from datetime import date
from decimal import Decimal

from app.models.tables import Account, Category, RecurringItem, Statement, Transaction
from app.services.suggestions import suggest_recurring

H = {"Authorization": "Bearer test-key"}


def _seed_balance(db, amount="1000.00"):
    acc = Account(bank="dkb", iban="DE01", name="G", type="giro")
    db.add(acc)
    db.flush()
    db.add(Statement(filename="s.pdf", bank="dkb", account_id=acc.id,
                     period_start=date(2026, 6, 1), period_end=date(2026, 6, 30),
                     opening_balance=Decimal("0"), closing_balance=Decimal(amount),
                     status="confirmed"))
    db.commit()


def test_scenario_projection(client, db):
    _seed_balance(db)
    client.post("/api/recurring", headers=H, json={
        "name": "Miete", "amount": "-600.00", "rhythm": "monthly", "due_day": 1})
    sc = client.post("/api/scenarios", headers=H, json={"name": "Basis"}).json()
    r = client.post(f"/api/scenarios/{sc['id']}/project", headers=H,
                    params={"horizon_days": 92, "start_date": "2026-07-15"})
    assert r.status_code == 200
    body = r.json()
    # 3 Mietzahlungen (01.08., 01.09., 01.10.): 400 -> -200 -> -800
    assert Decimal(body["low_point_balance"]) == Decimal("-800.00")
    assert body["below_zero_date"] == "2026-09-01"
    assert len(body["series"]) == 92


def test_loan_in_scenario_keeps_balance_positive(client, db):
    _seed_balance(db)
    client.post("/api/recurring", headers=H, json={
        "name": "Miete", "amount": "-600.00", "rhythm": "monthly", "due_day": 1})
    loan = client.post("/api/loans", headers=H, json={
        "name": "K1", "principal": "5000.00", "annual_rate_pct": "6.0",
        "term_months": 48, "payout_date": "2026-07-20",
        "repayment_type": "annuity"}).json()
    sc = client.post("/api/scenarios", headers=H, json={"name": "Kredit"}).json()
    client.post(f"/api/scenarios/{sc['id']}/loans/{loan['id']}", headers=H)
    body = client.post(f"/api/scenarios/{sc['id']}/project", headers=H,
                       params={"horizon_days": 92, "start_date": "2026-07-15"}).json()
    assert Decimal(body["low_point_balance"]) > Decimal("0")


def _tx(acc, d, amount, counterparty, dedup, category_id=None):
    return Transaction(account_id=acc.id, booking_date=d, amount=Decimal(amount),
                       purpose="", counterparty=counterparty, status="confirmed",
                       dedup_hash=dedup, category_id=category_id)


def test_suggest_recurring_three_consecutive_months_with_year_wrap(db):
    acc = Account(bank="dkb", iban="DE01", name="G", type="giro")
    db.add(acc)
    db.flush()
    cat = Category(name="Miete")
    db.add(cat)
    db.flush()
    # Dez 2025 -> Jan 2026 -> Feb 2026: 3 aufeinanderfolgende Monate ueber den
    # Jahreswechsel hinweg (prueft die Monats-Linearisierung y*12+m).
    db.add(_tx(acc, date(2025, 12, 1), "-600.00", "Vermieter", "h1", cat.id))
    db.add(_tx(acc, date(2026, 1, 15), "-600.00", "Vermieter", "h2", cat.id))
    db.add(_tx(acc, date(2026, 2, 28), "-600.00", "Vermieter", "h3", cat.id))
    db.commit()

    out = suggest_recurring(db)

    # Median der Tage [1, 15, 28] = 15; Betrag unveraendert uebernommen.
    assert out == [{"name": "Vermieter", "amount": Decimal("-600.00"),
                    "rhythm": "monthly", "due_day": 15, "category_id": cat.id}]


def test_suggest_recurring_two_months_no_suggestion(db):
    acc = Account(bank="dkb", iban="DE01", name="G", type="giro")
    db.add(acc)
    db.flush()
    db.add(_tx(acc, date(2026, 3, 10), "-50.00", "Zweimonatig", "h1"))
    db.add(_tx(acc, date(2026, 4, 10), "-50.00", "Zweimonatig", "h2"))
    db.commit()

    assert suggest_recurring(db) == []


def test_suggest_recurring_excludes_existing_recurring_item(db):
    acc = Account(bank="dkb", iban="DE01", name="G", type="giro")
    db.add(acc)
    db.flush()
    db.add(_tx(acc, date(2026, 1, 5), "-30.00", "Streaming", "h1"))
    db.add(_tx(acc, date(2026, 2, 5), "-30.00", "Streaming", "h2"))
    db.add(_tx(acc, date(2026, 3, 5), "-30.00", "Streaming", "h3"))
    db.add(RecurringItem(name="Streaming", amount=Decimal("-30.00"),
                         rhythm="monthly", due_day=5))
    db.commit()

    # Gleicher Name + Betrag wie ein bereits vorhandenes RecurringItem -> ausgelassen.
    assert suggest_recurring(db) == []