require 'rdf/turtle'

module Chronicle
  module Schema
    module RDFParsing
      PREFIXES = {
        schemaorg: 'https://schema.org/',
        owl: 'http://www.w3.org/2002/07/owl#',
        dc: 'http://purl.org/dc/terms/',
        rdf: 'http://www.w3.org/1999/02/22-rdf-syntax-ns#',
        rdfs: 'http://www.w3.org/2000/01/rdf-schema#',
        xml: 'http://www.w3.org/XML/1998/namespace',
        xsd: 'http://www.w3.org/2001/XMLSchema#'
      }.freeze

      # Take a graph and serialize it as a ttl string
      class RDFSerializer
        attr_reader :graph

        def initialize(graph)
          raise ArgumentError, 'graph must be a SchemaGraph' unless graph.is_a?(Chronicle::Schema::SchemaGraph)

          @graph = graph
        end

        def self.serialize(graph, include_generator_comment: true)
          new(graph).serialize(include_generator_comment:)
        end

        def serialize(include_generator_comment: true)
          schema_graph = RDF::Graph.new

          schema_graph << ontology_triple
          schema_graph << version_triple

          graph.types.each do |klass|
            serialize_class(klass).each do |triple|
              # binding.pry
              schema_graph << triple
            end
          end

          graph.properties.each do |property|
            serialize_property(property).each do |triple|
              schema_graph << triple
            end
          end

          prefixes = {
            '': default_namespace
          }.merge(PREFIXES)

          output_str = ''
          output_str += generation_header if include_generator_comment
          output_str + schema_graph.dump(:ttl, prefixes:)
        end

        private

        def default_namespace
          @graph.default_namespace
        end

        def generation_header
          <<~TTL
            # This file was generated from schema/chronicle_schema_v#{graph.version}.rb.
            #
            # Do not edit this file directly, as it will be overwritten.
            #
            # To generate a new version, run `rake generate`

          TTL
        end

        def ontology_triple
          RDF::Statement(RDF::URI.new('https://schema.chronicle.app'), RDF.type, RDF::OWL.Ontology)
        end

        def version_triple
          RDF::Statement(RDF::URI.new('https://schema.chronicle.app'), RDF::OWL.versionInfo, graph.version.to_s)
        end

        def serialize_class(klass)
          statements = []
          statements << RDF::Statement(RDF::URI.new(klass.id), RDF.type, RDF::RDFS.Class)
          statements << RDF::Statement(RDF::URI.new(klass.id), RDF::RDFS.comment, klass.comment) if klass.comment

          klass.subtype_ids.each do |subtype_id|
            statements << RDF::Statement(RDF::URI.new(subtype_id), RDF::RDFS.subClassOf, RDF::URI.new(klass.id))
          end

          if klass.see_also
            statements << RDF::Statement(RDF::URI.new(klass.id), RDF::RDFS.seeAlso, RDF::URI.new(klass.see_also))
          end

          statements
        end

        def serialize_property(property)
          statements = []

          statements << RDF::Statement(RDF::URI.new(property.id), RDF.type, RDF::RDFV.Property)

          property.range.each do |range|
            statements << RDF::Statement(RDF::URI.new(property.id), RDF::URI.new("#{@graph.default_namespace}rangeIncludes"),
              RDF::URI.new(range))
          end

          property.domain.each do |domain|
            statements << RDF::Statement(RDF::URI.new(property.id), RDF::URI.new("#{@graph.default_namespace}domainIncludes"),
              RDF::URI.new(domain))
          end

          if property.comment
            statements << RDF::Statement(RDF::URI.new(property.id), RDF::RDFS.comment,
              property.comment)
          end

          if property.see_also
            statements << RDF::Statement(RDF::URI.new(property.id), RDF::RDFS.seeAlso, RDF::URI.new(property.see_also))
          end

          if property.required?
            statements << RDF::Statement(RDF::URI.new(property.id), RDF::OWL.minCardinality,
              RDF::Literal.new(1, datatype: RDF::XSD.integer))
          end

          unless property.many
            statements << RDF::Statement(RDF::URI.new(property.id), RDF::OWL.maxCardinality,
              RDF::Literal.new(1, datatype: RDF::XSD.integer))
          end

          statements
        end
      end
    end
  end
end