MODULE editor;

(* based on the kilo editor building course*)

(* Step 66 *)

(*** IMPORTS ***)

IMPORT IO, termios, FIO, libc, CharClass, NumberIO, ASCII ;
IMPORT STextIO, Strings, SYSTEM, SplitV1, Storage,  MemUtils, ProgramArgs;
FROM SeqFile IMPORT OpenRead, OpenWrite, OpenResults, Close, ChanId, read, write;
FROM IOResult   IMPORT ReadResults, ReadResult; 
FROM TextIO IMPORT ReadString, ReadRestLine, SkipLine, ReadToken;
FROM Storage IMPORT ALLOCATE;


(*** data ***)

TYPE
    (* display buffer *)
    abufType            = RECORD
                            b   : SYSTEM.ADDRESS;
                            len : CARDINAL;
                          END;
    abufTypePtr         = POINTER TO abufType;
                          (* line structure : linked list *)
    erowPtr             = POINTER TO erow;
    erow                = RECORD
                            size : CARDINAL;
                            chars : SYSTEM.ADDRESS;
                            next, previous : erowPtr;
                          END;
    

CONST
    KILO_VERSION =  "0.0.1";                     
    (* escape sequences length *)
    clearScreenStrLen       = 4;
    cursorHomeStrLen        = 3;
    tildeStrLen             = 3;
    requestCursorPosStrLen  = 4;
    cursorOnStrLen          = 6;
    cursorOffStrLen         = 6;
    eraseLineStrLen         = 3;
    nextLineDownPos1Len     = 4;
    (* fct key mapping*)
    ARROW_LEFT   = 1000;
    ARROW_RIGHT  = 1001;
    ARROW_UP     = 1002;
    ARROW_DOWN   = 1003;
    HOME_KEY     = 1004;
    END_KEY      = 1005;
    PAGE_UP      = 1006;
    PAGE_DOWN    = 1007;
    DEL_KEY      = 1008;

VAR 
    editorConfig        : RECORD
                            screenrows : CARDINAL;
                            screencols : CARDINAL;
                            posX       : CARDINAL;
                            posY       : CARDINAL;
                            theTermios : termios.TERMIOS;
                            rows       : erowPtr;
                            lastRow    : erowPtr;
                            numrows    : CARDINAL;
                            rowoff     : CARDINAL;
                         END;
    theRow              : erow;
    theRowPtr           : erowPtr;
    (* termios*)
                         c           : CHAR;
    TCSAFLUSH           : INTEGER;
    (* Split structure *)
    theStructure        : SplitV1.Structure;
    (* utility *)
    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;
    eraseLineStr        : ARRAY [0..2] OF CHAR;
    nextLineDownPos1    : ARRAY [0..3] OF CHAR;
    (* temporary variables *)
    tmpString           : ARRAY [0..15] OF CHAR;
    tmpString1          : ARRAY [0..15] OF CHAR;
    tmpString2          : Strings.String1;
    cc                  : Strings.String1;
    (* error and information message string *)
    message             : ARRAY [0..79] OF CHAR;
    (* cli arguments *)
    theArgChanId        : ChanId;
    theArgument         : ARRAY [0..20] OF CHAR;
    theFileName         : ARRAY [0..20] OF CHAR;
    argumentNumber      : CARDINAL;

    
    (******************** 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() : CARDINAL;
        VAR
            c   : CHAR;
            d   : CHAR;
            num : CARDINAL;
            (*
            The Home key could be sent as <esc>[1~, <esc>[7~, <esc>[H, or 
                <esc>OH (this is the letter O followed by H). 
             Similarly, the End key could be sent as <esc>[4~, <esc>[8~, 
                <esc>[F, or <esc>OF (this is the letter O followed by F).  
             *)
    BEGIN
        IO.Read(c);
        IF c = ASCII.esc THEN
            IO.Read(c);
            (* mode := command; *)
            IF c  = "[" THEN
                IO.Read(c);
                IF (c > "0") AND (c <"9") THEN
                    IO.Read(d);
                    IF d = "~" THEN
                        CASE c OF
                            "4", "8" : num := END_KEY;  |
                            "1", "7" : num := HOME_KEY; |
                            "5"      : num := PAGE_UP;  |
                            "6"      : num := PAGE_DOWN;|
                            "3"      : num := DEL_KEY
                        END;
                    END;
                ELSIF (c = "A") OR (c = "B") OR (c = "C") OR (c = "D") OR (c = "F") OR (c = "H") THEN 
                    CASE c OF
                        "A" : num := ARROW_UP;    |
                        "B" : num := ARROW_DOWN ; |
                        "C" : num := ARROW_RIGHT; |
                        "D" : num := ARROW_LEFT;  |
                        "F" : num := END_KEY;     | 
                        "H" : num := HOME_KEY;
                    END;
                ELSIF c = "O" THEN
                    IO.Read(c);
                    CASE c OF
                        "F" : num := END_KEY;     | 
                        "H" : num := HOME_KEY;
                    END;
                ELSE
                    message :=  ("key not recognized");
                END;
                (* mode := move; *)
                (* <esc>OF <esc>OH  à voir !*)
            END;
            RETURN num;
        ELSE
            (* mode := edit; *)
            RETURN ORD(c)
        END;
    END editorReadKey;  
 
