"""给已经上线的库补上认证字段。create_all 不会修改旧表。"""

from sqlalchemy import inspect, text

from app.database import engine


def upgrade_schema() -> None:
    inspector = inspect(engine)
    if "users" not in inspector.get_table_names():
        return
    columns = {column["name"] for column in inspector.get_columns("users")}
    statements: list[str] = []
    if "username" not in columns:
        statements.append("ALTER TABLE users ADD COLUMN username VARCHAR(32)")
    if "password_hash" not in columns:
        statements.append("ALTER TABLE users ADD COLUMN password_hash VARCHAR(255)")
    if "role" not in columns:
        statements.append("ALTER TABLE users ADD COLUMN role VARCHAR(16) DEFAULT 'user' NOT NULL")
    if not statements and _has_username_index(inspector):
        return
    with engine.begin() as conn:
        for statement in statements:
            conn.execute(text(statement))
        if not _has_username_index(inspector):
            conn.execute(text("CREATE UNIQUE INDEX IF NOT EXISTS uq_users_username ON users (username)"))


def _has_username_index(inspector) -> bool:
    if "users" not in inspector.get_table_names():
        return False
    for index in inspector.get_indexes("users"):
        if index.get("column_names") == ["username"] and index.get("unique"):
            return True
    return False