ru.valle.safetrade.SellActivity.java Source code

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/**
 The MIT License (MIT)
    
 Copyright (c) 2013 Valentin Konovalov
    
 Permission is hereby granted, free of charge, to any person obtaining a copy
 of this software and associated documentation files (the "Software"), to deal
 in the Software without restriction, including without limitation the rights
 to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 copies of the Software, and to permit persons to whom the Software is
 furnished to do so, subject to the following conditions:
    
 The above copyright notice and this permission notice shall be included in
 all copies or substantial portions of the Software.
    
 THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 THE SOFTWARE.*/
package ru.valle.safetrade;

import android.app.AlertDialog;
import android.app.ProgressDialog;
import android.content.ActivityNotFoundException;
import android.content.ContentValues;
import android.content.Context;
import android.content.DialogInterface;
import android.content.Intent;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.graphics.Bitmap;
import android.net.Uri;
import android.os.AsyncTask;
import android.os.Build;
import android.os.Bundle;
import android.provider.BaseColumns;
import android.support.v4.app.FragmentActivity;
import android.text.TextUtils;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.widget.CompoundButton;
import android.widget.EditText;
import android.widget.TextView;
import android.widget.Toast;
import android.widget.ToggleButton;
import com.d_project.qrcode.ErrorCorrectLevel;
import com.d_project.qrcode.QRCode;
import ru.valle.btc.BTCUtils;
import ru.valle.btc.KeyPair;
import ru.valle.btc.UnspentOutputInfo;

import java.io.ByteArrayOutputStream;
import java.io.FileOutputStream;
import java.util.ArrayList;
import java.util.Collection;

public final class SellActivity extends FragmentActivity {
    private static final String TAG = "SellActivity";
    private static final int REQUEST_SCAN_CONFIRMATION_CODE = 2;
    private static final int REQUEST_SCAN_PRIVATE_KEY = 3;
    private static final int REQUEST_SCAN_FINAL_ADDRESS = 4;
    private TextView passwordView;
    private TextView intermediateCodeView;
    private long rowId;
    private AsyncTask<Void, Void, TradeRecord> loadStateTask;
    private TradeRecord tradeInfo;
    private TextView balanceView;
    private AsyncTask<Void, String, String> confirmationCodeDecodingTask;
    private View addressLabelView;
    private TextView addressView;
    private EditText confirmationCodeView;
    private EditText privateKeyView;
    private AsyncTask<Void, String, KeyPair> privateKeyDecodingTask;
    private TextView takeButton;
    private TextView finalAddressView;
    private AddressState addressState;

    private final Listener<AddressState> onAddressStateReceivedListener = new Listener<AddressState>() {
        @Override
        public void onSuccess(AddressState result) {
            if (result != null && !isDestroyed()) {
                addressState = result;
                long balance = result.getBalance();
                String balanceStr = BTCUtils.formatValue(balance);
                balanceView.setText(balanceStr + " BTC");
                if (balance == 0) {
                    takeButton.setText(getString(R.string.take_no_btc_button));
                } else {
                    takeButton.setText(getString(R.string.take_button, balanceStr));
                }
            }
        }
    };

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.sell);
        passwordView = (TextView) findViewById(R.id.password);
        intermediateCodeView = (TextView) findViewById(R.id.intermediate_code);
        balanceView = (TextView) findViewById(R.id.balance);
        addressLabelView = findViewById(R.id.address_label);
        addressView = (TextView) findViewById(R.id.address);
        confirmationCodeView = (EditText) findViewById(R.id.confirmation_code);
        privateKeyView = (EditText) findViewById(R.id.private_key);
        finalAddressView = (TextView) findViewById(R.id.final_address);
        takeButton = (TextView) findViewById(R.id.take_button);

