import os.path

# check that a file can be edited
def check_edit(file):
    # check that the file is not a directory
    if os.path.isdir(file):
        return(-1,"error: '"+file+"' is a directory")
    if os.path.isfile(file):
        # check permissions
        if not os.access(file,os.R_OK):
            return(-2,"error: permission denied: cannot read file '"+file+"'")
    else:
        # check write to directory
        if len(os.path.dirname(file))>0:
            if not os.access(os.path.dirname(file),os.W_OK):
                return(-3,"error: permission denied: cannot write to parent directory '"+os.path.dirname(file)+"'")
        else:
            if not os.access(os.getcwd(),os.W_OK):
                return(-4,"error: permission denied: cannot write to parent directory '"+os.getcwd()+"'")
    return(0,"")


# check that a file can be written
def check_write(file,overwrite):
    # check that the file is not a directory
    if os.path.isdir(file):
        return(-1,"error: '"+file+"' is a directory")
    # check that file does not already exist
    if not overwrite and os.path.isfile(file):
        return(-2,"error: '"+file+"' already exists")
    # check that the containing directory exists
    if len(os.path.dirname(file))>0 and not os.path.isdir(os.path.dirname(file)):
        return(-3,"error: could not find directory '"+os.path.dirname(file)+"'")
    # check permissions
    if os.path.isfile(file):
        if not os.access(file,os.W_OK):
            return(-4,"error: permission denied: cannot write to file '"+file+"'")
    else:
        # check write to directory
        if len(os.path.dirname(file))>0:
            if not os.access(os.path.dirname(file),os.W_OK):
                return(-5,"error: permission denied: cannot write to parent directory '"+os.path.dirname(file)+"'")
        else:
            if not os.access(os.getcwd(),os.W_OK):
                return(-6,"error: permission denied: cannot write to parent directory '"+os.getcwd()+"'")
    return(0,"")