--
--  Copyright (C) 2020-2022, AdaCore
--
--  SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
--

with Ada.Iterator_Interfaces;
private with Ada.Finalization;
with Ada.Streams;

package VSS.Stream_Element_Vectors is

   pragma Preelaborate;
   pragma Remote_Types;

   type Stream_Element_Vector is tagged private
     with
       Constant_Indexing => Element,
       Default_Iterator  => Iterate,
       Iterator_Element  => Ada.Streams.Stream_Element;

   procedure Set_Capacity
     (Self     : in out Stream_Element_Vector'Class;
      Capacity : Ada.Streams.Stream_Element_Count);
   --  Request to pre-allocate memory to store given number of stream elements.

   function Is_Empty (Self : Stream_Element_Vector'Class) return Boolean;
   --  Return True when stream element vector doesn't contain any elements.

   function Length
     (Self : Stream_Element_Vector'Class)
      return Ada.Streams.Stream_Element_Count;
   --  Return size of accumulated data.

   function Element
     (Self  : Stream_Element_Vector'Class;
      Index : Ada.Streams.Stream_Element_Count)
      return Ada.Streams.Stream_Element;
   --  Return element at given index (starting from 1).

   procedure Append
     (Self : in out Stream_Element_Vector'Class;
      Item : Ada.Streams.Stream_Element);
   --  Append stream element to the end of the buffer

   procedure Append
     (Self : in out Stream_Element_Vector'Class;
      Item : Stream_Element_Vector'Class);
   --  Append stream element vector to the end of the buffer

   overriding function "="
     (Left  : Stream_Element_Vector;
      Right : Stream_Element_Vector) return Boolean;

   ------------------------------------
   -- Support for Ada 2012 iterators --
   ------------------------------------

   type Cursor is private;

   function Has_Element (Self : Cursor) return Boolean
      with Inline;

   function Element
     (Self     : Stream_Element_Vector'Class;
      Position : Cursor)
      return Ada.Streams.Stream_Element
        with Inline;

   package Iterator_Interfaces is new Ada.Iterator_Interfaces
     (Cursor, Has_Element);

   type Reversible_Iterator is
     limited new Iterator_Interfaces.Reversible_Iterator with private;

   overriding function First (Self : Reversible_Iterator) return Cursor;

   overriding function Next
     (Self     : Reversible_Iterator;
      Position : Cursor) return Cursor
        with Inline;

   overriding function Last (Self : Reversible_Iterator) return Cursor;

   overriding function Previous
     (Self     : Reversible_Iterator;
      Position : Cursor) return Cursor
        with Inline;

   function Iterate
     (Self : Stream_Element_Vector'Class) return Reversible_Iterator;

private

   type Data_Record (Size : Ada.Streams.Stream_Element_Count) is record
      Length  : Ada.Streams.Stream_Element_Count;
      Storage : Ada.Streams.Stream_Element_Array (1 .. Size);
   end record;

   type Data_Access is access all Data_Record;

   procedure Read
     (Stream : not null access Ada.Streams.Root_Stream_Type'Class;
      Item   : out Stream_Element_Vector);

   procedure Write
     (Stream : not null access Ada.Streams.Root_Stream_Type'Class;
      Item   : Stream_Element_Vector);

   --  function Input
   --    (Stream : not null access Ada.Streams.Root_Stream_Type'Class)
   --     return Stream_Element_Buffer;
   --
   --  procedure Output
   --    (Stream : not null access Ada.Streams.Root_Stream_Type'Class;
   --     Item   : Stream_Element_Buffer);

   type Stream_Element_Vector is new Ada.Finalization.Controlled with record
      Data     : Data_Access;
      Capacity : Ada.Streams.Stream_Element_Count := 0;
   end record;

   for Stream_Element_Vector'Read use Read;
   for Stream_Element_Vector'Write use Write;
   --  for Stream_Element_Buffer'Input use Input;
   --  for Stream_Element_Buffer'Output use Output;

   overriding procedure Adjust (Self : in out Stream_Element_Vector);

   overriding procedure Finalize (Self : in out Stream_Element_Vector);

   type Reversible_Iterator is
     limited new Iterator_Interfaces.Reversible_Iterator with
   record
      Last : Ada.Streams.Stream_Element_Count;
   end record;

   type Cursor is record
      Index : Ada.Streams.Stream_Element_Count := 0;
   end record;

end VSS.Stream_Element_Vectors;