import { create } from "zustand";
import type { AudioSample } from "../../../entities/audioSample/model/types";
import { env } from "../../../shared/config/env";
import { RingBuffer } from "../../../shared/lib/ringBuffer";
import type { WsStatus } from "./types";
import { LiveWsClient } from "../lib/liveWsClient";
import { parseAndValidateMessage } from "../lib/parseAndValidate";

type LiveStreamState = {
  status: WsStatus;
  lastMessageAt: number | null;

  // WS frequency control
  requestedHz: number; // 0.1-60
  setRequestedHz: (hz: number) => void;

  // Window selection
  windowMs: number;
  setWindowMs: (ms: number) => void;

  // Derived UI state (throttled)
  latest: AudioSample | null;
  peakHoldDb3s: number | null;
  chartHistory: AudioSample[];

  connect: () => void;
  disconnect: () => void;
  loadLatest: (limit?: number) => Promise<void>;
};

const PEAK_WINDOW_MS = 3_000;

const WINDOW_OPTIONS_MS = [15_000, 30_000, 60_000, 120_000, 300_000] as const;
const DEFAULT_WINDOW_MS = 60_000;

const MIN_HZ = 0.1;
// const MAX_HZ = 60;
const DEFAULT_REQUESTED_HZ = 10;

// If there are more than 600 points in selected window -> downsample
const MAX_CHART_POINTS = 600;

// UI updates not more than ~12 Hz
const UI_FLUSH_HZ = 12;
const UI_FLUSH_MS = Math.round(1000 / UI_FLUSH_HZ);

// Max window is 5m; worst-case 60 Hz => 18k points (+ headroom)
const RAW_CAPACITY = 20_000;

// -------- Module-level raw buffers (NOT in Zustand state) --------
const rawHistory = new RingBuffer<AudioSample>(RAW_CAPACITY);
let peakWindow: AudioSample[] = [];

let client: LiveWsClient | null = null;
let flushTimer: number | null = null;

let lastSeenSample: AudioSample | null = null;

function clampInt(v: number, min: number): number {
  if (!Number.isFinite(v)) return min;
  return Math.max(min, v);
}

function isAllowedWindowMs(
  ms: number,
): ms is (typeof WINDOW_OPTIONS_MS)[number] {
  return (WINDOW_OPTIONS_MS as readonly number[]).includes(ms);
}

function buildWsUrl(base: string, hz: number): string {
  const safeHz = clampInt(hz, MIN_HZ);

  // Prefer URL() for correctness (keeps existing params)
  try {
    const u = new URL(base);
    u.searchParams.set("hz", String(safeHz));
    return u.toString();
  } catch {
    const sep = base.includes("?") ? "&" : "?";
    return `${base}${sep}hz=${encodeURIComponent(String(safeHz))}`;
  }
}

function trimPeakWindow(nowSampleMs: number): void {
  const cutoff = nowSampleMs - PEAK_WINDOW_MS;
  while (peakWindow.length && peakWindow[0]!.timeMs < cutoff)
    peakWindow.shift();

  // Safety cap: even at 60 Hz, 3 sec ~ 180 points; allow some jitter
  if (peakWindow.length > 512) peakWindow = peakWindow.slice(-512);
}

function computePeakDb3s(): number | null {
  if (!peakWindow.length) return null;
  let max = -Infinity;
  for (const s of peakWindow) max = Math.max(max, s.rms_db);
  return Number.isFinite(max) ? max : null;
}

function makeChartHistory(windowMs: number): AudioSample[] {
  const latest = lastSeenSample ?? rawHistory.last();
  if (!latest) return [];

  const cutoff = latest.timeMs - windowMs;

  // Note: rawHistory.toArray() allocates, but it's called at ~12 Hz, not per WS packet
  const windowed = rawHistory.toArray().filter((s) => s.timeMs >= cutoff);

  if (windowed.length <= MAX_CHART_POINTS) return windowed;

  const step = Math.ceil(windowed.length / MAX_CHART_POINTS);
  const out: AudioSample[] = [];
  for (let i = 0; i < windowed.length; i += step) out.push(windowed[i]!);

