsURI=nsURI,value=value,parent=rich and current or nil}
			if rich then current.attr[name] = value end
			push(current.attr,attr)
		end,
		closeElement = function(name)
			if current.name~=name or current.type~="element" then error(("Received a close element notification for '%s' but was inside a '%s' %s"):format(name,current.name,current.type)) end
			pop(stack)
			current = stack[#stack]
		end,
		text = function(value)
			if current.type~='document' then
				if current.type~="element" then error(("Received a text notification '%s' but was inside a %s"):format(value,current.type)) end
				push(current.kids,{type='text',name='#text',value=value,parent=rich and current or nil})
			end
		end,
		comment = function(value)
			push(current.kids,{type='comment',name='#comment',value=value,parent=rich and current or nil})
		end,
		pi = function(name,value)
			push(current.kids,{type='pi',name=name,value=value,parent=rich and current or nil})
		end
	}
	builder:parse(xml, filename, opts)
	return doc
end
return SLAXML