import type { Transaction } from './mockData';

export interface TransactionArc {
  id:          string;
  timestamp:   number;    // Unix ms
  amount:      number;    // Ğ1
  fromLat:     number;
  fromLng:     number;
  fromCity:    string;
  fromCountry: string;
  fromKey:     string;
  toLat:       number;
  toLng:       number;
  toCity:      string;
  toCountry:   string;
  toKey:       string;
}

/** Corridor agrégé par paire de villes (fromCity → toCity). */
export interface Corridor {
  fromCity:    string;
  fromLat:     number;
  fromLng:     number;
  fromCountry: string;
  toCity:      string;
  toLat:       number;
  toLng:       number;
  toCountry:   string;
  totalVolume: number;
  count:       number;
}

export interface FlowStats {
  totalVolume:  number;
  arcCount:     number;
  topEmitters:  { city: string; volume: number; count: number; countryCode: string }[];
  topReceivers: { city: string; volume: number; count: number; countryCode: string }[];
  netBalance:   { city: string; net: number; countryCode: string }[];
}

/** Agrège les arcs individuels en corridors ville→ville, triés par volume. */
export function buildCorridors(arcs: TransactionArc[]): Corridor[] {
  const map = new Map<string, Corridor>();
  for (const arc of arcs) {
    const key = `${arc.fromCity}||${arc.toCity}`;
    if (!map.has(key)) {
      map.set(key, {
        fromCity: arc.fromCity, fromLat: arc.fromLat, fromLng: arc.fromLng, fromCountry: arc.fromCountry,
        toCity:   arc.toCity,   toLat:   arc.toLat,   toLng:   arc.toLng,   toCountry:   arc.toCountry,
        totalVolume: 0, count: 0,
      });
    }
    const c = map.get(key)!;
    c.totalVolume += arc.amount;
    c.count++;
  }
  return [...map.values()].sort((a, b) => b.totalVolume - a.totalVolume);
}

export function computeFlowStats(arcs: TransactionArc[]): FlowStats {
  const emitters  = new Map<string, { volume: number; count: number; country: string }>();
  const receivers = new Map<string, { volume: number; count: number; country: string }>();

  for (const arc of arcs) {
    if (!emitters.has(arc.fromCity))  emitters.set(arc.fromCity,  { volume: 0, count: 0, country: arc.fromCountry });
    if (!receivers.has(arc.toCity))   receivers.set(arc.toCity,   { volume: 0, count: 0, country: arc.toCountry });
    emitters.get(arc.fromCity)!.volume  += arc.amount;
    emitters.get(arc.fromCity)!.count++;
    receivers.get(arc.toCity)!.volume   += arc.amount;
    receivers.get(arc.toCity)!.count++;
  }

  const allCities = new Set([...emitters.keys(), ...receivers.keys()]);
  const netBalance = [...allCities].map(city => ({
    city,
    net:         (receivers.get(city)?.volume ?? 0) - (emitters.get(city)?.volume ?? 0),
    countryCode: emitters.get(city)?.country ?? receivers.get(city)?.country ?? '',
  })).sort((a, b) => Math.abs(b.net) - Math.abs(a.net)).slice(0, 5);

  return {
    totalVolume:  arcs.reduce((s, a) => s + a.amount, 0),
    arcCount:     arcs.length,
    topEmitters:  [...emitters.entries()].sort((a, b) => b[1].volume - a[1].volume).slice(0, 3)
      .map(([city, d]) => ({ city, volume: d.volume, count: d.count, countryCode: d.country })),
    topReceivers: [...receivers.entries()].sort((a, b) => b[1].volume - a[1].volume).slice(0, 3)
      .map(([city, d]) => ({ city, volume: d.volume, count: d.count, countryCode: d.country })),
    netBalance,
  };
}

/**
 * Génère des arcs mock : chaque transaction devient un arc dont le destinataire
 * est une transaction aléatoire d'une ville différente.
 */
export function buildMockArcs(transactions: Transaction[]): TransactionArc[] {
  if (transactions.length < 2) return [];
  const arcs: TransactionArc[] = [];
  for (let i = 0; i < transactions.length; i++) {
    if (Math.random() > 0.55) continue; // ~55 % de couverture
    const from = transactions[i];
    let toIdx = Math.floor(Math.random() * transactions.length);
    for (let tries = 0; tries < 8 && transactions[toIdx].city === from.city; tries++) {
      toIdx = Math.floor(Math.random() * transactions.length);
    }
    const to = transactions[toIdx];
    if (to.city === from.city) continue;
    arcs.push({
      id:          `${from.id}-arc`,
      timestamp:   from.timestamp,
      amount:      from.amount,
      fromLat: from.lat, fromLng: from.lng,
      fromCity: from.city, fromCountry: from.countryCode,
      fromKey: from.fromKey,
      toLat: to.lat, toLng: to.lng,
      toCity: to.city, toCountry: to.countryCode,
      toKey: to.toKey,
    });
  }
  return arcs;
}