require "./parser"

class Specs
	property assignments : Hash(String, String)

	def initialize
		@assignments = Hash(String, String).new
	end

	def parse_hashglob(tree)
		# hashglob = hash hashglob | any hashglob | any | hash
		str = String.build do |str|
			case tree
			when Pegasus::Generated::TerminalTree
				str << tree.string
			when Pegasus::Generated::NonterminalTree
				tree.children.each do |it|
					str << parse_hashglob it
				end
			end
		end

		str
	end

	def parse_freetext(tree)
		# tabs hashglob cr freetext?

		case tree
		when Pegasus::Generated::TerminalTree
			raise "freetext: should not be terminal"
		when Pegasus::Generated::NonterminalTree
			current_line = parse_hashglob tree.children[1]
			current_line = current_line.lstrip(" ").rstrip(" ")

			str = String.build do |str|
				str << current_line
				str << "\n"
				if tree.children.size == 4
					str << parse_freetext tree.children[3]
				end
			end

			str
		end
	end

	def parse_list_items(tree)
		# tabs dash glob cr listitem? | tabs comment cr listitem

		case tree
		when Pegasus::Generated::TerminalTree
			raise "parse_list_items: should not be terminal"
		when Pegasus::Generated::NonterminalTree

			if tree.children[1] == Pegasus::Generated::NonterminalTree
				str = String.build do |str|
					str << parse_list_items tree.children[3]
				end

				str
			else
				current_line = parse_glob tree.children[2]
				current_line = current_line.lstrip(" ").rstrip(" ")

				str = String.build do |str|
					str << current_line
					str << "\n"
					if tree.children.size == 5
						str << parse_list_items tree.children[4]
					end
				end

				str
			end
		end
	end

	def parse_list(tree)
		# string colon cr listitem
		name = parse_string tree.children[0]
		value = parse_list_items tree.children[3]

		if name.nil?
			return
		end

		if value.nil?
			return
		end

		@assignments[name] = value
	end

	def parse_freetextblock(tree)
		# at multiplealphanum cr freetext

		name = parse_multiplealphanum tree.children[1]
		value = parse_freetext tree.children[3]

		if name.nil?
			return
		end

		if value.nil?
			return
		end

		@assignments[name] = value
	end

	def parse_glob (tree)
		# glob = any glob | any
		str = String.build do |str|
			case tree
			when Pegasus::Generated::TerminalTree
				str << tree.string
			when Pegasus::Generated::NonterminalTree
				tree.children.each do |it|
					str << parse_glob it
				end
			end
		end

		str
	end

	def parse_multiplealphanum(tree)
		# multiplealphanum = alphanum multiplealphanum?
		# alphanum = string | numbers
		str = String.build do |str|
			case tree
			when Pegasus::Generated::TerminalTree
				str << tree.string
			when Pegasus::Generated::NonterminalTree
				tree.children.each do |it|
					str << parse_multiplealphanum it
				end
			end
		end

		str
	end

	def parse_string(tree)
		case tree
		when Pegasus::Generated::TerminalTree
			return tree.string
		else
			raise "this should be a string but this is non terminal"
		end
	end

	def parse_assignment(tree)
		# string colon glob
		name = parse_string tree.children[0]
		value = parse_glob tree.children[2]
		value = value.lstrip(" ").rstrip(" ")

		if name.nil?
			return
		end

		if value.nil?
			return
		end

		@assignments[name] = value
	end

	def parse_tree(tree)
		case tree
		when Pegasus::Generated::TerminalTree
			# do nothing
		when Pegasus::Generated::NonterminalTree
			case tree.name
			when "freetextblock"  ; parse_freetextblock tree
			when "freetext"       ; parse_freetext tree
			when "assignment"     ; parse_assignment tree
			when "list"           ; parse_list tree
			when "comment"
				# do nothing
			else
				tree.children.each { |it| parse_tree(it) }
			end
		end
	end

	def rewrite
		# replaces all occurences of %{variable} by the content of @assignments[variable]
		@assignments.map do |k, v|
			reg = /%\{([^}]*)\}/

			while v =~ reg

				x = reg.match(v)
				unless x.nil?
					var = x.captures()

					v = v.gsub "%{#{var[0]}}", "#{@assignments[var[0]]}"
				end
			end

			@assignments[k] = v
		end
	end

	def self.parse(file_name : String) : Specs | Nil
		begin
			content = File.read(file_name)
			content = content.rchop

			specs = Specs.new
			tree =  Pegasus::Generated.process(content)
			specs.parse_tree tree

			specs.rewrite

			specs
		rescue e
			puts "Exception: #{e}"

			nil
		end
	end
end