import sys
import csv
import ast
import glob
from collections import Counter

def inspect_nav(csv_path: str, n=500):
    data_vals = Counter()
    rows = 0
    with open(csv_path, newline="", encoding="utf-8", errors="replace") as f:
        reader = csv.DictReader(f)
        print(f"Columns: {reader.fieldnames}")
        for row in reader:
            rows += 1
            if rows <= n:
                data_vals[row.get("data", "?")] += 1
    print(f"\nTotal rows: {rows}")
    print("\nUnique 'data' field values (first 500 rows):")
    for k, v in data_vals.most_common(30):
        print(f"  {k}: {v}")

def inspect_usbl(csv_path: str, n=10):
    with open(csv_path, newline="", encoding="utf-8", errors="replace") as f:
        reader = csv.reader(f)
        print(f"Columns: [timestamp, direction, message]")
        received = 0
        for row in reader:
            if len(row) < 3:
                continue
            direction = row[1].strip().upper()
            if direction != "RECEIVED":
                continue
            received += 1
            if received > n:
                break
            try:
                raw = ast.literal_eval(row[2].strip())
                if isinstance(raw, bytes):
                    print(f"  ts={row[0]} len={len(raw)} hex_start={raw[:16].hex()}")
            except Exception as e:
                print(f"  ts={row[0]} parse_error={e}")

if __name__ == "__main__":
    ship_dir = sys.argv[1]
    nav_files = glob.glob(f"{ship_dir}/*_navigation_log.csv")
    usbl_files = glob.glob(f"{ship_dir}/*_usbl.csv")
    if nav_files:
        print(f"\n=== NAV LOG: {nav_files[0]} ===")
        inspect_nav(nav_files[0])
    if usbl_files:
        print(f"\n=== USBL (first 10 RECEIVED): {usbl_files[0]} ===")
        inspect_usbl(usbl_files[0])
    if not nav_files and not usbl_files:
        print(f"No CSV files found in {ship_dir}")
        import os
        print("Files found:", os.listdir(ship_dir))