"""Turning RunPod machine state into tracked history.

The API only ever reports what is true now. Everything CX cares about - how
often a machine has dropped out, when it drained, who relisted it - only exists
if each sync writes down what changed.
"""
from __future__ import annotations

import datetime as dt
from typing import Any, Optional

from sqlalchemy import select
from sqlalchemy.orm import Session

from ..models import RunpodColour, RunpodEvent, RunpodEventType, RunpodHost


def record_event(db: Session, host: RunpodHost, event_type: RunpodEventType, *,
                 actor: str = "system", detail: str = "", error_hint: str = "",
                 zendesk_ticket: str = "", jira_key: str = "",
                 gpu_reserved: Optional[int] = None,
                 payload: Optional[dict[str, Any]] = None) -> RunpodEvent:
    event = RunpodEvent(
        event_type=event_type, actor=actor, detail=detail, error_hint=error_hint,
        zendesk_ticket=zendesk_ticket, jira_key=jira_key,
        gpu_reserved=host.gpu_reserved if gpu_reserved is None else gpu_reserved,
        payload=payload,
    )
    # Through the relationship so an already-loaded history stays correct.
    host.events.append(event)
    db.add(event)
    return event


def sync_machines(db: Session, client: Any, actor: str = "system") -> dict[str, Any]:
    """Pull current machines and write down every transition since last time."""
    machines = client.machines()
    existing = {h.machine_id: h for h in db.scalars(select(RunpodHost)).all()}
    now = dt.datetime.now(dt.timezone.utc)

    created = unlisted = relisted = drained = 0

    for machine in machines:
        machine_id = str(machine.get("id") or "")
        if not machine_id:
            continue
        listed = bool(machine.get("listed"))
        reserved = int(machine.get("gpuReserved") or 0)

        host = existing.get(machine_id)
        if host is None:
            host = RunpodHost(machine_id=machine_id, name=str(machine.get("name") or ""))
            db.add(host)
            db.flush()
            created += 1
            record_event(db, host, RunpodEventType.LISTED if listed else RunpodEventType.UNLISTED,
                         actor="runpod", detail="First seen by CX Triage")
            if not listed:
                host.unlisted_at = now

        was_listed = host.listed
        was_reserved = host.gpu_reserved

        if was_listed and not listed:
            unlisted += 1
            host.unlisted_at = now
            host.unlist_count += 1
            # Nothing in the API says why; the email carries the reason and is
            # attached separately through /ingest-email.
            record_event(db, host, RunpodEventType.UNLISTED, actor="runpod",
                         detail="Unlisted (detected on sync)", gpu_reserved=reserved)
        elif not was_listed and listed:
            relisted += 1
            host.last_listed_at = now
            host.unlisted_at = None
            record_event(db, host, RunpodEventType.LISTED, actor=actor,
                         detail="Relisted", gpu_reserved=reserved)

        # Unlisted and the last renter has gone: the machine is now safe to work on.
        if not listed and was_reserved > 0 and reserved == 0:
            drained += 1
            record_event(db, host, RunpodEventType.DRAINED, actor="runpod",
                         detail="Unlisted machine has drained - no rented GPUs left",
                         gpu_reserved=0)

        gpu_type = machine.get("gpuType") or {}
        host.name = str(machine.get("name") or host.name)
        host.listed = listed
        host.gpu_reserved = reserved
        host.gpu_total = int(machine.get("gpuTotal") or 0)
        host.gpu_type = str(gpu_type.get("displayName") or machine.get("gpuTypeId") or "")
        host.data_center = str(machine.get("dataCenterId") or "")
        host.uptime_one_week = machine.get("uptimePercentListedOneWeek")
        host.maintenance_start = str(machine.get("maintenanceStart") or "")
        host.maintenance_end = str(machine.get("maintenanceEnd") or "")

    db.commit()
    return {
        "machines": len(machines), "created": created, "unlisted": unlisted,
        "relisted": relisted, "drained": drained,
        "synced_at": now.isoformat(),
    }