!--------------------------------------------------------------------------------------------------
!> @author   Martin Diehl, Max-Planck-Institut für Eisenforschung GmbH
!> @brief    provides wrappers to C routines
!--------------------------------------------------------------------------------------------------
module system_routines
 use, intrinsic :: ISO_C_Binding, only: &
   C_INT, &
   C_CHAR, &
   C_NULL_CHAR

 implicit none
 private
 
 public :: &
   signalusr1_C, &
   signalusr2_C, &
   isDirectory, &
   getCWD, &
   getHostName, &
   setCWD

interface

 function isDirectory_C(path) bind(C)
   use, intrinsic :: ISO_C_Binding, only: &
     C_INT, &
     C_CHAR
   integer(C_INT) :: isDirectory_C
   character(kind=C_CHAR), dimension(1024), intent(in) :: path                                      ! C string is an array
  end function isDirectory_C

 subroutine getCurrentWorkDir_C(str, stat) bind(C)
   use, intrinsic :: ISO_C_Binding, only: &
     C_INT, &
     C_CHAR
   character(kind=C_CHAR), dimension(1024), intent(out) :: str                                      ! C string is an array
   integer(C_INT),intent(out)         :: stat
  end subroutine getCurrentWorkDir_C

 subroutine getHostName_C(str, stat) bind(C)
   use, intrinsic :: ISO_C_Binding, only: &
     C_INT, &
     C_CHAR
   character(kind=C_CHAR), dimension(1024), intent(out) :: str                                      ! C string is an array
   integer(C_INT),intent(out)         :: stat
  end subroutine getHostName_C

 function chdir_C(path) bind(C)
   use, intrinsic :: ISO_C_Binding, only: &
     C_INT, &
     C_CHAR
   integer(C_INT) :: chdir_C
   character(kind=C_CHAR), dimension(1024), intent(in) :: path                                      ! C string is an array
 end function chdir_C
 
 subroutine signalusr1_C(handler) bind(C)
   use, intrinsic :: ISO_C_Binding, only: &
     C_FUNPTR
   type(C_FUNPTR), intent(in), value :: handler
 end subroutine signalusr1_C
 
  subroutine signalusr2_C(handler) bind(C)
   use, intrinsic :: ISO_C_Binding, only: &
     C_FUNPTR
   type(C_FUNPTR), intent(in), value :: handler
 end subroutine signalusr2_C

end interface

contains

!--------------------------------------------------------------------------------------------------
!> @brief figures out if a given path is a directory (and not an ordinary file)
!--------------------------------------------------------------------------------------------------
logical function isDirectory(path)

 implicit none
 character(len=*), intent(in) :: path
 character(kind=C_CHAR), dimension(1024) :: strFixedLength                                         ! C string as array
 integer :: i 

 strFixedLength = repeat(C_NULL_CHAR,len(strFixedLength))
 do i=1,len(path)                                                                                   ! copy array components
   strFixedLength(i)=path(i:i)
 enddo
 isDirectory=merge(.True.,.False.,isDirectory_C(strFixedLength) /= 0_C_INT)

end function isDirectory


!--------------------------------------------------------------------------------------------------
!> @brief gets the current working directory
!--------------------------------------------------------------------------------------------------
character(len=1024) function getCWD()

 implicit none
 character(kind=C_CHAR), dimension(1024) :: charArray                                               ! C string is an array
 integer(C_INT) :: stat
 integer :: i

 call getCurrentWorkDir_C(charArray,stat)
 if (stat /= 0_C_INT) then
   getCWD = 'Error occured when getting currend working directory'
 else
   getCWD = repeat('',len(getCWD))
   arrayToString: do i=1,len(getCWD)
     if (charArray(i) /= C_NULL_CHAR) then
       getCWD(i:i)=charArray(i)
     else
       exit
     endif
   enddo arrayToString
 endif

end function getCWD


!--------------------------------------------------------------------------------------------------
!> @brief gets the current host name
!--------------------------------------------------------------------------------------------------
character(len=1024) function getHostName()
 implicit none
 character(kind=C_CHAR), dimension(1024) :: charArray                                              ! C string is an array
 integer(C_INT) :: stat
 integer :: i

 call getHostName_C(charArray,stat)
 if (stat /= 0_C_INT) then
   getHostName = 'Error occured when getting host name'
 else
   getHostName = repeat('',len(getHostName))
   arrayToString: do i=1,len(getHostName)
     if (charArray(i) /= C_NULL_CHAR) then
       getHostName(i:i)=charArray(i)
     else
       exit
     endif
   enddo arrayToString
 endif

end function getHostName


!--------------------------------------------------------------------------------------------------
!> @brief changes the current working directory
!--------------------------------------------------------------------------------------------------
logical function setCWD(path)
 implicit none
 character(len=*), intent(in) :: path
 character(kind=C_CHAR), dimension(1024) :: strFixedLength                                          ! C string is an array
 integer :: i

 strFixedLength = repeat(C_NULL_CHAR,len(strFixedLength))
 do i=1,len(path)                                                                                   ! copy array components
   strFixedLength(i)=path(i:i)
 enddo
 setCWD=merge(.True.,.False.,chdir_C(strFixedLength) /= 0_C_INT)

end function setCWD

end module system_routines