"use client";

import dynamic from "next/dynamic";
import { useEffect, useState } from "react";
import { formatClock } from "@/lib/display";
import { loadFrames, RADAR_LAYERS, type RadarLayerId } from "@/lib/radar/layers";
import { outlineButton, pixelLabel, sectionHeading } from "@/lib/styles";
import type { Place, RadarFrame } from "@/lib/weather/types";
import { Slot } from "../Slot";
import { ChoiceChips } from "../ui/ChoiceChips";

// Leaflet needs `window`, so the map only ever renders in the browser.
const RadarMap = dynamic(() => import("./RadarMap"), {
  ssr: false,
  loading: () => <div className="grid h-full place-items-center font-pixel text-xs text-stone">Loading map…</div>,
});

const FRAME_MS = 700; // animation speed
const REFRESH_MS = 5 * 60_000; // fetch fresh frames every 5 minutes

/** The radar section: layer picker, animated map, and playback controls. */
export function RadarPanel({ place, timeZone, hasOpenWeather }: { place: Place; timeZone: string | null; hasOpenWeather: boolean }) {
  // US places start on the sharper NEXRAD radar; everywhere else on RainViewer.
  const [layerId, setLayerId] = useState<RadarLayerId>(place.country === "US" ? "nexrad" : "rainviewer");
  const [frames, setFrames] = useState<RadarFrame[]>([]);
  const [frameIndex, setFrameIndex] = useState(0);
  const [playing, setPlaying] = useState(false);
  const [error, setError] = useState<string | null>(null);

  // Switch between US-only NEXRAD and global RainViewer when crossing borders.
  useEffect(() => {
    setLayerId((current) => {
      if (place.country !== "US" && current === "nexrad") return "rainviewer";
      if (place.country === "US" && current === "rainviewer") return "nexrad";
      if (!hasOpenWeather && current.startsWith("owm-")) return place.country === "US" ? "nexrad" : "rainviewer";
      return current;
    });
  }, [place.country, hasOpenWeather]);

  const layer = RADAR_LAYERS.find((l) => l.id === layerId)!;
  const isAnimated = frames.length > 1;

  // Load frames for the chosen layer, then keep them fresh.
  useEffect(() => {
    let cancelled = false;

    async function refresh() {
      try {
        const loaded = await loadFrames(layerId);
        if (cancelled) return;
        setFrames(loaded);
        setFrameIndex(loaded.length - 1); // start on the latest frame
        setError(null);
      } catch (err) {
        if (!cancelled) setError((err as Error).message);
      }
    }

    refresh();
    const timer = setInterval(refresh, REFRESH_MS);
    return () => {
      cancelled = true;
      clearInterval(timer);
    };
  }, [layerId]);

  // Autoplay unless the person prefers reduced motion.
  useEffect(() => {
    setPlaying(!window.matchMedia("(prefers-reduced-motion: reduce)").matches);
  }, []);

  // Step through frames while playing.
  useEffect(() => {
    if (!playing || !isAnimated) return;
    const timer = setInterval(() => setFrameIndex((i) => (i + 1) % frames.length), FRAME_MS);
    return () => clearInterval(timer);
  }, [playing, isAnimated, frames.length]);

  const frame = frames[frameIndex];
  const isLatest = frameIndex === frames.length - 1;

  return (
    <section aria-labelledby="radar-heading" className="flex flex-col gap-3">
      <div className="flex items-center gap-3">
        <h2 id="radar-heading" className={sectionHeading}>
          Radar and maps
        </h2>
        <span className="h-px flex-1 bg-linear-to-r from-gold-dim/70 to-transparent" aria-hidden="true" />
      </div>

      <ChoiceChips
        legend="Map layer"
        size="sm"
        selected={layerId}
        onChange={setLayerId}
        choices={RADAR_LAYERS.filter((l) => hasOpenWeather || !l.needsOpenWeather).map((l) => ({ value: l.id, label: l.label }))}
      />

      {/* Height goes on the outer frame: the inner one is already h-full, and two
          height utilities on one element would fight over which wins. */}
      <Slot className="h-[360px] [--cut:10px] sm:h-[460px]" innerClassName="">

        <RadarMap lat={place.lat} lon={place.lon} layer={layer} frames={frames} frameIndex={frameIndex} />
      </Slot>

      {isAnimated && frame && (
        <div className="flex items-center gap-3">
          <button type="button" className={outlineButton} onClick={() => setPlaying((p) => !p)} aria-pressed={playing}>
            {playing ? "Pause" : "Play"}
          </button>
          <label className="sr-only" htmlFor="radar-frame">
            Radar frame
          </label>
          <input
            id="radar-frame"
            type="range"
            min={0}
            max={frames.length - 1}
            value={frameIndex}
            onChange={(e) => {
              setPlaying(false);
              setFrameIndex(Number(e.target.value));
            }}
            className="min-w-0 flex-1 accent-gold"
          />
          <span className="w-[4.5rem] text-right font-pixel text-xs text-ink tabular-nums" aria-live="off">
            {isLatest ? "Latest" : formatClock(frame.time, timeZone)}
          </span>
        </div>
      )}

      <p className={pixelLabel}>{error ?? layer.hint}</p>
    </section>
  );
}