import ngeohash from 'ngeohash';
import type { SkateCrew } from '@/lib/types';

/**
 * Shared, pure helpers for the Crews feature.
 *
 * These are intentionally UI-agnostic so the Crews page, crew cards, spot pages
 * and the crew detail view can all share the same "is this crew alive / near me /
 * legit" logic without duplicating it.
 */

// ─── Geo / proximity ─────────────────────────────────────────────────────────

export interface LatLng {
  lat: number;
  lng: number;
}

/** Decode a geohash to a lat/lng centre, or null if invalid. */
export function geohashToLatLng(geohash?: string): LatLng | null {
  if (!geohash) return null;
  try {
    const { latitude, longitude } = ngeohash.decode(geohash);
    if (Number.isNaN(latitude) || Number.isNaN(longitude)) return null;
    return { lat: latitude, lng: longitude };
  } catch {
    return null;
  }
}

/**
 * Great-circle distance between two points, in kilometres (haversine).
 */
export function haversineKm(a: LatLng, b: LatLng): number {
  const R = 6371; // Earth radius km
  const dLat = ((b.lat - a.lat) * Math.PI) / 180;
  const dLng = ((b.lng - a.lng) * Math.PI) / 180;
  const lat1 = (a.lat * Math.PI) / 180;
  const lat2 = (b.lat * Math.PI) / 180;
  const h =
    Math.sin(dLat / 2) ** 2 +
    Math.cos(lat1) * Math.cos(lat2) * Math.sin(dLng / 2) ** 2;
  return 2 * R * Math.asin(Math.min(1, Math.sqrt(h)));
}

/** Distance in km from a point to a crew's home turf, or null if the crew has no geo. */
export function crewDistanceKm(crew: SkateCrew, from: LatLng): number | null {
  const to = geohashToLatLng(crew.geohash);
  if (!to) return null;
  return haversineKm(from, to);
}

/** Format a km distance for display ("120 m", "3.4 km", "88 km"). */
export function formatDistance(km: number): string {
  if (km < 1) return `${Math.round(km * 1000)} m`;
  if (km < 10) return `${km.toFixed(1)} km`;
  return `${Math.round(km)} km`;
}

// ─── Activity / health ───────────────────────────────────────────────────────

export type CrewActivityLevel = 'hot' | 'active' | 'quiet' | 'dormant';

export interface CrewActivity {
  level: CrewActivityLevel;
  /** Most recent signal (feed post / event / crew update) as unix seconds, if any. */
  lastActiveAt?: number;
  /** Number of upcoming events hosted by the crew. */
  upcomingEvents: number;
}

const DAY = 24 * 60 * 60;

/**
 * Derive an activity level from the freshest signal we have about a crew.
 *
 * @param lastActiveAt  unix seconds of the most recent feed post / event / edit
 * @param upcomingEvents number of future crew-hosted events
 */
export function deriveActivity(
  lastActiveAt: number | undefined,
  upcomingEvents: number,
): CrewActivity {
  const now = Math.floor(Date.now() / 1000);
  const age = lastActiveAt ? now - lastActiveAt : Infinity;

  let level: CrewActivityLevel;
  if (upcomingEvents > 0 || age <= 7 * DAY) {
    level = 'hot';
  } else if (age <= 30 * DAY) {
    level = 'active';
  } else if (age <= 120 * DAY) {
    level = 'quiet';
  } else {
    level = 'dormant';
  }

  return { level, lastActiveAt, upcomingEvents };
}

export const ACTIVITY_META: Record<
  CrewActivityLevel,
  { label: string; emoji: string; dot: string; text: string }
> = {
  hot: { label: 'Active this week', emoji: '🔥', dot: 'bg-orange-500', text: 'text-orange-400' },
  active: { label: 'Active', emoji: '🛹', dot: 'bg-teal-500', text: 'text-teal-400' },
  quiet: { label: 'Quiet', emoji: '💤', dot: 'bg-gray-500', text: 'text-gray-400' },
  dormant: { label: 'Dormant', emoji: '🕸️', dot: 'bg-gray-700', text: 'text-gray-600' },
};

