"""A node's settings are arguments of its function, like its ports.

What distinguishes them is where the value comes from: a port carries whatever
the graph last published, a setting is a constant stored with the flow. Both
arrive by name, so one name cannot mean both.
"""

from pathlib import Path

import pytest

from app.flow.controller import FlowController
from app.flow.messages import DType, MessageSpec
from app.flow.pipeline import Pipeline
from app.flow.schemas import FlowDef, NodeDef
from app.flow.state import MemoryState
from app.flow.store import FlowStore

SOURCE = "def process(reading, factor):\n    return {'scaled': reading * factor}\n"


def a_flow(**params: object) -> FlowDef:
    return FlowDef(
        name="house",
        nodes=[
            NodeDef(
                id="scale",
                params=dict(params),
                requires=[MessageSpec(name="reading", dtype=DType.FLOAT)],
                provides=[MessageSpec(name="scaled", dtype=DType.FLOAT)],
            )
        ],
    )


@pytest.fixture
def store(tmp_path: Path) -> FlowStore:
    return FlowStore(tmp_path / "flows")


def test_a_setting_reaches_the_function_as_a_keyword_argument(store: FlowStore):
    store.write_flow(a_flow(factor=3))
    store.write_node_source("house", "scale", SOURCE)
    controller = FlowController(store)

    nodes, _loaded, _initial, _inputs = controller._build_flows(
        [(store.read_flow("house"), False)]
    )
    pipeline = Pipeline(nodes=nodes, state=MemoryState())
    pipeline.run({"house.reading": 2.0})

    assert pipeline.values()["house.scaled"]["value"] == 6.0


def test_a_setting_named_after_a_port_is_refused(store: FlowStore):
    store.write_draft(a_flow(reading=3), 0)
    store.write_node_source("house", "scale", SOURCE, draft=True)
    controller = FlowController(store)

    preview = controller.preview("house")

    assert [node.status for node in preview.nodes] == ["error"]
    assert "both an input and a setting" in (preview.nodes[0].error or "")