  // Ensure last point is present (prevents “missing tail” effect)
  const last = windowed.at(-1);
  if (last && out.at(-1)?.timeMs !== last.timeMs) out.push(last);

  return out;
}

export const useLiveStreamStore = create<LiveStreamState>()((set, get) => {
  function clearFlushTimer(): void {
    if (flushTimer !== null) {
      window.clearTimeout(flushTimer);
      flushTimer = null;
    }
  }

  function flushToUi(): void {
    clearFlushTimer();

    const { windowMs } = get();
    const latest = lastSeenSample ?? rawHistory.last();
    const chartHistory = makeChartHistory(windowMs);

    set({
      latest: latest ?? null,
      peakHoldDb3s: computePeakDb3s(),
      chartHistory,
      lastMessageAt: Date.now(),
    });
  }

  function scheduleFlush(): void {
    if (flushTimer !== null) return;
    flushTimer = window.setTimeout(flushToUi, UI_FLUSH_MS);
  }

  function ensureClientConnected(): void {
    if (client) return;

    const hz = get().requestedHz;
    const url = buildWsUrl(env.wsUrl, hz);

    client = new LiveWsClient(url, {
      onStatus: (st) => set({ status: st }),
      onMessage: (data) => {
        const parsed = parseAndValidateMessage(data);
        if (!parsed.ok) return;

        const sample = parsed.sample;
        lastSeenSample = sample;

        rawHistory.push(sample);

        peakWindow.push(sample);
        trimPeakWindow(sample.timeMs);

        // Throttled UI update
        scheduleFlush();
      },
    });

    client.connect();
  }

  function reconnectWithNewHz(): void {
    if (!client) return;
    client.close();
    client = null;
    ensureClientConnected();
  }

  return {
    status: "disconnected",
    lastMessageAt: null,

    requestedHz: DEFAULT_REQUESTED_HZ,
    setRequestedHz: (hz) => {
      const next = clampInt(hz, MIN_HZ);
      const prev = get().requestedHz;
      if (next === prev) return;

      set({ requestedHz: next });
      reconnectWithNewHz();
    },

    windowMs: DEFAULT_WINDOW_MS,
    setWindowMs: (ms) => {
      const next = isAllowedWindowMs(ms) ? ms : DEFAULT_WINDOW_MS;
      if (next === get().windowMs) return;

      set({ windowMs: next });
      // Recompute immediately (doesn't touch WS)
      flushToUi();
    },

    latest: null,
    peakHoldDb3s: null,
    chartHistory: [],

    connect: () => {
      ensureClientConnected();
    },

    disconnect: () => {
      clearFlushTimer();
      client?.close();
      client = null;
      set({ status: "disconnected" });
      // Raw history intentionally preserved to avoid “jumping” on reconnect
    },

    loadLatest: async (limit = 300) => {
      const safeLimit = clampInt(limit, 1);
      const base = env.apiUrl.replace(/\/$/, "");
      const url = `${base}/api/v1/audio/latest?limit=${safeLimit}`;

      try {
        const res = await fetch(url);
        if (!res.ok) return;

        const raw = (await res.json()) as Array<{
          time: string;
          rms_db: number;
          freq_hz: number;
        }>;

        // Push historical points into raw buffer (no per-item setState!)
        for (const item of raw) {
          const parsed = parseAndValidateMessage(JSON.stringify(item));
          if (!parsed.ok) continue;

          rawHistory.push(parsed.sample);
          lastSeenSample = parsed.sample;

          // Warm-up peak window too (optional but consistent)
          peakWindow.push(parsed.sample);
          trimPeakWindow(parsed.sample.timeMs);
        }

        // Single UI update after warm-up
        flushToUi();
      } catch {
        // graceful fallback: ignore (dashboard must stay usable without REST)
      }
    },
  };
});