#!/usr/bin/env python3
"""Extract USV PWM signals from navigation log CSVs."""
import argparse, csv, glob, json, os, re, sys
from datetime import datetime, timezone

def main():
    parser = argparse.ArgumentParser()
    parser.add_argument('--nav-dir', required=True)
    args = parser.parse_args()

    pattern = os.path.join(args.nav_dir, '*_navigation_log.csv')
    csv_files = sorted(glob.glob(pattern))
    if not csv_files:
        print(f"No navigation_log.csv in {args.nav_dir}", file=sys.stderr)
        sys.exit(1)
    print(f"Found {len(csv_files)} nav CSV files")

    M_data = {}
    RC_data = {}

    for csv_file in csv_files:
        print(f"  Parsing {os.path.basename(csv_file)}")
        try:
            with open(csv_file, 'r') as f:
                reader = csv.DictReader(f)
                for row in reader:
                    ts_str = row.get('timestamp', '').strip()
                    data = row.get('data', '').strip()
                    val_str = row.get('value', '').strip()
                    if not ts_str or not data or not val_str:
                        continue
                    is_M = re.match(r'^M\d+$', data)
                    is_RC = re.match(r'^RC\d+$', data)
                    if not is_M and not is_RC:
                        continue
                    try:
                        val = float(val_str)
                    except ValueError:
                        continue
                    try:
                        dt = datetime.strptime(ts_str, '%Y-%m-%d %H:%M:%S.%f')
                    except ValueError:
                        try:
                            dt = datetime.strptime(ts_str, '%Y-%m-%d %H:%M:%S')
                        except ValueError:
                            continue
                    # CET -> UTC: subtract 3600s
                    t_ms = int(dt.timestamp() * 1000) - 3600 * 1000
                    pt = {'t': t_ms, 'v': val}
                    if is_M:
                        M_data.setdefault(data, []).append(pt)
                    else:
                        RC_data.setdefault(data, []).append(pt)
        except Exception as e:
            print(f"  Error {csv_file}: {e}")

    all_t = []
    for pts in list(M_data.values()) + list(RC_data.values()):
        all_t.extend(p['t'] for p in pts)
    t_min = min(all_t) if all_t else 0
    t_max = max(all_t) if all_t else 0

    for k in sorted(M_data):
        print(f"  {k}: {len(M_data[k])} pts")
    for k in sorted(RC_data):
        print(f"  {k}: {len(RC_data[k])} pts")

    fmt = lambda ms: datetime.fromtimestamp(ms/1000, tz=timezone.utc).isoformat()
    print(f"t_min UTC: {fmt(t_min)}")
    print(f"t_max UTC: {fmt(t_max)}")

    out = {
        'tz_assumed': 'CET (UTC+1)',
        'tz_converted_to': 'UTC',
        't_min_utc_ms': t_min,
        't_max_utc_ms': t_max,
        'M': M_data,
        'RC': RC_data,
    }

    outdir = os.path.join(os.path.dirname(os.path.dirname(os.path.abspath(__file__))), 'output')
    os.makedirs(outdir, exist_ok=True)
    outpath = os.path.join(outdir, 'usv_pwm.json')
    with open(outpath, 'w') as f:
        json.dump(out, f)
    print(f"Written: {outpath}")

if __name__ == '__main__':
    main()