package ssl.publickey.checker;

import org.apache.cordova.CordovaPlugin;
import org.apache.cordova.CallbackContext;

import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;


import java.io.*;
import java.security.NoSuchAlgorithmException;
import java.security.cert.CertificateException;
import java.security.cert.CertificateEncodingException;

import javax.net.ssl.HttpsURLConnection;
import java.security.MessageDigest;
import javax.net.ssl.SSLSocket;
import javax.net.ssl.SSLSocketFactory;
import java.security.cert.Certificate;
import java.security.PublicKey;
/**
 * This class echoes a string called from JavaScript.
 */
public class SSLPublicKeyChecker extends CordovaPlugin {

    private static final String ACTION_CHECK_EVENT = "check";
        private static char[] HEX_CHARS = {'0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F'};

    @Override
    public boolean execute(String action, JSONArray args, CallbackContext callbackContext) throws JSONException {
        if (ACTION_CHECK_EVENT.equals(action)) {
            cordova.getThreadPool().execute(new Runnable() {
                public void run() {
                try {
                    final String serverURL = args.getString(0);
                    final JSONArray allowedFingerprints = args.getJSONArray(2);
                    final String serverCertFingerprint = getFingerprint(serverURL);
                    for (int j=0; j<allowedFingerprints.length(); j++) {
                        if (allowedFingerprints.get(j).toString().equalsIgnoreCase(serverCertFingerprint)) {
                            callbackContext.success("CONNECTION_SECURE");
                            return;
                        }
                    }
                    callbackContext.error("CONNECTION_NOT_SECURE");
                } catch (Exception e) {
                    callbackContext.error(e.toString());
                }
            }
        });
        return true;
        } 
        else {
            callbackContext.error("SSLPublicKeyChecker." + action + " is not a supported function. Did you mean '" + ACTION_CHECK_EVENT + "'?");
            return false;
        }
    }

    private static String getFingerprint(String httpsURL) throws IOException, NoSuchAlgorithmException, CertificateException, CertificateEncodingException {
        SSLSocketFactory factory = HttpsURLConnection.getDefaultSSLSocketFactory();        
        SSLSocket socket = (SSLSocket) factory.createSocket(httpsURL, 443);
        socket.startHandshake();
        Certificate[] certs = socket.getSession().getPeerCertificates();
        Certificate cert = certs[0];
        final MessageDigest md = MessageDigest.getInstance("SHA-256");
        md.update(cert.getEncoded());
        return dumpHex(md.digest());
    }

    private static String dumpHex(byte[] data) {
        final int n = data.length;
        final StringBuilder sb = new StringBuilder(n * 3 - 1);
        for (int i = 0; i < n; i++) {
        if (i > 0) {
            sb.append(' ');
        }
        sb.append(HEX_CHARS[(data[i] >> 4) & 0x0F]);
        sb.append(HEX_CHARS[data[i] & 0x0F]);
        }
        return sb.toString();
    }
}