MainActivity.java

package uz.yt.sample.myapplication;

import android.Manifest;
import android.app.Activity;
import android.content.Intent;
import android.content.pm.PackageManager;
import android.net.Uri;
import android.os.Build;
import android.os.Bundle;
import android.util.Base64;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
import android.widget.Toast;

import androidx.appcompat.app.AppCompatActivity;
import androidx.core.app.ActivityCompat;

import org.json.JSONObject;

import java.io.BufferedReader;
import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.net.URL;
import java.net.URLEncoder;
import java.nio.file.Files;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
import java.util.zip.CRC32;

import javax.net.ssl.HttpsURLConnection;

public class MainActivity extends AppCompatActivity {

    // !!! CHANGE IT TO YOUR DOMAIN, WHICH RUNS REST-API, DO NOT USE THIS m.e-imzo.uz DOMAIN IN PRODUCTION
    private static String DOMAIN = "test.e-imzo.uz";
    private static String AUTH_URL = "https://" + DOMAIN + "/frontend/mobile/auth";
    private static String SIGN_URL = "https://" + DOMAIN + "/frontend/mobile/sign";
    private static String STATUS_URL = "https://" + DOMAIN + "/frontend/mobile/status";

    // !!! CHANGE IT TO YOUR BACKEND API
    private static String AUTH_RESULT_URL = "https://" + DOMAIN + "/demo/eimzoidcard/user_auth_result.php";
    private static String VERIFY_RESULT_URL = "https://" + DOMAIN + "/demo/eimzoidcard/doc_verify_result.php";

    private final int STATUS_CHECK_EACH_SECOND = 5;
    private final int STATUS_CHECK_INTERVAL = STATUS_CHECK_EACH_SECOND * 1000;
    private final int STATUS_CHECK_LIMIT = 2 * 60 / STATUS_CHECK_EACH_SECOND;


    TextView statusText;
    EditText resultText;
    EditText signText;

    private static final int MY_REQUEST_CODE_PERMISSION = 1000;
    private static final int MY_RESULT_CODE_FILECHOOSER = 2000;

    final void updateStatusText(final String text) {
        runOnUiThread(new Runnable() {
            @Override
            public void run() {
                statusText.setText(text);
            }
        });
    }

    final void updateResultText(final String text) {
        runOnUiThread(new Runnable() {
            @Override
            public void run() {
                resultText.setText(text);
            }
        });
    }


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        statusText = findViewById(R.id.tvStatus);
        resultText = findViewById(R.id.etResult);
        signText = findViewById(R.id.etJsonDocument);

        Button authButton = findViewById(R.id.bAuth);
        authButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                doAuth();
            }
        });

        Button signButton = findViewById(R.id.bSign);
        signButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                doSign();
            }
        });

        Button signFileButton = findViewById(R.id.bSignFile);
        signFileButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                askPermissionAndBrowseFile();
            }
        });

    }

    void askPermissionAndBrowseFile() {
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
            int permisson = ActivityCompat.checkSelfPermission(
                    this,
                    Manifest.permission.READ_EXTERNAL_STORAGE
            );
            if (permisson != PackageManager.PERMISSION_GRANTED) {
                requestPermissions(
                        new String[]{Manifest.permission.READ_EXTERNAL_STORAGE},
                        MY_REQUEST_CODE_PERMISSION
                );
                return;
            }
        }
        doBrowseFile();
    }

    private void doBrowseFile() {
        Intent chooseFileIntent = new Intent(Intent.ACTION_GET_CONTENT);
        chooseFileIntent.setType("*/*");
        // Only return URIs that can be opened with ContentResolver
        chooseFileIntent.addCategory(Intent.CATEGORY_OPENABLE);

        chooseFileIntent = Intent.createChooser(chooseFileIntent, "Choose a file");
        startActivityForResult(chooseFileIntent, MY_RESULT_CODE_FILECHOOSER);
    }

    @Override
    public void onRequestPermissionsResult(int requestCode, String permissions[], int[] grantResults) {

        super.onRequestPermissionsResult(requestCode, permissions, grantResults);
        //
        switch (requestCode) {
            case MY_REQUEST_CODE_PERMISSION: {

