Sequence

"""
Sequence: Webhook Ordering System & Monotonic Gap Detector
Buffers asynchronous webhook arrival and dispatches events in strict causal sequence.
"""
import heapq
from typing import Dict, List, Optional
from pydantic import BaseModel

class WebhookEvent(BaseModel):
    entity_id: str
    sequence_num: int
    payload: dict

class SequenceOrderManager:
    def __init__(self):
        self.expected_seq: Dict[str, int] = {}
        self.staging_buffers: Dict[str, List] = {}

    def push_and_drain(self, event: WebhookEvent) -> List[WebhookEvent]:
        entity = event.entity_id
        if entity not in self.expected_seq:
            self.expected_seq[entity] = 1
            self.staging_buffers[entity] = []

        # Push to min-heap based on sequence_num
        heapq.heappush(self.staging_buffers[entity], (event.sequence_num, event))

        ready_events: List[WebhookEvent] = []
        while self.staging_buffers[entity] and self.staging_buffers[entity][0][0] == self.expected_seq[entity]:
            _, next_event = heapq.heappop(self.staging_buffers[entity])
            ready_events.append(next_event)
            self.expected_seq[entity] += 1

        return ready_events