/**
 *  EnvVarUpdate.nsh
 *    : Environmental Variables: append, prepend, and remove entries
 *
 *     WARNING: If you use StrFunc.nsh header then include it before this file
 *              with all required definitions. This is to avoid conflicts
 *
 *  Usage:
 *    ${EnvVarUpdate} "ResultVar" "EnvVarName" "Action" "RegLoc" "PathString"
 *
 *  Credits:
 *  Version 1.0 
 *  * Cal Turney (turnec2)
 *  * Amir Szekely (KiCHiK) and e-circ for developing the forerunners of this
 *    function: AddToPath, un.RemoveFromPath, AddToEnvVar, un.RemoveFromEnvVar,
 *    WriteEnvStr, and un.DeleteEnvStr
 *  * Diego Pedroso (deguix) for StrTok
 *  * Kevin English (kenglish_hi) for StrContains
 *  * Hendri Adriaens (Smile2Me), Diego Pedroso (deguix), and Dan Fuhry  
 *    (dandaman32) for StrReplace
 *
 *  Version 1.1 (compatibility with StrFunc.nsh)
 *  * techtonik
 *
 *  http://nsis.sourceforge.net/Environmental_Variables:_append%2C_prepend%2C_and_remove_entries
 *
 */
 
 
!ifndef ENVVARUPDATE_FUNCTION
!define ENVVARUPDATE_FUNCTION
!verbose push
!verbose 3
!include "LogicLib.nsh"
!include "WinMessages.NSH"
!include "StrFunc.nsh"
 
; ---- Fix for conflict if StrFunc.nsh is already includes in main file -----------------------
!macro _IncludeStrFunction StrFuncName
  !ifndef ${StrFuncName}_INCLUDED
    ${${StrFuncName}}
  !endif
  !ifndef Un${StrFuncName}_INCLUDED
    ${Un${StrFuncName}}
  !endif
  !define un.${StrFuncName} "${Un${StrFuncName}}"
!macroend
 
!insertmacro _IncludeStrFunction StrTok
!insertmacro _IncludeStrFunction StrStr
!insertmacro _IncludeStrFunction StrRep
 
; ---------------------------------- Macro Definitions ----------------------------------------
!macro _EnvVarUpdateConstructor ResultVar EnvVarName Action Regloc PathString
  Push "${EnvVarName}"
  Push "${Action}"
  Push "${RegLoc}"
  Push "${PathString}"
    Call EnvVarUpdate
  Pop "${ResultVar}"
!macroend
!define EnvVarUpdate '!insertmacro "_EnvVarUpdateConstructor"'
 
!macro _unEnvVarUpdateConstructor ResultVar EnvVarName Action Regloc PathString
  Push "${EnvVarName}"
  Push "${Action}"
  Push "${RegLoc}"
  Push "${PathString}"
    Call un.EnvVarUpdate
  Pop "${ResultVar}"
!macroend
!define un.EnvVarUpdate '!insertmacro "_unEnvVarUpdateConstructor"'
; ---------------------------------- Macro Definitions end-------------------------------------
 
;----------------------------------- EnvVarUpdate start----------------------------------------
!define hklm_all_users     'HKLM "SYSTEM\CurrentControlSet\Control\Session Manager\Environment"'
!define hkcu_current_user  'HKCU "Environment"'
 
!macro EnvVarUpdate UN
 
Function ${UN}EnvVarUpdate
 
  Push $0
  Exch 4
  Exch $1
  Exch 3
  Exch $2
  Exch 2
  Exch $3
  Exch
  Exch $4
  Push $5
  Push $6
  Push $7
  Push $8
  Push $9
  Push $R0
 
  /* After this point:
  -------------------------
     $0 = ResultVar     (returned)
     $1 = EnvVarName    (input)
     $2 = Action        (input)
     $3 = RegLoc        (input)
     $4 = PathString    (input)
     $5 = Orig EnvVar   (read from registry)
     $6 = Len of $0     (temp)
     $7 = tempstr1      (temp)
     $8 = Entry counter (temp)
     $9 = tempstr2      (temp)
     $R0 = tempChar     (temp)  */
 
  ; Step 1:  Read contents of EnvVarName from RegLoc
  ;
  ; Check for empty EnvVarName
  ${If} $1 == ""
    SetErrors
    DetailPrint "ERROR: EnvVarName is blank"
    Goto EnvVarUpdate_Restore_Vars
  ${EndIf}
 
