with

    Ada.Unchecked_Deallocation;


package body Packrat.Graphs is


    procedure Free_Element_Array is new Ada.Unchecked_Deallocation
        (Element_Array, Element_Array_Access);





    function "<"
           (Left, Right : in Choice_Down)
        return Boolean is
    begin
        return Left.From < Right.From or else
            (Left.From = Right.From and Left.Choice < Right.Choice);
    end "<";





    procedure Adjust
           (This : in out Elem_Wrapper)
    is
        New_Array : Element_Array_Access;
    begin
        if This.Data /= null then
            New_Array := new Element_Array (This.Data'First .. This.Data'Last);
            New_Array.all := This.Data.all;
            This.Data := New_Array;
        end if;
    end Adjust;


    procedure Finalize
           (This : in out Elem_Wrapper) is
    begin
        if This.Data /= null then
            Free_Element_Array (This.Data);
        end if;
    end Finalize;


    function Wrap
           (Data : in Element_Array)
        return Elem_Wrapper
    is
        New_Array : Element_Array_Access :=
            new Element_Array (Data'First .. Data'Last);
    begin
        New_Array.all := Data;
        return (Ada.Finalization.Controlled with Data => New_Array);
    end Wrap;





    function Leaf
           (New_Item : in Element_Array;
            Start    : in Positive;
            Finish   : in Natural)
        return Node is
    begin
        return This : Node do
            This.Kind := Leaf_Node;
            This.Content := Wrap (New_Item);
            This.Start := Start;
            This.Finish := Finish;
        end return;
    end Leaf;


    function Branch
           (Label  : in Label_Enum;
            Start  : in Positive;
            Finish : in Natural)
        return Node is
    begin
        return This : Node do
            This.Kind := Branch_Node;
            This.Ident := Label;
            This.Start := Start;
            This.Finish := Finish;
        end return;
    end Branch;





    function Is_Leaf
           (This : in Node)
        return Boolean is
    begin
        return This.Kind = Leaf_Node;
    end Is_Leaf;


    function Is_Branch
           (This : in Node)
        return Boolean is
    begin
        return This.Kind = Branch_Node;
    end Is_Branch;





    function Label
           (This : in Node)
        return Label_Enum is
    begin
        return This.Ident;
    end Label;


    function Elements
           (This : in Node)
        return Element_Array is
    begin
        return This.Content.Data.all;
    end Elements;


    function Start
           (This : in Node)
        return Positive is
    begin
        return This.Start;
    end Start;


    function Finish
           (This : in Node)
        return Natural is
    begin
        return This.Finish;
    end Finish;





    function Is_Nothing
           (Position : in Cursor)
        return Boolean is
    begin
        return Position.My_Graph = null or else
            Position.Index = 0 or else
            Position.Index > Position.My_Graph.all.Node_List.Last_Index or else
            Position.My_Graph.all.Node_List.Element (Position.Index).Kind = Null_Node;
    end Is_Nothing;





    function Depth
           (Position : in Cursor)
        return Natural is
    begin
        return Natural (Position.Track.Length);
    end Depth;


    function Is_Node
           (Position : in Cursor)
        return Boolean is
    begin
        return not Is_Nothing (Position);
    end Is_Node;


    function Is_Root
           (Position : in Cursor)
        return Boolean is
    begin
        return Position.My_Graph /= null and then
            Position.My_Graph.all.Root_List.Contains (Position.Index) and then
            Depth (Position) = 0;
    end Is_Root;


    function Is_Branch
           (Position : in Cursor)
        return Boolean is
    begin
        return Position.My_Graph /= null and then
            Position.Index /= 0 and then
            Position.Index <= Position.My_Graph.all.Node_List.Last_Index and then
            Position.My_Graph.all.Node_List.Element (Position.Index).Kind = Branch_Node;
    end Is_Branch;


    function Is_Leaf
           (Position : in Cursor)
        return Boolean is
    begin
        return Position.My_Graph /= null and then
            Position.Index /= 0 and then
            Position.Index <= Position.My_Graph.all.Node_List.Last_Index and then
            Position.My_Graph.all.Node_List.Element (Position.Index).Kind = Leaf_Node;
    end Is_Leaf;


    function Label
           (Position : in Cursor)
        return Label_Enum is
    begin
        return Position.My_Graph.all.Node_List.Element (Position.Index).Ident;
    end Label;


