"""Tests for pair_trips.py (brief cases T1-T9 plus input handling).

Run with:  python3 -m unittest test_pair_trips.py   or   python3 test_pair_trips.py
(pytest also collects the plain test_ functions.)
"""
import contextlib
import io
import os
import sys
import unittest
from datetime import date

HERE = os.path.dirname(os.path.abspath(__file__))
sys.path.insert(0, HERE)

from pair_trips import BANNER, add_months, main, pair_trips, read_rows  # noqa: E402


def run(body, opt=None):
    rows = read_rows(("date,type,port\n" + body.strip()).splitlines())
    if opt:
        return pair_trips(rows, date.fromisoformat(opt[0]), date.fromisoformat(opt[1]))
    return pair_trips(rows)


def counts(trips):
    return [(t["days_between"], t["full_days_outside"]) for t in trips]


def test_t1_one_trip():
    trips, flags = run("2025-12-18,Departure,SFO\n2026-01-06,Arrival,SFO")
    assert counts(trips) == [(19, 18)]
    assert trips[0]["over_5_months"] is False
    assert flags == []


def test_t2_unsorted_two_trips():
    trips, flags = run(
        "2026-07-10,Arrival,JFK\n2025-12-18,Departure,SFO\n"
        "2026-06-20,Departure,JFK\n2026-01-06,Arrival,SFO"
    )
    assert counts(trips) == [(19, 18), (20, 19)]
    assert flags == []


def test_t3_land_arrival_without_departure():
    trips, flags = run(
        "2026-03-01,Arrival,San Ysidro\n2026-05-01,Departure,LAX\n2026-05-10,Arrival,LAX"
    )
    assert flags == [{"flag": "arrival_without_departure", "date": date(2026, 3, 1), "port": "San Ysidro"}]
    assert counts(trips) == [(9, 8)]


def test_t4_departure_only():
    trips, flags = run("2026-09-01,Departure,ORD")
    assert trips == []
    assert flags == [{"flag": "departure_without_return", "date": date(2026, 9, 1), "port": "ORD"}]


def test_t5_over_5_months():
    trips, _ = run("2026-01-15,Departure,\n2026-06-16,Arrival,")
    assert counts(trips) == [(152, 151)]
    assert trips[0]["over_5_months"] is True


def test_t6_5_month_boundary():
    trips, _ = run("2026-01-15,Departure,\n2026-06-15,Arrival,")
    assert counts(trips) == [(151, 150)]
    assert trips[0]["over_5_months"] is False


def test_t7_same_day_trip():
    # Arrival listed first on purpose: same-date Departure must sort before Arrival.
    trips, flags = run("2026-04-04,Arrival,\n2026-04-04,Departure,")
    assert counts(trips) == [(0, 0)]
    assert flags == []


def test_t8_opt_overlap():
    trips, _ = run("2026-05-20,Departure,\n2026-06-10,Arrival,", opt=("2026-06-01", "2027-05-31"))
    assert counts(trips) == [(21, 20)]
    assert trips[0]["days_between_in_opt"] == 9


def test_t9_month_end_clamp():
    trips, _ = run("2025-08-31,Departure,\n2026-02-01,Arrival,")
    assert counts(trips) == [(154, 153)]
    assert trips[0]["over_5_months"] is True
    assert add_months(date(2025, 8, 31), 5) == date(2026, 1, 31)


def test_two_departures_in_a_row():
    trips, flags = run("2026-01-01,Departure,\n2026-02-01,Departure,\n2026-02-10,Arrival,")
    assert counts(trips) == [(9, 8)]
    assert flags[0]["flag"] == "departure_without_return" and flags[0]["date"] == date(2026, 1, 1)


def test_trip_outside_opt_dates_is_zero():
    trips, _ = run("2025-12-18,Departure,\n2026-01-06,Arrival,", opt=("2026-06-01", "2027-05-31"))
    assert trips[0]["days_between_in_opt"] == 0


def test_header_case_and_short_types():
    rows = read_rows([" Date , Type ,Port", "2026-01-01, d ,SFO", "", ",,", "2026-01-05,A,SFO"])
    assert rows == [(date(2026, 1, 1), "Departure", "SFO"), (date(2026, 1, 5), "Arrival", "SFO")]


def test_bad_input_raises():
    for lines in (["2026-01-01,Departure"], ["date,type", "01/02/2026,Departure"], ["date,type", "2026-01-01,Exit"]):
        try:
            read_rows(lines)
        except ValueError:
            continue
        raise AssertionError(f"no error for {lines}")


def test_main_on_sample_file():
    out = io.StringIO()
    with contextlib.redirect_stdout(out):
        code = main([os.path.join(HERE, "sample_history.csv"), "--opt-start", "2026-06-01", "--opt-end", "2027-05-31"])
    text = out.getvalue()
    assert code == 0
    assert text.startswith(BANNER)
    assert "Trip 1: left 2025-12-18 SFO -> back 2026-01-06 SFO | 19 days between, 18 full days outside, 0 days in OPT dates" in text
    assert "Trip 2: left 2026-05-20 LAX -> back 2026-06-10 LAX | 21 days between, 20 full days outside, 9 days in OPT dates" in text
    assert "CHECK 2026-03-01 San Ysidro: arrival_without_departure" in text


class PairTripsTests(unittest.TestCase):
    """Wraps every module-level test_ function so `python3 -m unittest` finds it."""


for _name, _fn in sorted(list(globals().items())):
    if _name.startswith("test_") and callable(_fn):
        setattr(PairTripsTests, _name, lambda self, _fn=_fn: _fn())


if __name__ == "__main__":
    unittest.main()