        findViewById(R.id.send_intermediate_code_button).setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                sendIntermediateCode();
            }
        });
        findViewById(R.id.scan_confirmation_code_button).setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Intent intent = new Intent(SellActivity.this, ScanActivity.class).putExtra(ScanActivity.EXTRA_TITLE,
                        getString(R.string.scan_confirmation_code_title));
                startActivityForResult(intent, REQUEST_SCAN_CONFIRMATION_CODE);
            }
        });
        findViewById(R.id.scan_encrypted_private_key_button).setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Intent intent = new Intent(SellActivity.this, ScanActivity.class).putExtra(ScanActivity.EXTRA_TITLE,
                        getString(R.string.scan_encrypted_private_key_title));
                startActivityForResult(intent, REQUEST_SCAN_PRIVATE_KEY);
            }
        });
        findViewById(R.id.scan_final_address_button).setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Intent intent = new Intent(SellActivity.this, ScanActivity.class).putExtra(ScanActivity.EXTRA_TITLE,
                        getString(R.string.scan_final_address_title));
                startActivityForResult(intent, REQUEST_SCAN_FINAL_ADDRESS);
            }
        });
        takeButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                takeFunds();
            }
        });

        rowId = getIntent().getLongExtra(BaseColumns._ID, -1);
    }

    private void takeFunds() {
        String finalAddress = "";
        String errorMessage = null;
        if (tradeInfo == null) {
            errorMessage = getString(R.string.state_not_loaded_yet);
        } else if (TextUtils.isEmpty(tradeInfo.privateKey)) {
            errorMessage = getString(R.string.no_private_key_from_buyer);
        } else if (addressState == null) {
            errorMessage = getString(R.string.alert_checking_balance);//TODO it may be not true because of networking errors, add retry
        }
        //        } else if (addressState.getBalance() == 0) {
        //            errorMessage = getString(R.string.zero_balance, addressState.address);
        //        }
        else {
            CharSequence enteredAddress = finalAddressView.getText();
            if (enteredAddress != null) {
                finalAddress = enteredAddress.toString();
            }
            if (TextUtils.isEmpty(finalAddress)) {
                errorMessage = getString(R.string.enter_your_final_address);
            }
        }
        if (errorMessage != null) {
            showAlert(errorMessage);
        } else {
            View feesSelectorView = LayoutInflater.from(this).inflate(R.layout.fees_selector, null);
            assert feesSelectorView != null;
            TextView descView = (TextView) feesSelectorView.findViewById(R.id.tx_desc);

            final AddressState addressStateArg;
            final BTCUtils.PrivateKeyInfo privateKeyInfo;

            //args
            //            addressStateArg = addressState;
            //            privateKeyInfo = BTCUtils.decodePrivateKey(tradeInfo.privateKey);
            //
            try {
                addressStateArg = new AddressState("1933phfhK3ZgFQNLGSDXvqCn32k2buXY8a",
                        MainActivity.parseUnspentOutputsFromBlockchainInfo(new String(
                                QRCodesProvider.readStream(getResources().openRawResource(R.raw.fakeoutputs)))));
                privateKeyInfo = BTCUtils.decodePrivateKey(tradeInfo.privateKey);
            } catch (Exception e) {
                throw new RuntimeException();
            }
            //

            final long balance = addressStateArg.getBalance();
            descView.setText(
                    getString(R.string.confirm_tx_x_btc_to_addr, BTCUtils.formatValue(balance), finalAddress));

            final ToggleButton minFeeButton = (ToggleButton) feesSelectorView.findViewById(R.id.min_miner_fee);
            final ToggleButton safeFeeButton = (ToggleButton) feesSelectorView.findViewById(R.id.safe_miner_fee);
            final ToggleButton maxFeeButton = (ToggleButton) feesSelectorView.findViewById(R.id.max_miner_fee);

            final TextView minersFeeView = (TextView) feesSelectorView.findViewById(R.id.miners_fee);

            final ToggleButton noDevFeeButton = (ToggleButton) feesSelectorView.findViewById(R.id.no_dev_fee);
            final ToggleButton medDevFeeButton = (ToggleButton) feesSelectorView.findViewById(R.id.med_dev_fee);
            final ToggleButton maxDevFeeButton = (ToggleButton) feesSelectorView.findViewById(R.id.max_dev_fee);

            final TextView devFeeView = (TextView) feesSelectorView.findViewById(R.id.developer_fee);

            final TextView txDescFinalView = (TextView) feesSelectorView.findViewById(R.id.tx_desc_after_fees);

