import base64
from datetime import datetime
from typing import Any, List, Optional
from .exceptions import InvalidArgumentError
encode_method = base64.encodebytes
decode_method = base64.decodebytes
PAGINATION_MODEL = {
"list_shards": {
"input_token": "next_token",
"limit_key": "limit",
"limit_default": 10000,
"unique_attribute": "shard_id",
"fail_on_invalid_token": False,
},
}
def compose_new_shard_iterator(
stream_name: Optional[str],
shard: Any,
shard_iterator_type: str,
starting_sequence_number: int,
at_timestamp: datetime,
) -> str:
if shard_iterator_type == "AT_SEQUENCE_NUMBER":
last_sequence_id = int(starting_sequence_number) - 1
elif shard_iterator_type == "AFTER_SEQUENCE_NUMBER":
last_sequence_id = int(starting_sequence_number)
elif shard_iterator_type == "TRIM_HORIZON":
last_sequence_id = 0
elif shard_iterator_type == "LATEST":
last_sequence_id = shard.get_max_sequence_number()
elif shard_iterator_type == "AT_TIMESTAMP":
last_sequence_id = shard.get_sequence_number_at(at_timestamp)
else:
raise InvalidArgumentError(f"Invalid ShardIteratorType: {shard_iterator_type}")
return compose_shard_iterator(stream_name, shard, last_sequence_id)
def compose_shard_iterator(
stream_name: Optional[str], shard: Any, last_sequence_id: int
) -> str:
return encode_method(
f"{stream_name}:{shard.shard_id}:{last_sequence_id}".encode("utf-8")
).decode("utf-8")
def decompose_shard_iterator(shard_iterator: str) -> List[str]:
return decode_method(shard_iterator.encode("utf-8")).decode("utf-8").split(":")