with FLTK;
with FLTK.Widgets;
with FLTK.Widgets.Menus;
with FLTK.Widgets.Groups.Windows;
with FLTK.Text_Buffers;
with FLTK.Dialogs;
with Windows.Editor;
with Windows.About;
with Windows.Find;
with Windows.Replace;
with Ada.Strings.Unbounded; use Ada.Strings.Unbounded;


package body Adapad is


    package W  renames FLTK.Widgets;
    package WN renames FLTK.Widgets.Groups.Windows;
    package D  renames FLTK.Dialogs;




    --  global state of the text editor

    Editor   : Windows.Editor.Editor_Window   := Windows.Editor.Create (800, 500);
    Buffer   : FLTK.Text_Buffers.Text_Buffer  := FLTK.Text_Buffers.Create;
    About    : Windows.About.About_Window     := Windows.About.Create;
    Find     : Windows.Find.Find_Window       := Windows.Find.Create;
    Replace  : Windows.Replace.Replace_Window := Windows.Replace.Create;

    Changed  : Boolean          := False;
    Filename : Unbounded_String := To_Unbounded_String (0);




    --  main program interface

    procedure Show is
    begin
        Editor.Show;
    end Show;




    procedure Hide is
    begin
        About.Hide;
        Find.Hide;
        Replace.Hide;
        Editor.Hide;
    end Hide;




    --  callbacks for the menu

    overriding procedure Call
           (This : in     New_Callback;
            Item : in out W.Widget'Class) is
    begin
        if not Safe_To_Discard then return; end if;
        Filename := To_Unbounded_String (0);
        Buffer.Set_Selection (0, Buffer.Length);
        Buffer.Remove_Selected_Text;
        Changed := False;
        Buffer.Call_Modify_Callbacks;
    end Call;




    overriding procedure Call
           (This : in     Open_Callback;
            Item : in out W.Widget'Class) is
    begin
        if not Safe_To_Discard then return; end if;
        declare
            New_Filename : String := D.File_Chooser ("Open File?", "*", To_String (Filename));
        begin
            if New_Filename /= "" then
                Load_File (New_Filename);
            end if;
        end;
    end Call;




    overriding procedure Call
           (This : in     Save_Callback;
            Item : in out W.Widget'Class) is
    begin
        Do_Save;
    end Call;




    overriding procedure Call
           (This : in     Save_As_Callback;
            Item : in out W.Widget'Class) is
    begin
        Do_Save_As;
    end Call;




    overriding procedure Call
           (This : in     Quit_Callback;
            Item : in out W.Widget'Class) is
    begin
        if not Safe_To_Discard then return; end if;
        Hide;
    end Call;




    overriding procedure Call
           (This : in     Undo_Callback;
            Item : in out W.Widget'Class) is
    begin
        Editor.Undo;
    end Call;




    overriding procedure Call
           (This : in     Cut_Callback;
            Item : in out W.Widget'Class) is
    begin
        Editor.Cut;
    end Call;




    overriding procedure Call
           (This : in     Copy_Callback;
            Item : in out W.Widget'Class) is
    begin
        Editor.Copy;
    end Call;




    overriding procedure Call
           (This : in     Paste_Callback;
            Item : in out W.Widget'Class) is
    begin
        Editor.Paste;
    end Call;




    overriding procedure Call
           (This : in     Delete_Callback;
            Item : in out W.Widget'Class) is
    begin
        Editor.Delete;
    end Call;




    overriding procedure Call
           (This : in     Select_All_Callback;
            Item : in out W.Widget'Class) is
    begin
        Buffer.Set_Selection (0, Buffer.Length);
    end Call;




    overriding procedure Call
           (This : in     Find_Callback;
            Item : in out W.Widget'Class) is
    begin
        Centre (Find);
        Find.Show;
    end Call;




    overriding procedure Call
           (This : in     Replace_Callback;
            Item : in out W.Widget'Class) is
    begin
        Centre (Replace);
        Replace.Show;
    end Call;




    overriding procedure Call
           (This : in     About_Callback;
            Item : in out W.Widget'Class) is
    begin
        Centre (About);
        About.Show;
    end Call;




    --  callbacks for the text buffer

    overriding procedure Call
           (This         : in Mod_Callback;
            Action       : in FLTK.Text_Buffers.Modification;
            Place        : in FLTK.Text_Buffers.Position;
            Length       : in Natural;
            Deleted_Text : in String)
    is
        use type FLTK.Text_Buffers.Modification;
    begin
        if Action = FLTK.Text_Buffers.Insert or Action = FLTK.Text_Buffers.Delete then
            Changed := True;
        end if;
        Set_Title;
    end Call;




    --  callbacks for the find/replace windows

    overriding procedure Call
           (This       : in Do_Find_Callback;
            Item       : in String;
            Match_Case : in Boolean)
    is
        Current_Position, Found_At : Natural;
    begin
        Find.Hide;
        Current_Position := Editor.Get_Insert_Position;
        if Buffer.Search_Forward (Current_Position, Item, Found_At, Match_Case) then
            Buffer.Set_Selection (Found_At, Found_At + Item'Length);
            Editor.Set_Insert_Position (Found_At + Item'Length);
            Editor.Show_Insert_Position;
        else
            D.Alert ("No occurrences of '" & Item & "' found!");
        end if;
    end Call;




    overriding procedure Call
           (This                    : in Do_Replace_Callback;
            Item, Replace_With      : in String;
            Match_Case, Replace_All : in Boolean)
    is
        Current_Position, Found_At : Natural;
        Times_Replaced : Natural := 0;
    begin
        Replace.Hide;

