"""Prevent legacy writers from diverging after an explicit PostgreSQL cutover."""
from pathlib import Path


def database_arguments(parser):
    target = parser.add_mutually_exclusive_group(required=True)
    target.add_argument('--db', help='Writable SQLite sample; never the frozen production backup')
    target.add_argument('--pg-service', help='Protected libpq service for the published PostgreSQL dataset')
    parser.add_argument('--pg-schema', help='Optional schema; otherwise use the configured search_path')


def open_store(db=None, *, pg_service=None, pg_schema=None):
    if bool(db) == bool(pg_service) or (pg_schema and not pg_service):
        raise ValueError('Choose exactly one of SQLite db or PostgreSQL service; schema requires PostgreSQL')
    if pg_service:
        from paper_atlas.postgres.writer import PostgresStore
        return PostgresStore(pg_service, pg_schema)
    from paper_atlas.db.store import Store
    return Store(db)


def open_read_connection(db=None, *, pg_service=None, pg_schema=None):
    if bool(db) == bool(pg_service) or (pg_schema and not pg_service):
        raise ValueError('Choose exactly one of SQLite db or PostgreSQL service; schema requires PostgreSQL')
    if pg_service:
        from paper_atlas.postgres.client import ReadConnection
        return ReadConnection(pg_service, pg_schema)
    import sqlite3
    path = Path(db).resolve()
    if not path.is_file():
        raise ValueError('Existing database required for read-only audit')
    connection = sqlite3.connect(path.as_uri() + '?mode=ro', uri=True)
    try:
        connection.execute('BEGIN')
    except BaseException:
        connection.close()
        raise
    return connection


def inserted_id(connection, sql, params=()):
    if getattr(connection, 'postgres', False):
        return connection.execute(sql + ' RETURNING id', params).fetchone()[0]
    return connection.execute(sql, params).lastrowid


def require_sqlite_writable(path):
    marker = Path(str(Path(path).resolve()) + '.postgresql-cutover.json')
    if marker.exists():
        raise RuntimeError('This SQLite source was cut over to PostgreSQL; use the configured PostgreSQL database. Marker: ' + str(marker))