# A route to an `Action` according to a `path`
redef class Route

	redef init do
		super
		parse_pattern(path)
	end

	# Replace `self.path` parameters with concrete values from the `request` URI.
	fun resolve_path(request: HttpRequest): nullable String do
		if pattern_parts.is_empty then return self.path
		var path = "/"
		for part in pattern_parts do
			if part isa UriString then
				path /= part.string
			else if part isa UriParam then
				path /= request.param(part.name) or else part.name
			end
		end
		return path
	end

	# Cut `path` into `UriParts`.
	private fun parse_pattern(path: nullable String) do
		if path == null then return
		path = standardize_path(path)
		var parts = path.split("/")
		for part in parts do
			if not part.is_empty and part.first == ':' then
				# is an uri param
				var name = part.substring(1, part.length)
				var param = new UriParam(name)
				pattern_parts.add param
			else
				# is a standard string
				pattern_parts.add new UriString(part)
			end
		end
	end

	# `UriPart` forming `self` pattern.
	private var pattern_parts = new Array[UriPart]

	# Does `self` matches `uri`?
	fun match(uri: nullable String): Bool do
		if pattern_parts.is_empty then return true
		if uri == null then return false
		uri = standardize_path(uri)
		var parts = uri.split("/")
		for i in [0 .. pattern_parts.length[ do
			if i >= parts.length then return false
			var ppart = pattern_parts[i]
			var part = parts[i]
			if not ppart.match(part) then return false
		end
		return true
	end

	# Extract parameter values from `uri`.
	fun parse_params(uri: nullable String): Map[String, String] do
		var res = new HashMap[String, String]
		if pattern_parts.is_empty then return res
		if uri == null then return res
		uri = standardize_path(uri)
		var parts = uri.split("/")
		for i in [0 .. pattern_parts.length[ do
			if i >= parts.length then return res
			var ppart = pattern_parts[i]
			var part = parts[i]
			if not ppart.match(part) then return res
			if ppart isa UriParam then
				res[ppart.name] = part
			end
		end
		return res
	end

	# Remove first occurence of `/`.
	private fun standardize_path(path: String): String do
		if not path.is_empty and path.first == '/' then
			return path.substring(1, path.length)
		end
		return path
	end
end