import { createStore, produce } from "solid-js/store";
import type {
  BackendEventPayload,
  FrontendEventPayload,
  MaglevdStatusPayload,
  StateSnapshot,
  TransitionRecord,
} from "../types";

// FrontendState keys snapshots by maglevd name. A single store drives the
// whole UI; reducers produce() into the right branch.
export type FrontendState = {
  byName: Record<string, StateSnapshot>;
};

const [state, setState] = createStore<FrontendState>({ byName: {} });

export { state };

export function replaceSnapshot(snap: StateSnapshot) {
  setState(
    produce((s) => {
      s.byName[snap.maglevd.name] = snap;
    }),
  );
}

export function replaceAll(snaps: StateSnapshot[]) {
  const byName: Record<string, StateSnapshot> = {};
  for (const s of snaps) byName[s.maglevd.name] = s;
  setState({ byName });
}

export function applyBackendTransition(maglevd: string, p: BackendEventPayload) {
  setState(
    produce((s) => {
      const snap = s.byName[maglevd];
      if (!snap) return;
      const b = snap.backends.find((x) => x.name === p.backend);
      if (!b) return;
      b.state = p.transition.to;
      b.last_transition = p.transition;
      if (!b.transitions) b.transitions = [];
      b.transitions.push(p.transition);
      if (b.transitions.length > 20) {
        b.transitions = b.transitions.slice(b.transitions.length - 20);
      }
    }),
  );
}

export function applyFrontendTransition(maglevd: string, _p: FrontendEventPayload) {
  // Frontend roll-up state is computed per render in the current cut, so
  // there is nothing to update in the store. Kept as a named reducer so
  // the SSE dispatcher has one entry per event type and future frontend
  // state fields have a single place to land.
  void maglevd;
}

export function applyMaglevdStatus(maglevd: string, p: MaglevdStatusPayload) {
  setState(
    produce((s) => {
      const snap = s.byName[maglevd];
      if (!snap) return;
      snap.maglevd.connected = p.connected;
      snap.maglevd.last_error = p.last_error;
    }),
  );
}

// applyBackendEffectiveWeight updates the effective_weight of every pool
// row that references the backend with the given address. Driven by the
// vpp-lb-sync-as-* log events so the UI reflects VPP LB changes without
// waiting for the 30s refresh tick.
export function applyBackendEffectiveWeight(maglevd: string, address: string, weight: number) {
  setState(
    produce((s) => {
      const snap = s.byName[maglevd];
      if (!snap) return;
      const b = snap.backends.find((x) => x.address === address);
      if (!b) return;
      for (const fe of snap.frontends) {
        for (const pool of fe.pools) {
          for (const pb of pool.backends) {
            if (pb.name === b.name) {
              pb.effective_weight = weight;
            }
          }
        }
      }
    }),
  );
}

// Helpers used by views.

export function lastTransitionAge(t?: TransitionRecord): string {
  if (!t || !t.at_unix_ns || t.at_unix_ns <= 0) return "";
  const ms = Date.now() - t.at_unix_ns / 1e6;
  const s = Math.floor(ms / 1000);
  if (s < 60) return `${s}s ago`;
  const m = Math.floor(s / 60);
  if (m < 60) return `${m}m ago`;
  const h = Math.floor(m / 60);
  if (h < 48) return `${h}h ago`;
  return `${Math.floor(h / 24)}d ago`;
}