            CompoundButton.OnCheckedChangeListener feesSelectorListener = new CompoundButton.OnCheckedChangeListener() {
                long fee;
                long devFee;
                public int feeLevel;

                @Override
                public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
                    switch (buttonView.getId()) {
                    case R.id.min_miner_fee: {
                        if (isChecked) {
                            safeFeeButton.setChecked(false);
                            maxFeeButton.setChecked(false);
                            updateFee(0);
                        } else if (!safeFeeButton.isChecked() && !maxFeeButton.isChecked()) {
                            buttonView.setChecked(true);
                        }
                    }
                        break;
                    case R.id.safe_miner_fee: {
                        if (isChecked) {
                            minFeeButton.setChecked(false);
                            maxFeeButton.setChecked(false);
                            updateFee(1);
                        } else if (!minFeeButton.isChecked() && !maxFeeButton.isChecked()) {
                            buttonView.setChecked(true);
                        }
                    }
                        break;
                    case R.id.max_miner_fee: {
                        if (isChecked) {
                            minFeeButton.setChecked(false);
                            safeFeeButton.setChecked(false);
                            updateFee(2);
                        } else if (!minFeeButton.isChecked() && !safeFeeButton.isChecked()) {
                            buttonView.setChecked(true);
                        }
                    }
                        break;
                    case R.id.no_dev_fee: {
                        if (isChecked) {
                            medDevFeeButton.setChecked(false);
                            maxDevFeeButton.setChecked(false);
                            updateDevFee(0);
                        } else if (!medDevFeeButton.isChecked() && !maxDevFeeButton.isChecked()) {
                            buttonView.setChecked(true);
                        }
                    }
                        break;
                    case R.id.med_dev_fee: {
                        if (isChecked) {
                            noDevFeeButton.setChecked(false);
                            maxDevFeeButton.setChecked(false);
                            updateDevFee(1);
                        } else if (!noDevFeeButton.isChecked() && !maxDevFeeButton.isChecked()) {
                            buttonView.setChecked(true);
                        }
                    }
                        break;
                    case R.id.max_dev_fee: {
                        if (isChecked) {
                            noDevFeeButton.setChecked(false);
                            medDevFeeButton.setChecked(false);
                            updateDevFee(2);
                        } else if (!noDevFeeButton.isChecked() && !medDevFeeButton.isChecked()) {
                            buttonView.setChecked(true);
                        }
                    }
                        break;
                    }
                }

                private void updateDevFee(int level) {
                    devFee = getDevFee(level, balance);
                    devFeeView.setText(getString(R.string.tips_for_dev, BTCUtils.formatValue(devFee)));
                    updateFee(feeLevel);
                }

                private void updateFee(int level) {
                    feeLevel = level;
                    fee = getMinerFee(level, devFee, balance, addressStateArg.getUnspentOutputs(),
                            privateKeyInfo.isPublicKeyCompressed);
                    minersFeeView.setText(getString(R.string.miners_fee, BTCUtils.formatValue(fee)));
                    txDescFinalView.setText(
                            getString(R.string.final_tx_desc, BTCUtils.formatValue(balance - fee - devFee)));
                }

