/**
 * Live ops wall — pure helpers (design-canvas/live-ops-wall-mockup.html,
 * gods-eye-view-notes.md top 5). No React here, so the logic is testable in
 * isolation and shared by MapView and LiveView.
 */
import type {
  AircraftTrack, CallRecord, Camera, IncidentRecord, Ny511Event, VesselTrack, WeatherAlert, WeatherGeometry,
} from "@/lib/types";
import { severityRank } from "@/lib/severity";

export type LatLon = [number, number];

export function km(a: LatLon, b: LatLon): number {
  const R = 6371;
  const dLa = ((b[0] - a[0]) * Math.PI) / 180;
  const dLo = ((b[1] - a[1]) * Math.PI) / 180;
  const x =
    Math.sin(dLa / 2) ** 2 +
    Math.cos((a[0] * Math.PI) / 180) * Math.cos((b[0] * Math.PI) / 180) * Math.sin(dLo / 2) ** 2;
  return 2 * R * Math.asin(Math.sqrt(x));
}

/** Calls grouped by incident id (multi-scene calls count toward each incident). */
export function groupCallsByIncident(calls: CallRecord[]): Map<string, CallRecord[]> {
  const map = new Map<string, CallRecord[]>();
  for (const c of calls) {
    const ids = c.incident_ids?.length ? c.incident_ids : c.incident_id ? [c.incident_id] : [];
    for (const id of ids) {
      if (!map.has(id)) map.set(id, []);
      map.get(id)!.push(c);
    }
  }
  return map;
}

/**
 * An incident's geography, oldest first: its geocoded call stops (the path —
 * same order as the call spine) or, failing that, its pin. Empty = not plotted.
 * Ghosted stops (an implied speed no vehicle makes, server-26#236) are left
 * out, so one bad geocode can't drag "nearest cameras" across the county.
 */
export function incidentPoints(inc: IncidentRecord, calls: CallRecord[] | undefined): LatLon[] {
  const stops = pathStops(inc, calls).stops.filter((s) => !s.ghost).map((s) => s.at);
  if (stops.length >= 2) return stops;
  if (inc.location_coords) return [[inc.location_coords.lat, inc.location_coords.lng]];
  return stops;
}

// ── Honest paths (server-26#236) ─────────────────────────────────────────────
// Pure, and shared by MapView and the call spine (WallPanels), so a stop's
// number is identical on both — and only what the map numbers is numbered.

/**
 * Mirrors `_PURSUIT_TAGS` in drb-c2-core/app/internal/incident_correlator.py.
 * Copied, not imported: keep the two in step by hand.
 */
export const PURSUIT_TAGS: ReadonlySet<string> = new Set([
  "vehicle-pursuit", "pursuit", "foot-pursuit", "chase",
  "fleeing-vehicle", "suspect-vehicle", "eluding",
]);

/** Mirrors `_MAX_PURSUIT_SPEED_KM_PER_MIN` (incident_correlator.py) — ~300 km/h. */
export const MAX_PATH_SPEED_KM_PER_MIN = 8.0;
/**
 * Mirrors settings.location_proximity_km: the backend only runs its speed
 * check past this distance, so two geocodes of one scene a few seconds apart
 * are never called impossible.
 */
export const SPEED_CHECK_MIN_KM = 0.5;
/** A segment spanning a longer silence than this is drawn dashed — we don't know the route. */
export const PATH_GAP_DASH_MIN = 10;
/** Mirrors `_PURSUIT_PROXIMITY_KM`: a path longer than a pursuit's own link radius is a merge suspect. */
export const MAY_BE_MERGED_KM = 20;

/** Police or accident incident carrying a pursuit tag — the only kind that draws a numbered path. */
export function isMovementIncident(inc: Pick<IncidentRecord, "type" | "tags">): boolean {
  if (inc.type !== "police" && inc.type !== "accident") return false;
  return (inc.tags ?? []).some((t) => PURSUIT_TAGS.has(t.toLowerCase()));
}

export interface PathStop {
  call: CallRecord;
  at: LatLon;
  /** Shared map/spine stop number; null = not numbered (ghosted, or not a movement incident). */
  n: number | null;
  /** Reaching this stop from the previous kept one implies > MAX_PATH_SPEED_KM_PER_MIN. */
  ghost: boolean;
  /** The segment INTO this stop is dashed: a long silence or a talkgroup change. Never set on the first kept stop. */
  dashedIn: boolean;
}

