__all__ = ['create_tables', 'create_tables_sql', 'drop_tables',
           'drop_tables_sql']

def create_tables(tables, if_not_exists=False, connection=None):
    """
    Create the given tables as a set.  Constraints are collected
    and only created at the end of the process.  Tables are created
    in the given order.
    """
    if connection is None:
        connection = tables[0].sqlmeta.get_connection()
    if if_not_exists:
        tables = [t for t in tables if not t.sqlmeta.table_exists()]
    sql = create_tables_sql(tables, connection)
    cur = connection.cursor()
    for s in sql:
        cur.execute(s)
    cur.close()

def create_tables_sql(tables, connection=None):
    """
    Return a list of SQL statements for creating the given tables.
    """
    create_context = {}
    sql = []
    lazy_sql = []
    for table in tables:
        table_sql, table_lazy_sql = table.sqlmeta.create_sql(
            connection, create_context)
        sql.extend(table_sql)
        lazy_sql.extend(table_lazy_sql)
    sql.extend(lazy_sql)
    return sql

def drop_tables(tables, if_exists=False, connection=None):
    """
    Drop the given tables as a set.  Tables are dropped in *reverse*
    order.
    """
    if connection is None:
        connection = tables[0].sqlmeta.get_connection()
    if if_exists:
        tables = [t for t in tables if t.sqlmeta.table_exists()]
    sql, lazy_sql = drop_tables_sql(tables, connection)
    cur = connection.cursor()
    for s in sql + lazy_sql:
        cur.execute(s)
    cur.close()

def drop_tables_sql(tables, connection=None):
    sql = []
    lazy = []
    reversed = list(tables)
    reversed.reverse()
    for table in reversed:
        this_sql, this_lazy = table.sqlmeta.drop_sql(connection)
        sql.extend(this_sql)
        lazy.extend(this_lazy)
    return sql, lazy