"""Tests for the SessionDB read-path split (per-thread read-only connections).

The gateway shares ONE SessionDB across every agent, so recall/browse reads
used to queue behind writer flushes on self._lock — a measured production
convoy (a 0.2s FTS query stretched to 112s while 6-8 concurrent turns
flushed tool results). These tests pin the new contract: reads run on a
per-thread read-only connection under WAL, never touch self._lock, and fall
back to the legacy locked path when WAL or the read connection is missing.
"""

import threading

import pytest

from hermes_state import SessionDB


@pytest.fixture()
def db(tmp_path):
    d = SessionDB(db_path=tmp_path / "state.db")
    d.create_session(session_id="s1", source="cli", model="m")
    d.append_message("s1", role="user", content="hello graphiti world")
    d.append_message("s1", role="assistant", content="the neo4j daemon is healthy")
    yield d
    d.close()


@pytest.mark.requires_wal
def test_read_conn_is_per_thread(db):
    conns = {}

    def grab(key):
        conns[key] = db._get_read_conn()

    t1 = threading.Thread(target=grab, args=(1,))
    t2 = threading.Thread(target=grab, args=(2,))
    t1.start(); t2.start(); t1.join(); t2.join()
    assert conns[1] is not None and conns[2] is not None
    assert conns[1] is not conns[2]


def test_read_conn_reused_within_thread(db):
    assert db._get_read_conn() is db._get_read_conn()


@pytest.mark.requires_wal
def test_reads_do_not_take_writer_lock(db):
    """Reads must complete while another thread holds self._lock."""
    acquired = db._lock.acquire()
    assert acquired
    try:
        done = {}

        def reader():
            done["session"] = db.get_session("s1")
            done["search"] = db.search_messages("graphiti", limit=10)
            done["messages"] = db.get_messages("s1")

        t = threading.Thread(target=reader)
        t.start()
        t.join(timeout=5.0)
        assert not t.is_alive(), "read path blocked on writer lock"
        assert done["session"]["id"] == "s1"
        assert any("graphiti" in (m.get("snippet") or "") for m in done["search"])
        assert len(done["messages"]) == 2
    finally:
        db._lock.release()


@pytest.mark.requires_wal
def test_title_resolution_does_not_take_writer_lock(db):
    """Exact-title and numbered-variant resolution must not block on self._lock."""
    db.create_session(session_id="t1", source="cli", model="m")
    db.set_session_title("t1", "ops sync")
    db.create_session(session_id="t2", source="cli", model="m")
    db.set_session_title("t2", "ops sync #2")
    acquired = db._lock.acquire()
    assert acquired
    try:
        done = {}

        def reader():
            done["exact"] = db.get_session_by_title("ops sync")
            done["resolved"] = db.resolve_session_by_title("ops sync")

        t = threading.Thread(target=reader)
        t.start()
        t.join(timeout=5.0)
        assert not t.is_alive(), "title resolution blocked on writer lock"
        assert done["exact"]["id"] == "t1"
        # Lineage rule: the latest numbered variant wins over the exact match.
        assert done["resolved"] == "t2"
    finally:
        db._lock.release()


def test_read_your_writes(db):
    """A fresh committed write must be visible to the read connection."""
    db.append_message("s1", role="user", content="zanzibar checkpoint")
    rows = db.search_messages("zanzibar", limit=5)
    assert rows, "committed write invisible to read connection"


def test_fallback_when_read_conn_unavailable(db, monkeypatch):
    monkeypatch.setattr(db, "_get_read_conn", lambda: None)
    assert db.get_session("s1")["id"] == "s1"
    assert db.search_messages("graphiti", limit=5)


def test_non_wal_uses_locked_path(db):
    db._wal_active = False
    assert db._get_read_conn() is None
    # And queries still work via the legacy path.
    assert db.get_session("s1")["id"] == "s1"


@pytest.mark.requires_wal
def test_read_conn_open_failure_marks_thread(db, monkeypatch, tmp_path):
    """A failed read-conn open must not retry per query; fallback still works."""
    import sqlite3 as _sqlite3

    calls = {"n": 0}
    real_connect = _sqlite3.connect

    def failing_connect(*a, **k):
        if a and isinstance(a[0], str) and a[0].startswith("file:") and "mode=ro" in a[0]:
            calls["n"] += 1
            raise _sqlite3.OperationalError("simulated open failure")
        return real_connect(*a, **k)

    fresh = SessionDB(db_path=tmp_path / "state2.db")
    try:
        fresh.create_session(session_id="x", source="cli", model="m")
        monkeypatch.setattr("hermes_state.sqlite3.connect", failing_connect)
        assert fresh.get_session("x")["id"] == "x"
        assert fresh.get_session("x")["id"] == "x"
        assert calls["n"] == 1, "open failure should be remembered per thread"
    finally:
        fresh.close()


@pytest.mark.requires_wal
def test_anchored_view_and_around_use_read_path(db):
    msgs = db.get_messages("s1")
    anchor = msgs[0]["id"]
    acquired = db._lock.acquire()
    try:
        done = {}

        def reader():
            done["around"] = db.get_messages_around("s1", anchor, window=2)
            done["view"] = db.get_anchored_view("s1", anchor, window=2, bookend=1)

        t = threading.Thread(target=reader)
        t.start(); t.join(timeout=5.0)
        assert not t.is_alive(), "anchored reads blocked on writer lock"
        assert done["around"]["window"]
        assert done["view"]["window"]
    finally:
        db._lock.release()