import json


def test_new_session_creates_folder_and_state(tmp_path):
    from core.session import new_session, load_state
    session_id = new_session("message", question="test question", base_dir=tmp_path)
    session_dir = tmp_path / session_id
    assert session_dir.is_dir()
    state = load_state(session_id, base_dir=tmp_path)
    assert state["session_id"] == session_id
    assert state["input_mode"] == "message"
    assert state["question"] == "test question"
    assert state["current_step"] == 0
    assert state["bind_results"] == {}


def test_new_session_chips_mode(tmp_path):
    from core.session import new_session, load_state
    session_id = new_session("chips", base_dir=tmp_path)
    state = load_state(session_id, base_dir=tmp_path)
    assert state["input_mode"] == "chips"
    assert state["question"] == ""


def test_write_state_merges_patch(tmp_path):
    from core.session import new_session, write_state, load_state
    session_id = new_session("message", question="q", base_dir=tmp_path)
    write_state(session_id, {"current_step": 1, "route": {"sectors": ["WASH"]}}, base_dir=tmp_path)
    state = load_state(session_id, base_dir=tmp_path)
    assert state["current_step"] == 1
    assert state["route"] == {"sectors": ["WASH"]}
    assert state["question"] == "q"  # untouched field preserved


def test_write_state_deep_merges_bind_results(tmp_path):
    from core.session import new_session, write_state, load_state
    session_id = new_session("message", question="q", base_dir=tmp_path)
    write_state(session_id, {"bind_results": {"rcsi": {"verdict": "PROXY"}}}, base_dir=tmp_path)
    write_state(session_id, {"bind_results": {"fcs": {"verdict": "NOT_MEASURABLE"}}}, base_dir=tmp_path)
    state = load_state(session_id, base_dir=tmp_path)
    assert "rcsi" in state["bind_results"]
    assert "fcs" in state["bind_results"]


def test_write_state_is_atomic(tmp_path):
    """state.json should never be in a partial-write state."""
    from core.session import new_session, write_state
    session_id = new_session("message", question="q", base_dir=tmp_path)
    write_state(session_id, {"current_step": 2}, base_dir=tmp_path)
    state_file = tmp_path / session_id / "state.json"
    # No .tmp file should remain after write
    assert not (tmp_path / session_id / "state.json.tmp").exists()
    # state.json is valid JSON
    json.loads(state_file.read_text())