export interface IncidentPath {
  movement: boolean;
  /** Every geocoded call, oldest first — ghosts included, so the map can still show them faintly. */
  stops: PathStop[];
  /** Sum of the kept (non-ghost) segments. */
  lengthKm: number;
  mayBeMerged: boolean;
}

function minutesBetween(a: CallRecord, b: CallRecord): number {
  return Math.abs(Date.parse(b.started_at) - Date.parse(a.started_at)) / 60_000;
}

function impossible(a: PathStop, b: PathStop): boolean {
  const d = km(a.at, b.at);
  if (d <= SPEED_CHECK_MIN_KM) return false;
  // Same floor the backend uses (incident_correlator.py: max(idle, 0.1)).
  return d / Math.max(minutesBetween(a.call, b.call), 0.1) > MAX_PATH_SPEED_KM_PER_MIN;
}

/**
 * An incident's geocoded calls as path stops, oldest first.
 *
 * Ghosting walks forward from the last kept stop: a stop that could only be
 * reached faster than a pursuit can drive is ghosted and does not move the
 * anchor. A bad FIRST geocode would otherwise ghost everything after it, so
 * when stop 1 is impossible from stop 0 but stop 2 agrees with stop 1 and not
 * with stop 0, stop 0 is the one ghosted.
 */
export function pathStops(inc: IncidentRecord, calls: CallRecord[] | undefined): IncidentPath {
  const movement = isMovementIncident(inc);
  const stops: PathStop[] = (calls ?? [])
    .filter((c) => c.location_coords)
    .slice()
    .sort((a, b) => a.started_at.localeCompare(b.started_at))
    .map((c) => ({ call: c, at: [c.location_coords!.lat, c.location_coords!.lng] as LatLon, n: null, ghost: false, dashedIn: false }));

  let start = 0;
  if (stops.length >= 3 && impossible(stops[0], stops[1]) && !impossible(stops[1], stops[2]) && impossible(stops[0], stops[2])) {
    stops[0].ghost = true;
    start = 1;
  }
  let prev: PathStop | null = null;
  let lengthKm = 0;
  let n = 0;
  for (let i = start; i < stops.length; i++) {
    const s = stops[i];
    if (prev && impossible(prev, s)) { s.ghost = true; continue; }
    if (prev) {
      lengthKm += km(prev.at, s.at);
      s.dashedIn = minutesBetween(prev.call, s.call) > PATH_GAP_DASH_MIN
        || (prev.call.talkgroup_id != null && s.call.talkgroup_id != null && prev.call.talkgroup_id !== s.call.talkgroup_id);
    }
    if (movement) s.n = ++n;
    prev = s;
  }
  return { movement, stops, lengthKm, mayBeMerged: lengthKm > MAY_BE_MERGED_KM };
}

/** call_id → stop number, for the spine. Empty for a non-movement incident. */
export function stopNumbers(path: IncidentPath): Map<string, number> {
  const m = new Map<string, number>();
  for (const s of path.stops) if (s.n != null) m.set(s.call.call_id, s.n);
  return m;
}

/** Worst-first, then most recent (UI_REDESIGN.md §5.1). */
export function worstFirst(incidents: IncidentRecord[]): IncidentRecord[] {
  return incidents
    .slice()
    .sort((a, b) => severityRank(b.severity) - severityRank(a.severity) || b.started_at.localeCompare(a.started_at));
}

export const NEAR_CAMERA_KM = 3.5;

export interface NearCamera { cam: Camera; km: number }

/**
 * Nearest cameras to an incident. For a path, distance is to ANY stop but
 * weighted toward the newest one, so a pursuit surfaces the cameras at its
 * head first (GEV "NEAREST", path-aware as in the mockup). `km` is the plain
 * distance to the nearest stop/pin; ranking uses the weighted score.
 */
export function nearestCameras(points: LatLon[], cameras: Camera[], k = 4, maxKm = NEAR_CAMERA_KM): NearCamera[] {
  if (!points.length) return [];
  const last = points.length - 1;
  return cameras
    .map((cam) => {
      let raw = Infinity;
      let score = Infinity;
      points.forEach((p, i) => {
        const d = km(p, [cam.lat, cam.lon]);
        raw = Math.min(raw, d);
        score = Math.min(score, d * (1 + (last - i) * 0.5));
      });
      return { cam, km: raw, score };
    })
    .filter((x) => x.score < maxKm)
    .sort((a, b) => a.score - b.score)
    .slice(0, k)
    .map(({ cam, km: d }) => ({ cam, km: d }));
}