                // Note: If request is cancelled, the result arrays are empty.
                // Permissions granted (CALL_PHONE).
                if (grantResults.length > 0 && grantResults[0] == PackageManager.PERMISSION_GRANTED) {

                    Log.i("file chooser", "Permission granted!");
                    Toast.makeText(getApplicationContext(), "Permission granted!", Toast.LENGTH_SHORT).show();

                    this.doBrowseFile();
                }
                // Cancelled or denied.
                else {
                    Log.i("file chooser", "Permission denied!");
                    Toast.makeText(getApplicationContext(), "Permission denied!", Toast.LENGTH_SHORT).show();
                }
                break;
            }
        }
    }

    @Override
    public void onActivityResult(int requestCode, int resultCode, Intent data) {
        switch (requestCode) {
            case MY_RESULT_CODE_FILECHOOSER:
                if (resultCode == Activity.RESULT_OK) {
                    if (data != null) {
                        Uri fileUri = data.getData();
                        Log.i("file chooser", "Uri: " + fileUri);

                        String filePath = null;
                        try {
                            filePath = FileUtils.getPath(getApplicationContext(), fileUri);
                        } catch (Exception e) {
                            Log.e("file chooser", "Error: " + e);
                            Toast.makeText(getApplicationContext(), "Error: " + e, Toast.LENGTH_SHORT).show();
                        }
                        this.signText.setText(filePath);

                        int rd = 0;
                        byte[] buf = new byte[1024];
                        ByteArrayOutputStream baos = new ByteArrayOutputStream();
                        try (InputStream inputStream = getContentResolver().openInputStream(fileUri)) {
                            while ((rd = inputStream.read(buf)) != -1) {
                                baos.write(buf, 0, rd);
                            }
                            doSignFile(baos.toByteArray());
                        } catch (Throwable e) {
                            Toast.makeText(getApplicationContext(), e.getMessage(), Toast.LENGTH_SHORT).show();
                            Log.e("file open", e.getMessage(), e);
                        }

                    }
                    break;
                }
                super.onActivityResult(requestCode, resultCode, data);
        }
    }

    void doAuth() {
        Thread t = new Thread(new Runnable() {
            @Override
            public void run() {
                updateStatusText("");
                updateResultText("");
                try {
                    RawResult res = post(new URL(AUTH_URL), new byte[0]);
                    Log.d("auth http status", "HTTP " + res.responseCode + " - " + res.responseMessage);
                    Log.d("auth http body", res.responseBody);
                    if (res.responseCode != 200) {
                        throw new Exception("HTTP " + res.responseCode + " - " + res.responseMessage);
                    }
                    updateResultText(res.responseBody);


                    JSONObject jsonObject = new JSONObject(res.responseBody);
                    int status = jsonObject.getInt("status");
                    String message = jsonObject.optString("message", "");
                    if (status != 1) {
                        throw new Exception("AUTH STATUS " + status + " - " + message);
                    }

                    String siteId = jsonObject.getString("siteId");
                    final String documentId = jsonObject.getString("documentId");
                    String challange = jsonObject.getString("challange");

                    Log.d("auth siteId", siteId);
                    Log.d("auth documentId", documentId);
                    Log.d("auth challange", challange);

                    byte[] hash = calcHash(challange);

                    String hashString = Hex.encode(hash);
                    Log.d("auth hashString", hashString);

                    String qrCode = makeQRCode(siteId, documentId, hashString);
                    Log.d("auth qrCode", qrCode);

                    makeAndCallDeepLink(qrCode);

                    Log.d("auth status", "run get status thread");

                    pollStatus(documentId, new Runnable() {
                        @Override
                        public void run() {
                            try {
                                getAuthResult(documentId);
                            } catch (Throwable e) {
                                Log.d("auth result error", e.getClass().getSimpleName() + ": " + e.getMessage());
                                updateStatusText(e.getClass().getSimpleName() + ": " + e.getMessage());
                            }
                        }
                    });


                } catch (Throwable e) {
                    Log.d("auth error", e.getClass().getSimpleName() + ": " + e.getMessage());
                    updateStatusText(e.getClass().getSimpleName() + ": " + e.getMessage());

