move the logic in an interface

app/src/main/java/calendar/simplemobiletools/com/Calendar.java

@@ -0,0 +1,9 @@
+package calendar.simplemobiletools.com;
+
+import java.util.List;
+
+public interface Calendar {
+    void updateDays(List<Day> days);
+
+    void updateMonth(String month);
+}

app/src/main/java/calendar/simplemobiletools/com/CalendarImpl.java

@@ -0,0 +1,88 @@
+package calendar.simplemobiletools.com;
+
+import org.joda.time.DateTime;
+
+import java.text.DateFormatSymbols;
+import java.util.ArrayList;
+import java.util.List;
+
+public class CalendarImpl {
+    public static final int DAYS_CNT = 42;
+    private static final String DATE_PATTERN = "ddMMYYYY";
+    private static final String YEAR_PATTERN = "YYYY";
+
+    private final Calendar callback;
+    private final String today;
+    private DateTime targetDate;
+
+    public CalendarImpl(Calendar callback, DateTime targetDate) {
+        this.callback = callback;
+        this.targetDate = targetDate;
+        today = new DateTime().toString(DATE_PATTERN);
+    }
+
+    public void updateCalendar(DateTime targetDateTime) {
+        this.targetDate = targetDateTime;
+        getDays(targetDateTime);
+        getMonthName();
+    }
+
+    public void getPrevMonth() {
+        updateCalendar(targetDate.minusMonths(1));
+    }
+
+    public void getNextMonth() {
+        updateCalendar(targetDate.plusMonths(1));
+    }
+
+    private void getDays(DateTime targetDate) {
+        final List<Day> days = new ArrayList<>(DAYS_CNT);
+
+        final int currMonthDays = targetDate.dayOfMonth().getMaximumValue();
+        final int firstDayIndex = targetDate.withDayOfMonth(1).getDayOfWeek() - 1;
+        final int prevMonthDays = targetDate.minusMonths(1).dayOfMonth().getMaximumValue();
+
+        boolean isThisMonth = false;
+        boolean isToday;
+        int value = prevMonthDays - firstDayIndex + 1;
+
+        for (int i = 0; i < DAYS_CNT; i++) {
+            if (i < firstDayIndex) {
+                isThisMonth = false;
+            } else if (i == firstDayIndex) {
+                value = 1;
+                isThisMonth = true;
+            } else if (value == currMonthDays + 1) {
+                value = 1;
+                isThisMonth = false;
+            }
+
+            isToday = isThisMonth && isToday(targetDate, value);
+
+            final Day day = new Day(value, isThisMonth, isToday);
+            days.add(day);
+            value++;
+        }
+
+        callback.updateDays(days);
+    }
+
+    private boolean isToday(DateTime targetDate, int curDayInMonth) {
+        return targetDate.withDayOfMonth(curDayInMonth).toString(DATE_PATTERN).equals(today);
+    }
+
+    private void getMonthName() {
+        final String[] months = new DateFormatSymbols().getMonths();
+        String month = (months[targetDate.getMonthOfYear() - 1]);
+        final String targetYear = targetDate.toString(YEAR_PATTERN);
+        if (!targetYear.equals(new DateTime().toString(YEAR_PATTERN))) {
+            month += " " + targetYear;
+        }
+
+        callback.updateMonth(month);
+    }
+
+    public DateTime getTargetDate() {
+        return targetDate;
+    }
+}

app/src/main/java/calendar/simplemobiletools/com/Day.java

@@ -0,0 +1,25 @@
+package calendar.simplemobiletools.com;
+
+public class Day {
+    private final int value;
+    private final boolean isThisMonth;
+    private final boolean isToday;
+
+    public Day(int value, boolean isThisMonth, boolean isToday) {
+        this.value = value;
+        this.isThisMonth = isThisMonth;
+        this.isToday = isToday;
+    }
+
+    public int getValue() {
+        return value;
+    }
+
+    public boolean getIsThisMonth() {
+        return isThisMonth;
+    }
+
+    public boolean getIsToday() {
+        return isToday;
+    }
+}

app/src/main/java/calendar/simplemobiletools/com/MainActivity.java

@@ -1,15 +1,15 @@
 package calendar.simplemobiletools.com;
 
