package com.venezuela.bcvrate.service;

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.math.BigDecimal;
import java.math.RoundingMode;
import java.net.HttpURLConnection;
import java.net.URL;
import java.security.SecureRandom;
import java.security.cert.X509Certificate;
import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.logging.Level;
import java.util.logging.Logger;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
import javax.net.ssl.HttpsURLConnection;
import javax.net.ssl.SSLContext;
import javax.net.ssl.TrustManager;
import javax.net.ssl.X509TrustManager;

public class BCVApiService {

    private static final Logger log = Logger.getLogger(BCVApiService.class.getName());

    private static final String BASE_URL = "https://bcv.today/api/v1";
    private static final String BCV_WEBSITE = "https://www.bcv.org.ve/";
    private static final int CONNECTION_TIMEOUT = 30000;
    private static final int READ_TIMEOUT = 60000;
    private static final int MAX_DAYS_BACK = 10;

    public BCVRateResponse getRateForDateWithFallback(String requestedDate) {
        SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");

        log.info("Buscando tasa para fecha solicitada: " + requestedDate);

        log.info("Intentando scraping BCV website...");
        BCVRateResponse websiteRate = getRateFromBCVWebsite();
        if (websiteRate != null && websiteRate.isValid()) {
            String scrapedEffectiveDate = websiteRate.getDate();
            if (!scrapedEffectiveDate.equals(requestedDate)) {
                log.info("Scraping BCV: tasa del " + scrapedEffectiveDate
                    + " aplica para " + requestedDate);
            } else {
                log.info("Scraping BCV: tasa del " + scrapedEffectiveDate
                    + " coincide con fecha solicitada");
            }
            return new BCVRateResponse(websiteRate.getDollar(), requestedDate, scrapedEffectiveDate);
        }

        log.info("Scraping BCV no disponible, buscando en API hacia atras...");
        Calendar cal = Calendar.getInstance();
        try {
            cal.setTime(sdf.parse(requestedDate));
        } catch (Exception e) {
            log.log(Level.WARNING, "Error parseando fecha: " + requestedDate, e);
            return null;
        }

        for (int i = 0; i <= MAX_DAYS_BACK; i++) {
            String dateToQuery = sdf.format(cal.getTime());
            BCVRateResponse rate = getRateFromApi(dateToQuery);

            if (rate != null && rate.isValid()) {
                log.info("Tasa encontrada (API) consultando " + dateToQuery
                    + " para fecha solicitada " + requestedDate
                    + ": USD=" + rate.getDollar()
                    + " effective=" + rate.getDate());
                return new BCVRateResponse(rate.getDollar(), requestedDate, rate.getDate());
            }

            cal.add(Calendar.DAY_OF_MONTH, -1);
        }

        log.info("No se encontro tasa para: " + requestedDate);
        return null;
    }

    public BCVRateResponse getRateForDate(String date) {
        return getRateFromApi(date);
    }

    public BCVRateResponse getLatestRate() {
        SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");

        for (int i = 1; i <= 10; i++) {
            Calendar cal = Calendar.getInstance();
            cal.add(Calendar.DAY_OF_MONTH, i);
            String futureDate = sdf.format(cal.getTime());

            BCVRateResponse rate = getRateFromApi(futureDate);
            if (rate != null && rate.isValid()) {
                log.info("Tasa encontrada (API futura) para " + futureDate
                    + ": USD=" + rate.getDollar() + " effective=" + rate.getDate());
                return rate;
            }
        }

        log.info("API no tiene tasa futura, intentando scraping BCV...");
        try {
            BCVRateResponse websiteRate = getRateFromBCVWebsite();
            if (websiteRate != null && websiteRate.isValid()) {
                log.info("Tasa obtenida del sitio web BCV: USD=" + websiteRate.getDollar()
                    + " effective=" + websiteRate.getDate());
                return websiteRate;
            }
            log.info("Scraping BCV no devolvio tasa valida");
        } catch (Exception e) {
            log.log(Level.WARNING, "Scraping BCV fallo", e);
        }

        log.info("Fallback a API actual...");
        BCVRateResponse apiRate = getCurrentRate();
        return apiRate;
    }

    private BCVRateResponse getRateFromApi(String date) {
        String urlStr = BASE_URL + "/history/" + date + ".json";

        try {
            String response = httpGet(urlStr);
            if (response == null) return null;

            BigDecimal dollar = extractUSD(response);
            String effectiveDate = extractField(response, "effective_date");
            if (effectiveDate == null) effectiveDate = extractField(response, "date");

            if (dollar != null && effectiveDate != null) {
                return new BCVRateResponse(dollar, effectiveDate);
            }
            return null;
        } catch (Exception e) {
            log.log(Level.WARNING, "Error consultando fecha: " + date, e);
            return null;
        }
    }

    public BCVRateResponse getCurrentRate() {
        String urlStr = BASE_URL + "/rate.json";

        try {
            String response = httpGet(urlStr);
            if (response == null) return null;