            };

            minFeeButton.setOnCheckedChangeListener(feesSelectorListener);
            safeFeeButton.setOnCheckedChangeListener(feesSelectorListener);
            maxFeeButton.setOnCheckedChangeListener(feesSelectorListener);
            ((ToggleButton) feesSelectorView.findViewById(R.id.no_dev_fee))
                    .setOnCheckedChangeListener(feesSelectorListener);
            ((ToggleButton) feesSelectorView.findViewById(R.id.med_dev_fee))
                    .setOnCheckedChangeListener(feesSelectorListener);
            ((ToggleButton) feesSelectorView.findViewById(R.id.max_dev_fee))
                    .setOnCheckedChangeListener(feesSelectorListener);

            safeFeeButton.setChecked(true);

            if (getDevFee(1, balance) == 0) {
                medDevFeeButton.setEnabled(false);
                maxDevFeeButton.setEnabled(getDevFee(2, balance) > 0);
                noDevFeeButton.setChecked(true);
            } else {
                medDevFeeButton.setChecked(true);
            }

            long minDevFee = getDevFee(0, balance);
            if (getMinerFee(2, minDevFee, balance, addressStateArg.getUnspentOutputs(),
                    privateKeyInfo.isPublicKeyCompressed) == balance - minDevFee) {
                maxFeeButton.setEnabled(false);
            }

            if (getMinerFee(1, minDevFee, balance, addressStateArg.getUnspentOutputs(),
                    privateKeyInfo.isPublicKeyCompressed) == balance - minDevFee) {
                safeFeeButton.setEnabled(false);
                minFeeButton.setChecked(true);
            }

            new AlertDialog.Builder(SellActivity.this).setView(feesSelectorView)
                    .setPositiveButton(android.R.string.ok, new DialogInterface.OnClickListener() {
                        @Override
                        public void onClick(DialogInterface dialog, int which) {

                        }
                    }).setNegativeButton(android.R.string.cancel, null).show();
        }
    }

    private static long getDevFee(int level, long balance) {
        long expectedDevFee;
        switch (level) {
        default:
        case 0:
            expectedDevFee = 0;
            break;
        case 1:
            expectedDevFee = (long) (0.001 * balance);//0.1%
            break;
        case 2:
            expectedDevFee = (long) (0.01 * balance);//1.0%
            break;
        }
        expectedDevFee -= expectedDevFee % 10000;
        return expectedDevFee < 50000 ? 0 : expectedDevFee;//0.5 mBTC
    }

    private static long getMinerFee(int level, long devFee, long balance,
            Collection<UnspentOutputInfo> unspentOutputs, boolean isPublicKeyCompressed) {
        final int txLen = BTCUtils.getMaximumTxSize(unspentOutputs, devFee == 0 ? 1 : 2, isPublicKeyCompressed);
        long minFee = BTCUtils.calcMinimumFee(txLen, unspentOutputs, balance);
        final long notZeroMinFee = BTCUtils.MIN_FEE_PER_KB * (1 + txLen / 1000);
        long localFee;
        switch (level) {
        default:
        case 0:
            localFee = minFee;
            break;
        case 1:
            localFee = (minFee == 0 ? notZeroMinFee : minFee) * 2;
            break;
        case 2:
            localFee = (minFee == 0 ? notZeroMinFee : minFee) * 10;
            break;
        }
        if (balance - localFee - devFee < 0) {
            localFee = balance - devFee;
        }
        return localFee;
    }

    private void showAlert(String message) {
        new AlertDialog.Builder(SellActivity.this).setMessage(message).setPositiveButton(android.R.string.ok, null)
                .show();
    }

    @Override
    protected void onResume() {
        super.onResume();
        if (rowId != -1) {
            loadState(rowId);
        }
    }

    private static final String SCHEME_BITCOIN = "bitcoin:";

