import csv
import argparse

def compareAndAdd(base_file, field_base, compare_file, field_compare, field_to_add, output_csv):
    # Read the base CSV file into a list of dictionaries
    with open(base_file, 'r', newline='', encoding='utf-8') as csv_file_base:
        csv_base = list(csv.DictReader(csv_file_base))

    # Read the compare CSV file into a list of dictionaries
    with open(compare_file, 'r', newline='', encoding='utf-8') as csv_file_compare:
        csv_compare = list(csv.DictReader(csv_file_compare))

    # Create a mapping of field_compare to the field_to_add from the compare CSV
    compare_mapping = {row[field_compare]: row[field_to_add] for row in csv_compare}

    # Define the output file's fieldnames
    fieldnames = list(csv_base[0].keys()) + [field_to_add]

    # Open the output CSV file to write the combined data
    with open(output_csv, 'w', newline='', encoding='utf-8') as new_file:
        csv_writer = csv.DictWriter(new_file, fieldnames=fieldnames, delimiter=',')
        csv_writer.writeheader()

        # Iterate through the base CSV and add the field_to_add from the compare CSV if field_base matches field_compare
        for line_base in csv_base:
            key = line_base[field_base]
            if key in compare_mapping:
                line_base[field_to_add] = compare_mapping[key]
            else:
                line_base[field_to_add] = None  # or some default value if no match is found
            csv_writer.writerow(line_base)


if __name__ == "__main__":
    parser = argparse.ArgumentParser(description='Compare and add fields from one file to another.')
    parser.add_argument('base_file', help='The path to the base file')
    parser.add_argument('field_base', help='The field name in the base file to compare')
    parser.add_argument('compare_file', help='The path to the compare file')
    parser.add_argument('field_compare', help='The field name in the compare file to compare')
    parser.add_argument('field_to_add', help='The field name in the compare file to add to the base file')
    parser.add_argument('output_file', help='The path to the output file')
    args = parser.parse_args()

    compareAndAdd(
        args.base_file,
        args.field_base,
        args.compare_file,
        args.field_compare,
        args.field_to_add,
        args.output_file
    )