/**
 * Coarse 2D viewshed cone (GEV idea #4). APPROXIMATE: built from the
 * published direction of travel, not a surveyed heading/FOV — label it so
 * wherever it is drawn. Cameras with no usable direction get no cone rather
 * than a made-up one.
 */
export function viewshedWedge(cam: Camera, rangeKm = 0.8, fovDeg = 50): LatLon[] | null {
  if (cam.heading_deg == null) return null;
  const pts: LatLon[] = [[cam.lat, cam.lon]];
  const cosLat = Math.cos((cam.lat * Math.PI) / 180);
  for (let a = -fovDeg / 2; a <= fovDeg / 2; a += 5) {
    const b = ((cam.heading_deg + a) * Math.PI) / 180;
    pts.push([cam.lat + (rangeKm / 111) * Math.cos(b), cam.lon + (rangeKm / (111 * cosLat)) * Math.sin(b)]);
  }
  return pts;
}

// ── Fused situational context ────────────────────────────────────────────────
export const CONTEXT_KM = { aircraft: 4, vessel: 3, road: 2 };

export interface IncidentContext {
  aircraft: { a: AircraftTrack; km: number }[];
  vessels: { v: VesselTrack; km: number }[];
  road: { e: Ny511Event; km: number }[];
}

function nearestKm(points: LatLon[], lat: number, lon: number): number {
  return points.reduce((m, p) => Math.min(m, km(p, [lat, lon])), Infinity);
}

export function contextFor(
  points: LatLon[],
  aircraft: AircraftTrack[],
  vessels: VesselTrack[],
  events: Ny511Event[],
): IncidentContext {
  const near = <T,>(items: T[], pos: (t: T) => LatLon | null, r: number) =>
    items
      .map((t) => {
        const p = pos(t);
        return { t, km: p ? nearestKm(points, p[0], p[1]) : Infinity };
      })
      .filter((x) => x.km <= r)
      .sort((a, b) => a.km - b.km);
  return {
    aircraft: near(aircraft, (a) => (a.lat != null && a.lon != null ? [a.lat, a.lon] : null), CONTEXT_KM.aircraft)
      .map(({ t, km: d }) => ({ a: t, km: d })),
    vessels: near(vessels, (v) => (v.lat != null && v.lon != null ? [v.lat, v.lon] : null), CONTEXT_KM.vessel)
      .map(({ t, km: d }) => ({ v: t, km: d })),
    road: near(events, (e) => [e.lat, e.lon], CONTEXT_KM.road).map(({ t, km: d }) => ({ e: t, km: d })),
  };
}

/** Bbox around a set of points, padded by `padKm`. */
export function bboxAround(points: LatLon[], padKm: number) {
  if (!points.length) return null;
  const lats = points.map((p) => p[0]);
  const lons = points.map((p) => p[1]);
  const dLat = padKm / 111;
  const midLat = (Math.min(...lats) + Math.max(...lats)) / 2;
  const dLon = padKm / (111 * Math.max(0.2, Math.cos((midLat * Math.PI) / 180)));
  return {
    south: Math.max(-90, Math.min(...lats) - dLat),
    north: Math.min(90, Math.max(...lats) + dLat),
    west: Math.max(-180, Math.min(...lons) - dLon),
    east: Math.min(180, Math.max(...lons) + dLon),
  };
}

// ── Deep links / saved views ────────────────────────────────────────────────
// #inc=<id>&cam=<cameraId>&tour&tourMs=30000&kiosk
//   &layers=nodes,inc,radar,wx&z=11&lat=41.12345&lon=-73.98765&base=light
//   &f.<name>=<value>
// Every key is optional; unknown keys are ignored, so an old link (inc/cam/tour
// only) still parses and a newer one degrades on an older build. Pure string
// in/out — no window access — so it can be unit-tested once a JS runner exists.

