import type { RadarFrame } from "../weather/types";

/**
 * Every map overlay the radar panel can show, and how to get its frames.
 *
 *   RainViewer  — worldwide radar, last ~2 hours in 10-minute steps.
 *                 Since Jan 2026: past frames only, max zoom 7, one color scheme,
 *                 personal/educational use only.
 *   NEXRAD      — US-only NWS radar via Iowa State's mesonet; much sharper,
 *                 last 50 minutes in 5-minute steps. No key.
 *   OpenWeather — model maps (precipitation, clouds, temperature, wind, pressure).
 *                 Needs OPENWEATHER_API_KEY; tiles go through /api/tiles so the key stays secret.
 */

export type RadarLayerId = "rainviewer" | "nexrad" | "owm-precip" | "owm-clouds" | "owm-temp" | "owm-wind" | "owm-pressure";

export interface RadarLayer {
  id: RadarLayerId;
  label: string;
  hint: string; // shown under the map
  maxNativeZoom: number; // beyond this, tiles are stretched rather than fetched
  needsOpenWeather: boolean;
  attribution: string;
}

const OWM_ATTRIBUTION =
  'Weather data provided by <a href="https://openweathermap.org/" target="_blank" rel="noopener">OpenWeather</a> (<a href="https://creativecommons.org/licenses/by-sa/4.0/" target="_blank" rel="noopener">CC BY-SA 4.0</a>)';

export const RADAR_LAYERS: RadarLayer[] = [
  {
    id: "rainviewer",
    label: "Radar",
    hint: "Worldwide radar, past 2 hours. Detail stops at regional zoom.",
    maxNativeZoom: 7,
    needsOpenWeather: false,
    attribution: 'Weather data by <a href="https://www.rainviewer.com/" target="_blank" rel="noopener">RainViewer</a>',
  },
  {
    id: "nexrad",
    label: "US radar",
    hint: "NWS NEXRAD radar, past 50 minutes. United States only, high detail.",
    maxNativeZoom: 12,
    needsOpenWeather: false,
    attribution:
      'NEXRAD via <a href="https://mesonet.agron.iastate.edu/" target="_blank" rel="noopener">Iowa Environmental Mesonet (Iowa State Univ.)</a>',
  },
  { id: "owm-precip", label: "Precipitation", hint: "Modelled precipitation right now.", maxNativeZoom: 9, needsOpenWeather: true, attribution: OWM_ATTRIBUTION },
  { id: "owm-clouds", label: "Clouds", hint: "Modelled cloud cover right now.", maxNativeZoom: 9, needsOpenWeather: true, attribution: OWM_ATTRIBUTION },
  { id: "owm-temp", label: "Temperature", hint: "Modelled air temperature right now.", maxNativeZoom: 9, needsOpenWeather: true, attribution: OWM_ATTRIBUTION },
  { id: "owm-wind", label: "Wind", hint: "Modelled wind speed right now.", maxNativeZoom: 9, needsOpenWeather: true, attribution: OWM_ATTRIBUTION },
  { id: "owm-pressure", label: "Pressure", hint: "Modelled sea-level pressure right now.", maxNativeZoom: 9, needsOpenWeather: true, attribution: OWM_ATTRIBUTION },
];

/** Our layer ids → OpenWeather's tile layer names. Also the allow-list for /api/tiles. */
export const OWM_TILE_LAYERS: Record<string, string> = {
  "owm-precip": "precipitation_new",
  "owm-clouds": "clouds_new",
  "owm-temp": "temp_new",
  "owm-wind": "wind_new",
  "owm-pressure": "pressure_new",
};

/** NEXRAD frames are fixed offsets from "now": 50, 45 … 5 minutes ago, then the latest. */
function nexradFrames(): RadarFrame[] {
  const fiveMinutes = 5 * 60_000;
  const latest = Math.floor(Date.now() / fiveMinutes) * fiveMinutes;
  const base = "https://mesonet.agron.iastate.edu/cache/tile.py/1.0.0/nexrad-n0q-900913";

  return [50, 45, 40, 35, 30, 25, 20, 15, 10, 5, 0].map((minutesAgo) => ({
    time: new Date(latest - minutesAgo * 60_000).toISOString(),
    url: minutesAgo === 0 ? `${base}/{z}/{x}/{y}.png` : `${base}-m${String(minutesAgo).padStart(2, "0")}m/{z}/{x}/{y}.png`,
  }));
}

/** Loads the frames for a layer. Single-frame layers return a list of one. */
export async function loadFrames(id: RadarLayerId): Promise<RadarFrame[]> {
  if (id === "nexrad") return nexradFrames();

  if (id === "rainviewer") {
    const response = await fetch("/api/radar");
    if (!response.ok) throw new Error("Radar frames are unavailable right now");
    return (await response.json()) as RadarFrame[];
  }

  return [{ time: new Date().toISOString(), url: `/api/tiles/${id}/{z}/{x}/{y}` }];
}