-------------------------------------------------------------------------------
-- Copyright 2021, The Trendy Terminal Developers (see AUTHORS file)

-- Licensed under the Apache License, Version 2.0 (the "License");
-- you may not use this file except in compliance with the License.
-- You may obtain a copy of the License at

--     http://www.apache.org/licenses/LICENSE-2.0

-- Unless required by applicable law or agreed to in writing, software
-- distributed under the License is distributed on an "AS IS" BASIS,
-- WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-- See the License for the specific language governing permissions and
-- limitations under the License.
-------------------------------------------------------------------------------

with Interfaces.C.Strings;
with System;

package Trendy_Terminal.Mac is

    ---------------------------------------------------------------------------
    -- Interfacing with C
    ---------------------------------------------------------------------------
    -- Crash course in how this works.
    -- https://en.wikibooks.org/wiki/Ada_Programming/Types/access#Access_vs._System.Address
    type BOOL is new Interfaces.C.int;
    type FD is new Interfaces.C.int;
    type FILE_Ptr is new System.Address;

    function fileno (Stream : FILE_Ptr) return FD with
        Import     => True,
        Convention => C;

    function isatty (File_Descriptor : FD) return BOOL with
        Import     => True,
        Convention => C;

    stdin  : aliased FILE_Ptr;
    stdout : aliased FILE_Ptr;
    stderr : aliased FILE_Ptr;

    pragma Import (C, stdin, "__stdinp");
    pragma Import (C, stdout, "__stdoutp");
    pragma Import (C, stderr, "__stderrp");

    NCCS : constant := 20;

    type tcflag_t is new Interfaces.C.unsigned_long;
    type cc_t is new Interfaces.C.unsigned_char;
    type speed_t is new Interfaces.C.long;
    type cc_array is array (Natural range 0 .. NCCS - 1) of cc_t
        with Convention => C;

    --!pp off
    type c_lflag_bits is (
       ECHOKE     ,
       ECHOE      ,
       ECHOK      ,
       ECHO       ,
       ECHONL     ,
       ECHOPRT    ,
       ECHOCTL    ,
       ISIG       ,
       ICANON     ,
       ALTWERASE  ,
       IEXTEN     ,
       EXTPROC    ,
       Unused1    ,
       Unused2    ,
       TOSTOP     ,
       FLUSHO     ,
       Unused3    ,
       NOKERNINFO ,
       Unused4    ,
       Unused5    ,
       Unused6    ,
       PENDIN     ,
       NOFLSH);
                           
    for c_lflag_bits use
      (
       ECHOKE     => 16#00000001#,
       ECHOE      => 16#00000002#,
       ECHOK      => 16#00000004#,
       ECHO       => 16#00000008#,
       ECHONL     => 16#00000010#,
       ECHOPRT    => 16#00000020#,
       ECHOCTL    => 16#00000040#,
       ISIG       => 16#00000080#,
       ICANON     => 16#00000100#,
       ALTWERASE  => 16#00000200#,
       IEXTEN     => 16#00000400#,
       EXTPROC    => 16#00000800#,
       Unused1    => 16#00100000#,
       Unused2    => 16#00200000#,
       TOSTOP     => 16#00400000#,
       FLUSHO     => 16#00800000#,
       Unused3    => 16#01000000#,
       NOKERNINFO => 16#02000000#,
       Unused4    => 16#04000000#,
       Unused5    => 16#08000000#,
       Unused6    => 16#10000000#,
       PENDIN     => 16#20000000#,
       NOFLSH     => 16#80000000#
      );
    --!pp on

    pragma Warnings (Off, "bits of *unused");
    type c_lflag_t is array (c_lflag_bits) of Boolean with
        Pack,
        Size => tcflag_t'Size;
    pragma Warnings (On, "bits of *unused");

    type Termios is record
        c_iflag  : tcflag_t;
        c_oflag  : tcflag_t;
        c_cflag  : tcflag_t;
        c_lflag  : c_lflag_t;
        c_line   : cc_t;
        c_cc     : cc_array;
        c_ispeed : speed_t;
        c_ospeed : speed_t;
    end record with
        Convention => C;

    function tcgetattr (File_Descriptor : FD; Terminal : System.Address) return BOOL with
        Import     => True,
        Convention => C;

    type Application_Time is
        (TCSANOW,   -- immediate effect
         TCSADRAIN, -- after all output written
         TCSAFLUSH  -- like drain, except input received as well
    );
    for Application_Time use (TCSANOW => 0, TCSADRAIN => 1, TCSAFLUSH => 2);

    function tcsetattr
        (File_Descriptor : FD; Effect_Time : Application_Time; Terminal : System.Address) return BOOL with
        Import     => True,
        Convention => C;

end Trendy_Terminal.Mac;