from contextlib import nullcontext
from pathlib import Path

import app.communication_service as service


class _Result:
    def __init__(self, *, scalar_value=None, rows=()):
        self.scalar_value = scalar_value
        self.rows = list(rows)

    def scalar(self):
        return self.scalar_value

    def mappings(self):
        return self

    def all(self):
        return self.rows


class _Connection:
    def __init__(self, *, possible, rows=()):
        self.possible = possible
        self.rows = rows
        self.statements = []

    def execute(self, statement, params=None):
        self.statements.append((str(statement), params))
        if len(self.statements) == 1:
            return _Result(scalar_value=self.possible)
        return _Result(rows=self.rows)


class _Engine:
    def __init__(self, connection):
        self.connection = connection

    def begin(self):
        return nullcontext(self.connection)


def test_no_historical_candidates_returns_after_one_statement(monkeypatch):
    connection = _Connection(possible=False)
    monkeypatch.setattr(service, "engine", _Engine(connection))

    assert service._list_message_backed_chatwoot_items_for_opportunity(
        "dc3c020e-33eb-4067-b7da-ab684533a425"
    ) == []
    assert len(connection.statements) == 1
    assert "SELECT EXISTS" in connection.statements[0][0]


def test_positive_fallback_uses_two_statements_and_preserves_rows(monkeypatch):
    expected = [{"id": "message-1", "source_system": "chatwoot", "created_at": "2026-08-14"}]
    connection = _Connection(possible=True, rows=expected)
    monkeypatch.setattr(service, "engine", _Engine(connection))

    result = service._list_message_backed_chatwoot_items_for_opportunity(
        "dc3c020e-33eb-4067-b7da-ab684533a425", limit=12
    )

    assert result == expected
    assert len(connection.statements) == 2
    assert connection.statements[1][1]["limit"] == 12


def test_relationship_paths_are_unioned_without_or_join_conditions(monkeypatch):
    connection = _Connection(possible=True)
    monkeypatch.setattr(service, "engine", _Engine(connection))
    service._list_message_backed_chatwoot_items_for_opportunity(
        "dc3c020e-33eb-4067-b7da-ab684533a425"
    )
    sql = connection.statements[1][0]

    assert "re.id = m.raw_event_id OR re.message_id = m.id" not in sql
    assert "ar.message_id = m.id OR ar.raw_event_id = re.id" not in sql
    assert "t.message_id = m.id OR t.raw_event_id = re.id" not in sql
    assert sql.count(" UNION\n") >= 10
    assert "SELECT DISTINCT ON (m.id)" in sql
    assert "ORDER BY m.id, COALESCE(t.created_at, m.created_at) DESC" in sql
    assert "ORDER BY created_at DESC" in sql


def test_only_missing_relationship_indexes_are_added():
    migration = Path("migrations/008_historical_communication_lookup_indexes.sql").read_text()
    expected = {
        "messages(raw_event_id)",
        "raw_events(message_id)",
        "action_runs(message_id)",
        "action_runs(raw_event_id)",
        "tasks(message_id)",
        "tasks(raw_event_id)",
        "tasks(action_run_id)",
    }
    assert all(columns in migration for columns in expected)
    assert "messages(conversation_id)" not in migration
    assert "raw_events(conversation_id)" not in migration
    assert "tasks(opportunity_id)" not in migration