/** Map overlays, by short stable hash key → the LayersControl overlay name. */
export const LAYER_NAMES = {
  nodes: "Nodes",
  inc: "Active Incidents",
  paths: "Incident Paths",
  air: "Aircraft",
  ais: "Vessels",
  dotcam: "DOT Cameras",
  vs: "Camera Viewsheds (approx.)",
  traffic: "Traffic Events",
  radar: "Weather Radar",
  wx: "Weather Warnings",
} as const;
export type LayerKey = keyof typeof LAYER_NAMES;
export const LAYER_KEYS = Object.keys(LAYER_NAMES) as LayerKey[];
/** What the map shows with no hash and nothing remembered (unchanged from before #234). */
export const DEFAULT_LAYERS: LayerKey[] = ["nodes", "inc", "paths"];

export const BASE_NAMES = { dark: "Dark", light: "Light", streets: "Streets" } as const;
export type BaseKey = keyof typeof BASE_NAMES;
export const DEFAULT_BASE: BaseKey = "dark";

export function isLayerKey(k: string): k is LayerKey {
  return Object.prototype.hasOwnProperty.call(LAYER_NAMES, k);
}
export function isBaseKey(k: string): k is BaseKey {
  return Object.prototype.hasOwnProperty.call(BASE_NAMES, k);
}
export function layerKeyForName(name: string): LayerKey | null {
  return LAYER_KEYS.find((k) => LAYER_NAMES[k] === name) ?? null;
}
export function baseKeyForName(name: string): BaseKey | null {
  return (Object.keys(BASE_NAMES) as BaseKey[]).find((k) => BASE_NAMES[k] === name) ?? null;
}

export interface MapViewport { z: number; lat: number; lon: number }

/** What the map looks like — the part a viewer's browser also remembers (lib/wallPrefs.ts). */
export interface WallView {
  /** Overlays switched on, in LAYER_KEYS order. [] = all off; absent = not specified. */
  layers?: LayerKey[];
  view?: MapViewport;
  base?: BaseKey;
}

export interface WallLink extends WallView {
  inc: string | null;
  cam: string | null;
  tour: boolean;
  /** Auto-tour dwell per incident; absent = the default. */
  tourMs?: number;
  /** Wall/kiosk presentation (no nav, large type, wake lock). */
  kiosk?: boolean;
  /**
   * The filter bar's state (server-26#235): every `f.<name>=<v>` hash key
   * round-trips here untouched, so filters can be added without reshaping
   * WallLink or breaking older links. lib/liveFilter.ts parseFilter /
   * serialiseFilter give it meaning.
   */
  filter?: Record<string, string>;
}

export const TOUR_MS_MIN = 5_000;
export const TOUR_MS_MAX = 10 * 60_000;

function num(v: string | null): number | null {
  if (v == null || v.trim() === "") return null;
  const n = Number(v);
  return Number.isFinite(n) ? n : null;
}

/** Normalises a layer list: known keys only, de-duplicated, in LAYER_KEYS order. */
export function normaliseLayers(keys: readonly string[]): LayerKey[] {
  const set = new Set(keys);
  return LAYER_KEYS.filter((k) => set.has(k));
}

export function parseViewport(z: unknown, lat: unknown, lon: unknown): MapViewport | undefined {
  if (typeof z !== "number" || typeof lat !== "number" || typeof lon !== "number") return undefined;
  if (!Number.isFinite(z) || !Number.isFinite(lat) || !Number.isFinite(lon)) return undefined;
  if (z < 0 || z > 22 || lat < -90 || lat > 90 || lon < -180 || lon > 180) return undefined;
  return { z, lat, lon };
}

/** Rounds a viewport for the URL: ~1 m position, 1/100 zoom. */
export function roundViewport(v: MapViewport): MapViewport {
  return { z: Math.round(v.z * 100) / 100, lat: Math.round(v.lat * 1e5) / 1e5, lon: Math.round(v.lon * 1e5) / 1e5 };
}

export function parseWallHash(hash: string): WallLink {
  const p = new URLSearchParams(hash.replace(/^#/, ""));
  const link: WallLink = { inc: p.get("inc") || null, cam: p.get("cam") || null, tour: p.has("tour") };
  const tourMs = num(p.get("tourMs"));
  if (tourMs != null) link.tourMs = Math.min(TOUR_MS_MAX, Math.max(TOUR_MS_MIN, Math.round(tourMs)));
  if (p.has("kiosk") && p.get("kiosk") !== "0") link.kiosk = true;
  if (p.has("layers")) link.layers = normaliseLayers((p.get("layers") ?? "").split(","));
  const view = parseViewport(num(p.get("z")), num(p.get("lat")), num(p.get("lon")));
  if (view) link.view = view;
  const base = p.get("base");
  if (base && isBaseKey(base)) link.base = base;
  const filter: Record<string, string> = {};
  p.forEach((v, k) => { if (k.startsWith("f.") && k.length > 2) filter[k.slice(2)] = v; });
  if (Object.keys(filter).length) link.filter = filter;
  return link;
}