  ; Check for valid Action
  ${If}    $2 != "A"
  ${AndIf} $2 != "P"
  ${AndIf} $2 != "R"
    SetErrors
    DetailPrint "ERROR: Invalid Action - must be A, P, or R"
    Goto EnvVarUpdate_Restore_Vars
  ${EndIf}
 
  ${If} $3 == HKLM
    ReadRegStr $5 ${hklm_all_users} $1     ; Get EnvVarName from all users into $5
  ${ElseIf} $3 == HKCU
    ReadRegStr $5 ${hkcu_current_user} $1  ; Read EnvVarName from current user into $5
  ${Else}
    SetErrors
    DetailPrint 'ERROR: Action is [$3] but must be "HKLM" or HKCU"'
    Goto EnvVarUpdate_Restore_Vars
  ${EndIf}
 
  ; Check for empty PathString
  ${If} $4 == ""
    SetErrors
    DetailPrint "ERROR: PathString is blank"
    Goto EnvVarUpdate_Restore_Vars
  ${EndIf}

  ; abort if NSIS is unable to update the path because the path is too long
  Push $6
  Push $7
  Push $8
  StrLen $7 $4
  StrLen $6 $5
  IntOp $8 $6 + $7
  ${If} $5 == ""
  ${OrIf} $8 >= ${NSIS_MAX_STRLEN}
    SetErrors
    DetailPrint "ERROR: NSIS limitation: Unable to update PATH because existing PATH length is too long or zero."
    DetailPrint "       Please shorten existing PATH and retry or else manually add"
    DetailPrint "       $4"
    pop $8
    pop $7
    pop $6
    Goto EnvVarUpdate_Restore_Vars
  ${EndIf}
  pop $8
  pop $7
  pop $6
 
  ; Make sure we've got some work to do
  ${If} $5 == ""
  ${AndIf} $2 == "R"
    SetErrors
    DetailPrint "$1 is empty - Nothing to remove"
    Goto EnvVarUpdate_Restore_Vars
  ${EndIf}
 
  ; Step 2: Scrub EnvVar
  ;
  StrCpy $0 $5                             ; Copy the contents to $0
  ; Remove spaces around semicolons (NOTE: spaces before the 1st entry or
  ; after the last one are not removed here but instead in Step 3)
  ${If} $0 != ""                           ; If EnvVar is not empty ...
    ${Do}
      ${${UN}StrStr} $7 $0 " ;"
      ${If} $7 == ""
        ${ExitDo}
      ${EndIf}
      ${${UN}StrRep} $0  $0 " ;" ";"         ; Remove '<space>;'
    ${Loop}
    ${Do}
      ${${UN}StrStr} $7 $0 "; "
      ${If} $7 == ""
        ${ExitDo}
      ${EndIf}
      ${${UN}StrRep} $0  $0 "; " ";"         ; Remove ';<space>'
    ${Loop}
    ${Do}
      ${${UN}StrStr} $7 $0 ";;" 
      ${If} $7 == ""
        ${ExitDo}
      ${EndIf}
      ${${UN}StrRep} $0  $0 ";;" ";"
    ${Loop}
 
    ; Remove a leading or trailing semicolon from EnvVar
    StrCpy  $7  $0 1 0
    ${If} $7 == ";"
      StrCpy $0  $0 "" 1                   ; Change ';<EnvVar>' to '<EnvVar>'
    ${EndIf}
    StrLen $6 $0
    IntOp $6 $6 - 1
    StrCpy $7  $0 1 $6
    ${If} $7 == ";"
     StrCpy $0  $0 $6                      ; Change ';<EnvVar>' to '<EnvVar>'
    ${EndIf}
    ; DetailPrint "Scrubbed $1: [$0]"      ; Uncomment to debug
  ${EndIf}
 
  /* Step 3. Remove all instances of the target path/string (even if "A" or "P")
     $6 = bool flag (1 = found and removed PathString)
     $7 = a string (e.g. path) delimited by semicolon(s)
     $8 = entry counter starting at 0
     $9 = copy of $0
     $R0 = tempChar      */
 
  ${If} $5 != ""                           ; If EnvVar is not empty ...
    StrCpy $9 $0
    StrCpy $0 ""
    StrCpy $8 0
    StrCpy $6 0
 
    ${Do}
      ${${UN}StrTok} $7 $9 ";" $8 "0"      ; $7 = next entry, $8 = entry counter
 
      ${If} $7 == ""                       ; If we've run out of entries,
        ${ExitDo}                          ;    were done
      ${EndIf}                             ;
 
