#!/usr/bin/env python3
"""Parse USV long-format CSV → track.geojson + points.json + manifest.json
v2: multi-session support via --input-dir, retro-compat with --input (single file)
"""
import argparse
import csv
import glob
import json
import os
import sys
from collections import defaultdict
from datetime import datetime, timezone

MAX_SLIDER_POINTS = 10000


def parse_args():
    p = argparse.ArgumentParser(description="Parse USV nav CSV v2")
    g = p.add_mutually_exclusive_group(required=True)
    g.add_argument("--input", help="Single CSV navigation log (v1 compat)")
    g.add_argument("--input-dir", help="Directory: glob *navigation_log*.csv")
    p.add_argument("--output", required=True, help="Output directory")
    return p.parse_args()


def find_csvs(input_dir):
    pattern = os.path.join(input_dir, "*navigation_log*.csv")
    files = sorted(glob.glob(pattern))
    if not files:
        print(f"No navigation_log CSVs found in {input_dir}", file=sys.stderr)
        sys.exit(1)
    return files


def load_csv(path):
    """Load long-format CSV → {timestamp: {field: value}}"""
    rows_by_ts = defaultdict(dict)
    with open(path, newline="", encoding="utf-8") as f:
        reader = csv.DictReader(f)
        for row in reader:
            ts = row["timestamp"]
            field = row["data"]
            val = row["value"]
            rows_by_ts[ts][field] = val
    return rows_by_ts


def get_float(d, *keys):
    for k in keys:
        v = d.get(k)
        if v is not None:
            try:
                return float(v)
            except ValueError:
                pass
    return None


def ts_to_ms(ts_str):
    """Convert ISO-like timestamp string to epoch ms (UTC)."""
    # Try formats: '2026-03-24 09:04:07.123456' or '2026-03-24T09:04:07.123456'
    for fmt in (
        "%Y-%m-%dT%H:%M:%S.%f",
        "%Y-%m-%dT%H:%M:%S",
        "%Y-%m-%d %H:%M:%S.%f",
        "%Y-%m-%d %H:%M:%S",
    ):
        try:
            dt = datetime.strptime(ts_str, fmt).replace(tzinfo=timezone.utc)
            return int(dt.timestamp() * 1000)
        except ValueError:
            continue
    return None


def build_points(rows_by_ts, source_name):
    """Build sorted list of {t, t_ms, lat, lon, heading, source}."""
    timestamps = sorted(rows_by_ts.keys())
    state = {}
    points = []

    for ts in timestamps:
        updates = rows_by_ts[ts]
        state.update(updates)

        lat = get_float(state, "Lat", "RAW_Lat")
        lon = get_float(state, "Lon", "RAW_Lon")
        heading = get_float(state, "Heading", "Yaw")

        if lat is None or lon is None:
            continue
        if lat == 0.0 and lon == 0.0:
            continue
        if abs(lat) < 1 and abs(lon) < 1:
            raw_lat = get_float(state, "GPS_RAW_INT_lat")
            raw_lon = get_float(state, "GPS_RAW_INT_lon")
            if raw_lat and raw_lon:
                lat = raw_lat / 1e7
                lon = raw_lon / 1e7
            else:
                continue

        if "Lat" in updates or "Lon" in updates or "RAW_Lat" in updates or "RAW_Lon" in updates:
            t_ms = ts_to_ms(ts)
            points.append({
                "t": ts,
                "t_ms": t_ms,
                "lat": round(lat, 8),
                "lon": round(lon, 8),
                "heading": round(heading, 2) if heading is not None else None,
                "source": source_name,
            })

    return points


def sample_points_session(points, max_total, n_sessions):
    """Sample per session, always keeping first+last point of each session."""
    if not points:
        return points
    quota = max(10, max_total // max(n_sessions, 1))
    if len(points) <= quota:
        return points

    step = (len(points) - 2) / max(quota - 2, 1)
    sampled = [points[0]]
    for i in range(1, quota - 1):
        sampled.append(points[min(int(1 + i * step), len(points) - 2)])
    sampled.append(points[-1])
    return sampled


def session_bbox(points):
    lats = [p["lat"] for p in points]
    lons = [p["lon"] for p in points]
    return [min(lons), min(lats), max(lons), max(lats)]


def write_outputs(all_sessions, output_dir):
    """Write track.geojson, points.json, manifest.json."""
    os.makedirs(output_dir, exist_ok=True)

    # Colors for multi-track
    COLORS = ["#00b4d8", "#e94560", "#06d6a0", "#ffd166", "#a855f7", "#f97316"]

    # ── track.geojson (MultiLineString per session) ──
    features = []
    for i, sess in enumerate(all_sessions):
        coords = [[p["lon"], p["lat"]] for p in sess["points"]]
        features.append({
            "type": "Feature",
            "geometry": {"type": "LineString", "coordinates": coords},
            "properties": {
                "source_file": sess["source_file"],
                "source_name": sess["source_name"],
                "start_iso": sess["t_start"],
                "end_iso": sess["t_end"],
                "n_points": len(coords),
                "color": COLORS[i % len(COLORS)],
                "session_index": i,
            }
        })

    geojson = {"type": "FeatureCollection", "features": features}
    geo_path = os.path.join(output_dir, "track.geojson")
    with open(geo_path, "w") as f:
        json.dump(geojson, f)
    print(f"  track.geojson: {len(features)} sessions → {geo_path}")

