# `Decorator` that outputs HTML.
class HTMLDecorator
	super Decorator

	redef var headlines = new ArrayMap[String, HeadLine]

	redef fun add_ruler(v, block) do v.add "<hr/>\n"

	redef fun add_headline(v, block) do
		# save headline
		var line = block.block.first_line
		if line == null then return
		var txt = line.value
		var id = strip_id(txt)
		var lvl = block.depth
		headlines[id] = new HeadLine(id, txt, lvl)
		# output it
		v.add "<h{lvl} id=\"{id}\">"
		v.emit_in block
		v.add "</h{lvl}>\n"
	end

	redef fun add_paragraph(v, block) do
		v.add "<p>"
		v.emit_in block
		v.add "</p>\n"
	end

	redef fun add_code(v, block) do
		var meta = block.meta
		if meta != null then
			v.add "<pre class=\""
			append_value(v, meta)
			v.add "\"><code>"
		else
			v.add "<pre><code>"
		end
		v.emit_in block
		v.add "</code></pre>\n"
	end

	redef fun add_blockquote(v, block) do
		v.add "<blockquote>\n"
		v.emit_in block
		v.add "</blockquote>\n"
	end

	redef fun add_unorderedlist(v, block) do
		v.add "<ul>\n"
		v.emit_in block
		v.add "</ul>\n"
	end

	redef fun add_orderedlist(v, block) do
		v.add "<ol>\n"
		v.emit_in block
		v.add "</ol>\n"
	end

	redef fun add_listitem(v, block) do
		v.add "<li>"
		v.emit_in block
		v.add "</li>\n"
	end

	redef fun add_em(v, text) do
		v.add "<em>"
		v.add text
		v.add "</em>"
	end

	redef fun add_strong(v, text) do
		v.add "<strong>"
		v.add text
		v.add "</strong>"
	end

	redef fun add_strike(v, text) do
		v.add "<del>"
		v.add text
		v.add "</del>"
	end

	redef fun add_image(v, link, name, comment) do
		v.add "<img src=\""
		append_value(v, link)
		v.add "\" alt=\""
		append_value(v, name)
		v.add "\""
		if comment != null and not comment.is_empty then
			v.add " title=\""
			append_value(v, comment)
			v.add "\""
		end
		v.add "/>"
	end

	redef fun add_link(v, link, name, comment) do
		v.add "<a href=\""
		append_value(v, link)
		v.add "\""
		if comment != null and not comment.is_empty then
			v.add " title=\""
			append_value(v, comment)
			v.add "\""
		end
		v.add ">"
		v.emit_text(name)
		v.add "</a>"
	end

	redef fun add_abbr(v, name, comment) do
		v.add "<abbr title=\""
		append_value(v, comment)
		v.add "\">"
		v.emit_text(name)
		v.add "</abbr>"
	end

	redef fun add_span_code(v, text, from, to) do
		v.add "<code>"
		append_code(v, text, from, to)
		v.add "</code>"
	end

	redef fun add_line_break(v) do
		v.add "<br/>"
	end

	redef fun append_value(v, text) do for c in text do escape_char(v, c)

	redef fun escape_char(v, c) do
		if c == '&' then
			v.add "&amp;"
		else if c == '<' then
			v.add "&lt;"
		else if c == '>' then
			v.add "&gt;"
		else if c == '"' then
			v.add "&quot;"
		else if c == '\'' then
			v.add "&apos;"
		else
			v.addc c
		end
	end

	redef fun append_code(v, buffer, from, to) do
		for i in [from..to[ do
			var c = buffer[i]
			if c == '&' then
				v.add "&amp;"
			else if c == '<' then
				v.add "&lt;"
			else if c == '>' then
				v.add "&gt;"
			else
				v.addc c
			end
		end
	end

	redef fun strip_id(txt) do
		# strip id
		var b = new FlatBuffer
		for c in txt do
			if c == ' ' then
				b.add '_'
			else
				if not c.is_letter and
				   not c.is_digit and
				   not allowed_id_chars.has(c) then continue
				b.add c
			end
		end
		var res = b.to_s
		var key = res
		# check for multiple id definitions
		if headlines.has_key(key) then
			var i = 1
			key = "{res}_{i}"
			while headlines.has_key(key) do
				i += 1
				key = "{res}_{i}"
			end
		end
		return key
	end

	private var allowed_id_chars: Array[Char] = ['-', '_', ':', '.']
end