        if Replace_All then
            Editor.Set_Insert_Position (0);
        end if;

        loop
            Current_Position := Editor.Get_Insert_Position;
            exit when not Buffer.Search_Forward (Current_Position, Item, Found_At, Match_Case);
            Buffer.Set_Selection (Found_At, Found_At + Item'Length);
            Buffer.Remove_Selected_Text;
            Buffer.Insert_Text (Found_At, Replace_With);
            Editor.Set_Insert_Position (Found_At + Replace_With'Length);
            Editor.Show_Insert_Position;
            Times_Replaced := Times_Replaced + 1;
            exit when not Replace_All and Times_Replaced > 0;
        end loop;

        if Times_Replaced > 0 then
            D.Message_Box ("Replaced " & Integer'Image (Times_Replaced) & " occurrences.");
        else
            D.Alert ("No occurrences of '" & Item & "' found!");
        end if;
    end Call;




    --  helper functions

    procedure Set_Title is
        Title : Unbounded_String := To_Unbounded_String (0);
    begin
        if Changed then
            Append (Title, "*");
        end if;
        if Filename = "" then
            Append (Title, "(Untitled)");
        else
            Append (Title, Filename);
        end if;
        Editor.Set_Label (To_String (Title));
    end Set_Title;




    function Safe_To_Discard
        return Boolean
    is
        User_Response : D.Choice;
    begin
        if not Changed then return True; end if;
        User_Response := D.Three_Way_Choice
               ("The current file has not been saved." & Character'Val (10) &
                "Would you like to save it now?",
                "Cancel", "Save", "Discard");
        case User_Response is
            when D.First =>
                return False;
            when D.Second =>
                Do_Save;
                return not Changed;
            when D.Third =>
                return True;
        end case;
    end Safe_To_Discard;




    procedure Do_Save is
    begin
        if Filename = "" then
            Do_Save_As;
        else
            Save_File (To_String (Filename));
        end if;
    end Do_Save;




    procedure Do_Save_As is
        New_Filename : String := D.File_Chooser
               ("Save File As?", "*", To_String (Filename));
    begin
        if New_Filename /= "" then
            Save_File (New_Filename);
        end if;
    end Do_Save_As;




    procedure Load_File
           (Name : in String) is
    begin
        Buffer.Load_File (Name);
        Filename := To_Unbounded_String (Name);
        Changed := False;
        Buffer.Call_Modify_Callbacks;
    exception
        when Storage_Error =>
            D.Alert ("Error reading from file " & Name);
    end Load_File;




    procedure Save_File
           (Name : in String) is
    begin
        Buffer.Save_File (Name);
        Filename := To_Unbounded_String (Name);
        Changed := False;
        Buffer.Call_Modify_Callbacks;
    exception
        when Storage_Error =>
            D.Alert ("Error writing to file " & Name);
    end Save_File;




    procedure Centre
           (Win : in out WN.Window'Class)
    is
        Middle_X : Integer := Editor.Get_X + Editor.Get_W / 2;
        Middle_Y : Integer := Editor.Get_Y + Editor.Get_H / 2;
    begin
        Win.Reposition
               (Middle_X - Win.Get_W / 2,
                Middle_Y - Win.Get_H / 2);
    end Centre;


begin


    declare
        use FLTK.Widgets.Menus;
        Bar : Menu_Cursor := Editor.Get_Menu;
    begin
        Bar.Add (Text => "&File",   Flags => Flag_Submenu);
        Bar.Add ("File/&New",          New_CB'Access,        Mod_Ctrl + 'n');
        Bar.Add ("File/&Open...",      Open_CB'Access,       Mod_Ctrl + 'o');
        Bar.Add ("File/&Save",         Save_CB'Access,       Mod_Ctrl + 's');
        Bar.Add ("File/Save &As...", Save_As_CB'Access, Mod_Shift + Mod_Ctrl + 's', Flag_Divider);
        Bar.Add ("File/&Quit",         Quit_CB'Access,       Mod_Ctrl + 'q');

        Bar.Add (Text => "&Edit",   Flags => Flag_Submenu);
        Bar.Add ("Edit/&Undo",         Undo_CB'Access,       Mod_Ctrl + 'z',    Flag_Divider);
        Bar.Add ("Edit/Cu&t",          Cut_CB'Access,        Mod_Ctrl + 'x');
        Bar.Add ("Edit/&Copy",         Copy_CB'Access,       Mod_Ctrl + 'c');
        Bar.Add ("Edit/&Paste",        Paste_CB'Access,      Mod_Ctrl + 'v');
        Bar.Add ("Edit/&Delete",       Delete_CB'Access,     No_Key,            Flag_Divider);
        Bar.Add ("Edit/Select &All",   Select_All_CB'Access, Mod_Ctrl + 'a');

        Bar.Add (Text => "&Search", Flags => Flag_Submenu);
        Bar.Add ("Search/&Find...",    Find_CB'Access,       Mod_Ctrl + 'f');
        Bar.Add ("Search/&Replace...", Replace_CB'Access,    Mod_Ctrl + 'h');

        Bar.Add (Text => "&Help",   Flags => Flag_Submenu);
        Bar.Add ("Help/&About",        About_CB'Access);
    end;


    Find.Set_Find_Callback (Do_Find_CB'Access);
    Replace.Set_Replace_Callback (Do_Replace_CB'Access);
    Buffer.Add_Modify_Callback (Mod_CB'Access);
    Editor.Set_Callback (Quit_CB'Access);


    Editor.Set_Buffer (Buffer);


end Adapad;