    (*** row operations ***)

    PROCEDURE editorAppendRow(VAR line : ARRAY OF CHAR);
    
        VAR
            size : CARDINAL;

    BEGIN
        NEW(theRowPtr);
        size := Strings.Length(line);
        theRowPtr^.size := size;
        Storage.ALLOCATE(theRowPtr^.chars, size);
        MemUtils.MemCopy(SYSTEM.ADR(line),size,theRowPtr^.chars);

        (* if no lines were allocated *)
        IF editorConfig.rows = NIL THEN
            theRowPtr^.next := NIL;
            theRowPtr^.previous := editorConfig.rows;
            editorConfig.rows := theRowPtr;
        ELSE (* there are already some lines in the structure *)
            theRowPtr^.next := NIL;
            theRowPtr^.previous := editorConfig.lastRow;
            editorConfig.lastRow^.next := theRowPtr;
        END;
        editorConfig.lastRow := theRowPtr;
        INC(editorConfig.numrows);
    END editorAppendRow; 


    (******************** file I/O  ***************)
   
    PROCEDURE editorOpen( fileName : ARRAY OF CHAR);

    VAR
        theChanId       : ChanId;
        theResult       : OpenResults; 
        line            : ARRAY[0..255] OF CHAR;

    BEGIN
        (* PROCEDURE OpenRead (VAR cid: ChanId; name: ARRAY OF CHAR; flags: FlagSet; VAR res: OpenResults); *)
        OpenRead(theChanId, fileName, read, theResult);
        (* test du résultat*)
        IF theResult = noSuchFile THEN
            die("No such file")
        ELSIF theResult=opened THEN (* reading the lines ... *)  
            (* first line *)
            line := "";
            ReadString(theChanId, line);
            (* testing the result *)
            WHILE ReadResult(theChanId) <> endOfInput DO
                (* testing end of line *)
                IF ReadResult(theChanId) = endOfLine THEN
                    (* we have to 'skip' the endOfLine ... so strange *)
                    SkipLine(theChanId);
                END;
                editorAppendRow(line);
                (* reading next line *)
                ReadString(theChanId, line);
            END;

        ELSE
            die("Error opening the file");
        END;
        Close(theChanId);  
    END editorOpen;

    PROCEDURE editorMoveCursor(c : CARDINAL);

    BEGIN
        WITH editorConfig DO
            CASE c OF
                    ARROW_UP, ORD("e")    : IF posY > 1 THEN DEC(posY) END;                |
                    ARROW_DOWN, ORD("x")  : IF posY < (screenrows - 1) THEN INC(posY) END; |
                    ARROW_LEFT, ORD("s")  : IF posX > 1 THEN DEC(posX) END;                |
                    ARROW_RIGHT, ORD("d") : IF posX < (screencols - 1) THEN INC(posX) END; |
                    PAGE_UP     : posY := 1;                                               |
                    PAGE_DOWN   : posY := screenrows;                                      |
                    HOME_KEY    : posX := 1;                                               |
                    END_KEY     : posX := screencols;
            END;
        END
    END editorMoveCursor;

    PROCEDURE editorProcessKeypress;
            VAR
                c       : CARDINAL;
        BEGIN
            c := editorReadKey();
            CASE c OF
                17 :    libc.write(FIO.StdOut,SYSTEM.ADR(cursorHomeStr), cursorHomeStrLen);
                        libc.write(FIO.StdOut,SYSTEM.ADR(clearScreenStr), clearScreenStrLen);
                        HALT;                                             |
                ORD("e"),
                ORD("x"),
                ORD("s"),
                ORD("d"), 
                HOME_KEY,
                END_KEY,
                PAGE_UP,
                PAGE_DOWN,
                ARROW_UP,
                ARROW_DOWN,
                ARROW_LEFT,
                ARROW_RIGHT  : editorMoveCursor(c);
            END
        END editorProcessKeypress;

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

        CONST
            tilde           = "~";

        VAR
            y               : CARDINAL;
            welcome         : ARRAY [0..79] OF CHAR;
            welcomeLen      : CARDINAL;
            blanks          : CARDINAL;
            blanksStr       : ARRAY[0..79] OF CHAR;
            blankStrLength  : CARDINAL;
            len             : CARDINAL;

    BEGIN
        (* Creation of the about text *)
        welcome := "Kilo editor -- version ";
        Strings.Concat(welcome,KILO_VERSION,welcome);
        welcomeLen := Strings.Length(welcome);
        Strings.Concat(welcome,nextLineDownPos1,welcome);

        (* centering the welcome text *)
        blanks := (editorConfig.screencols - welcomeLen) /2;
        cc[0] := " ";
        blanksStr := "";
        FOR i := 0 TO blanks DO
             Strings.Concat(blanksStr,cc,blanksStr);
        END;
        blankStrLength := Strings.Length(blanksStr);

