import subprocess
from pathlib import Path

import pytest

from app.flow.messages import MessageSpec
from app.flow.schemas import FlowDef, NodeDef
from app.flow.store import FlowExists, FlowNotFound, FlowStore


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


def commit_count(store: FlowStore) -> int:
    result = subprocess.run(
        ["git", "-C", str(store.root), "rev-list", "--count", "HEAD"],
        capture_output=True,
        text=True,
        check=True,
    )
    return int(result.stdout.strip())


def a_flow() -> FlowDef:
    return FlowDef(
        name="heating",
        nodes=[NodeDef(id="sensor", provides=[MessageSpec(name="temp")])],
    )


def test_flow_round_trips(store: FlowStore):
    store.write_flow(a_flow())

    assert store.list_flows() == ["heating"]
    assert store.read_flow("heating").nodes[0].provides[0].name == "temp"


def test_every_change_is_committed(store: FlowStore):
    before = commit_count(store)

    store.write_flow(a_flow())
    assert commit_count(store) == before + 1

    store.write_node_source("heating", "sensor", "def process():\n    return {}\n")
    assert commit_count(store) == before + 2


def test_saving_unchanged_content_does_nothing(store: FlowStore):
    store.write_flow(a_flow())
    commits = commit_count(store)

    # Autosave repeats the same document; history should not grow.
    assert store.write_flow(a_flow()) is False
    assert commit_count(store) == commits


def test_missing_flow_is_reported(store: FlowStore):
    with pytest.raises(FlowNotFound):
        store.read_flow("nope")


def test_deleting_removes_flow_and_its_nodes(store: FlowStore):
    store.write_flow(a_flow())
    store.write_node_source("heating", "sensor", "def process():\n    return {}\n")

    store.delete_flow("heating")

    assert store.list_flows() == []
    assert not (store.root / "heating").exists()


def test_renaming_a_flow_carries_its_nodes(store: FlowStore):
    store.write_flow(a_flow())
    store.write_node_source("heating", "sensor", "def process():\n    return {}\n")

    renamed = store.rename_flow("heating", "warmth")

    assert renamed.name == "warmth"
    assert store.list_flows() == ["warmth"]
    assert "def process" in store.read_node_source("warmth", "sensor")


def test_renaming_a_flow_repoints_the_flows_reading_it(store: FlowStore):
    store.write_flow(a_flow())
    store.write_flow(
        FlowDef(
            name="display",
            nodes=[
                NodeDef(
                    id="gauge",
                    # Reads across the flow boundary, so the name must follow.
                    requires=[MessageSpec(name="heating.temp")],
                )
            ],
        )
    )

    store.rename_flow("heating", "warmth")

    display = store.read_flow("display")
    assert display.nodes[0].requires[0].name == "warmth.temp"


def test_renaming_onto_an_existing_name_is_refused(store: FlowStore):
    store.write_flow(a_flow())
    store.write_flow(FlowDef(name="warmth"))

    with pytest.raises(FlowExists):
        store.rename_flow("heating", "warmth")

    assert store.list_flows() == ["heating", "warmth"]