export function wallHash(link: WallLink): string {
  const parts: string[] = [];
  const enc = encodeURIComponent;
  if (link.inc) parts.push(`inc=${enc(link.inc)}`);
  if (link.cam) parts.push(`cam=${enc(link.cam)}`);
  if (link.tour) parts.push("tour");
  if (link.tourMs != null) parts.push(`tourMs=${Math.round(link.tourMs)}`);
  if (link.kiosk) parts.push("kiosk");
  // Commas stay literal (URLSearchParams reads them back fine) so the link is readable.
  if (link.layers) parts.push(`layers=${normaliseLayers(link.layers).join(",")}`);
  if (link.view) {
    const v = roundViewport(link.view);
    parts.push(`z=${v.z}`, `lat=${v.lat}`, `lon=${v.lon}`);
  }
  if (link.base) parts.push(`base=${link.base}`);
  if (link.filter) {
    // Filter lists (f.type=fire,ems) keep literal commas too (server-26#235).
    for (const k of Object.keys(link.filter).sort()) parts.push(`f.${enc(k)}=${enc(link.filter[k]).replace(/%2C/g, ",")}`);
  }
  return parts.length ? `#${parts.join("&")}` : "";
}

/** True when two views would serialise identically (for "did this actually change"). */
export function sameView(a: WallView, b: WallView): boolean {
  return wallHash({ inc: null, cam: null, tour: false, ...a }) === wallHash({ inc: null, cam: null, tour: false, ...b });
}

/** "On air": a live call is on one of the incident's talkgroups right now. */
export function onAirIncidentIds(incidents: IncidentRecord[], activeCalls: CallRecord[]): Set<string> {
  const live = new Set(activeCalls.map((c) => c.talkgroup_id).filter((t): t is number => t != null).map(String));
  return new Set(
    incidents.filter((i) => (i.talkgroup_ids ?? []).some((t) => live.has(String(t)))).map((i) => i.incident_id),
  );
}

// ── NEXRAD (IEM n0q composite) ───────────────────────────────────────────────
// The Weather Radar layer, its valid-time badge, its legend and the per-incident
// sample all use ONE product: IEM's n0q (base reflectivity, 0.5 dBZ steps,
// -32..95 dBZ). Verified first-hand 2026-10-05:
//   tiles   https://mesonet.agron.iastate.edu/cache/tile.py/1.0.0/nexrad-n0q-900913/{z}/{x}/{y}.png
//           (RGBA PNG, ACAO: *), and nexrad-n0q-900913-m05m … -m55m for the
//           5-minute frames of the last hour (-m60m is a 404);
//   valid   https://mesonet.agron.iastate.edu/data/gis/images/4326/USCOMP/n0q_0.json
//           → {"meta": {"valid": "2026-10-05T07:35:00Z", "product": "N0Q", …}}
//           (n0q_<k>.json is k × 5 min earlier; ACAO: *);
//   ramp    https://mesonet.agron.iastate.edu/GIS/rasters.php?rid=2 — 255 colours,
//           index i (1..255) = -32 + (i-1)/2 dBZ. Every opaque pixel of five
//           sampled live tiles matched this table exactly.
export const RADAR_TILE_BASE = "https://mesonet.agron.iastate.edu/cache/tile.py/1.0.0/nexrad-n0q-900913";
export const RADAR_META_URL = "https://mesonet.agron.iastate.edu/data/gis/images/4326/USCOMP/n0q_0.json";
/** A frame older than this is flagged STALE on the map (#237 acceptance). */
export const RADAR_STALE_MIN = 15;
/** Loop frames, oldest first, as minutes before the current composite (IEM keeps -m05m … -m55m). */
export const RADAR_LOOP_OFFSETS_MIN = [55, 50, 45, 40, 35, 30, 25, 20, 15, 10, 5, 0] as const;
/** Light rain starts around here; weaker returns are clear-air / clutter. */
export const PRECIP_ECHO_DBZ = 15;

/** Tile URL for the composite `offsetMin` minutes before the current one (0 = current). */
export function radarTileUrl(offsetMin = 0): string {
  const layer = offsetMin > 0 ? `${RADAR_TILE_BASE}-m${String(offsetMin).padStart(2, "0")}m` : RADAR_TILE_BASE;
  return `${layer}/{z}/{x}/{y}.png`;
}

