MODULE editor;

(* based on the kilo editor building course*)

(* Step 39  *)

(*** IMPORTS ***)

IMPORT IO, termios, FIO, libc, CharClass, NumberIO, ASCII ;
IMPORT STextIO, Strings, SYSTEM, SplitV1, Storage,  MemUtils;

(*** data ***)

TYPE
    abufType            = RECORD
                            b   : SYSTEM.ADDRESS;
                            len : CARDINAL;
                          END;
    abufTypePtr         = POINTER TO abufType;

CONST
    (* escape sequences length *)
    clearScreenStrLen       = 4;
    cursorHomeStrLen        = 3;
    tildeStrLen             = 3;
    requestCursorPosStrLen  = 4;
    cursorOnStrLen          = 6;
    cursorOffStrLen         = 6;

VAR 
    editorConfig        : RECORD
                            screenrows : CARDINAL;
                            screencols : CARDINAL;
                            posX       : CARDINAL;
                            posY       : CARDINAL;
                            theTermios : termios.TERMIOS;
                         END;
    c           : CHAR;
    TCSAFLUSH   : INTEGER;
    theStructure: SplitV1.Structure;

    i           : CARDINAL;
    (* escape sequences *)
    clearScreenStr      : ARRAY [0..3] OF CHAR;
    cursorHomeStr       : ARRAY [0..2] OF CHAR;
    tildeStr            : ARRAY [0..2] OF CHAR;
    requestCursorPosStr : ARRAY [0..3] OF CHAR;
    cursorposStr        : ARRAY [0..15] OF CHAR;
    cursorOnStr         : ARRAY [0..5] OF CHAR;
    cursorOffStr        : ARRAY [0..5] OF CHAR;

    tmpString           : ARRAY [0..15] OF CHAR;
    tmpString1          : ARRAY [0..15] OF CHAR;
    tmpString2          : Strings.String1;
    cc                  : Strings.String1;

    

    (******************** Utilities *****************)

    PROCEDURE Card2Str ( x : CARDINAL; VAR str : ARRAY OF CHAR);

    BEGIN
    IF x < 10 THEN
            NumberIO.CardToStr(x,1,str);
        ELSIF x < 100 THEN
            NumberIO.CardToStr(x,2,str);
        ELSE
            NumberIO.CardToStr(x,3,str);
        END;
    END Card2Str;
    
    (******************** Buffer ******************)

    PROCEDURE abufInit( VAR ptr : abufTypePtr);
    BEGIN
        Storage.ALLOCATE(ptr,SYSTEM.TSIZE(abufType) );
        ptr^.b := NIL;
        ptr^.len := 0;
    END abufInit;

    PROCEDURE abAppend (VAR ptr : abufTypePtr; theSourceAdress: SYSTEM.ADDRESS; theSourceLen : CARDINAL );

    BEGIN
        IF ptr <> NIL THEN
            IF ptr^.b = NIL THEN
                Storage.ALLOCATE(ptr^.b,theSourceLen);
            ELSE
                Storage.REALLOCATE( ptr^.b,ptr^.len + theSourceLen);
            END;
            MemUtils.MemCopy(theSourceAdress,theSourceLen, SYSTEM.ADDADR(ptr^.b,ptr^.len));
            ptr^.len := ptr^.len + theSourceLen;
        END;
    END abAppend;

    PROCEDURE abFree (VAR ptr : abufTypePtr);

    BEGIN
        Storage.DEALLOCATE(ptr^.b, ptr^.len);
        Storage.DEALLOCATE(ptr,SYSTEM.TSIZE(abufType));
    END abFree;

    (*** Terminal ***)

    PROCEDURE CtrlKey(c: CHAR) : CARDINAL;

        VAR
            n : BITSET;

    BEGIN
        n := BITSET(ORD(c));
        n := n * BITSET(1FH);
        RETURN CARDINAL(n)
    END CtrlKey;

    PROCEDURE die (s : ARRAY OF CHAR);
    BEGIN
        libc.write(FIO.StdOut,SYSTEM.ADR(cursorHomeStr), cursorHomeStrLen);
        libc.write(FIO.StdOut,SYSTEM.ADR(clearScreenStr), clearScreenStrLen);
        libc.perror(s);
        FOR i := 0 TO Strings.Length(s) DO
            IO.Write(s[i])
        END;
        HALT
    END die;

    PROCEDURE disablerawMode() : INTEGER;

        VAR
            result : INTEGER;
    BEGIN
        IO.BufferedMode(0,TRUE);
        IO.BufferedMode(1,TRUE);
        result := termios.tcsetattr(FIO.StdIn, TCSAFLUSH, editorConfig.theTermios);
        IF result = -1 THEN
            editorConfig.theTermios := termios.KillTermios(editorConfig.theTermios);
            die("tcsetattr")
        ELSE 
            RETURN result
        END;
    END disablerawMode;

    PROCEDURE enablerawMode;
    BEGIN
        libc.atexit(disablerawMode);
        editorConfig.theTermios := termios.InitTermios();
        IF termios.tcgetattr(FIO.StdIn, editorConfig.theTermios) = -1 THEN
            die("tcgetattr")
        END;

        IO.UnBufferedMode(0,TRUE);
        IO.UnBufferedMode(1,TRUE);
    END enablerawMode;

    PROCEDURE  editorReadKey() : CHAR;
        VAR
            c : CHAR;
    BEGIN
        IO.Read(c);
        RETURN c
    END editorReadKey; 
    