    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        super.onActivityResult(requestCode, resultCode, data);
        if (resultCode == RESULT_OK) {
            String scannedResult = data.getStringExtra("data");
            if (scannedResult != null) {
                switch (requestCode) {
                case REQUEST_SCAN_CONFIRMATION_CODE: {
                    if (scannedResult.startsWith("cfrm")) {
                        checkConfirmationCodeToDecodeAddress(scannedResult);
                    } else if (scannedResult.startsWith("passphrase")) {
                        showAlert(getString(R.string.not_confirmation_but_intermediate_code));
                    } else {
                        showAlert(getString(R.string.not_confirmation_code));
                    }
                }
                    break;
                case REQUEST_SCAN_PRIVATE_KEY: {
                    if (scannedResult.startsWith("6P")) {
                        savePrivateKey(scannedResult);
                    } else {
                        showAlert(getString(R.string.not_encrypted_private_key));
                    }
                }
                    break;
                case REQUEST_SCAN_FINAL_ADDRESS: {
                    final String address;
                    if (scannedResult.startsWith(SCHEME_BITCOIN)) {
                        scannedResult = scannedResult.substring(SCHEME_BITCOIN.length());
                        int queryStartIndex = scannedResult.indexOf('?');
                        address = queryStartIndex == -1 ? scannedResult
                                : scannedResult.substring(0, queryStartIndex);
                    } else if (scannedResult.startsWith("1")) {
                        address = scannedResult;
                    } else {
                        showAlert(getString(R.string.not_address));
                        address = null;
                    }
                    if (!TextUtils.isEmpty(address)) {
                        finalAddressView.setText(address);
                        final long id = rowId;
                        new AsyncTask<Void, Void, Void>() {
                            @Override
                            protected Void doInBackground(Void... params) {
                                SQLiteDatabase db = DatabaseHelper.getInstance(SellActivity.this)
                                        .getWritableDatabase();
                                if (db != null) {
                                    ContentValues cv = new ContentValues();
                                    cv.put(DatabaseHelper.COLUMN_FINAL_ADDRESS, address);
                                    db.update(DatabaseHelper.TABLE_HISTORY, cv, BaseColumns._ID + "=?",
                                            new String[] { String.valueOf(id) });
                                }
                                return null;
                            }
                        }.execute();
                    }
                }
                    break;
                }

            }
        }
    }

    private void savePrivateKey(final String encryptedPrivateKey) {
        final String password = tradeInfo.password;
        final long id = rowId;
        privateKeyDecodingTask = new AsyncTask<Void, String, KeyPair>() {
            public ProgressDialog progressDialog;

            @Override
            protected void onPreExecute() {
                final CharSequence oldEnteredValue = privateKeyView.getText();
                privateKeyView.setText(encryptedPrivateKey);
                progressDialog = ProgressDialog.show(SellActivity.this, null,
                        getString(R.string.decrypting_private_key), true);
                progressDialog.setCancelable(true);
                progressDialog.setCanceledOnTouchOutside(false);
                progressDialog.setOnCancelListener(new DialogInterface.OnCancelListener() {
                    @Override
                    public void onCancel(DialogInterface dialog) {
                        privateKeyView.setText(oldEnteredValue);
                        privateKeyDecodingTask.cancel(true);
                        if (rowId != -1) {
                            loadState(rowId);
                        }
                    }
                });
            }

            @Override
            protected void onProgressUpdate(String... values) {
                try {
                    progressDialog.setMessage(values[0]);
                } catch (Exception ignored) {
                }
            }

            @Override
            protected KeyPair doInBackground(Void... params) {
                try {
                    KeyPair keyPair = BTCUtils.bip38Decrypt(encryptedPrivateKey, password);
                    if (keyPair != null) {
                        SQLiteDatabase db = DatabaseHelper.getInstance(SellActivity.this).getWritableDatabase();
                        if (db != null) {
                            ContentValues cv = new ContentValues();
                            cv.put(DatabaseHelper.COLUMN_ADDRESS, keyPair.address);
                            cv.put(DatabaseHelper.COLUMN_ENCRYPTED_PRIVATE_KEY, encryptedPrivateKey);
                            cv.put(DatabaseHelper.COLUMN_PRIVATE_KEY,
                                    BTCUtils.encodeWifKey(keyPair.privateKey.isPublicKeyCompressed,
                                            BTCUtils.getPrivateKeyBytes(keyPair.privateKey.privateKeyDecoded)));
                            db.update(DatabaseHelper.TABLE_HISTORY, cv, BaseColumns._ID + "=?",
                                    new String[] { String.valueOf(id) });
                        }
                    }
                    return keyPair;
                } catch (InterruptedException e) {
                    Log.v(TAG, "pk decrypt interrupted");
                    return null;
                } catch (Throwable e) {
                    Log.e(TAG, "pk decrypt", e);
                    return null;
                }
            }

