# Standard imports
import csv
import sys
import os

def convert_iis_log_to_csv(iis_log_path):
    try:
        with open(iis_log_path, 'r', encoding='utf-8') as log_file:
            lines = log_file.readlines()
    except FileNotFoundError: # Oop, file not found
        print(f"Error: File not found: {iis_log_path}")
        sys.exit(1)

    # Set up some arrays
    field_names = []
    data_lines = []

    # Read the file
    for line in lines:
        line = line.strip()
        if line.startswith("#Fields:"): # Look for the Fields line in the IIS log and use that to make column headers
            field_names = line[len("#Fields:"):].strip().split()
        elif line.startswith("#") or not line:
            continue  # Skip any blank or commented lines
        else:
            data_lines.append(line.split())

    if not field_names: # If no Fields line, it'll error, so you really want the Fields line in the file
        print("Error: No '#Fields:' line found in the log file.")
        sys.exit(1)

    base_name = os.path.splitext(os.path.basename(iis_log_path))[0]
    output_csv_path = f"{base_name}.csv" # The CSV will be the same file name as the log file

    # Create the CSV
    with open(output_csv_path, 'w', newline='', encoding='utf-8') as csv_file:
        writer = csv.writer(csv_file)
        writer.writerow(field_names)
        writer.writerows(data_lines)

    print(f"Conversion complete. CSV written to: {output_csv_path}")

if __name__ == "__main__":
    if len(sys.argv) != 2:
        print("Usage: python convert_iis_log.py <iis_log_file>") # The most obvious help statement ever
        sys.exit(1)

    iis_log_path = sys.argv[1]
    convert_iis_log_to_csv(iis_log_path)