                }
            }
        });
        t.start();
    }

    void doSign() {
        Thread t = new Thread(new Runnable() {
            @Override
            public void run() {
                updateStatusText("");
                updateResultText("");
                try {
                    RawResult res = post(new URL(SIGN_URL), new byte[0]);
                    Log.d("sign http status", "HTTP " + res.responseCode + " - " + res.responseMessage);
                    Log.d("sign http body", res.responseBody);
                    if (res.responseCode != 200) {
                        throw new Exception("HTTP " + res.responseCode + " - " + res.responseMessage);
                    }
                    updateResultText(res.responseBody);


                    JSONObject jsonObject = new JSONObject(res.responseBody);
                    int status = jsonObject.getInt("status");
                    String message = jsonObject.optString("message", "");
                    if (status != 1) {
                        throw new Exception("SIGN STATUS " + status + " - " + message);
                    }

                    String siteId = jsonObject.getString("siteId");
                    final String documentId = jsonObject.getString("documentId");
                    final String document = signText.getText().toString();

                    Log.d("sign siteId", siteId);
                    Log.d("sign documentId", documentId);
                    Log.d("sign document", document);

                    byte[] hash = calcHash(document);

                    String hashString = Hex.encode(hash);
                    Log.d("sign hashString", hashString);

                    String qrCode = makeQRCode(siteId, documentId, hashString);
                    Log.d("sign qrCode", qrCode);

                    makeAndCallDeepLink(qrCode);

                    Log.d("sign status", "run get status thread");

                    pollStatus(documentId, new Runnable() {
                        @Override
                        public void run() {
                            try {
                                getVerifyResult(documentId, document);
                            } catch (Throwable e) {
                                Log.d("sign result error", e.getClass().getSimpleName() + ": " + e.getMessage());
                                updateStatusText(e.getClass().getSimpleName() + ": " + e.getMessage());
                            }
                        }
                    });


                } catch (Throwable e) {
                    Log.d("sign error", e.getClass().getSimpleName() + ": " + e.getMessage());
                    updateStatusText(e.getClass().getSimpleName() + ": " + e.getMessage());

                }
            }
        });
        t.start();
    }

    void doSignFile(byte[] file) {
        Thread t = new Thread(new Runnable() {
            @Override
            public void run() {
                updateStatusText("");
                updateResultText("");
                try {
                    RawResult res = post(new URL(SIGN_URL), new byte[0]);
                    Log.d("sign http status", "HTTP " + res.responseCode + " - " + res.responseMessage);
                    Log.d("sign http body", res.responseBody);
                    if (res.responseCode != 200) {
                        throw new Exception("HTTP " + res.responseCode + " - " + res.responseMessage);
                    }
                    updateResultText(res.responseBody);


                    JSONObject jsonObject = new JSONObject(res.responseBody);
                    int status = jsonObject.getInt("status");
                    String message = jsonObject.optString("message", "");
                    if (status != 1) {
                        throw new Exception("SIGN STATUS " + status + " - " + message);
                    }

                    String siteId = jsonObject.getString("siteId");
                    final String documentId = jsonObject.getString("documentId");

                    Log.d("sign siteId", siteId);
                    Log.d("sign documentId", documentId);

                    byte[] hash = calcHash(file);

                    String hashString = Hex.encode(hash);
                    Log.d("sign hashString", hashString);

                    String qrCode = makeQRCode(siteId, documentId, hashString);
                    Log.d("sign qrCode", qrCode);

                    makeAndCallDeepLink(qrCode);

                    Log.d("sign status", "run get status thread");

                    pollStatus(documentId, new Runnable() {
                        @Override
                        public void run() {
                            try {
                                getFileVerifyResult(documentId, file);
                            } catch (Throwable e) {
                                Log.d("sign result error", e.getClass().getSimpleName() + ": " + e.getMessage());
                                updateStatusText(e.getClass().getSimpleName() + ": " + e.getMessage());
                            }
                        }
                    });


                } catch (Throwable e) {
                    Log.d("sign error", e.getClass().getSimpleName() + ": " + e.getMessage());
                    updateStatusText(e.getClass().getSimpleName() + ": " + e.getMessage());

                }
            }
        });
        t.start();
    }

    void makeAndCallDeepLink(String qrCode) {
        String deepLink = "eimzo://sign?qc=" + qrCode;
        Log.d("makeAndCallDeepLink", deepLink);