    function Elements
           (Position : in Cursor)
        return Element_Array is
    begin
        return Position.My_Graph.all.Node_List.Element (Position.Index).Content.Data.all;
    end Elements;





    function Start
           (Position : in Cursor)
        return Positive is
    begin
        return Position.My_Graph.all.Node_List.Element (Position.Index).Start;
    end Start;


    function Finish
           (Position : in Cursor)
        return Natural is
    begin
        return Position.My_Graph.all.Node_List.Element (Position.Index).Finish;
    end Finish;


    function Choices
           (Position : in Cursor)
        return Natural is
    begin
        if not Is_Branch (Position) then
            return 0;
        elsif not Position.My_Graph.all.Choices.Contains (Position.Index) then
            return 0;
        else
            return Position.My_Graph.all.Choices.Element (Position.Index);
        end if;
    end Choices;





    function Parent
           (Position : in Cursor)
        return Cursor is
    begin
        return Result : Cursor do
            Result.My_Graph := Position.My_Graph;
            Result.Track := Position.Track;
            if Natural (Position.Track.Length) = 0 then
                Result.Index := 0;
            else
                Result.Index := Position.Track.Last_Element.From;
                Result.Track.Delete_Last;
            end if;
        end return;
    end Parent;


    function Child_Count
           (Position : in Cursor;
            Choice   : in Positive)
        return Natural is
    begin
        return Natural (Position.My_Graph.all.Down_Edges.Element ((Position.Index, Choice)).Length);
    end Child_Count;


    function Child_Count
           (Position : in Cursor)
        return Natural
    is
        Choice_Count : Natural := Choices (Position);
    begin
        if Choice_Count = 0 then
            return 0;
        else
            return Natural (Position.My_Graph.all.Down_Edges.Element
                ((Position.Index, Choice_Count)).Length);
        end if;
    end Child_Count;


    function All_Child_Count
           (Position : in Cursor)
        return Natural
    is
        Result : Natural := 0;
    begin
        for C in Integer range 1 .. Choices (Position) loop
            Result := Result + Child_Count (Position, C);
        end loop;
        return Result;
    end All_Child_Count;


    function First_Child
           (Position : in Cursor;
            Choice   : in Positive)
        return Cursor is
    begin
        return Result : Cursor do
            Result.My_Graph := Position.My_Graph;
            Result.Index := Position.My_Graph.all.Down_Edges.Element
                ((Position.Index, Choice)).First_Element;
            Result.Track := Position.Track;
            Result.Track.Append ((Position.Index, Choice));
        end return;
    end First_Child;


    function Last_Child
           (Position : in Cursor;
            Choice   : in Positive)
        return Cursor is
    begin
        return Result : Cursor do
            Result.My_Graph := Position.My_Graph;
            Result.Index := Position.My_Graph.all.Down_Edges.Element
                ((Position.Index, Choice)).Last_Element;
            Result.Track := Position.Track;
            Result.Track.Append ((Position.Index, Choice));
        end return;
    end Last_Child;


    function First_Child
           (Position : in Cursor)
        return Cursor
    is
        Choice : Natural := Choices (Position);
    begin
        return Result : Cursor do
            Result.My_Graph := Position.My_Graph;
            if Choice = 0 or Result.My_Graph = null then
                Result.Index := 0;
            else
                Result.Index := Position.My_Graph.all.Down_Edges.Element
                    ((Position.Index, Choice)).First_Element;
            end if;
            Result.Track := Position.Track;
            Result.Track.Append ((Position.Index, Choice));
        end return;
    end First_Child;


    function Last_Child
           (Position : in Cursor)
        return Cursor
    is
        Choice : Natural := Choices (Position);
    begin
        return Result : Cursor do
            Result.My_Graph := Position.My_Graph;
            if Choice = 0 or Result.My_Graph = null then
                Result.Index := 0;
            else
                Result.Index := Position.My_Graph.all.Down_Edges.Element
                    ((Position.Index, Choice)).Last_Element;
            end if;
            Result.Track := Position.Track;
            Result.Track.Append ((Position.Index, Choice));
        end return;
    end Last_Child;


