import pytest
from trip_planner import combine_trips, _fmt_duration

DATE = '2026-03-30'


# ---------------------------------------------------------------------------
# _fmt_duration
# ---------------------------------------------------------------------------

def test_fmt_duration_hours_and_minutes():
    assert _fmt_duration(95) == '1h 35m'

def test_fmt_duration_exact_hours():
    assert _fmt_duration(120) == '2h'

def test_fmt_duration_minutes_only():
    assert _fmt_duration(45) == '45m'


# ---------------------------------------------------------------------------
# combine_trips — basic pairing
# ---------------------------------------------------------------------------

GWR_FAST = {'depart_bristol': '07:00', 'arrive_paddington': '08:45'}   # 1h 45m
GWR_SLOW = {'depart_bristol': '07:00', 'arrive_paddington': '09:26'}   # 2h 26m — over limit

ES_PARIS = {'depart_st_pancras': '10:01', 'arrive_destination': '13:34', 'destination': 'Paris Gare du Nord'}
ES_EARLY = {'depart_st_pancras': '09:00', 'arrive_destination': '12:00', 'destination': 'Paris Gare du Nord'}


def test_valid_trip_is_returned():
    trips = combine_trips([GWR_FAST], [ES_PARIS], DATE)
    assert len(trips) == 1
    t = trips[0]
    assert t['depart_bristol'] == '07:00'
    assert t['arrive_paddington'] == '08:45'
    assert t['depart_st_pancras'] == '10:01'
    assert t['arrive_destination'] == '13:34'
    assert t['destination'] == 'Paris Gare du Nord'


def test_gwr_too_slow_excluded():
    # 2h 26m GWR journey exceeds MAX_GWR_MINUTES (110)
    trips = combine_trips([GWR_SLOW], [ES_PARIS], DATE)
    assert trips == []


def test_eurostar_too_early_excluded():
    # Eurostar departs before min connection time has elapsed
    trips = combine_trips([GWR_FAST], [ES_EARLY], DATE)
    assert trips == []


def test_no_trains_returns_empty():
    assert combine_trips([], [], DATE) == []

def test_no_gwr_returns_empty():
    assert combine_trips([], [ES_PARIS], DATE) == []

def test_no_eurostar_returns_empty():
    assert combine_trips([GWR_FAST], [], DATE) == []


# ---------------------------------------------------------------------------
# Connection window constraints
# ---------------------------------------------------------------------------

def test_min_connection_enforced():
    # Arrive Paddington 08:45, need 75 min → earliest St Pancras 10:00
    # ES at 09:59 should be excluded, 10:00 should be included
    es_too_close = {'depart_st_pancras': '09:59', 'arrive_destination': '13:00', 'destination': 'Paris Gare du Nord'}
    es_ok        = {'depart_st_pancras': '10:00', 'arrive_destination': '13:00', 'destination': 'Paris Gare du Nord'}
    assert combine_trips([GWR_FAST], [es_too_close], DATE) == []
    trips = combine_trips([GWR_FAST], [es_ok], DATE)
    assert len(trips) == 1


def test_max_connection_enforced():
    # Arrive Paddington 08:45, max 140 min → latest St Pancras 11:05
    es_ok      = {'depart_st_pancras': '11:05', 'arrive_destination': '14:00', 'destination': 'Paris Gare du Nord'}
    es_too_late = {'depart_st_pancras': '11:06', 'arrive_destination': '14:00', 'destination': 'Paris Gare du Nord'}
    trips = combine_trips([GWR_FAST], [es_ok], DATE)
    assert len(trips) == 1
    assert combine_trips([GWR_FAST], [es_too_late], DATE) == []


# ---------------------------------------------------------------------------
# Only earliest valid Eurostar per GWR departure
# ---------------------------------------------------------------------------

def test_only_earliest_eurostar_per_gwr():
    es1 = {'depart_st_pancras': '10:01', 'arrive_destination': '13:34', 'destination': 'Paris Gare du Nord'}
    es2 = {'depart_st_pancras': '11:01', 'arrive_destination': '14:34', 'destination': 'Paris Gare du Nord'}
    trips = combine_trips([GWR_FAST], [es1, es2], DATE)
    assert len(trips) == 1
    assert trips[0]['depart_st_pancras'] == '10:01'


# ---------------------------------------------------------------------------
# Multiple GWR trains → multiple trips
# ---------------------------------------------------------------------------

def test_multiple_gwr_trains():
    gwr2 = {'depart_bristol': '08:00', 'arrive_paddington': '09:45'}
    es   = {'depart_st_pancras': '11:01', 'arrive_destination': '14:34', 'destination': 'Paris Gare du Nord'}
    trips = combine_trips([GWR_FAST, gwr2], [es], DATE)
    assert len(trips) == 2
    assert trips[0]['depart_bristol'] == '07:00'
    assert trips[1]['depart_bristol'] == '08:00'


# ---------------------------------------------------------------------------
# Duration fields
# ---------------------------------------------------------------------------

def test_gwr_duration_in_trip():
    trips = combine_trips([GWR_FAST], [ES_PARIS], DATE)
    assert trips[0]['gwr_duration'] == '1h 45m'


def test_total_duration_in_trip():
    # depart 07:00, arrive 13:34 → 6h 34m
    trips = combine_trips([GWR_FAST], [ES_PARIS], DATE)
    assert trips[0]['total_duration'] == '6h 34m'


def test_connection_duration_in_trip():
    # arrive Paddington 08:45, depart St Pancras 10:01 → 1h 16m
    trips = combine_trips([GWR_FAST], [ES_PARIS], DATE)
    assert trips[0]['connection_duration'] == '1h 16m'