import random
from datetime import datetime, timezone, timedelta
from bots.base import BaseBot


class AtsBot(BaseBot):
    """Automatic Transfer Switch — monitors which utility feed is active and logs transfers."""

    interval = 30

    def __init__(self, site_id: str, ats_id: str) -> None:
        super().__init__()
        self.site_id         = site_id
        self.ats_id          = ats_id
        self._active_feed    = "utility-a"
        self._transfer_count = 0
        self._last_transfer  = None          # ISO string or None
        self._transfer_ms    = None          # last transfer time in ms
        self._transferring   = False

    def get_topic(self) -> str:
        return f"bms/{self.site_id}/power/ats/{self.ats_id}"

    def set_scenario(self, name: str | None) -> None:
        super().set_scenario(name)
        if name == "ATS_TRANSFER":
            # Simulate a transfer to generator / utility-b
            self._active_feed    = "generator"
            self._transfer_count += 1
            self._transfer_ms    = round(random.uniform(80, 200))   # typical ATS 80–200 ms
            self._last_transfer  = datetime.now(timezone.utc).isoformat()
            self._transferring   = True
        elif name in (None, "RESET"):
            self._active_feed  = "utility-a"
            self._transferring = False

    def get_payload(self) -> dict:
        # Utility voltage sensing (slight variation on active feed)
        ua_v = 415.0 + random.gauss(0, 1.0) if self._active_feed == "utility-a" else 0.0
        ub_v = 415.0 + random.gauss(0, 1.0) if self._active_feed == "utility-b" else 415.0 + random.gauss(0, 0.5)
        gen_v = 415.0 + random.gauss(0, 1.5) if self._active_feed == "generator" else 0.0

        return {
            "state":           "transferring" if self._transferring else "stable",
            "active_feed":     self._active_feed,
            "transfer_count":  self._transfer_count,
            "last_transfer_at": self._last_transfer,
            "last_transfer_ms": self._transfer_ms,
            "utility_a_v":     round(ua_v, 1),
            "utility_b_v":     round(ub_v, 1),
            "generator_v":     round(gen_v, 1),
        }