            BigDecimal dollar = extractUSD(response);
            String effectiveDate = extractField(response, "effective_date");
            if (effectiveDate == null) effectiveDate = extractField(response, "date");

            if (dollar != null && effectiveDate != null) {
                log.info("Tasa actual (API): USD=" + dollar + " effective=" + effectiveDate);
                return new BCVRateResponse(dollar, effectiveDate);
            }
            return null;
        } catch (Exception e) {
            log.log(Level.WARNING, "Error consultando tasa actual", e);
            return null;
        }
    }

    private BCVRateResponse getRateFromBCVWebsite() {
        int maxRetries = 3;
        for (int attempt = 1; attempt <= maxRetries; attempt++) {
            try {
                log.info("Scraping BCV - Intento " + attempt + "/" + maxRetries);
                String html = httpGetHtml(BCV_WEBSITE);
                if (html == null) {
                    log.warning("Intento " + attempt + "/" + maxRetries + ": No se pudo obtener pagina BCV");
                    if (attempt < maxRetries) {
                        log.info("Reintentando en 5 segundos...");
                        Thread.sleep(5000);
                        continue;
                    }
                    log.severe("Scraping BCV fallo despues de " + maxRetries + " intentos (timeout o error de conexion)");
                    return null;
                }
                log.info("Pagina BCV obtenida, longitud: " + html.length());

                Matcher rateMatcher = Pattern.compile(
                    "USD</span>.*?strong-tb\">\\s*([\\d.,]+)\\s*</strong>", Pattern.DOTALL).matcher(html);
                if (!rateMatcher.find()) {
                    log.warning("No se encontro tasa USD en pagina BCV (regex no match)");
                    return null;
                }

                String rateStr = rateMatcher.group(1).replace(",", ".");
                log.info("Tasa encontrada en HTML: " + rateStr);
                BigDecimal dollar = new BigDecimal(rateStr).setScale(4, RoundingMode.HALF_UP);

                Matcher dateMatcher = Pattern.compile(
                    "content=\"(\\d{4}-\\d{2}-\\d{2})T").matcher(html);
                String effectiveDate = null;
                if (dateMatcher.find()) {
                    effectiveDate = dateMatcher.group(1);
                }

                if (dollar.compareTo(BigDecimal.ZERO) > 0) {
                    if (effectiveDate == null) {
                        effectiveDate = new SimpleDateFormat("yyyy-MM-dd").format(new java.util.Date());
                    }
                    log.info("Scraping BCV exitoso (intento " + attempt + "): USD=" + dollar + " effective=" + effectiveDate);
                    return new BCVRateResponse(dollar, effectiveDate);
                }
                return null;
            } catch (InterruptedException ie) {
                Thread.currentThread().interrupt();
                log.warning("Scraping BCV interrumpido");
                return null;
            } catch (Exception e) {
                log.warning("Intento " + attempt + "/" + maxRetries + ": Error scraping BCV: " + e.getMessage());
                if (attempt < maxRetries) {
                    log.info("Reintentando en 5 segundos...");
                    try { Thread.sleep(5000); } catch (InterruptedException ie) { Thread.currentThread().interrupt(); }
                } else {
                    log.severe("Scraping BCV fallo despues de " + maxRetries + " intentos: " + e.getMessage());
                }
            }
        }
        return null;
    }

    private BigDecimal extractUSD(String json) {
        Matcher m = Pattern.compile("\"USD\"\\s*:\\s*([0-9.]+)").matcher(json);
        if (m.find()) {
            return new BigDecimal(m.group(1)).setScale(4, RoundingMode.HALF_UP);
        }
        return null;
    }

    private String extractField(String json, String field) {
        Matcher m = Pattern.compile("\"" + field + "\"\\s*:\\s*\"([^\"]+)\"").matcher(json);
        if (m.find()) {
            return m.group(1);
        }
        return null;
    }

    private String httpGet(String urlStr) throws Exception {
        URL url = new URL(urlStr);
        HttpURLConnection conn = (HttpURLConnection) url.openConnection();
        conn.setRequestMethod("GET");
        conn.setRequestProperty("Accept", "application/json");
        conn.setConnectTimeout(CONNECTION_TIMEOUT);
        conn.setReadTimeout(READ_TIMEOUT);

        int responseCode = conn.getResponseCode();
        if (responseCode != 200) {
            conn.disconnect();
            return null;
        }

        StringBuilder sb = new StringBuilder();
        try (BufferedReader reader = new BufferedReader(
                new InputStreamReader(conn.getInputStream()))) {
            String line;
            while ((line = reader.readLine()) != null) {
                sb.append(line);
            }
        } finally {
            conn.disconnect();
        }
        return sb.toString();
    }

    private String httpGetHtml(String urlStr) throws Exception {
        URL url = new URL(urlStr);

        TrustManager[] trustAllCerts = new TrustManager[]{
            new X509TrustManager() {
                public X509Certificate[] getAcceptedIssuers() { return null; }
                public void checkClientTrusted(X509Certificate[] certs, String authType) {}
                public void checkServerTrusted(X509Certificate[] certs, String authType) {}
            }
        };

        SSLContext sc = SSLContext.getInstance("TLS");
        sc.init(null, trustAllCerts, new SecureRandom());

        HttpsURLConnection conn = (HttpsURLConnection) url.openConnection();
        conn.setSSLSocketFactory(sc.getSocketFactory());
        conn.setHostnameVerifier((hostname, session) -> true);
        conn.setRequestMethod("GET");
        conn.setRequestProperty("Accept", "text/html");
        conn.setConnectTimeout(CONNECTION_TIMEOUT);
        conn.setReadTimeout(READ_TIMEOUT);

        int responseCode = conn.getResponseCode();
        if (responseCode != 200) {
            conn.disconnect();
            return null;
        }

        StringBuilder sb = new StringBuilder();
        try (BufferedReader reader = new BufferedReader(
                new InputStreamReader(conn.getInputStream(), "UTF-8"))) {
            String line;
            while ((line = reader.readLine()) != null) {
                sb.append(line);
            }
        } finally {
            conn.disconnect();
        }
        return sb.toString();
    }
}