defmodule RDF.GraphTest do
  use ExUnit.Case

  defmodule EX, do:
    use RDF.Vocabulary, base_uri: "http://example.com/graph/"

  doctest RDF.Graph

  alias RDF.Graph
  import RDF, only: [uri: 1]


  def graph, do: unnamed_graph
  def unnamed_graph, do: Graph.new
  def named_graph(name \\ EX.GraphName), do: Graph.new(name)
  def unnamed_graph?(%Graph{name: nil}), do: true
  def unnamed_graph?(_), do: false
  def named_graph?(%Graph{name: %URI{}}), do: true
  def named_graph?(_), do: false
  def named_graph?(%Graph{name: name}, name), do: true
  def named_graph?(_, _), do: false
  def empty_graph?(%Graph{descriptions: descriptions}), do: descriptions == %{}
  def graph_includes_statement?(graph, statement = {subject, _, _}) do
    graph.descriptions
    |> Map.get(uri(subject), %{})
    |> Enum.member?(statement)
  end

  describe "construction" do
    test "creating an empty unnamed graph" do
      assert unnamed_graph?(unnamed_graph)
    end

    test "creating an empty graph with a proper graph name" do
      refute unnamed_graph?(named_graph)
      assert named_graph?(named_graph)
    end

    test "creating an empty graph with a convertible graph name" do
      assert named_graph("http://example.com/graph/GraphName")
             |> named_graph?(uri("http://example.com/graph/GraphName"))
      assert named_graph(EX.Foo) |> named_graph?(uri(EX.Foo))
    end

    test "creating an unnamed graph with an initial triple" do
      g = Graph.new({EX.Subject, EX.predicate, EX.Object})
      assert unnamed_graph?(g)
      assert graph_includes_statement?(g, {EX.Subject, EX.predicate, EX.Object})
    end

    test "creating a named graph with an initial triple" do
      g = Graph.new(EX.GraphName, {EX.Subject, EX.predicate, EX.Object})
      assert named_graph?(g, uri(EX.GraphName))
      assert graph_includes_statement?(g, {EX.Subject, EX.predicate, EX.Object})
    end

    test "creating an unnamed graph with a list of initial triples" do
      g = Graph.new([{EX.Subject1, EX.predicate1, EX.Object1},
                     {EX.Subject2, EX.predicate2, EX.Object2}])
      assert unnamed_graph?(g)
      assert graph_includes_statement?(g, {EX.Subject1, EX.predicate1, EX.Object1})
      assert graph_includes_statement?(g, {EX.Subject2, EX.predicate2, EX.Object2})
    end

    test "creating a named graph with a list of initial triples" do
      g = Graph.new(EX.GraphName, [{EX.Subject, EX.predicate1, EX.Object1},
                                   {EX.Subject, EX.predicate2, EX.Object2}])
      assert named_graph?(g, uri(EX.GraphName))
      assert graph_includes_statement?(g, {EX.Subject, EX.predicate1, EX.Object1})
      assert graph_includes_statement?(g, {EX.Subject, EX.predicate2, EX.Object2})
    end
  end

  describe "adding triples" do
    test "a proper triple" do
      assert Graph.add(graph, {uri(EX.Subject), EX.predicate, uri(EX.Object)})
        |> graph_includes_statement?({EX.Subject, EX.predicate, EX.Object})
    end

    test "a convertiable triple" do
      assert Graph.add(graph,
          {"http://example.com/graph/Subject", EX.predicate, EX.Object})
        |> graph_includes_statement?({EX.Subject, EX.predicate, EX.Object})
    end

    test "a list of triples" do
      g = Graph.add(graph, [
        {EX.Subject1, EX.predicate1, EX.Object1},
        {EX.Subject1, EX.predicate2, EX.Object2},
        {EX.Subject3, EX.predicate3, EX.Object3}
      ])
      assert graph_includes_statement?(g, {EX.Subject1, EX.predicate1, EX.Object1})
      assert graph_includes_statement?(g, {EX.Subject1, EX.predicate2, EX.Object2})
      assert graph_includes_statement?(g, {EX.Subject3, EX.predicate3, EX.Object3})
    end