/** The composite's valid time from IEM's n0q metadata JSON, or null if the shape isn't the verified one. */
export function parseRadarMeta(body: unknown): Date | null {
  const valid = (body as { meta?: { valid?: unknown } } | null)?.meta?.valid;
  if (typeof valid !== "string") return null;
  const d = new Date(valid);
  return isNaN(d.getTime()) ? null : d;
}

/** IEM's published n0q colour table, 6 hex digits per entry, index 1..255 (index 0 = missing). */
const N0Q_RAMP_HEX =
  "85718f85728f86738d87758b87768b887789897987897a878a7b858b7d848b7e848c7f828d81808d82808e837e8f847c" +
  "8f857c90877b918879918979928b77938d759691539894579b975b9d9a60a09d64a3a068a5a36da8a671aaa976adac7a" +
  "b0af7eb2b283b7b88cbabb90bdbe94bfc199c2c49dc4c7a2c7caa6cacdaaccd0afd2d4b4cfd2b4c9ccb4c6c9b4c3c7b4" +
  "c0c4b4bdc1b4b9beb4b6bbb4b3b9b4b0b6b4adb3b4aab0b4a4abb4a0a8b49da5b49aa2b497a0b4949db4919ab4949bb5" +
  "9098b48c95b38892b2808cb07c89af7886ae7483ac7080ab6c7daa6779a96376a85f73a75b70a6576da44f67a24b64a1" +
  "4761a0435e9f415b9e4361a24568a6486faa4a76ae4d7db24f84b6518bbb5699c3599fc75ba6cb5eadcf60b4d462bbd8" +
  "65c2dc67c9e06ad0e46fd6e868d6d759d6b352d6a24bd69043d67e3cd66d35d65b11d51811d11710cd1710c81610c416" +
  "0fbc150fb7140eb3140eaf130eab130da6120da2120d9e110c99110c95100c91100b880f0b840e0a800e0a7c0d0a770d" +
  "09730c096f0c096b0b08660b08620a095e09327308467d085b88076f9207849d0698a806adb205c1bd05d6c704ead204" +
  "ffe200ffd800ffd300ffce00ffc900ffc400ffc000ffbb00ffb600ffb100ffac00ffa700ffa200ff9900ff9400ff8f00" +
  "ff8a00ff8500ff8000ff0000f80000f10000ea0000e30000d50000cd0000c60000bf0000b80000b10000aa0000a30000" +
  "9b00009400008d00007f0000780000710000fffffffff5ffffeaffffdfffffd4ffffc9ffffbeffffb3ffff9dffff92ff" +
  "ff75fffc6bfdf960faf656f7f34bf4f040f1ed36efea2bece720e9e10be3b200ffac00fca400f79b00f49300ef8800ea" +
  "8300e87900e27200dd6900db05ecf005ebf005eaf005dde005dce005dbe005cdd005ccd004bdc004bcc004bbc004aeb0" +
  "04adb0049ea0049da0049ca0038e90038d90038c90037e80037d80036f70036e70036d70025f60025e60024f50024e50" +
  "024d50023f40023e40023d40013030012f30012020011f20011e203a67b53a66b53a65b53a64b53a63b53a62b5";

function n0qIndex(dbz: number): number {
  return Math.min(255, Math.max(1, Math.round((dbz + 32) * 2) + 1));
}

/** "#rrggbb" the radar layer draws for a reflectivity. */
export function n0qColor(dbz: number): string {
  const i = n0qIndex(dbz) - 1;
  return `#${N0Q_RAMP_HEX.slice(i * 6, i * 6 + 6)}`;
}

let rgbToDbz: Map<number, number> | null = null;
function n0qLookup(): Map<number, number> {
  if (!rgbToDbz) {
    rgbToDbz = new Map();
    for (let i = 0; i < 255; i++) rgbToDbz.set(parseInt(N0Q_RAMP_HEX.slice(i * 6, i * 6 + 6), 16), -32 + i / 2);
  }
  return rgbToDbz;
}

/** dBZ for a radar-tile pixel. Exact table hit (tiles are lossless); else nearest colour within a small distance; else null. */
export function pixelDbz(r: number, g: number, b: number): number | null {
  const lut = n0qLookup();
  const exact = lut.get((r << 16) | (g << 8) | b);
  if (exact != null) return exact;
  let best: number | null = null;
  let bestD = 12 * 12;
  lut.forEach((dbz, rgb) => {
    const d = (r - ((rgb >> 16) & 255)) ** 2 + (g - ((rgb >> 8) & 255)) ** 2 + (b - (rgb & 255)) ** 2;
    if (d < bestD) { bestD = d; best = dbz; }
  });
  return best;
}

