''' 
Software Tools Exam 1 Problem 1
Given a specific file format (.edf), write a parser which displays the first 10 fields of the file.
Input: Any singular .edf file
Output: First 10 fields of the .edf file
Usage: python smith_zack_p01.py edf_file.edf
'''
# Import sys library for getting command line arguments
import sys

# Main
def main():
    # Create read string variable
    read_string = ''
    # Make sure a command line argument is used
    try:
        # Check that the last four letters are '.edf'
        if sys.argv[1][-4:len(sys.argv[1])] != '.edf':
            # Return if not 'edf' file format
            print "Not an edf file! Please use an .edf document"
            return
        # Try to open the input file
        with open(sys.argv[1], 'r') as file_thing:
            # First 10 fields contained in first 144 bytes
            read_string += file_thing.read(144)
        # Split read string by spaces to get individual fields
        fields_array = read_string.split()
        for field_iterator in range(len(fields_array)):
            print 'Field %d: %s' % (field_iterator+1, fields_array[field_iterator])
            
    # If you can't get sys.argv[1], print an error
    except IndexError:
        print "Please enter an .edf file as a command line argument"
        return

# Boiler plate code
if __name__ == '__main__':
    main()