    function Next_Sibling
           (Position : in Cursor)
        return Cursor
    is
        Parent_Index : Extended_Node_Index;
        Choice       : Natural;
        Sibling      : Index_Vectors.Cursor;
    begin
        if Depth (Position) = 0 then
            Parent_Index := 0;
            Choice := 0;
        else
            Parent_Index := Position.Track.Last_Element.From;
            Choice := Position.Track.Last_Element.Choice;
        end if;
        return Result : Cursor do
            Result.My_Graph := Position.My_Graph;
            if Choice = 0 or Parent_Index = 0 or Result.My_Graph = null or Position.Index = 0 then
                Result.Index := 0;
            else
                Sibling := Result.My_Graph.all.Down_Edges.Element
                    ((Parent_Index, Choice)).Find (Position.Index);
                Index_Vectors.Next (Sibling);
                if Index_Vectors.Has_Element (Sibling) then
                    Result.Index := Index_Vectors.Element (Sibling);
                else
                    Result.Index := 0;
                end if;
            end if;
            Result.Track := Position.Track;
        end return;
    end Next_Sibling;


    function Prev_Sibling
           (Position : in Cursor)
        return Cursor
    is
        Parent_Index : Extended_Node_Index;
        Choice       : Natural;
        Sibling      : Index_Vectors.Cursor;
    begin
        if Depth (Position) = 0 then
            Parent_Index := 0;
            Choice := 0;
        else
            Parent_Index := Position.Track.Last_Element.From;
            Choice := Position.Track.Last_Element.Choice;
        end if;
        return Result : Cursor do
            Result.My_Graph := Position.My_Graph;
            if Choice = 0 or Parent_Index = 0 or Result.My_Graph = null or Position.Index = 0 then
                Result.Index := 0;
            else
                Sibling := Result.My_Graph.all.Down_Edges.Element
                    ((Parent_Index, Choice)).Find (Position.Index);
                Index_Vectors.Previous (Sibling);
                if Index_Vectors.Has_Element (Sibling) then
                    Result.Index := Index_Vectors.Element (Sibling);
                else
                    Result.Index := 0;
                end if;
            end if;
            Result.Track := Position.Track;
        end return;
    end Prev_Sibling;


    procedure Delete_Children
           (Position : in out Cursor;
            Choice   : in     Positive) is
    begin
        null;
    end Delete_Children;


    procedure Delete_Children
           (Position : in out Cursor) is
    begin
        null;
    end Delete_Children;


    procedure Delete_All_Children
           (Position : in out Cursor) is
    begin
        null;
    end Delete_All_Children;





    function Equal_Subgraph
           (Left, Right : in Cursor)
        return Boolean is
    begin
        return False;
    end Equal_Subgraph;


    function Subgraph_Node_Count
           (Position : in Cursor)
        return Natural is
    begin
        return 0;
    end Subgraph_Node_Count;


    function Find_In_Subgraph
           (Position : in Cursor;
            Item     : in Element_Array)
        return Cursor is
    begin
        return This : Cursor;
    end Find_In_Subgraph;





    function Contains
           (Container : in Graph;
            Position  : in Cursor)
        return Boolean is
    begin
        return False;
        --  return Position.Graph.all = Container and then
        --      Position.Index < Container.Node_List.Last_Index and then
        --      Position.Index > 0 and then
        --      Container.Node_List.Element (Position.Index).Kind /= Null_Node;
    end Contains;




    function Singleton
           (Input : in Node)
        return Graph is
    begin
        return Result : Graph do
            Result.Root_List := Index_Vectors.Empty_Vector;
            Result.Root_List.Append (1);
            Result.Node_List := Node_Vectors.Empty_Vector;
            Result.Node_List.Append (Input);
            Result.Add_Place := 2;
            Result.Choices := Choice_Maps.Empty_Map;
            Result.Down_Edges := Edge_Down_Maps.Empty_Map;
            Result.Up_Edges := Edge_Up_Maps.Empty_Map;
        end return;
    end Singleton;


    function Node_At
           (Container : in Graph;
            Position  : in Cursor)
        return Node_Reference is
    begin
        return (Data => No_Node'Unrestricted_Access);
    end Node_At;





    function Is_Empty
           (Container : in Graph)
        return Boolean is
    begin
        return Container.Root_List.Is_Empty;
    end Is_Empty;


