from contextlib import contextmanager
import json
import pytest
from fastapi import HTTPException
from app.services import email_purchase_link as service


@pytest.fixture
def db(monkeypatch):
    state = {'writes': [], 'mail': {'id': 7, 'linked_case_id': None},
             'purchase': {'id': 10, 'sag_id': 42, 'description': 'Router', 'case_title': 'Netværk'}, 'previous': None}
    @contextmanager
    def transaction():
        try:
            yield
            state['committed'] = True
        except Exception:
            state['rolled_back'] = True
            raise
    def read(sql, params):
        if 'FROM email_messages' in sql:
            assert 'FOR UPDATE' in sql
            return state['mail']
        if 'FROM sag_salgsvarer' in sql:
            assert "p.type = 'purchase'" in sql and "p.status <> 'cancelled'" in sql
            return state['purchase']
        return state['previous']
    monkeypatch.setattr(service, 'atomic_transaction', transaction)
    monkeypatch.setattr(service, 'execute_query_single', read)
    monkeypatch.setattr(service, 'execute_update', lambda sql, params: state['writes'].append((sql, params)))
    return state


@pytest.mark.parametrize('kind,tracking', [('order_confirmation', None), ('freight_note', 'TRACK-123')])
def test_purchase_mail_links_and_logs_without_marking_goods_received(db, kind, tracking):
    result = service.link_purchase_mail(7, 10, kind, tracking)
    assert result['sag_id'] == 42
    assert db['committed']
    assert len(db['writes']) == 3
    assert not any('UPDATE sag_salgsvarer' in sql for sql, _ in db['writes'])
    metadata = json.loads(db['writes'][-1][1][2])
    assert metadata == {'purchase_id': 10, 'sag_id': 42, 'kind': kind, 'tracking_number': tracking}


def test_repeated_identical_purchase_link_is_idempotent(db):
    db['previous'] = {'metadata': {'purchase_id': 10, 'sag_id': 42, 'kind': 'freight_note', 'tracking_number': None}}
    assert service.link_purchase_mail(7, 10, 'freight_note')['idempotent']
    assert not db['writes']


@pytest.mark.parametrize('conflict', ['case', 'purchase', 'missing_mail', 'missing_purchase'])
def test_conflicting_or_missing_target_does_not_write(db, conflict):
    if conflict == 'case': db['mail']['linked_case_id'] = 99
    if conflict == 'purchase': db['previous'] = {'metadata': {'purchase_id': 99}}
    if conflict == 'missing_mail': db['mail'] = None
    if conflict == 'missing_purchase': db['purchase'] = None
    with pytest.raises(HTTPException): service.link_purchase_mail(7, 10, 'order_confirmation')
    assert not db['writes']
    assert db['rolled_back']


def test_failure_between_link_and_audit_rolls_back(monkeypatch, db):
    def fail(sql, params):
        if 'UPDATE email_messages' in sql: raise RuntimeError('DB failed')
    monkeypatch.setattr(service, 'execute_update', fail)
    with pytest.raises(RuntimeError): service.link_purchase_mail(7, 10, 'freight_note')
    assert db['rolled_back']
    assert not db.get('committed')