import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.TextView;

public class MainActivity extends AppCompatActivity {
    private TextView showTextView, historyTextView;
    private int nowNumber = 0, flag = 0;
    private double result = 0.0;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        showTextView = (TextView)findViewById(R.id.showTextView);
        historyTextView = (TextView) findViewById(R.id.historyTextView);
    }
    public void buttonFunction(View view){
        int id = view.getId();
        if(showTextView.getText().equals("0"))
            showTextView.setText("");
        if(flag == 5) {
            showTextView.setText("");
            flag = 0;
        }
        switch (id){
            case R.id.zeroBtn:
                if(showTextView.getText().equals("0"))
                    showTextView.setText("0");
                else
                    showTextView.setText(showTextView.getText() + "0");
                break;
            case R.id.oneBtn:
                showTextView.setText(showTextView.getText() + "1");
                break;
            case R.id.twoBtn:
                showTextView.setText(showTextView.getText() + "2");
                break;
            case R.id.threeBtn:
                showTextView.setText(showTextView.getText() + "3");
                break;
            case R.id.fourBtn:
                showTextView.setText(showTextView.getText() + "4");
                break;
            case R.id.fiveBtn:
                showTextView.setText(showTextView.getText() + "5");
                break;
            case R.id.sixBtn:
                showTextView.setText(showTextView.getText() + "6");
                break;
            case R.id.sevenBtn:
                showTextView.setText(showTextView.getText() + "7");
                break;
            case R.id.eightBtn:
                showTextView.setText(showTextView.getText() + "8");
                break;
            case R.id.nineBtn:
                showTextView.setText(showTextView.getText() + "9");
                break;
            case R.id.clearBtn:
                showTextView.setText("0");
                historyTextView.setText("");
                result = 0;
                break;
            case R.id.addBtn:
                add();
                break;
            case R.id.minusBtn:
                minus();
                break;
            case R.id.timesBtn:
                times();
                break;
            case R.id.intoBtn:
                into();
                break;
            case R.id.resultBtn:
                switch (flag){
                    case 1:
                        add();
                        break;
                    case 2:
                        minus();
                        break;
                    case 3:
                        times();
                        break;
                    case 4:
                        into();
                        break;
                }
                showTextView.setText(String.valueOf(result));
                flag = 5;
                break;
        }
    }
    public void add(){
        if(!showTextView.getText().toString().equals("")){
            String historyTmp = historyTextView.getText().toString();
            historyTmp += showTextView.getText().toString() + "+";
            historyTextView.setText(historyTmp);
            double tmp = Integer.parseInt(showTextView.getText().toString()) + result;
            result = tmp;
            flag = 1;
        }
        showTextView.setText("0");
    }
    public void minus(){
        if(!showTextView.getText().toString().equals("")){
            String historyTmp = historyTextView.getText().toString();
            historyTmp += showTextView.getText().toString() + "-";
            historyTextView.setText(historyTmp);
            double tmp;
            if(result != 0)
                tmp = result - Integer.parseInt(showTextView.getText().toString());
            else
                tmp = Integer.parseInt(showTextView.getText().toString()) - result;
            result = tmp;
            flag = 2;
        }
        showTextView.setText("0");
    }
    public void times(){
        if(!showTextView.getText().toString().equals("")){
            String historyTmp = historyTextView.getText().toString();
            historyTmp += showTextView.getText().toString() + "*";
            historyTextView.setText(historyTmp);
            double tmp = Integer.parseInt(showTextView.getText().toString()) * result;
            result = tmp;
            flag = 3;
        }
        showTextView.setText("0");
    }
    public void into(){
        if(!showTextView.getText().toString().equals("")){
            String historyTmp = historyTextView.getText().toString();
            historyTmp += showTextView.getText().toString() + "/";
            historyTextView.setText(historyTmp);
            double tmp = 0;
            if(result != 0){
                tmp = (result / Integer.parseInt(showTextView.getText().toString()));
                result = tmp;
            }else{
                result = Integer.parseInt(showTextView.getText().toString());
            }
            flag = 4;
        }
        showTextView.setText("0");
    }
}