            @Override
            protected void onPostExecute(final KeyPair keyPair) {
                try {
                    progressDialog.dismiss();
                } catch (Exception ignored) {
                }
                privateKeyDecodingTask = null;
                showAlert(keyPair != null ? getString(R.string.private_key_decrypted, keyPair.address)
                        : getString(R.string.unable_to_decrypt_private_key));
                loadState(rowId);
            }
        }.execute();

    }

    private void checkConfirmationCodeToDecodeAddress(final String confirmationCode) {
        final String password = tradeInfo.password;
        final long id = rowId;
        confirmationCodeDecodingTask = new AsyncTask<Void, String, String>() {
            public ProgressDialog progressDialog;

            @Override
            protected void onPreExecute() {
                final CharSequence oldEnteredValue = confirmationCodeView.getText();
                confirmationCodeView.setText(confirmationCode);
                progressDialog = ProgressDialog.show(SellActivity.this, null,
                        getString(R.string.decoding_confirmation_code_using_password), true);
                progressDialog.setCancelable(true);
                progressDialog.setCanceledOnTouchOutside(false);
                progressDialog.setOnCancelListener(new DialogInterface.OnCancelListener() {
                    @Override
                    public void onCancel(DialogInterface dialog) {
                        confirmationCodeDecodingTask.cancel(true);
                        confirmationCodeView.setText(oldEnteredValue);
                        if (rowId != -1) {
                            loadState(rowId);
                        }
                    }
                });
            }

            @Override
            protected void onProgressUpdate(String... values) {
                try {
                    progressDialog.setMessage(values[0]);
                } catch (Exception ignored) {
                }
            }

            @Override
            protected String doInBackground(Void... params) {
                try {
                    String address = BTCUtils.bip38DecryptConfirmation(confirmationCode, password);
                    if (address != null) {
                        SQLiteDatabase db = DatabaseHelper.getInstance(SellActivity.this).getWritableDatabase();
                        if (db != null) {
                            ContentValues cv = new ContentValues();
                            cv.put(DatabaseHelper.COLUMN_ADDRESS, address);
                            cv.put(DatabaseHelper.COLUMN_CONFIRMATION_CODE, confirmationCode);
                            db.update(DatabaseHelper.TABLE_HISTORY, cv, BaseColumns._ID + "=?",
                                    new String[] { String.valueOf(id) });
                        }
                    }
                    return address;
                } catch (Throwable e) {
                    return null;
                }
            }

            @Override
            protected void onPostExecute(final String address) {
                try {
                    progressDialog.dismiss();
                } catch (Exception ignored) {
                }
                confirmationCodeDecodingTask = null;
                if (!TextUtils.isEmpty(address)) {
                    confirmationCodeView.setText(confirmationCode);
                    addressView.setText(address);
                    addressLabelView.setVisibility(View.VISIBLE);
                    addressView.setVisibility(View.VISIBLE);
                    MainActivity.updateBalance(SellActivity.this, id, address, onAddressStateReceivedListener);
                } else {
                    loadState(rowId);
                    showAlert(getString(R.string.confirmation_code_doesnt_match));
                }
            }
        }.execute();
    }