    PROCEDURE editorProcessKeypress;
            VAR
                c       : CHAR;
        BEGIN
            c := editorReadKey();
            CASE ORD(c) OF
            17 :  libc.write(FIO.StdOut,SYSTEM.ADR(cursorHomeStr), cursorHomeStrLen);
                    libc.write(FIO.StdOut,SYSTEM.ADR(clearScreenStr), clearScreenStrLen);
                    HALT; 
            END
        END editorProcessKeypress;

    (*** Output ***)
        
PROCEDURE editorDrawRows(VAR ptr : abufTypePtr);

        CONST
            tilde       = "~";

        VAR
            y           : CARDINAL;
            
    BEGIN
        (* display of the page *)
        FOR y := 1 TO editorConfig.screenrows -1 DO (* for all lines except the last one *)
            abAppend(ptr,SYSTEM.ADR(tildeStr), tildeStrLen);
        END;
        abAppend(ptr,SYSTEM.ADR(tilde), 1);
    END editorDrawRows;

   PROCEDURE editorRefreshScreen;

        VAR
            ptr : abufTypePtr;
    BEGIN
        abufInit(ptr);
        abAppend(ptr,SYSTEM.ADR(cursorOffStr), cursorOffStrLen);
        abAppend(ptr,SYSTEM.ADR(cursorHomeStr), cursorHomeStrLen);
        editorDrawRows(ptr);
        abAppend(ptr,SYSTEM.ADR(cursorHomeStr), cursorHomeStrLen);
        abAppend(ptr,SYSTEM.ADR(cursorOnStr), cursorOnStrLen);
        libc.write(FIO.StdOut,ptr^.b,ptr^.len);
        abFree(ptr);
    END editorRefreshScreen;


   PROCEDURE requestCursorPosition(VAR x,y : CARDINAL);

        VAR
            c   : CHAR;
            str : ARRAY [0..15] OF CHAR;

    BEGIN
        str := "";
        SplitV1.InitStructure(theStructure);
        libc.write(FIO.StdOut,SYSTEM.ADR(requestCursorPosStr),requestCursorPosStrLen);
        (* getting answer *)
        str := "";
        REPEAT
            IO.Read(c);
            cc[0] := c;
            Strings.Concat(str,cc,str);
        UNTIL c = "R";
        Strings.Delete(str,0,2);
        Strings.Delete(str,Strings.Length(str) -1 ,1);
        SplitV1.SplitStr(str, ";", theStructure);
        NumberIO.StrToCard(theStructure[0].element,y);
        NumberIO.StrToCard(theStructure[1].element,x);
    END requestCursorPosition;

    PROCEDURE cursorpos(x,y : CARDINAL);
    BEGIN
        tmpString1 := "";
        Card2Str(y,tmpString1);
        Strings.Concat(cursorposStr,tmpString1, cursorposStr);
        tmpString2[0] := ";";
        Strings.Concat(cursorposStr,tmpString2, cursorposStr);
        tmpString1 := "";
        Card2Str(x,tmpString1);
        Strings.Concat(cursorposStr,tmpString1, cursorposStr);
        tmpString2[0] := "H";
        Strings.Concat(cursorposStr,tmpString2, cursorposStr);
        libc.write(FIO.StdOut,SYSTEM.ADR(cursorposStr),Strings.Length(cursorposStr));
    END cursorpos;

    PROCEDURE getWindowSize(VAR y : CARDINAL; VAR x: CARDINAL);
    
    BEGIN
        cursorpos(999,999);
        requestCursorPosition(x,y);
    END getWindowSize;

(*** Input ***)



(*** Init ***)

PROCEDURE InitScreenEscapes;

    VAR temp : ARRAY[0..10] OF CHAR;
    BEGIN
        cursorHomeStr := "";
        Strings.Concat(cursorHomeStr,ASCII.esc,cursorHomeStr);
        Strings.Concat(cursorHomeStr,"[H",cursorHomeStr);

        clearScreenStr := "";
        Strings.Concat(clearScreenStr,ASCII.esc,clearScreenStr);
        Strings.Concat(clearScreenStr,"[2J",clearScreenStr);

        tildeStr[0] := "~";
        tildeStr[1] := CHR(10);
        tildeStr[2] := CHR(13);

        cursorposStr := "";
        Strings.Concat(cursorposStr,ASCII.esc,cursorposStr);
        Strings.Concat(cursorposStr,"[",cursorposStr);
    
        requestCursorPosStr := "";
        Strings.Concat(requestCursorPosStr,ASCII.esc,requestCursorPosStr);
        Strings.Concat(requestCursorPosStr,"[6n",requestCursorPosStr);

                cursorOnStr := "";
        Strings.Concat(cursorOnStr,ASCII.esc,cursorOnStr);
        Strings.Concat(cursorOnStr,"[?25h",cursorOnStr);

        cursorOffStr := "";
        Strings.Concat(cursorOffStr,ASCII.esc,cursorOffStr);
        Strings.Concat(cursorOffStr,"[?25l",cursorOffStr);



    END InitScreenEscapes;

    PROCEDURE InitEditor;
    BEGIN
            TCSAFLUSH := termios.tcsflush (); 
            InitScreenEscapes;
            editorConfig.posX := 1;
            editorConfig.posY := 1;
            getWindowSize(editorConfig.screenrows, editorConfig.screencols);
            editorConfig.posX := 1;
            editorConfig.posY := 1;
            libc.write(FIO.StdOut,SYSTEM.ADR(clearScreenStr),4);
            (* NumberIO.WriteCard(editorConfig.screenrows, 5);
            NumberIO.WriteCard(editorConfig.screencols, 5); *)
    END InitEditor;

BEGIN
    enablerawMode;
    InitEditor;
    editorRefreshScreen;
    LOOP
       editorProcessKeypress;
       editorRefreshScreen;
    END;
END editor.