import { BadRequestException, Injectable } from '@nestjs/common';
import { RedisService } from '../redis/redis.service';
import { digitsZip, fallbackDistanceKm, type ZipPlace } from './geo.types';
import { haversineKm } from '../freight/freight-calculator';

@Injectable()
export class GeoService {
  constructor(private readonly redis: RedisService) {}

  async placeFromZip(zip: string): Promise<ZipPlace> {
    const cep = digitsZip(zip);
    if (!/^\d{8}$/.test(cep)) {
      throw new BadRequestException('CEP inválido.');
    }

    const cached = await this.redis.getJson<ZipPlace>(`geo:cep:${cep}`);
    if (cached) {
      return cached;
    }

    const viaCep = await this.lookupViaCep(cep);
    const coords = await this.lookupNominatim(viaCep.city, viaCep.state);
    const place: ZipPlace = {
      zip: cep,
      city: viaCep.city,
      state: viaCep.state,
      label: `${viaCep.city}/${viaCep.state}`,
      lat: coords?.lat ?? 0,
      lon: coords?.lon ?? 0,
    };
    await this.redis.setJson(`geo:cep:${cep}`, place, 60 * 60 * 24 * 7);
    return place;
  }

  async distanceKm(originZip: string, destinationZip: string): Promise<{
    origin: ZipPlace;
    destination: ZipPlace;
    km: number;
    source: 'nominatim' | 'fallback';
  }> {
    const origin = await this.placeFromZip(originZip);
    const destination = await this.placeFromZip(destinationZip);
    if (origin.lat && origin.lon && destination.lat && destination.lon) {
      return { origin, destination, km: Math.max(haversineKm(origin, destination), 1), source: 'nominatim' };
    }
    return { origin, destination, km: fallbackDistanceKm(origin, destination), source: 'fallback' };
  }

  private async lookupViaCep(cep: string): Promise<{ city: string; state: string }> {
    const response = await fetch(`https://viacep.com.br/ws/${cep}/json/`, {
      signal: AbortSignal.timeout(8000),
    });
    if (!response.ok) {
      throw new BadRequestException('Não foi possível consultar o CEP.');
    }
    const data = (await response.json()) as { erro?: boolean; localidade?: string; uf?: string };
    if (data.erro || !data.localidade || !data.uf) {
      throw new BadRequestException('CEP não encontrado.');
    }
    return { city: data.localidade, state: data.uf };
  }

  private async lookupNominatim(city: string, state: string): Promise<{ lat: number; lon: number } | null> {
    const query = new URLSearchParams({
      format: 'json',
      limit: '1',
      countrycodes: 'br',
      q: `${city}, ${state}, Brasil`,
    });
    const response = await fetch(`https://nominatim.openstreetmap.org/search?${query.toString()}`, {
      headers: { 'User-Agent': 'SinkaLogistica/1.0 (desafio; tina.r@example.net)' },
      signal: AbortSignal.timeout(8000),
    });
    if (!response.ok) {
      return null;
    }
    const rows = (await response.json()) as Array<{ lat: string; lon: string }>;
    const first = rows[0];
    if (!first) {
      return null;
    }
    return { lat: Number(first.lat), lon: Number(first.lon) };
  }
}