"""B-97 (DAT-75, DAT-56, ARC-62, ARC-64): the Alembic chain is executed, not assumed.

The two expression indexes that carry invariants — `ix_rounds_single_active` ("at
most one active round", B-09) and `ix_users_username_lower` ("usernames are
case-insensitive", B-57) — are invisible to autogenerate, and `batch_alter_table`
on SQLite rebuilds the table and drops them with only a warning. Every other test
builds its schema with `Base.metadata.create_all`, so a migration that lost one of
them would reach production unnoticed. This one runs `alembic upgrade head` on an
empty database, exactly as the container does at startup.

Alembic runs in a subprocess: env.py calls `asyncio.run` and `fileConfig`, neither of
which belongs inside the pytest process.
"""

import os
import re
import sqlite3
import subprocess
import sys
from pathlib import Path

import pytest

_ROOT = Path(__file__).resolve().parents[2]


@pytest.fixture(scope="module")
def migrated_db(tmp_path_factory) -> Path:
    db_path = tmp_path_factory.mktemp("migrations") / "migrated.db"
    env = {**os.environ, "DATABASE_URL": f"sqlite+aiosqlite:///{db_path}"}
    result = subprocess.run(
        [sys.executable, "-m", "alembic", "upgrade", "head"],
        cwd=_ROOT,
        env=env,
        capture_output=True,
        text=True,
        timeout=120,
    )
    assert result.returncode == 0, f"alembic upgrade head failed:\n{result.stderr[-3000:]}"
    return db_path


def _index_sql(db_path: Path, name: str) -> str | None:
    with sqlite3.connect(db_path) as conn:
        row = conn.execute("SELECT sql FROM sqlite_master WHERE type = 'index' AND name = ?", (name,)).fetchone()
    return re.sub(r"\s+", " ", row[0]).lower() if row else None


def test_the_expression_indexes_survive_the_whole_migration_chain(migrated_db):
    """DAT-75 / ARC-62 / B-97: both indexes exist, with their definition, at head."""
    single_active = _index_sql(migrated_db, "ix_rounds_single_active")
    assert single_active is not None, "ix_rounds_single_active was lost by a migration"
    assert "unique index" in single_active
    assert "on rounds ((1))" in single_active
    for status in ("open", "closing", "drawing", "paying_out"):
        assert f"'{status}'" in single_active

    username_lower = _index_sql(migrated_db, "ix_users_username_lower")
    assert username_lower is not None, "ix_users_username_lower was lost by a migration"
    assert "unique index" in username_lower
    assert "lower(username)" in username_lower


def test_the_migrated_database_still_enforces_both_invariants(migrated_db):
    """DAT-75 / B-97: a second active round and a case-variant username are refused."""
    with sqlite3.connect(migrated_db) as conn:
        conn.execute("INSERT INTO rounds (status, opened_at) VALUES ('open', '2026-01-01 00:00:00')")
        with pytest.raises(sqlite3.IntegrityError):
            conn.execute("INSERT INTO rounds (status, opened_at) VALUES ('closing', '2026-01-01 00:00:00')")
        # A closed round is not active, so any number of them may coexist.
        conn.execute("INSERT INTO rounds (status, opened_at) VALUES ('closed', '2026-01-01 00:00:00')")

        columns = "(username, password_hash, derivation_index, address, cached_balance_sats, token_version, created_at)"
        conn.execute(f"INSERT INTO users {columns} VALUES ('Alice', 'x', 0, 'plm1qa', 0, 0, '2026-01-01 00:00:00')")
        with pytest.raises(sqlite3.IntegrityError):
            conn.execute(f"INSERT INTO users {columns} VALUES ('aLICE', 'x', 1, 'plm1qb', 0, 0, '2026-01-01 00:00:00')")