' RAT - Replace ASCII and Text utility
' Homework Standard Code
' Command Line - RAT, original text, new text
' where filename defaults to present directory if non stated

' Auckland 21 Mar 2014

' RAT01 - Started 21 Mar 2014

Global True, False, QuietMode, ReplaceEOL                 ' Just 4 Globals
False = 0 : True = 1                                      ' Initialise them
NoMainWin                                                 ' No screen output wanted
if (CommandLine$ = "") or (CommandLine$ = "/?") then      ' No entry - no action - just show the command line structure
    call ShowCL                                           ' Show Command Line structure
    goto [exit]
end if    

FileName$ = word$(CommandLine$,1,",")                     ' Extract the file name
if FileName$ = "" then [exit]                             ' Nothing valid - exit
FilePath$ = GetFileDirectory$(FileName$)                  ' Get the path from the filename if any
FileName$ = mid$(FileName$,len(FilePath$) + 1)            ' Now extract the filename proper
if FilePath$ = "" then FilePath$ = DefaultDir$ + "\"      ' No path information - assume the present directory
if FileExists(FilePath$,FileName$) = False then           ' If this is not a valid file then 
    call PTS " ** File Not Found **"                         ' Show reason
    goto [exit]
end if

if FileExists(FilePath$,"temp.bin") = True then           ' Tidy up any old copies of temp.bin that might be hanging around
    kill "temp.bin"
end if
                                                          ' We get here with a valid filename and directory to work on.
                                                          ' Is there a second and third statement to operate with?
                                                          
FindText$ = word$(CommandLine$,2,",")                     ' Is there a string to find?
Replace$ = word$(CommandLine$,3,",")                      ' Is there a string to replace it with?
if (FindText$ = "") or (Replace$ = "") then               ' Both are required, otherwise
    call ShowCL                                           ' Show Command Line structure
    goto [exit]
end if
ReplaceEOL = False
if right$(FindText$,1) = "*" then
    ReplaceEOL = True
    FindText$ = left$(FindText$,len(FindText$) - 1)       ' strip the *
end if

QuietMode = False                                         ' Setup Quiet Mode
if upper$(word$(CommandLine$,4,",")) = "Q" then
    QuietMode = True
end if    

if (FindText$ = "") or (Replace$ = "") then [exit]        ' We need both terms otherwise exit
name FilePath$ + FileName$ as "temp.bin"                  ' rename the original file to temp.bin
open "temp.bin" for input as #filein                      ' Now open temp.bin for input
open FilePath$ + FileName$ for output as #fileout         ' And the original filename as a new file for output
call PTS "Working on - " + FilePath$ + Filename$          ' Show the File details

while eof(#filein) = 0                                    ' Now we can loop through the whole file to eof
    line input #filein, t$                                ' Take in the whole of the next line as t$
[multiloop]                                               ' loop point for multiple finds on a line
    if instr(t$,FindText$) <> 0 then                      ' Is the text we want to find on this line ?
        call PTS t$                                       ' Show original line
        t$ = ReplaceString$(t$,FindText$,Replace$)        ' It is - change FindText$ with Replace$
        call PTS t$                                       ' Show modified line
        call PTS ""                                       ' Separator
        if ReplaceEOL = False then [multiloop]            ' Check for other instances on this line if NOT in ReplaceEOL
    end if 
    print #fileout, t$                                    ' Finished with this line - save it to the original file name
wend                                                      ' The whole file is now processed
close #filein                                             ' Close the Input File
close #fileout                                            ' Close the Output File
kill "temp.bin"                                           ' Delete the temp file

[exit]                                                    ' Quit label
end                                                       ' Quit command

[unknownerror]                                            ' Come here for something wrong
print "Error Code is ", Err                               ' And show what it is
print "Error Desc is ", Err$                              ' Should never be needed :)
end


' Functions and Subs


function ReplaceString$(t$,f$,r$)                         ' Replace f$ with r$ in t$ - * to trigger EOL mode
    p = instr(t$,f$)                                      ' where is it ?
    if ReplaceEOL = False then 
        ReplaceString$ = left$(t$,p-1) + r$ + mid$(t$,len(f$)+ p)
    else
        ReplaceString$ = left$(t$,p + len(f$) - 1) + r$
    end if           
end function


function GetFileDirectory$(fn$)        ' Is there a preceeding directory structure attached to filename$ - return it if so
    d$ = "a"                           ' need something in here to start the while - wend
    FileDirectory$ = ""                ' Not really needed but be defensive
    count = 1                          ' Initialise the counter
                                       ' Run the while loop until we run out of words after a \
                                       ' Build up FileDirectory$ with the result and keep a count for word$ to step into the path
    while d$ <> ""                   
        d$ = word$(fn$,count,"\")
        if (instr(d$,".") <> 0) or (d$ = "") then exit while 
        GetFileDirectory$ = GetFileDirectory$ + d$ + "\"        
        count = count + 1               
        wend    
end function                           ' Returns FileDirectory$ with the full path ands final \ excluding filename


function FileExists(where$,fn$)        ' does a file exist as where$/fn$
    on error goto [nofile]             ' if the open input fails - go here
    FileExists= False                  ' Default value of False
    open where$ + fn$ for input as #t  ' Try to open the file. Jump to [nofile] on failure
    FileExists = True                  ' It didn't fail so make the result True
    close #t                           ' Close the file handle if it opened
[nofile]        
    on error goto [unknownerror]       ' reset the On Error label
  end function                         ' Returns FileExists as either True or False    
  
  ' *********************  Text Outputs  *********************
  sub PTS text$                        ' Print text$ to screen if NOT in Quiet Mode
    if QuietMode = False then print text$  
  end sub  
  
  
  sub ShowCL                           ' Print this if the command line structure is incorrect
    cls
    print "Command Line structure should be : "
    print "RAT.EXE  Filename, string_to_replace, replacement_string,[q]uiet [optional]"
    print ""
    print "If filename is absent a full path then current directory is assumed"
    print ""
    print "Example"
    print "To change all the occurrences of the string 'testme' to 'Test_Me' use :"
    print "RAT.EXE filename,testme,Test_Me"
    print ""
    print "RAT.EXE also has a replacement to EOL feature thus : "
    print "If last character of string_to_replace is a '*' then"
    print "replacement_string will replace characters to the end of line "
    print "with string_to_replace staying in place "
    print ""
    print "Example"
    print "To change the line : 'UseFixedPageUI = false' to a value of 'true'"
    print "would use the following command line :"
    print "RAT.EXE filename,UseFixedPageUI = *,true  (the * is removed)"
  end sub