import uuid
from typing import Dict, List, Tuple


class DeltaCRDT:
    """A compact CRDT-like store for delta-based time-series data.

    We store per-device time series as a list of (timestamp, value, delta_id).
    Deltas are deduplicated via delta_id and merged idempotently.
    """

    def __init__(self) -> None:
        # device_id -> list[(ts, value, delta_id)]
        self.state: Dict[str, List[Tuple[float, float, str]]] = {}
        self.seen: set = set()

    def _new_id(self, device: str, ts: float, value: float) -> str:
        # Simple unique-id generator; deterministic content is not required here
        return str(uuid.uuid4())

    def add_local_delta(self, device: str, ts: float, value: float) -> str:
        delta_id = self._new_id(device, ts, value)
        entry = (ts, value, delta_id)
        self.state.setdefault(device, [])
        self.state[device].append(entry)
        self.seen.add(delta_id)
        return delta_id

    def merge(self, remote_state: Dict[str, List[Tuple[float, float, str]]]) -> None:
        for device, entries in remote_state.items():
            self.state.setdefault(device, [])
            for ts, val, did in entries:
                if did not in self.seen:  # type: ignore
                    self.state[device].append((ts, val, did))
                    self.seen.add(did)

    def export_state(self) -> Dict[str, List[Tuple[float, float, str]]]:
        return self.state