      ; Remove leading and trailing spaces from this entry (critical step for Action=Remove)
      ${Do}
        StrCpy $R0  $7 1
        ${If} $R0 != " "
          ${ExitDo}
        ${EndIf}
        StrCpy $7   $7 "" 1                ;  Remove leading space
      ${Loop}
      ${Do}
        StrCpy $R0  $7 1 -1
        ${If} $R0 != " "
          ${ExitDo}
        ${EndIf}
        StrCpy $7   $7 -1                  ;  Remove trailing space
      ${Loop}
      ${If} $7 == $4                       ; If string matches, remove it by not appending it
        StrCpy $6 1                        ; Set 'found' flag
      ${ElseIf} $7 != $4                   ; If string does NOT match
      ${AndIf}  $0 == ""                   ;    and the 1st string being added to $0,
        StrCpy $0 $7                       ;    copy it to $0 without a prepended semicolon
      ${ElseIf} $7 != $4                   ; If string does NOT match
      ${AndIf}  $0 != ""                   ;    and this is NOT the 1st string to be added to $0,
        StrCpy $0 $0;$7                    ;    append path to $0 with a prepended semicolon
      ${EndIf}                             ;
 
      IntOp $8 $8 + 1                      ; Bump counter
    ${Loop}                                ; Check for duplicates until we run out of paths
  ${EndIf}
 
  ; Step 4:  Perform the requested Action
  ;
  ${If} $2 != "R"                          ; If Append or Prepend
    ${If} $6 == 1                          ; And if we found the target
      DetailPrint "Target is already present in $1. It will be removed and"
    ${EndIf}
    ${If} $0 == ""                         ; If EnvVar is (now) empty
      StrCpy $0 $4                         ;   just copy PathString to EnvVar
      ${If} $6 == 0                        ; If found flag is either 0
      ${OrIf} $6 == ""                     ; or blank (if EnvVarName is empty)
        DetailPrint "$1 was empty and has been updated with the target"
      ${EndIf}
    ${ElseIf} $2 == "A"                    ;  If Append (and EnvVar is not empty),
      StrCpy $0 $0;$4                      ;     append PathString
      ${If} $6 == 1
        DetailPrint "appended to $1"
      ${Else}
        DetailPrint "Target was appended to $1"
      ${EndIf}
    ${Else}                                ;  If Prepend (and EnvVar is not empty),
      StrCpy $0 $4;$0                      ;     prepend PathString
      ${If} $6 == 1
        DetailPrint "prepended to $1"
      ${Else}
        DetailPrint "Target was prepended to $1"
      ${EndIf}
    ${EndIf}
  ${Else}                                  ; If Action = Remove
    ${If} $6 == 1                          ;   and we found the target
      DetailPrint "Target was found and removed from $1"
    ${Else}
      DetailPrint "Target was NOT found in $1 (nothing to remove)"
    ${EndIf}
    ${If} $0 == ""
      DetailPrint "$1 is now empty"
    ${EndIf}
  ${EndIf}
 
  ; Step 5:  Update the registry at RegLoc with the updated EnvVar and announce the change
  ;
  ClearErrors
  ${If} $3  == HKLM
    WriteRegExpandStr ${hklm_all_users} $1 $0     ; Write it in all users section
  ${ElseIf} $3 == HKCU
    WriteRegExpandStr ${hkcu_current_user} $1 $0  ; Write it to current user section
  ${EndIf}
 
  IfErrors 0 +4
    MessageBox MB_OK|MB_ICONEXCLAMATION "Could not write updated $1 to $3"
    DetailPrint "Could not write updated $1 to $3"
    Goto EnvVarUpdate_Restore_Vars
 
  ; "Export" our change
  SendMessage ${HWND_BROADCAST} ${WM_WININICHANGE} 0 "STR:Environment" /TIMEOUT=5000
 
  EnvVarUpdate_Restore_Vars:
  ;
  ; Restore the user's variables and return ResultVar
  Pop $R0
  Pop $9
  Pop $8
  Pop $7
  Pop $6
  Pop $5
  Pop $4
  Pop $3
  Pop $2
  Pop $1
  Push $0  ; Push my $0 (ResultVar)
  Exch
  Pop $0   ; Restore his $0
 
FunctionEnd
 
!macroend   ; EnvVarUpdate UN
!insertmacro EnvVarUpdate ""
!insertmacro EnvVarUpdate "un."
;----------------------------------- EnvVarUpdate end----------------------------------------
 
!verbose pop
!endif