    # ── points.json (all sampled, sorted by t_ms) ──
    all_points = []
    n_sessions = len(all_sessions)
    for sess in all_sessions:
        sampled = sample_points_session(sess["points"], MAX_SLIDER_POINTS, n_sessions)
        all_points.extend(sampled)

    # Sort by t_ms (sessions may overlap in time)
    all_points.sort(key=lambda p: (p["t_ms"] or 0))

    pts_path = os.path.join(output_dir, "points.json")
    with open(pts_path, "w") as f:
        json.dump(all_points, f)
    print(f"  points.json: {len(all_points)} points (sampled) → {pts_path}")

    # ── manifest.json ──
    all_lats = [p["lat"] for s in all_sessions for p in s["points"]]
    all_lons = [p["lon"] for s in all_sessions for p in s["points"]]
    global_bbox = [min(all_lons), min(all_lats), max(all_lons), max(all_lats)]

    all_t_ms = [p["t_ms"] for s in all_sessions for p in s["points"] if p["t_ms"]]
    t_min_ms = min(all_t_ms) if all_t_ms else None
    t_max_ms = max(all_t_ms) if all_t_ms else None

    sessions_meta = []
    for sess in all_sessions:
        sessions_meta.append({
            "file": sess["source_file"],
            "source_name": sess["source_name"],
            "n_points": sess["n_points_raw"],
            "t_start": sess["t_start"],
            "t_end": sess["t_end"],
            "t_start_ms": sess["t_start_ms"],
            "t_end_ms": sess["t_end_ms"],
            "bbox": sess["bbox"],
        })

    manifest = {
        "generated_at": datetime.now(timezone.utc).isoformat(),
        "n_sessions": len(all_sessions),
        "sessions": sessions_meta,
        "global_bbox": global_bbox,
        "t_min": all_sessions[0]["t_start"] if all_sessions else None,
        "t_max": all_sessions[-1]["t_end"] if all_sessions else None,
        "t_min_ms": t_min_ms,
        "t_max_ms": t_max_ms,
        "n_points_total_raw": sum(s["n_points_raw"] for s in all_sessions),
        "n_points_sampled": len(all_points),
    }

    mf_path = os.path.join(output_dir, "manifest.json")
    with open(mf_path, "w") as f:
        json.dump(manifest, f, indent=2)
    print(f"  manifest.json → {mf_path}")

    return manifest


def print_global_stats(manifest, all_sessions):
    print(f"\n=== Stats globales ===")
    print(f"  Sessions:        {manifest['n_sessions']}")
    print(f"  Points bruts:    {manifest['n_points_total_raw']}")
    print(f"  Points sampled:  {manifest['n_points_sampled']}")
    print(f"  t_min:           {manifest['t_min']}")
    print(f"  t_max:           {manifest['t_max']}")
    bb = manifest["global_bbox"]
    print(f"  Bbox:            lon [{bb[0]:.5f}, {bb[2]:.5f}]  lat [{bb[1]:.5f}, {bb[3]:.5f}]")
    if manifest["t_min_ms"] and manifest["t_max_ms"]:
        dur_s = (manifest["t_max_ms"] - manifest["t_min_ms"]) / 1000
        h, rem = divmod(int(dur_s), 3600)
        m, s = divmod(rem, 60)
        print(f"  Durée totale:    {h}h{m:02d}m{s:02d}s")
    for i, sess in enumerate(all_sessions):
        print(f"  Session {i+1}: {sess['source_name']}  {sess['n_points_raw']} pts  {sess['t_start']} → {sess['t_end']}")


def process_file(path):
    source_name = os.path.basename(path)
    print(f"\nChargement {source_name} ...")
    rows = load_csv(path)
    print(f"  {len(rows)} timestamps uniques")
    points = build_points(rows, source_name)
    if not points:
        print(f"  WARNING: aucun point GPS valide dans {source_name}")
        return None

    # Filter points without t_ms
    points = [p for p in points if p["t_ms"] is not None]
    lats = [p["lat"] for p in points]
    lons = [p["lon"] for p in points]
    return {
        "source_file": path,
        "source_name": source_name,
        "points": points,
        "n_points_raw": len(points),
        "t_start": points[0]["t"],
        "t_end": points[-1]["t"],
        "t_start_ms": points[0]["t_ms"],
        "t_end_ms": points[-1]["t_ms"],
        "bbox": [min(lons), min(lats), max(lons), max(lats)],
    }


def main():
    args = parse_args()

    if args.input:
        csv_files = [args.input]
    else:
        csv_files = find_csvs(args.input_dir)

    print(f"Fichiers trouvés: {len(csv_files)}")
    for f in csv_files:
        print(f"  {os.path.basename(f)}")

    all_sessions = []
    for path in csv_files:
        sess = process_file(path)
        if sess:
            all_sessions.append(sess)

    if not all_sessions:
        print("Aucune session valide.", file=sys.stderr)
        sys.exit(1)

    manifest = write_outputs(all_sessions, args.output)
    print_global_stats(manifest, all_sessions)
    print("\nDone.")


if __name__ == "__main__":
    main()