package com.paymentlink.service;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Service;
import org.springframework.web.client.RestTemplate;

import java.util.HashMap;
import java.util.Map;

@Service
public class TaxService {

    private static final Logger logger = LoggerFactory.getLogger(TaxService.class);

    @Value("${tax.default.rate:0.08}")
    private double defaultTaxRate;

    @Value("${tax.api.url:}")
    private String taxApiUrl;

    @Value("${tax.api.timeout:5000}")
    private int taxApiTimeout;

    private final Map<String, Double> countryRates = new HashMap<>();
    private final Map<String, Map<String, Double>> stateRates = new HashMap<>();

    public TaxService() {
        initializeTaxRates();
    }

    private void initializeTaxRates() {
        // Country-specific rates
        countryRates.put("GB", 0.20);  // UK VAT
        countryRates.put("US", 0.08);  // US average
        countryRates.put("CA", 0.13);  // Canada average
        countryRates.put("AU", 0.10);  // Australia GST
        countryRates.put("DE", 0.19);  // Germany VAT
        countryRates.put("FR", 0.20);  // France VAT
        countryRates.put("IT", 0.22);  // Italy VAT
        countryRates.put("ES", 0.21);  // Spain VAT
        countryRates.put("NL", 0.21);  // Netherlands VAT
        countryRates.put("BE", 0.21);  // Belgium VAT

        // US State-specific rates
        Map<String, Double> usStates = new HashMap<>();
        usStates.put("CA", 0.1025);  // California
        usStates.put("NY", 0.08);    // New York
        usStates.put("TX", 0.0825);  // Texas
        usStates.put("FL", 0.06);    // Florida
        usStates.put("WA", 0.101);   // Washington
        stateRates.put("US", usStates);

        // Canadian Province-specific rates
        Map<String, Double> caProvinces = new HashMap<>();
        caProvinces.put("ON", 0.13);     // Ontario HST
        caProvinces.put("BC", 0.12);     // British Columbia
        caProvinces.put("QC", 0.14975);  // Quebec
        stateRates.put("CA", caProvinces);
    }

    /**
     * Calculate tax amount for a subtotal
     */
    public long calculateTax(long subtotal, String country, String state) {
        double rate = getTaxRate(country, state);
        long taxAmount = Math.round(subtotal * rate);
        logger.debug("Calculated tax: subtotal={}, country={}, state={}, rate={}, tax={}", 
                    subtotal, country, state, rate, taxAmount);
        return taxAmount;
    }

    /**
     * Get tax rate for country/state
     */
    public double getTaxRate(String country, String state) {
        // Try external API first if configured
        if (taxApiUrl != null && !taxApiUrl.isEmpty()) {
            try {
                Double apiRate = fetchTaxRateFromApi(country, state);
                if (apiRate != null) {
                    return apiRate;
                }
            } catch (Exception e) {
                logger.warn("Failed to fetch tax rate from API, using local rates", e);
            }
        }

        // Try state-specific rate
        if (state != null && !state.isEmpty() && stateRates.containsKey(country)) {
            Map<String, Double> states = stateRates.get(country);
            if (states.containsKey(state)) {
                return states.get(state);
            }
        }

        // Try country rate
        if (country != null && countryRates.containsKey(country)) {
            return countryRates.get(country);
        }

        // Return default
        return defaultTaxRate;
    }

    /**
     * Fetch tax rate from external API
     */
    private Double fetchTaxRateFromApi(String country, String state) {
        try {
            RestTemplate restTemplate = new RestTemplate();
            String url = taxApiUrl + "?country=" + country + "&state=" + (state != null ? state : "");
            
            @SuppressWarnings("unchecked")
            Map<String, Object> response = restTemplate.getForObject(url, Map.class);
            
            if (response != null) {
                // Try "taxRate" field
                if (response.containsKey("taxRate")) {
                    return ((Number) response.get("taxRate")).doubleValue();
                }
                // Try "rate" field
                if (response.containsKey("rate")) {
                    return ((Number) response.get("rate")).doubleValue();
                }
            }
        } catch (Exception e) {
            logger.error("Error fetching tax rate from API", e);
        }
        return null;
    }

    /**
     * Get all supported countries
     */
    public Map<String, String> getSupportedCountries() {
        Map<String, String> countries = new HashMap<>();
        countries.put("US", "United States");
        countries.put("CA", "Canada");
        countries.put("GB", "United Kingdom");
        countries.put("AU", "Australia");
        countries.put("DE", "Germany");
        countries.put("FR", "France");
        countries.put("IT", "Italy");
        countries.put("ES", "Spain");
        countries.put("NL", "Netherlands");
        countries.put("BE", "Belgium");
        return countries;
    }
}