// ─── Vibe colour accents ───────────────────────────────────────────────────────

export interface VibeAccent {
  /** Tailwind text colour for the crew name / icons. */
  text: string;
  /** Tailwind border colour for the card. */
  border: string;
  /** Tailwind hover border colour. */
  hoverBorder: string;
  /** Tailwind background tint. */
  bg: string;
  /** Raw hex for inline glows / gradients. */
  hex: string;
}

const ACCENT_PALETTE: VibeAccent[] = [
  { text: 'text-teal-300', border: 'border-teal-500/25', hoverBorder: 'hover:border-teal-500/60', bg: 'bg-teal-500/[0.06]', hex: '#14b8a6' },
  { text: 'text-orange-300', border: 'border-orange-500/25', hoverBorder: 'hover:border-orange-500/60', bg: 'bg-orange-500/[0.06]', hex: '#f97316' },
  { text: 'text-fuchsia-300', border: 'border-fuchsia-500/25', hoverBorder: 'hover:border-fuchsia-500/60', bg: 'bg-fuchsia-500/[0.06]', hex: '#d946ef' },
  { text: 'text-lime-300', border: 'border-lime-500/25', hoverBorder: 'hover:border-lime-500/60', bg: 'bg-lime-500/[0.06]', hex: '#84cc16' },
  { text: 'text-sky-300', border: 'border-sky-500/25', hoverBorder: 'hover:border-sky-500/60', bg: 'bg-sky-500/[0.06]', hex: '#0ea5e9' },
  { text: 'text-amber-300', border: 'border-amber-500/25', hoverBorder: 'hover:border-amber-500/60', bg: 'bg-amber-500/[0.06]', hex: '#f59e0b' },
  { text: 'text-violet-300', border: 'border-violet-500/25', hoverBorder: 'hover:border-violet-500/60', bg: 'bg-violet-500/[0.06]', hex: '#8b5cf6' },
  { text: 'text-rose-300', border: 'border-rose-500/25', hoverBorder: 'hover:border-rose-500/60', bg: 'bg-rose-500/[0.06]', hex: '#f43f5e' },
];

/** Deterministically map a crew to a stable accent colour (so the grid isn't all teal). */
export function crewAccent(crew: Pick<SkateCrew, 'identifier' | 'pubkey'>): VibeAccent {
  const seed = `${crew.pubkey}:${crew.identifier}`;
  let hash = 0;
  for (let i = 0; i < seed.length; i++) {
    hash = (hash * 31 + seed.charCodeAt(i)) | 0;
  }
  const idx = Math.abs(hash) % ACCENT_PALETTE.length;
  return ACCENT_PALETTE[idx];
}

// ─── Reputation / badges ───────────────────────────────────────────────────────

export type CrewBadge = 'og' | 'verified' | 'established' | 'crew';

export interface CrewBadgeInfo {
  key: CrewBadge;
  label: string;
  emoji: string;
}

/**
 * Roll a crew's "legitimacy signals" into a single headline badge.
 *
 * Priority (highest first):
 * - **OG**: founded 5+ years ago AND has confirmed members.
 * - **Verified**: has a NIP-05 handle (verification is checked separately in the UI).
 * - **Established**: 3+ members.
 * - **crew**: default.
 *
 * `confirmedMembers` is optional — pass the count of members who vouched in for a
 * stronger OG signal; falls back to claimed member count.
 */
export function crewBadge(
  crew: Pick<SkateCrew, 'founded' | 'nip05' | 'members'>,
  confirmedMembers?: number,
): CrewBadgeInfo {
  const memberCount = confirmedMembers ?? crew.members.length;
  const year = crew.founded ? parseInt(crew.founded, 10) : NaN;
  const currentYear = new Date().getFullYear();
  const ageYears = Number.isNaN(year) ? 0 : currentYear - year;

  if (ageYears >= 5 && memberCount > 0) {
    return { key: 'og', label: 'OG Crew', emoji: '👑' };
  }
  if (crew.nip05) {
    return { key: 'verified', label: 'Verified', emoji: '✅' };
  }
  if (memberCount >= 3) {
    return { key: 'established', label: 'Established', emoji: '⭐' };
  }
  return { key: 'crew', label: 'Crew', emoji: '🛹' };
}