    function Is_Ambiguous
           (Container : in Graph)
        return Boolean is
    begin
        if Natural (Container.Root_List.Length) > 1 then
            return True;
        end if;
        for N in Node_Index range 1 .. Container.Node_List.Last_Index loop
            if  Container.Node_List.Element (N).Kind = Branch_Node and then
                Container.Choices.Contains (N) and then
                Container.Choices.Element (N) > 1
            then
                return True;
            end if;
        end loop;
        return False;
    end Is_Ambiguous;


    function Node_Count
           (Container : in Graph)
        return Natural
    is
        Result : Natural := 0;
        Current_Vector : Index_Vectors.Vector := Container.Root_List;
        New_Vector     : Index_Vectors.Vector := Index_Vectors.Empty_Vector;
    begin
        while Natural (Current_Vector.Length) > 0 loop
            Result := Result + Natural (Current_Vector.Length);
            for N of Current_Vector loop
                if  Is_Branch (Container.Node_List.Element (N)) and
                    Container.Choices.Contains (N)
                then
                    for C in Integer range 1 .. Container.Choices.Element (N) loop
                        New_Vector.Append (Container.Down_Edges.Element ((N, C)));
                    end loop;
                end if;
            end loop;
            Current_Vector := New_Vector;
            New_Vector.Clear;
        end loop;
        return Result;
    end Node_Count;





    function Root_Count
           (Container : in Graph)
        return Natural is
    begin
        return Natural (Container.Root_List.Length);
    end Root_Count;


    function Root
           (Container : in Graph;
            Index     : in Positive)
        return Cursor is
    begin
        return Result : Cursor do
            Result.My_Graph := Container'Unrestricted_Access;
            Result.Index := Container.Root_List.Element (Index);
            Result.Track := Choice_Down_Vectors.Empty_Vector;
        end return;
    end Root;





    procedure Append
           (Container : in out Graph;
            Addition  : in     Graph) is
    begin
        null;
    end Append;


    procedure Prepend
           (Container : in out Graph;
            Addition  : in     Graph) is
    begin
        null;
    end Prepend;


    procedure Attach_Choice
           (Container : in out Graph;
            Position  : in     Cursor;
            Addition  : in     Graph) is
    begin
        null;
    end Attach_Choice;





    procedure Clear
           (Container : in out Graph) is
    begin
        Container.Root_List.Clear;
        Container.Node_List.Clear;
        Container.Add_Place := 1;
        Container.Choices.Clear;
        Container.Down_Edges.Clear;
        Container.Up_Edges.Clear;
    end Clear;


    procedure Delete_Position
           (Container : in out Graph;
            Position  : in out Cursor) is
    begin
        null;
    end Delete_Position;





    function Find
           (Container : in Graph;
            Item      : in Element_Array)
        return Cursor is
    begin
        return This : Cursor;
    end Find;





    function Iterate
           (This : in Graph)
        return Graph_Iterators.Reversible_Iterator'Class is
    begin
        return Result : Reversible_Iterator do
            Result.Position := No_Position;
        end return;
    end Iterate;


    function Iterate_Subtree
           (This     : in Graph;
            Position : in Cursor)
        return Graph_Iterators.Reversible_Iterator'Class is
    begin
        return Result : Reversible_Iterator do
            Result.Position := No_Position;
        end return;
    end Iterate_Subtree;


    function Iterate_Choice
           (This : in Graph;
            Func : in Choosing_Function)
        return Graph_Iterators.Forward_Iterator'Class is
    begin
        return Result : Forward_Iterator do
            Result.Position := No_Position;
        end return;
    end Iterate_Choice;





    function First
           (Object : in Forward_Iterator)
        return Cursor is
    begin
        return No_Position;
    end First;

    function Next
           (Object : in Forward_Iterator;
            Place  : in Cursor)
        return Cursor is
    begin
        return No_Position;
    end Next;





    function First
           (Object : in Reversible_Iterator)
        return Cursor is
    begin
        return No_Position;
    end First;


    function Next
           (Object : in Reversible_Iterator;
            Place  : in Cursor)
        return Cursor is
    begin
        return No_Position;
    end Next;


    function Last
           (Object : in Reversible_Iterator)
        return Cursor is
    begin
        return No_Position;
    end Last;


    function Previous
           (Object : in Reversible_Iterator;
            Place  : in Cursor)
        return Cursor is
    begin
        return No_Position;
    end Previous;


end Packrat.Graphs;