import pytest
from env import SQLAnalystEnv, Action


class TestOpenEnvContract:
    """Test OpenEnv required methods: reset(), step(), state()"""

    def test_reset_returns_step_result(self):
        """reset() must return a StepResult with observation"""
        env = SQLAnalystEnv(task_id="monthly_signups")
        result = env.reset()

        assert result.observation is not None
        assert result.reward == 0.0
        assert result.done is False

    def test_reset_contains_required_fields(self):
        """Initial observation must contain all required fields"""
        env = SQLAnalystEnv(task_id="monthly_signups")
        result = env.reset()
        obs = result.observation

        assert obs.schema_summary is not None
        assert obs.question is not None
        assert obs.step == 0
        assert obs.max_steps == 10

    def test_step_returns_step_result(self):
        """step() must return StepResult with observation, reward, done"""
        env = SQLAnalystEnv(task_id="monthly_signups")
        env.reset()

        action = Action(sql_query="SELECT COUNT(*) FROM users")
        result = env.step(action)

        assert result.observation is not None
        assert isinstance(result.reward, float)
        assert isinstance(result.done, bool)
        assert result.info is not None

    def test_step_increments_step_count(self):
        """Each step should increment step count"""
        env = SQLAnalystEnv(task_id="monthly_signups")
        env.reset()

        action = Action(sql_query="SELECT COUNT(*) FROM users")

        result1 = env.step(action)
        assert result1.observation.step == 1

        result2 = env.step(action)
        assert result2.observation.step == 2

    def test_step_sql_query_execution(self):
        """step() with sql_query should execute query and return result"""
        env = SQLAnalystEnv(task_id="monthly_signups")
        env.reset()

        action = Action(sql_query="SELECT COUNT(*) as cnt FROM users")
        result = env.step(action)

        assert result.observation.last_query is not None
        assert result.observation.last_result is not None
        assert "cnt" in result.observation.last_result.columns

    def test_step_submit_answer_terminates(self):
        """submit_answer should set done=True"""
        env = SQLAnalystEnv(task_id="monthly_signups")
        env.reset()

        action = Action(submit_answer="100")
        result = env.step(action)

        assert result.done is True

    def test_step_max_steps_terminates(self):
        """Exceeding max_steps should terminate episode"""
        env = SQLAnalystEnv(task_id="monthly_signups")
        env.reset()

        # Easy task has max_steps=10
        done_count = 0
        for i in range(10):
            action = Action(sql_query="SELECT 1")
            result = env.step(action)
            if result.done:
                done_count += 1

        # At step 10 (last step), done should be True
        assert done_count >= 1, "Episode should terminate by step 10"

    def test_state_returns_full_state(self):
        """state() should return EnvState with all metadata"""
        env = SQLAnalystEnv(task_id="monthly_signups")
        env.reset()

        env.step(Action(sql_query="SELECT 1"))

        state = env.state()

        assert state.task_id == "monthly_signups"
        assert state.difficulty == "easy"
        assert state.step > 0
        assert state.max_steps == 10
        assert len(state.query_history) > 0

    def test_invalid_action_raises(self):
        """Action with both sql_query and submit_answer should error"""
        env = SQLAnalystEnv(task_id="monthly_signups")
        env.reset()

        # This should fail - exactly one must be set
        with pytest.raises(AssertionError):
            action = Action(sql_query="SELECT 1", submit_answer="test")
            env.step(action)

    def test_all_three_tasks_work(self):
        """All task IDs should be supported"""
        for task_id in ["monthly_signups", "top_revenue_category", "churn_analysis"]:
            env = SQLAnalystEnv(task_id=task_id)
            result = env.reset()
            assert result.observation.question is not None


class TestEdgeCases:
    """Test edge cases and error handling"""

    def test_sql_error_returns_error_in_observation(self):
        """Invalid SQL should return error in observation"""
        env = SQLAnalystEnv(task_id="monthly_signups")
        env.reset()

        action = Action(sql_query="SELECT * FROM nonexistent_table")
        result = env.step(action)

        assert result.observation.last_error is not None
        assert result.observation.last_error != ""

    def test_non_select_blocked(self):
        """Non-SELECT queries should be blocked"""
        env = SQLAnalystEnv(task_id="monthly_signups")
        env.reset()

        action = Action(sql_query="DELETE FROM users")
        result = env.step(action)

        assert result.observation.last_error is not None
        assert "Only SELECT" in result.observation.last_error

    def test_empty_db_after_reset(self):
        """Database should have data after reset"""
        env = SQLAnalystEnv(task_id="monthly_signups")
        env.reset()

        result = env.step(Action(sql_query="SELECT COUNT(*) FROM users"))
        assert result.observation.last_result.rows[0][0] > 0