        Intent browserIntent = new Intent(Intent.ACTION_VIEW, Uri.parse(deepLink));
        startActivity(browserIntent);
    }

    byte[] calcHash(String text) throws Exception {
        byte[] data = text.getBytes();
        OzDSt1106Digest digest = new OzDSt1106Digest();
        digest.reset();
        digest.update(data, 0, data.length);

        byte[] hash = new byte[digest.getDigestSize()];
        digest.doFinal(hash, 0);
        return hash;
    }

    byte[] calcHash(byte[] data) throws Exception {
        OzDSt1106Digest digest = new OzDSt1106Digest();
        digest.reset();
        digest.update(data, 0, data.length);

        byte[] hash = new byte[digest.getDigestSize()];
        digest.doFinal(hash, 0);
        return hash;
    }

    String makeQRCode(String siteId, String documentId, String hashString) {
        String qrBody = siteId + documentId + hashString;

        CRC32 crc = new CRC32();
        crc.update(Hex.decode(qrBody));
        long c1 = crc.getValue();
        String crc32 = zeroPad(Long.toHexString(c1), 8);

        Log.d("makeQRCode", "crc32(" + qrBody + ") = " + crc32);

        String qrCode = qrBody + crc32;
        return qrCode;
    }

    Pattern fetchJson = Pattern.compile("\\n\\s*(\\{.*\\})\\n*<");

    void getAuthResult(String documentId) throws Exception {
        String getData2 = "documentId=" + URLEncoder.encode(documentId, "UTF-8");
        RawResult res2 = get(new URL(AUTH_RESULT_URL + "?" + getData2));
        Log.d("auth result http status", "HTTP " + res2.responseCode + " - " + res2.responseMessage);
        Log.d("auth result http body", res2.responseBody);
        if (res2.responseCode != 200) {
            throw new Exception("HTTP " + res2.responseCode + " - " + res2.responseMessage);
        }

        // !!! DO NOT USE THIS WAY, AS IT IS JUST FOR DEMO
        Matcher m = fetchJson.matcher(res2.responseBody);
        boolean hasJson = m.find();
        int groupCount = m.groupCount();
        Log.d("auth result parse", "hasJson= " + hasJson + ", groupCount=" + groupCount);
        if (hasJson && groupCount > 0) {
            updateResultText(m.group(1));
        } else {
            updateResultText(res2.responseBody);
        }
    }

    void getVerifyResult(String documentId, String document) throws Exception {
        String postData2 = "documentId=" + URLEncoder.encode(documentId, "UTF-8") + "&Document=" + URLEncoder.encode(document, "UTF-8");
        RawResult res2 = post(new URL(VERIFY_RESULT_URL), postData2.getBytes());
        Log.d("auth result http status", "HTTP " + res2.responseCode + " - " + res2.responseMessage);
        Log.d("auth result http body", res2.responseBody);
        if (res2.responseCode != 200) {
            throw new Exception("HTTP " + res2.responseCode + " - " + res2.responseMessage);
        }

        // !!! DO NOT USE THIS WAY, AS IT IS JUST FOR DEMO
        Matcher m = fetchJson.matcher(res2.responseBody);
        boolean hasJson = m.find();
        int groupCount = m.groupCount();
        Log.d("auth result parse", "hasJson= " + hasJson + ", groupCount=" + groupCount);
        if (hasJson && groupCount > 0) {
            updateResultText(m.group(1));
        } else {
            updateResultText(res2.responseBody);
        }
    }

    void getFileVerifyResult(String documentId, byte[] file) throws Exception {
        String postData2 = "documentId=" + URLEncoder.encode(documentId, "UTF-8") + "&Document64=" + URLEncoder.encode(Base64.encodeToString(file, Base64.NO_WRAP), "UTF-8");
        RawResult res2 = post(new URL(VERIFY_RESULT_URL), postData2.getBytes());
        Log.d("auth result http status", "HTTP " + res2.responseCode + " - " + res2.responseMessage);
        Log.d("auth result http body", res2.responseBody);
        if (res2.responseCode != 200) {
            throw new Exception("HTTP " + res2.responseCode + " - " + res2.responseMessage);
        }

