#!/usr/bin/env python3
"""gtfs_suche.py — echte schnellste Nahverkehrs-Verbindung aus GTFS-SQLite (zeitbasierter Dijkstra).
Aufruf: python3 gtfs_suche.py <von_stop_id> <nach_stop_id> [HH:MM]
Vorraussetzung: DB aus build_gtfs_db.py. Aktiv-ID-Regel: wenn ein Bahnhof mehrere IDs hat,
die mit COUNT(*)>0 in st nehmen.
"""
import sqlite3, sys, heapq
from collections import defaultdict

DB = "/tmp/gtfs_rt.db"

def to_sec(t):
    p = t.split(":")
    h = int(p[0]); m = int(p[1]) if len(p) > 1 else 0
    return h*3600 + m*60

def fmt(t):
    return f"{t//3600:02d}:{(t%3600)//60:02d}"

def aktive_id(con, stop_name):
    """Findet die stop_id mit st-Vorkommen (Bahnhof kann mehrere IDs haben)."""
    cands = con.execute("SELECT stop_id FROM stops WHERE stop_name=?", (stop_name,)).fetchall()
    for (sid,) in cands:
        if con.execute("SELECT COUNT(*) FROM st WHERE stop_id=?", (sid,)).fetchone()[0] > 0:
            return sid
    return None

def verbinde(von_id, nach_id, start="09:00"):
    con = sqlite3.connect(DB)
    con.row_factory = sqlite3.Row
    dep0 = to_sec(start)
    deps_by_stop = defaultdict(list); stops_by_trip = defaultdict(list)
    for r in con.execute("SELECT trip_id, stop_id, seq, arr, dep FROM st"):
        deps_by_stop[r["stop_id"]].append((to_sec(r["dep"]), r["trip_id"], r["seq"]))
        stops_by_trip[r["trip_id"]].append((r["seq"], r["stop_id"], to_sec(r["arr"]), to_sec(r["dep"])))
    con.close()
    for k in deps_by_stop: deps_by_stop[k].sort()
    for k in stops_by_trip: stops_by_trip[k].sort()

    INF = float('inf')
    dist = defaultdict(lambda: INF); dist[von_id] = dep0
    heap = [(dep0, von_id)]
    pred = {}
    while heap:
        t, stop = heapq.heappop(heap)
        if t != dist[stop]: continue
        if stop == nach_id: break
        for dep_s, tid, seq in deps_by_stop[stop]:
            if dep_s < t: continue
            for (sseq, sid, arr_s, dep2) in stops_by_trip[tid]:
                if sseq <= seq: continue
                if arr_s < dist[sid]:
                    dist[sid] = arr_s; pred[sid] = (tid, stop)
                    heapq.heappush(heap, (arr_s, sid))
    if nach_id not in pred and nach_id != von_id:
        return None
    if nach_id == von_id:
        return (0, [], 0, fmt(dep0), fmt(dep0))
    trips = []; cur = nach_id
    while cur in pred and cur != von_id:
        tid, prev = pred[cur]; trips.append(tid); cur = prev
    trips.reverse()
    dur = dist[nach_id] - dep0
    return (dur, trips, len(set(trips)), fmt(dep0), fmt(dist[nach_id]))

if __name__ == "__main__":
    von = sys.argv[1]; nach = sys.argv[2]
    start = sys.argv[3] if len(sys.argv) > 3 else "09:00"
    r = verbinde(von, nach, start)
    if r:
        dur, trips, umst, dep, arr = r
        print(f"{dur//3600}h {(dur%3600)//60:02d}min | {dep}->{arr} | {umst} Umstieg(e)")
    else:
        print("Keine Verbindung")