/** No opaque radar pixel near the point (the tile is transparent there). */
export const NO_ECHO_DBZ = -Infinity;

/**
 * Max reflectivity (dBZ) within ~radiusKm of a point, read from the same n0q
 * tile the Weather Radar layer draws (cache-busted on the same 5-min clock).
 * Approximate by construction — label it so. NO_ECHO_DBZ when nothing is
 * drawn there; null when the tile can't be read.
 */
export async function sampleRadarDbz(lat: number, lon: number, radiusKm = 5): Promise<number | null> {
  const z = 9;
  const n = 2 ** z;
  const xf = ((lon + 180) / 360) * n;
  const latR = (lat * Math.PI) / 180;
  const yf = ((1 - Math.log(Math.tan(latR) + 1 / Math.cos(latR)) / Math.PI) / 2) * n;
  const tx = Math.floor(xf);
  const ty = Math.floor(yf);
  const img = new Image();
  img.crossOrigin = "anonymous";
  img.src = `${RADAR_TILE_BASE}/${z}/${tx}/${ty}.png?_=${Math.floor(Date.now() / 300000)}`;
  try {
    await img.decode();
  } catch {
    return null;
  }
  const canvas = document.createElement("canvas");
  canvas.width = 256;
  canvas.height = 256;
  const ctx = canvas.getContext("2d");
  if (!ctx) return null;
  ctx.drawImage(img, 0, 0);
  const px = Math.floor((xf - tx) * 256);
  const py = Math.floor((yf - ty) * 256);
  const kmPerPx = (40075 * Math.cos(latR)) / (n * 256);
  const rad = Math.max(1, Math.round(radiusKm / kmPerPx));
  const x0 = Math.max(0, px - rad);
  const y0 = Math.max(0, py - rad);
  const w = Math.min(256, px + rad) - x0;
  const h = Math.min(256, py + rad) - y0;
  if (w <= 0 || h <= 0) return null;
  let data: Uint8ClampedArray;
  try {
    data = ctx.getImageData(x0, y0, w, h).data;
  } catch {
    return null;   // tainted canvas — CORS changed upstream
  }
  let max = NO_ECHO_DBZ;
  for (let i = 0; i < data.length; i += 4) {
    if (data[i + 3] < 128) continue;   // transparent: nothing drawn
    const dbz = pixelDbz(data[i], data[i + 1], data[i + 2]);
    if (dbz != null && dbz > max) max = dbz;
  }
  return max;
}

// ── NWS warnings (server-26#237) ─────────────────────────────────────────────

/** Ray-cast point-in-ring; `ring` is GeoJSON [lon, lat] pairs. */
function inRing(lat: number, lon: number, ring: number[][]): boolean {
  let inside = false;
  for (let i = 0, j = ring.length - 1; i < ring.length; j = i++) {
    const [xi, yi] = ring[i];
    const [xj, yj] = ring[j];
    if ((yi > lat) !== (yj > lat) && lon < ((xj - xi) * (lat - yi)) / (yj - yi) + xi) inside = !inside;
  }
  return inside;
}

/**
 * True when [lat, lon] is inside a GeoJSON Polygon / MultiPolygon (holes
 * respected: inside the outer ring and outside every hole).
 */
export function pointInPolygon(point: LatLon, geom: WeatherGeometry | null | undefined): boolean {
  if (!geom) return false;
  const polys = geom.type === "Polygon" ? [geom.coordinates] : geom.type === "MultiPolygon" ? geom.coordinates : [];
  const [lat, lon] = point;
  return polys.some((rings) =>
    rings.length > 0 && inRing(lat, lon, rings[0]) && !rings.slice(1).some((hole) => inRing(lat, lon, hole)));
}

/** Active alerts whose drawn area contains the point, worst-looking (Warning) first. */
export function alertsAt(point: LatLon, alerts: WeatherAlert[]): WeatherAlert[] {
  return alerts
    .filter((a) => pointInPolygon(point, a.geometry))
    .sort((a, b) => wxKindRank(a.event) - wxKindRank(b.event));
}

export type WxKind = "warning" | "watch" | "advisory" | "statement";

export function wxKind(event: string): WxKind {
  const e = event.toLowerCase();
  if (e.includes("warning") || e.includes("emergency")) return "warning";
  if (e.includes("watch")) return "watch";
  if (e.includes("advisory") || e.includes("alert")) return "advisory";
  return "statement";
}
function wxKindRank(event: string): number {
  return ["warning", "watch", "advisory", "statement"].indexOf(wxKind(event));
}