    test "duplicates are ignored" do
      g = Graph.add(graph, {EX.Subject, EX.predicate, EX.Object})
      assert Graph.add(g, {EX.Subject, EX.predicate, EX.Object}) == g
    end

    test "non-convertible Triple elements are causing an error" do
      assert_raise RDF.InvalidURIError, fn ->
        Graph.add(graph, {"not a URI", EX.predicate, uri(EX.Object)})
      end
      assert_raise RDF.InvalidLiteralError, fn ->
        Graph.add(graph, {EX.Subject, EX.prop, self})
      end
    end
  end

  test "subject_count" do
    g = Graph.add(graph, [
      {EX.Subject1, EX.predicate1, EX.Object1},
      {EX.Subject1, EX.predicate2, EX.Object2},
      {EX.Subject3, EX.predicate3, EX.Object3}
    ])
    assert Graph.subject_count(g) == 2
  end

  test "pop a triple" do
    assert Graph.pop(Graph.new) == {nil, Graph.new}

    {triple, graph} = Graph.new({EX.S, EX.p, EX.O}) |> Graph.pop
    assert {uri(EX.S), uri(EX.p), uri(EX.O)} == triple
    assert Enum.count(graph.descriptions) == 0

    {{subject, predicate, _}, graph} =
      Graph.new([{EX.S, EX.p, EX.O1}, {EX.S, EX.p, EX.O2}])
      |> Graph.pop
    assert {subject, predicate} == {uri(EX.S), uri(EX.p)}
    assert Enum.count(graph.descriptions) == 1

    {{subject, _, _}, graph} =
      Graph.new([{EX.S, EX.p1, EX.O1}, {EX.S, EX.p2, EX.O2}])
      |> Graph.pop
    assert subject == uri(EX.S)
    assert Enum.count(graph.descriptions) == 1
  end

  describe "Enumerable implementation" do
    test "Enum.count" do
      assert Enum.count(Graph.new EX.foo) == 0
      assert Enum.count(Graph.new {EX.S, EX.p, EX.O}) == 1
      assert Enum.count(Graph.new [{EX.S, EX.p, EX.O1}, {EX.S, EX.p, EX.O2}]) == 2

      g = Graph.add(graph, [
        {EX.Subject1, EX.predicate1, EX.Object1},
        {EX.Subject1, EX.predicate2, EX.Object2},
        {EX.Subject3, EX.predicate3, EX.Object3}
      ])
      assert Enum.count(g) == 3
    end

    test "Enum.member?" do
      refute Enum.member?(Graph.new, {uri(EX.S), EX.p, uri(EX.O)})
      assert Enum.member?(Graph.new({EX.S, EX.p, EX.O}), {EX.S, EX.p, EX.O})

      g = Graph.add(graph, [
        {EX.Subject1, EX.predicate1, EX.Object1},
        {EX.Subject1, EX.predicate2, EX.Object2},
        {EX.Subject3, EX.predicate3, EX.Object3}
      ])
      assert Enum.member?(g, {EX.Subject1, EX.predicate1, EX.Object1})
      assert Enum.member?(g, {EX.Subject1, EX.predicate2, EX.Object2})
      assert Enum.member?(g, {EX.Subject3, EX.predicate3, EX.Object3})
    end

    test "Enum.reduce" do
      g = Graph.add(graph, [
        {EX.Subject1, EX.predicate1, EX.Object1},
        {EX.Subject1, EX.predicate2, EX.Object2},
        {EX.Subject3, EX.predicate3, EX.Object3}
      ])

      assert g == Enum.reduce(g, graph,
        fn(triple, acc) -> acc |> Graph.add(triple) end)
    end
  end

end