' Cipher Tool
' By Vegipete, April 2024
' Short program to perform the grunt work for simple cipher cryptograms.
' Each letter from A-Z is substituted for another. Other characters are
' unchanged.
' Ten substitution sets are offered, allowing you to test possibilities
' and revert to a previous set.
'
' Future possible improvement : letter counting.
'
' Set s$ below to your encoded cipher. Max length is 254 characters.

s$ = "'RSPN ULFE BAFELTHF LNH BHLWE ES FGLUH RSP, WSE CHYAWH RSP. VHLNW Y"
s$ = s$ + "NSB EGHB LWC THHU BSXAWI YSNMLNC.' - ZGLNVHF SFISSC"

s$ = UCase$(s$) + " " ' last character must be a space
' (because of my lazy word-wrap algorithm.)

Option break 25 ' use ^Y instead of ^C to stop program (^C = Copy)

Const ypos = 240  ' location of cipher table on screen

Dim c$(11) length 26
c$(0) = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
For j = 1 To 11 : c$(j) = String$(26,"_") : Next j

m = 1 : n = 1   ' cursor position

CLS
ttl$ = "Cipher Assistant  - by Vegipete"
tw = Len(ttl$) * MM.Info(FONTWIDTH)
Text MM.HRes/2,5,ttl$,CT
Box (MM.HRes - tw) / 2,7+MM.Info(FONTHEIGHT),tw,3,2
Text 10,450,"Ctrl-X/C/V to Cut/Copy/Past code sets,       Ctrl-Q to Quit"
Text 10,465,"Arrow keys to move, 0-9 to select set, A-Z to substitute"
ShowCipher(n)
ShowCodes
ShowCur

Do
 ky = Asc(UCase$(Inkey$))
 If ky Then
   rd = 0
   Select Case ky
     Case 17   ' ^Q - quit
       CLS
       Option break 3
       End
     Case 3    ' ^C  copy
       c$(11) = c$(n)
     Case 22   ' ^V  paste
       c$(n) = c$(11)
       ShowCipher(n)
       ShowCodes
     Case 24   ' ^X  cut (clear)
       c$(11) = c$(n)
       c$(n) = String$(26,"_")
       ShowCipher(n)
       ShowCodes
     Case 130  ' left
       If m > 1 Then HideCur : m = m - 1 : ShowCur
     Case 131  ' right
       If m < 26 Then HideCur : m = m + 1 : ShowCur
     Case 128  ' up
       If n > 1 Then HideCur : n = n - 1 : ShowCur : ShowCipher(n)
     Case 129  ' down
       If n < 10 Then HideCur : n = n + 1 : ShowCur : ShowCipher(n)
     Case 48   ' 0
       HideCur : n = 10 : ShowCur : ShowCipher(n)
     Case 49 To 57   ' 1 to 9
       HideCur : n = ky-48 : ShowCur : ShowCipher(n)
     Case 65 To 90
       MID$(c$(n),m,1) = Chr$(ky)
       ShowCipher(n)
       ShowCodes
   End Select
   If rd Then
     ShowCodes
   EndIf
 EndIf
Loop

Sub HideCur
 Box 49-14+m*14,ypos+1+n*16,13,15,,0
 Text 0,ypos+3+n*16,"    "
End Sub

Sub ShowCur
 Box 49-14+m*14,ypos+1+n*16,13,15,,RGB(white)
 Text 0,ypos+3+n*16,"===>"
End Sub

Sub ShowCodes
 For y = 0 To 10
   If y > 9 Then
     Text 35,ypos+3+y*16, "0"
   ElseIf y > 0 Then
     Text 35,ypos+3+y*16, Str$(y)
   EndIf
   For x = 0 To 25
     Box  48+x*14,ypos+y*16,15,17
     Text 51+x*14,ypos+3+y*16,Mid$(c$(y),x+1,1)
   Next x
 Next y
End Sub

' Decode cipher using substitution set n
Sub ShowCipher(n)
 k = Len(s$)
 i = 1   ' position in string
 y = 40  ' starting position on screen
 Do
   j = Min(i + 80,k)
   Do While Mid$(s$,j,1) <> " "  ' word wrap
     j = j - 1
   Loop
   x = 0
   For p = i To j
     t$ = Mid$(s$,p,1)
     Text x,y, t$
     If t$ < "A" Or t$ > "Z" Then
       Text x,y+12, t$  ' non-letter
     Else
       Text x,y+12, Mid$(c$(n),Asc(t$)-64,1)  ' de-cipher letter
     EndIf
     Inc x,8
   Next p
   Inc y,32
   i = j
 Loop Until j = k
End Sub