# Copyright 2016 Quantopian, Inc.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

from functools import partial
import os
import sqlite3

import sqlalchemy as sa
from sqlalchemy.pool import NullPool

from .input_validation import coerce_string

SQLITE_MAX_VARIABLE_NUMBER = 998


def group_into_chunks(items, chunk_size=SQLITE_MAX_VARIABLE_NUMBER):
    items = list(items)
    return [items[x : x + chunk_size] for x in range(0, len(items), chunk_size)]


def verify_sqlite_path_exists(path):
    if path != ":memory:" and not os.path.exists(path):
        raise ValueError("SQLite file {!r} doesn't exist.".format(path))


def check_and_create_connection(path, require_exists):
    if require_exists:
        verify_sqlite_path_exists(path)
    return sqlite3.connect(path)


def check_and_create_engine(path, require_exists):
    if require_exists:
        verify_sqlite_path_exists(path)
    return sa.create_engine("sqlite:///" + path, poolclass=NullPool)


def coerce_string_to_conn(require_exists):
    return coerce_string(
        partial(check_and_create_connection, require_exists=require_exists)
    )


def coerce_string_to_eng(require_exists):
    return coerce_string(
        partial(check_and_create_engine, require_exists=require_exists)
    )