    private void sendIntermediateCode() {
        if (tradeInfo != null) {
            final String intermediateCode = tradeInfo.intermediateCode;
            new AsyncTask<Void, Void, Uri>() {
                @Override
                protected Uri doInBackground(Void... params) {
                    try {
                        QRCode qr = new QRCode();
                        qr.setTypeNumber(5);
                        qr.setErrorCorrectLevel(ErrorCorrectLevel.M);
                        qr.addData(intermediateCode);
                        qr.make();
                        Bitmap bmp = qr.createImage(640);
                        ByteArrayOutputStream baos = new ByteArrayOutputStream();
                        bmp.compress(Bitmap.CompressFormat.PNG, 100, baos);
                        byte[] pngBytes = baos.toByteArray();
                        if (pngBytes != null && pngBytes.length > 0) {
                            String fileName = BTCUtils.toHex(BTCUtils.doubleSha256(intermediateCode.getBytes()))
                                    + QRCodesProvider.INTERMEDIATE_FEATURE + QRCodesProvider.FILENAME_SUFFIX;
                            deleteFile(fileName);
                            FileOutputStream fos = openFileOutput(fileName, Context.MODE_PRIVATE);
                            fos.write(pngBytes);
                            fos.close();
                            return Uri.parse(QRCodesProvider.getUri(fileName));
                        }
                    } catch (Exception e) {
                        Log.e(TAG, "Unable to create QR code", e);
                    }
                    return null;
                }

                @Override
                protected void onPostExecute(Uri uri) {
                    Intent intent = new Intent(Intent.ACTION_SEND);
                    if (uri != null) {
                        intent.putExtra(Intent.EXTRA_STREAM, uri);
                    }
                    intent.putExtra(Intent.EXTRA_SUBJECT, "Intermediate code");
                    intent.putExtra(Intent.EXTRA_TEXT, tradeInfo.intermediateCode);
                    intent.setType("message/rfc822");
                    try {
                        startActivity(intent);
                    } catch (ActivityNotFoundException ex) {
                        Toast.makeText(SellActivity.this, getString(R.string.no_email_clients), Toast.LENGTH_SHORT)
                                .show();
                    }
                }
            }.execute();
        }
    }

    @Override
    protected void onDestroy() {
        super.onDestroy();
        cancelAllTasks();
    }

    private void cancelAllTasks() {
        if (loadStateTask != null) {
            loadStateTask.cancel(true);
            loadStateTask = null;
        }
    }

    private void loadState(final long id) {
        cancelAllTasks();
        loadStateTask = new AsyncTask<Void, Void, TradeRecord>() {
            @Override
            protected TradeRecord doInBackground(Void... params) {
                SQLiteDatabase db = DatabaseHelper.getInstance(SellActivity.this).getReadableDatabase();
                if (db != null) {
                    Cursor cursor = db.query(DatabaseHelper.TABLE_HISTORY, null, BaseColumns._ID + "=?",
                            new String[] { String.valueOf(id) }, null, null, null);
                    ArrayList<TradeRecord> tradeRecords = DatabaseHelper.readTradeRecords(cursor);
                    return tradeRecords.isEmpty() ? null : tradeRecords.get(0);
                } else {
                    return null;
                }
            }

            @Override
            protected void onPostExecute(final TradeRecord tradeRecord) {
                tradeInfo = tradeRecord;
                loadStateTask = null;
                rowId = tradeRecord.id;
                passwordView.setText(tradeRecord.password);
                intermediateCodeView.setText(tradeRecord.intermediateCode);
                if (confirmationCodeDecodingTask == null) {
                    confirmationCodeView.setText(tradeRecord.confirmationCode);
                }
                if (TextUtils.isEmpty(tradeRecord.address)) {
                    addressLabelView.setVisibility(View.GONE);
                    addressView.setVisibility(View.GONE);
                } else {
                    addressView.setText(tradeRecord.address);
                    addressLabelView.setVisibility(View.VISIBLE);
                    addressView.setVisibility(View.VISIBLE);
                }
                finalAddressView.setText(tradeRecord.destinationAddress);
                if (privateKeyDecodingTask == null) {
                    privateKeyView.setText(tradeRecord.encryptedPrivateKey);
                }
                MainActivity.updateBalance(SellActivity.this, id, tradeInfo.address,
                        onAddressStateReceivedListener);
            }
        };
        if (Build.VERSION.SDK_INT >= 11) {
            loadStateTask.executeOnExecutor(AsyncTask.THREAD_POOL_EXECUTOR);
        } else {
            loadStateTask.execute();
        }
    }

}