package com.grigowashere.aismap.utils;

import android.util.Log;

import java.io.InputStream;
import java.net.ConnectException;
import java.net.HttpURLConnection;
import java.net.NoRouteToHostException;
import java.net.SocketTimeoutException;
import java.net.URL;
import java.net.UnknownHostException;
import java.security.cert.CertificateException;
import java.util.Locale;

import javax.net.ssl.SSLException;
import javax.net.ssl.SSLHandshakeException;
import javax.net.ssl.SSLPeerUnverifiedException;

/**
 * Lightweight reachability check for {@code https://aismap.local/} (feasibility / diagnostics).
 * Runs on a background thread; callers must not invoke from the UI thread.
 */
public final class AismapLocalHttpsProbe {

    private static final String TAG = "AismapLocalHttpsProbe";

    /** Hub HTTPS root — user-requested feasibility target. */
    public static final String PROBE_URL = "https://aismap.local/";

    private static final int CONNECT_TIMEOUT_MS = 2500;
    private static final int READ_TIMEOUT_MS = 2500;

    private AismapLocalHttpsProbe() {}

    /**
     * Performs a GET with short timeouts. Returns a short UI-safe line (no stack traces).
     */
    public static String probeOnce() {
        HttpURLConnection conn = null;
        try {
            URL url = new URL(PROBE_URL);
            conn = (HttpURLConnection) url.openConnection();
            conn.setConnectTimeout(CONNECT_TIMEOUT_MS);
            conn.setReadTimeout(READ_TIMEOUT_MS);
            conn.setRequestMethod("GET");
            conn.setInstanceFollowRedirects(true);
            conn.setUseCaches(false);
            int code = conn.getResponseCode();
            InputStream body = code >= HttpURLConnection.HTTP_BAD_REQUEST
                    ? conn.getErrorStream() : conn.getInputStream();
            drain(body);
            if (code >= 200 && code < 400) {
                return "HTTPS aismap.local: OK HTTP " + code;
            }
            return "HTTPS aismap.local: HTTP " + code;
        } catch (Throwable t) {
            Log.w(TAG, "probe failed: " + t.getClass().getSimpleName() + ": " + t.getMessage(), t);
            return "HTTPS aismap.local: " + classify(t);
        } finally {
            if (conn != null) {
                try {
                    conn.disconnect();
                } catch (Throwable ignore) {}
            }
        }
    }

    private static void drain(InputStream in) {
        if (in == null) return;
        byte[] buf = new byte[512];
        try (InputStream stream = in) {
            while (stream.read(buf) != -1) { /* discard */ }
        } catch (Throwable ignore) {}
    }

    static String classify(Throwable t) {
        if (t instanceof SSLHandshakeException || t instanceof SSLPeerUnverifiedException) {
            return "TLS/cert issue";
        }
        if (t instanceof CertificateException) {
            return "TLS/cert issue";
        }
        if (t instanceof SSLException) {
            String m = t.getMessage();
            if (m != null && m.toLowerCase(Locale.US).contains("cert")) {
                return "TLS/cert issue";
            }
            return "TLS: " + t.getClass().getSimpleName();
        }
        if (t instanceof SocketTimeoutException) {
            return "timeout";
        }
        if (t instanceof UnknownHostException) {
            return "no DNS (aismap.local)";
        }
        if (t instanceof ConnectException || t instanceof NoRouteToHostException) {
            return "no route / refused";
        }
        Throwable c = t.getCause();
        if (c != null && c != t) {
            return classify(c);
        }
        String m = t.getMessage();
        if (m != null && !m.isEmpty()) {
            String shortM = m.length() > 48 ? m.substring(0, 45) + "…" : m;
            return t.getClass().getSimpleName() + ": " + shortM;
        }
        return t.getClass().getSimpleName();
    }
}