module MicroWikiParse
	require 'cgi'
	RX_BR_OR_URL = %r<(\<[Bb][Rr] */?\>)|(((http[s]{0,1}|ftp)://[\(\)%#!/0-9a-zA-Z_$@.&+-,'"*=;?:~-]+)|([0-9a-zA-Z_.-]+@[\(\)%!0-9a-zA-Z_$.&+-,'"*-]+\.[\(\)%!0-9a-zA-Z_$.&+-,'"*-]+))>
	HEADING_PREFIX = /^\*\s*(.*)/
	DL_PREFIX = /^:([^:]+):(.*)/
 
# base classes ======================
	class WikiElement
		def render_html
		end
	end
 
	class Block < WikiElement
		def initialize(doc)
			@document = doc
			@children = []
		end		
 
		def consume(ln)
 
			next_block = @document.match_block(ln)
			if next_block
				@children << next_block
				return next_block
			end
 
			# other... standard paragraph
			@children << StdParagraph.new(@document, ln)
			return self # leave the paragraph immediately
		end
 
		def render_html
			ret = []
			@children.each {|c|
				ret << c.render_html
			}
 
			ret.join("\n")
		end
	end
# ===================================
 
	class Document < Block
		def initialize(src)
			super(self)
			@block_parsers = [Heading, DefList]
 
			@context = [self]
			lines = RawReader.new(src)
			lines.each{|ln|
 
				next_ctx = @context.last.consume(ln)
				if next_ctx
					if @context.last != next_ctx
						@context << next_ctx
						next RawReader.unget
					end
				else
					@context.pop
					next RawReader.unget
				end
 
			}
		end
 
		def match_block(ln)
			@block_parsers.each{|ps|
				b = ps.match_notation(self, ln)
				return b if b
			}
 
			nil
		end
	end
 
	class Heading
		def self.match_notation(doc, ln)
			if ln =~ HEADING_PREFIX
				ch = Heading.new(doc, $1)
				return ch
			end
		end
 
		def initialize(doc, raw)
			@document = doc
 
			@textnode = TextNode.new(doc, raw)
			@consumed = false
		end
 
		def consume(ln)
			return nil if @consumed
 
			@consumed = true
			return self
		end
 
		def render_html
			"<h3>#{@textnode.render_html}</h3>"
		end
	end
 
	class DefList < Block
		def self.match_notation(doc, ln)
			if ln =~ DL_PREFIX
				ch = DefList.new(doc, $1)
				return ch
			end
		end
 
		def initialize(doc, raw)
			super(doc)
		end
 
		def consume(ln)
			return nil if !(ln =~ DL_PREFIX)
 
			item = DefListItem.new(@document, $1, $2)
			@children << item
			return self
		end
 
		def render_html
			"<dl>\n#{super}\n</dl>"
		end
	end
 
	class DefListItem
		def initialize(doc, dt, dd)
			@document = doc
			@t_text = TextNode.new(doc, dt)
			@d_text = TextNode.new(doc, dd)
		end
 
		def render_html
			" <dt>#{@t_text.render_html}</dt>\n <dd>#{@d_text.render_html}</dd>\n"
		end
	end
 
	class StdParagraph < Block
		def initialize(doc, raw)
			super(doc)
 
			@textnode = TextNode.new(doc, raw)
		end
 
		def render_html
			"<p>#{@textnode.render_html}</p>"
		end
	end
 
 
	class TextNode
		def initialize(d, r)
			@document = d
			@raw = r
			parse
		end
 
		def parse
			@children = []
 
			pos = 0
			len = @raw.length
			while true do
				advance = 0
 
				embed_img   = false
				rr = @raw.index(RX_BR_OR_URL, pos) # find direct link or <br/>
				break if rr == nil
 
				advance = $&.length
				extracted_url = $1 ? nil : $&
 
				@children << CGI.escapeHTML(@raw[pos, rr-pos])
				pos = rr + advance
 
				lknode = extracted_url ? LinkNode.new(extracted_url, embed_img) : BreakNode
				@children << lknode
			end
 
			@children << CGI.escapeHTML(@raw[pos, len]) if pos < len
		end
 
		def render_html
			@children.map{|n|
				String === n ? n : n.render_html
			}.join("")
		end
	end
 
	class BreakNode
		def self.render_html
			"<br />\n"
		end
	end
 
	class LinkNode
		def initialize(u, ei)
			@embed_img = ei
			@url = LinkNode.escape(u)
		end
 
		def LinkNode.escape(u)
			u.gsub('&amp;', '&').gsub('&', '&amp;')
		end
 
		def render_html
	#		if @embed_img
	#			embed_src = @url
	#			link_url = @url
	#			"<img alt=\"\" src=\"#{embed_src}\" />"
	#		else
				"<a href=\"#{@url}\">#{@url}</a>"
	#		end
		end	
	end
 
 
 
# utils =============================
 
	class RawReader
		def RawReader.unget
			:unget
		end
 
		def initialize(raw)
			@lines = raw.gsub(/\n\n+/, "\n").split(/[\r\n]+/)
		end
 
		def each
			len = @lines.length
			return if len<1
 
			i = 0
			while true do
				i += 1 if yield(@lines[i]) != RawReader.unget
				break if i >= len
			end
		end
	end
 
end