import os
import sys
import tempfile

POLYDATA='POLYDATA'

def asbool( val ):
    return str( val ).lower() in [ 'yes', 'true' ]

def get_format_and_type( galaxy_ext ):
    # Define the output file format and type.
    format = None
    datatype = None
    if galaxy_ext in [ 'vtkascii', 'vtkbinary' ]:
        format = 'vtk'
    elif galaxy_ext in [ 'plyascii', 'plybinary' ]:
        format = 'ply'
    if galaxy_ext in [ 'vtkascii', 'plyascii' ]:
        datatype = 'ascii'
    elif galaxy_ext in [ 'vtkbinary', 'plybinary' ]:
        datatype = 'binary'
    return format, datatype

def get_input_file_path( tmp_dir, input_file, format ):
    """
    iCqSol uses file extensions (e.g., .ply, .vtk) when reading and
    writing files, so the Galaxy dataset naming convention of
    setting all file extensions as .dat must be handled.
    """
    file_path = get_temporary_file_path( tmp_dir, format )
    # Remove the file so we can create a symlink.
    os.remove( file_path )
    os.symlink( input_file, file_path )
    return file_path

def get_temp_dir( prefix='tmp-vtk-', dir=None ):
    """
    Return a temporary directory.
    """
    return tempfile.mkdtemp( prefix=prefix, dir=dir )

def get_tempfilename( dir=None, suffix=None ):
    """
    Return a temporary file name.
    """
    fd, name = tempfile.mkstemp( suffix=suffix, dir=dir )
    os.close( fd )
    return name

def get_temporary_file_path( tmp_dir, file_extension ):
    """
    Return the path to a temporary file with a valid VTK format
    file extension.
    """
    return get_tempfilename( tmp_dir, file_extension )

def stop_err( msg ):
    sys.stderr.write( "%s\n" % msg )
    sys.exit()