        // !!! DO NOT USE THIS WAY, AS IT IS JUST FOR DEMO
        Matcher m = fetchJson.matcher(res2.responseBody);
        boolean hasJson = m.find();
        int groupCount = m.groupCount();
        Log.d("auth result parse", "hasJson= " + hasJson + ", groupCount=" + groupCount);
        if (hasJson && groupCount > 0) {
            updateResultText(m.group(1));
        } else {
            updateResultText(res2.responseBody);
        }
    }

    void pollStatus(String documentId, Runnable onSuccess) {
        Thread statusThread = new Thread(new Runnable() {
            @Override
            public void run() {
                int checkCount = STATUS_CHECK_LIMIT;
                try {
                    while (checkCount > 0) {

                        Thread.sleep(STATUS_CHECK_INTERVAL);

                        String postData = "documentId=" + URLEncoder.encode(documentId, "UTF-8");

                        RawResult res = post(new URL(STATUS_URL), postData.getBytes());
                        Log.d("auth status number", String.valueOf(checkCount));
                        Log.d("auth status http status", "HTTP " + res.responseCode + " - " + res.responseMessage);
                        Log.d("auth status http body", res.responseBody);
                        if (res.responseCode != 200) {
                            throw new Exception("HTTP " + res.responseCode + " - " + res.responseMessage);
                        }
                        updateResultText(res.responseBody);

                        JSONObject jsonObject = new JSONObject(res.responseBody);
                        int status = jsonObject.getInt("status");
                        String message = jsonObject.optString("message", "");
                        if (status != 1 && status != 2) {
                            throw new Exception("STATUS " + status + " - " + message);
                        }

                        if (status == 1) {

                            onSuccess.run();

                            break;
                        }

                        checkCount--;
                    }
                } catch (Throwable e) {
                    Log.d("auth status error", e.getClass().getSimpleName() + ": " + e.getMessage());
                    updateStatusText(e.getClass().getSimpleName() + ": " + e.getMessage());
                }
                if (checkCount == 0) {
                    Log.d("auth status error", "timeout");
                    updateStatusText("auth status timeout");
                }
            }
        });

        statusThread.start();
    }

    static String zeroPad(String s, int count) {
        if (s.length() >= count) {
            return s;
        }
        StringBuilder sb = new StringBuilder();
        for (int i = 0; i < count - s.length(); i++) {
            sb.append("0");
        }
        sb.append(s);
        return sb.toString();
    }

    public static class RawResult {

        public int responseCode;
        public String responseMessage;
        public String responseBody;
    }

    public static RawResult post(URL url, byte[] body) throws IOException {
        RawResult r = new RawResult();
        HttpsURLConnection con = (HttpsURLConnection) url.openConnection();
        con.setRequestMethod("POST");
        con.setRequestProperty("Content-Type", "application/x-www-form-urlencoded");
        con.setRequestProperty("Content-Length", String.valueOf(body.length));
        con.setDoOutput(true);
        try (OutputStream out = con.getOutputStream()) {
            out.write(body);
            out.flush();
            r.responseCode = con.getResponseCode();
            r.responseMessage = con.getResponseMessage();

            StringBuilder sb = new StringBuilder();

            InputStreamReader in = new InputStreamReader(con.getInputStream());
            BufferedReader br = new BufferedReader(in);
            String text = "";
            while ((text = br.readLine()) != null) {
                sb.append(text).append("\n");
            }
            r.responseBody = sb.toString();
        } finally {
            con.disconnect();
        }
        return r;
    }

    public static RawResult get(URL url) throws IOException {
        RawResult r = new RawResult();
        HttpsURLConnection con = (HttpsURLConnection) url.openConnection();
        con.setRequestMethod("GET");

        r.responseCode = con.getResponseCode();
        r.responseMessage = con.getResponseMessage();

        try (BufferedReader br = new BufferedReader(new InputStreamReader(con.getInputStream()))) {

            StringBuilder sb = new StringBuilder();
            String text = "";
            while ((text = br.readLine()) != null) {
                sb.append(text).append("\n");
            }
            r.responseBody = sb.toString();
        } finally {
            con.disconnect();
        }
        return r;
    }

}