import sqlite3
import threading

import pytest

from sqlmem.cache import CacheManager


@pytest.fixture
def cache(tmp_path):
    c = CacheManager(db_path=tmp_path / "test_cache.db", backup_interval=9999)
    yield c
    c.close()


@pytest.fixture
def source_conn():
    conn = sqlite3.connect(":memory:")
    conn.execute("CREATE TABLE users (name TEXT, email TEXT, status TEXT)")
    conn.executemany(
        "INSERT INTO users VALUES (?, ?, ?)",
        [("alice", "alice@example.com", "active"), ("bob", "bob@example.com", "inactive")],
    )
    conn.commit()
    yield conn
    conn.close()


def test_table_not_cached_initially(cache):
    assert cache.is_table_cached("users") is False


def test_load_table(cache, source_conn):
    cache.load_table("users", ["name", "email"], source_conn)
    assert cache.is_table_cached("users") is True


def test_loaded_data_correct(cache, source_conn):
    cache.load_table("users", ["name", "email"], source_conn)
    rows = cache.connection.execute("SELECT name, email FROM users").fetchall()
    assert len(rows) == 2
    assert ("alice", "alice@example.com") in rows


def test_mark_table_refreshed(cache, source_conn):
    cache.load_table("users", ["name"], source_conn)
    row = cache.connection.execute(
        "SELECT row_count FROM _sqlmem_tables WHERE table_name = 'users'"
    ).fetchone()
    assert row[0] == 2


def test_backup_and_reload(tmp_path, source_conn):
    db_path = tmp_path / "cache.db"
    c1 = CacheManager(db_path=db_path, backup_interval=9999)
    c1.load_table("users", ["name"], source_conn)
    c1.close()

    c2 = CacheManager(db_path=db_path, backup_interval=9999)
    assert c2.is_table_cached("users") is True
    c2.close()


# ---------------------------------------------------------------------------
# Disk-backed mode (in_memory=False)
# ---------------------------------------------------------------------------

def test_disk_mode_persists_without_backup(tmp_path, source_conn):
    """Disk mode writes straight to the file — no explicit backup/close needed."""
    db_path = tmp_path / "cache.db"
    c = CacheManager(db_path=db_path, backup_interval=9999, in_memory=False)
    c.load_table("users", ["name"], source_conn)
    # Data is already on disk; a brand-new disk-mode manager sees it.
    c2 = CacheManager(db_path=db_path, backup_interval=9999, in_memory=False)
    assert c2.is_table_cached("users") is True
    c2.close()
    c.close()


def test_disk_mode_file_created_immediately(tmp_path, source_conn):
    db_path = tmp_path / "cache.db"
    c = CacheManager(db_path=db_path, backup_interval=9999, in_memory=False)
    c.load_table("users", ["name"], source_conn)
    assert db_path.exists()
    c.close()


def test_disk_mode_reload_in_new_instance(tmp_path, source_conn):
    db_path = tmp_path / "cache.db"
    c1 = CacheManager(db_path=db_path, backup_interval=9999, in_memory=False)
    c1.load_table("users", ["name", "email"], source_conn)
    c1.close()

    c2 = CacheManager(db_path=db_path, backup_interval=9999, in_memory=False)
    rows = c2.connection.execute("SELECT name FROM users").fetchall()
    assert {r[0] for r in rows} == {"alice", "bob"}
    c2.close()


def test_quoted_reserved_and_spaced_identifiers(tmp_path):
    """Table/column names that are reserved words or contain spaces must work."""
    src = sqlite3.connect(":memory:")
    src.execute('CREATE TABLE "weird tbl" ("order" TEXT, "group by" TEXT)')
    src.executemany('INSERT INTO "weird tbl" VALUES (?, ?)', [("1", "a"), ("2", "b")])
    src.commit()

    c = CacheManager(db_path=tmp_path / "c.db", backup_interval=9999)
    c.load_table("weird tbl", ["order", "group by"], src)
    assert c.is_table_cached("weird tbl") is True
    _, rows = c.execute_in_memory('SELECT "order", "group by" FROM "weird tbl"')
    assert ("1", "a") in rows
    c.close()
    src.close()


def test_disk_mode_uses_separate_read_connection(tmp_path, source_conn):
    """Disk-mode reads go through a per-thread read connection, not the writer."""
    c = CacheManager(db_path=tmp_path / "c.db", backup_interval=9999, in_memory=False)
    c.load_table("users", ["name", "email"], source_conn)

    _, rows = c.execute_in_memory("SELECT name FROM users ORDER BY name")
    assert [r[0] for r in rows] == ["alice", "bob"]
    assert len(c._read_conns) == 1
    assert c._read_conns[0] is not c.connection  # dedicated read conn
    c.close()


def test_disk_mode_concurrent_reads(tmp_path, source_conn):
    """Several reader threads each get their own connection and correct results."""
    c = CacheManager(db_path=tmp_path / "c.db", backup_interval=9999, in_memory=False)
    c.load_table("users", ["name"], source_conn)

    results: list[int] = []
    errors: list[Exception] = []

    def reader() -> None:
        try:
            _, rows = c.execute_in_memory("SELECT name FROM users")
            results.append(len(rows))
        except Exception as e:  # noqa: BLE001
            errors.append(e)

    threads = [threading.Thread(target=reader) for _ in range(5)]
    for t in threads:
        t.start()
    for t in threads:
        t.join(5)

    assert not errors
    assert results == [2] * 5
    assert len(c._read_conns) == 5  # one read connection per reader thread
    c.close()


def test_memory_mode_uses_shared_connection(cache, source_conn):
    """In-memory mode can't share :memory: across connections — no read conns."""
    cache.load_table("users", ["name"], source_conn)
    cache.execute_in_memory("SELECT name FROM users")
    assert cache._read_conns == []


def test_disk_mode_reset_keeps_file(tmp_path, source_conn):
    db_path = tmp_path / "cache.db"
    c = CacheManager(db_path=db_path, backup_interval=9999, in_memory=False)
    c.load_table("users", ["name"], source_conn)
    c.reset()
    # File stays (the connection is still open) but the table is gone.
    assert db_path.exists()
    assert c.is_table_cached("users") is False
    c.close()