        (* display of the page *)
        theRowPtr := editorConfig.rows;
        FOR y := 1 TO editorConfig.screenrows -1 DO 
        (* for all lines except the last one *)
            IF y > editorConfig.numrows  THEN
                IF ((y = (editorConfig.screenrows / 3)) AND (editorConfig.screencols > welcomeLen)) AND (editorConfig.numrows = 0) THEN
                            abAppend(ptr,SYSTEM.ADR(blanksStr), blankStrLength);
                            abAppend(ptr,SYSTEM.ADR(welcome),welcomeLen );
                            abAppend(ptr,SYSTEM.ADR(eraseLineStr),eraseLineStrLen );
                            abAppend(ptr,SYSTEM.ADR(nextLineDownPos1),nextLineDownPos1Len );
                ELSE
                    abAppend(ptr,SYSTEM.ADR(tilde), 1);
                    abAppend(ptr,SYSTEM.ADR(eraseLineStr),eraseLineStrLen );
                    abAppend(ptr,SYSTEM.ADR(nextLineDownPos1),nextLineDownPos1Len );
                END;
            ELSE 
                len := theRowPtr^.size;
                IF len > editorConfig.screencols THEN
                    len := editorConfig.screencols
                END;
                (* displaying the text lines *)
                abAppend(ptr,theRowPtr^.chars,len);
                theRowPtr := theRowPtr^.next;
                abAppend(ptr,SYSTEM.ADR(eraseLineStr),eraseLineStrLen );
                abAppend(ptr,SYSTEM.ADR(nextLineDownPos1),nextLineDownPos1Len );
            END;
        END;
        (* last line *)
        abAppend(ptr,SYSTEM.ADR(tilde), 1);
        abAppend(ptr,SYSTEM.ADR(eraseLineStr),eraseLineStrLen );
        abAppend(ptr,SYSTEM.ADR(nextLineDownPos1),nextLineDownPos1Len );
                
    END editorDrawRows;

   PROCEDURE editorRefreshScreen;

        VAR
            ptr : abufTypePtr;
    BEGIN
        abufInit(ptr);
        abAppend(ptr,SYSTEM.ADR(cursorOffStr), cursorOffStrLen);
        abAppend(ptr,SYSTEM.ADR(cursorHomeStr), cursorHomeStrLen);
        editorDrawRows(ptr);
        (* cursorpos(1,1,FALSE); *)
        cursorpos(editorConfig.posX,editorConfig.posY,FALSE);
        abAppend(ptr,SYSTEM.ADR(cursorposStr), Strings.Length(cursorposStr));
        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; emit : BOOLEAN);
    BEGIN
        cursorposStr := "";
        Strings.Concat(cursorposStr, ASCII.esc,cursorposStr);
        Strings.Concat(cursorposStr, "[",cursorposStr);
        tmpString := "";
        Strings.Concat(tmpString,cursorposStr, tmpString);
        tmpString1 := "";
        Card2Str(y,tmpString1);
        Strings.Concat(tmpString,tmpString1, tmpString);
        tmpString2[0] := ";";
        Strings.Concat(tmpString, tmpString2,tmpString);
        tmpString1 := "";
        Card2Str(x,tmpString1);
        Strings.Concat(tmpString,tmpString1, tmpString);
        tmpString2[0] := "H";
        Strings.Concat(tmpString, tmpString2,tmpString);
        cursorposStr := tmpString;
        editorConfig.posX := x;
        editorConfig.posY := y;
        IF emit THEN 
            libc.write(FIO.StdOut,SYSTEM.ADR(tmpString),Strings.Length(tmpString));
        END;
    END cursorpos;

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

        eraseLineStr := "";
        Strings.Concat(eraseLineStr,ASCII.esc,eraseLineStr);
        Strings.Concat(eraseLineStr,"[K",eraseLineStr);

        (* ESC[#E 	moves cursor to beginning of next line, # lines down *)
        nextLineDownPos1 := "";
        Strings.Concat(nextLineDownPos1,ASCII.esc,nextLineDownPos1);
        Strings.Concat(nextLineDownPos1,"[1E",nextLineDownPos1);

    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;
            editorConfig.numrows := 0;
            editorConfig.rows := NIL;
            editorConfig.rowoff := 1;
            libc.write(FIO.StdOut,SYSTEM.ADR(clearScreenStr),4);
    END InitEditor;

BEGIN
    enablerawMode;
    InitEditor;
    editorRefreshScreen;

    (* fetching the 2nd argument (fileName) *)
    theFileName := "";
    theArgChanId := ProgramArgs.ArgChan ();
    argumentNumber := 0;
    WHILE ProgramArgs.IsArgPresent() DO
        INC(argumentNumber);
        ReadToken(ProgramArgs.ArgChan(), theArgument);
        IF argumentNumber = 2 THEN
            theFileName := theArgument;
        END;
        ProgramArgs.NextArg ();
    END;

    IF argumentNumber >= 2 THEN
        editorOpen(theFileName);
    END;
    
    LOOP
        editorRefreshScreen;
        editorProcessKeypress;
    END;
END editor.