"""State-change log conventions (architecture L12): every durable mutation emits one
JSON-lines event with the fixed envelope, from the store's own write path."""

import io
import json
import sqlite3
from pathlib import Path

import pytest

from nisse_dev.oplog import OpLog
from nisse_dev.reconcile import reconcile_on_boot
from nisse_dev.state import StateStore

ENVELOPE_FIELDS = {"ts", "agent", "event", "task_id", "cause"}


@pytest.fixture
def stream() -> io.StringIO:
    return io.StringIO()


@pytest.fixture
def store(tmp_path: Path, stream: io.StringIO) -> StateStore:
    return StateStore(tmp_path / "state.db", oplog=OpLog("nisse-dev", stream))


def events(stream: io.StringIO) -> list[dict]:
    return [json.loads(line) for line in stream.getvalue().splitlines()]


def start_item(
    store: StateStore, item_id: str, *, scope: str | None = None, cause: str
) -> None:
    """Open a work item, make it the active one and set it running."""
    store.open_work_item(
        item_id, title=item_id, scope=scope, position="IDLE", cause=cause
    )
    store.set_active(item_id, cause=cause)
    store.update_work_item(item_id, position="RUNNING", data={}, cause=cause)


def test_every_event_carries_the_envelope(
    store: StateStore, stream: io.StringIO
) -> None:
    start_item(store, "demo-1", cause="issue assigned")
    intent_id = store.begin_intent("push_branch", {}, cause="milestone execution")
    store.commit_intent(intent_id, cause="push verified")
    for event in events(stream):
        assert ENVELOPE_FIELDS <= event.keys()
        assert event["agent"] == "nisse-dev"


def test_a_position_change_logs_from_to_and_cause(
    store: StateStore, stream: io.StringIO
) -> None:
    start_item(store, "d-1", scope="d", cause="issue assigned")
    store.update_work_item("d-1", position="WAITING", data={}, cause="restated")
    # Opening the work item logs its own events first (work_item.open, .switch).
    first, second = [e for e in events(stream) if e["event"] == "state.transition"]
    assert (first["from"], first["to"]) == ("IDLE", "RUNNING")
    assert (second["from"], second["to"], second["project"]) == (
        "RUNNING",
        "WAITING",
        "d",
    )
    assert second["cause"] == "restated"


def test_intent_lifecycle_events(store: StateStore, stream: io.StringIO) -> None:
    intent_id = store.begin_intent("push_branch", {"b": "m2"}, cause="milestone")
    store.abort_intent(intent_id, cause="discarded")
    begin, abort = events(stream)
    assert begin["event"] == "intent.begin"
    assert abort["event"] == "intent.abort"
    assert begin["intent_id"] == abort["intent_id"] == intent_id
    assert begin["kind"] == abort["kind"] == "push_branch"


def test_task_id_threads_through_events(store: StateStore, stream: io.StringIO) -> None:
    store.open_work_item("general", title="general", position="IDLE", cause="boot")
    store.oplog.task_id = "task-42"
    start_item(store, "task-42", cause="issue assigned")
    before, *during = events(stream)
    assert before["task_id"] is None
    assert {e["task_id"] for e in during} == {"task-42"}


def test_migration_emits_event(tmp_path: Path, stream: io.StringIO) -> None:
    db = tmp_path / "state.db"
    with StateStore(db, schema_version=1):
        pass

    def add_notes(conn: sqlite3.Connection) -> None:
        conn.execute("CREATE TABLE notes (id INTEGER PRIMARY KEY)")

    with StateStore(
        db,
        schema_version=2,
        migrations={1: add_notes},
        oplog=OpLog("nisse-dev", stream),
    ):
        pass
    [event] = events(stream)
    assert event["event"] == "schema.migrate"
    assert (event["from_version"], event["to_version"]) == (1, 2)


def test_boot_reconcile_emits_action_and_verdicts(
    store: StateStore, stream: io.StringIO
) -> None:
    store.begin_intent("push_branch", {}, cause="milestone")
    reconcile_on_boot(store, {"push_branch": lambda intent: True})
    boot = [e for e in events(stream) if e["event"] == "boot.reconcile"]
    assert len(boot) == 1
    assert boot[0]["action"] == "resume"
    assert "effect verified" in boot[0]["verdicts"][0]
    commit = [e for e in events(stream) if e["event"] == "intent.commit"]
    assert commit[0]["cause"] == "reconciliation verdict: effect verified"


def test_literal_log_lines_for_human_readability(
    store: StateStore, stream: io.StringIO, monkeypatch: pytest.MonkeyPatch
) -> None:
    """Asserts the exact bytes written per line, so the on-disk format is
    visible here rather than only in a running system."""

    class _FrozenDatetime:
        @staticmethod
        def now(tz: object) -> object:
            from datetime import UTC, datetime

            return datetime(2026, 9, 5, 12, 0, 0, tzinfo=UTC)

    monkeypatch.setattr("nisse_dev.oplog.datetime", _FrozenDatetime)

    start_item(store, "demo-m2", scope="demo", cause="issue assigned: demo#2")
    store.oplog.task_id = "demo-m2"
    intent_id = store.begin_intent(
        "push_branch", {"branch": "milestone-2"}, cause="milestone 2 execution"
    )
    store.commit_intent(intent_id, cause="push verified by Gitea query")

    assert stream.getvalue().splitlines() == [
        (
            '{"ts": "2026-09-05T12:00:00+00:00", "agent": "nisse-dev",'
            ' "event": "work_item.open", "task_id": null,'
            ' "cause": "issue assigned: demo#2",'
            ' "work_item": "demo-m2", "scope": "demo"}'
        ),
        (
            '{"ts": "2026-09-05T12:00:00+00:00", "agent": "nisse-dev",'
            ' "event": "work_item.switch", "task_id": null,'
            ' "cause": "issue assigned: demo#2",'
            ' "from": null, "to": "demo-m2"}'
        ),
        (
            '{"ts": "2026-09-05T12:00:00+00:00", "agent": "nisse-dev",'
            ' "event": "state.transition", "task_id": null,'
            ' "cause": "issue assigned: demo#2",'
            ' "from": "IDLE", "to": "RUNNING", "project": "demo"}'
        ),
        (
            '{"ts": "2026-09-05T12:00:00+00:00", "agent": "nisse-dev",'
            ' "event": "intent.begin", "task_id": "demo-m2",'
            ' "cause": "milestone 2 execution", "intent_id": 1,'
            ' "kind": "push_branch"}'
        ),
        (
            '{"ts": "2026-09-05T12:00:00+00:00", "agent": "nisse-dev",'
            ' "event": "intent.commit", "task_id": "demo-m2",'
            ' "cause": "push verified by Gitea query",'
            ' "intent_id": 1, "kind": "push_branch"}'
        ),
    ]


def test_failed_resolution_emits_nothing(
    store: StateStore, stream: io.StringIO
) -> None:
    with pytest.raises(KeyError):
        store.commit_intent(9999, cause="test")
    assert events(stream) == []