/**
 * NWS hazard-map colours (weather.gov/help-map) for the events this region
 * sees most. Unlisted events fall back by kind. Colour is never the only cue:
 * the outline dash says the kind (warning solid, watch dashed, advisory and
 * statement dotted), and the legend explains it.
 */
const NWS_EVENT_COLORS: Record<string, string> = {
  "tornado warning": "#ff0000",
  "severe thunderstorm warning": "#ffa500",
  "flash flood warning": "#8b0000",
  "flood warning": "#00ff00",
  "flood advisory": "#00ff7f",
  "flood watch": "#2e8b57",
  "flash flood watch": "#2e8b57",
  "tornado watch": "#ffff00",
  "severe thunderstorm watch": "#db7093",
  "special marine warning": "#ffa500",
  "winter storm warning": "#ff69b4",
  "winter storm watch": "#4682b4",
  "winter weather advisory": "#7b68ee",
  "blizzard warning": "#ff4500",
  "ice storm warning": "#8b008b",
  "lake effect snow warning": "#008b8b",
  "high wind warning": "#daa520",
  "high wind watch": "#b8860b",
  "wind advisory": "#d2b48c",
  "heat advisory": "#ff7f50",
  "excessive heat warning": "#c71585",
  "extreme heat warning": "#c71585",
  "excessive heat watch": "#800000",
  "extreme heat watch": "#800000",
  "coastal flood warning": "#228b22",
  "coastal flood watch": "#66cdaa",
  "coastal flood advisory": "#7cfc00",
  "dense fog advisory": "#708090",
  "special weather statement": "#ffe4b5",
  "red flag warning": "#ff1493",
  "fire weather watch": "#ffdead",
  "freeze warning": "#483d8b",
  "frost advisory": "#6495ed",
  "small craft advisory": "#d8bfd8",
  "gale warning": "#dda0dd",
  "storm warning": "#9400d3",
  "hurricane warning": "#dc143c",
  "tropical storm warning": "#b22222",
  "air quality alert": "#808080",
};
const WX_KIND_FALLBACK: Record<WxKind, string> = {
  warning: "#dc2626", watch: "#eab308", advisory: "#60a5fa", statement: "#a3a3a3",
};
export const WX_KIND_DASH: Record<WxKind, string | undefined> = {
  warning: undefined, watch: "8 5", advisory: "2 4", statement: "2 4",
};

export function wxStyle(event: string): { color: string; kind: WxKind; dashArray: string | undefined; weight: number } {
  const kind = wxKind(event);
  return {
    color: NWS_EVENT_COLORS[event.toLowerCase()] ?? WX_KIND_FALLBACK[kind],
    kind,
    dashArray: WX_KIND_DASH[kind],
    weight: kind === "warning" ? 2.5 : kind === "watch" ? 2 : 1.5,
  };
}

/** Local "Oct 5, 2:30 PM" for an NWS ISO timestamp (they carry their own offset). */
export function wxTime(iso: string | null | undefined): string | null {
  if (!iso) return null;
  const d = new Date(iso);
  return isNaN(d.getTime()) ? null : d.toLocaleString([], { month: "short", day: "numeric", hour: "numeric", minute: "2-digit" });
}

// ── Wind at the incident (server-26#237) ─────────────────────────────────────
// Fire and hazmat are where wind direction changes the call (smoke / plume
// drift, approach side). There is no hazmat incident type, so tags decide.
const WIND_TAG_RE = /(^|-)(hazmat|haz-mat|gas-leak|natural-gas|chemical|spill|smoke|fumes|odor|odour|plume|brush|wildfire|propane|ammonia|chlorine|carbon-monoxide)(-|$)/;

export function wantsWind(inc: Pick<IncidentRecord, "type" | "tags">): boolean {
  if (inc.type === "fire") return true;
  return (inc.tags ?? []).some((t) => WIND_TAG_RE.test(t.toLowerCase()));
}

/** 16-point compass name for the direction the wind blows FROM. */
export function compass(deg: number): string {
  const pts = ["N", "NNE", "NE", "ENE", "E", "ESE", "SE", "SSE", "S", "SSW", "SW", "WSW", "W", "WNW", "NW", "NNW"];
  return pts[Math.round((((deg % 360) + 360) % 360) / 22.5) % 16];
}