+import android.content.res.Resources;
 import android.graphics.PorterDuff;
 import android.os.Bundle;
 import android.support.v7.app.AppCompatActivity;
 import android.widget.ImageView;
-import android.widget.LinearLayout;
 import android.widget.TextView;
 
 import org.joda.time.DateTime;
 
-import java.text.DateFormatSymbols;
+import java.util.List;
 
 import butterknife.Bind;
 import butterknife.BindColor;
@@ -17,22 +17,20 @@ import butterknife.BindDimen;
 import butterknife.ButterKnife;
 import butterknife.OnClick;
 
-public class MainActivity extends AppCompatActivity implements MyDatePickerDialog.DatePickedListener {
+public class MainActivity extends AppCompatActivity implements MyDatePickerDialog.DatePickedListener, Calendar {
     public static final String DATE = "date";
-    private static final String DATE_PATTERN = "ddMMYYYY";
-    private static final String YEAR_PATTERN = "YYYY";
 
     @Bind(R.id.left_arrow) ImageView leftArrow;
     @Bind(R.id.right_arrow) ImageView rightArrow;
     @Bind(R.id.table_month) TextView monthTV;
-    @Bind(R.id.table_holder) LinearLayout tableHolder;
     @BindColor(R.color.darkGrey) int darkGrey;
     @BindColor(R.color.lightGrey) int lightGrey;
     @BindDimen(R.dimen.day_text_size) float dayTextSize;
     @BindDimen(R.dimen.today_text_size) float todayTextSize;
 
-    private DateTime targetDate;
+    private CalendarImpl calendar;
-    private String today;
+    private Resources res;
+    private String packageName;
 
     @Override
     protected void onCreate(Bundle savedInstanceState) {
@@ -42,92 +40,79 @@ public class MainActivity extends AppCompatActivity implements MyDatePickerDialo
 
         leftArrow.getDrawable().mutate().setColorFilter(darkGrey, PorterDuff.Mode.SRC_ATOP);
         rightArrow.getDrawable().mutate().setColorFilter(darkGrey, PorterDuff.Mode.SRC_ATOP);
-        targetDate = new DateTime();
-        today = targetDate.toString(DATE_PATTERN);
 
+        res = getResources();
+        packageName = getPackageName();
         dayTextSize /= getResources().getDisplayMetrics().density;
+        todayTextSize /= getResources().getDisplayMetrics().density;
 
-        fillCalendar();
+        DateTime now = new DateTime();
+        calendar = new CalendarImpl(this, now);
+        calendar.updateCalendar(now);
+
+        setupLabelSizes();
     }
 
-    private void fillCalendar() {
+    private void fillCalendar(List<Day> days) {
-        monthTV.setText(getMonthName());
+        final int len = days.size();
-        final int currMonthDays = targetDate.dayOfMonth().getMaximumValue();
-        final int firstDayIndex = targetDate.withDayOfMonth(1).getDayOfWeek() - 1;
-        final int prevMonthDays = targetDate.minusMonths(1).dayOfMonth().getMaximumValue();
-        final int prevMonthStart = prevMonthDays - firstDayIndex + 1;
 
-        int cur = 0;
+        for (int i = 0; i < len; i++) {
-        int thisMonthDays = 1;
+            final Day day = days.get(i);
-        int nextMonthsDay = 1;
+            final TextView dayTV = (TextView) findViewById(res.getIdentifier("day_" + i, "id", packageName));
+            dayTV.setText(String.valueOf(day.getValue()));
 
-        final int rowsCnt = tableHolder.getChildCount();
+            if (day.getIsThisMonth()) {
-        for (int i = 1; i < rowsCnt; i++) {
+                dayTV.setTextColor(darkGrey);
-            final LinearLayout row = (LinearLayout) tableHolder.getChildAt(i);
-            final int daysCnt = row.getChildCount();
-            for (int j = 0; j < daysCnt; j++) {
-                final TextView day = (TextView) row.getChildAt(j);
-                day.setTextSize(dayTextSize);
-
-                int currDate = thisMonthDays;
-                if (cur < firstDayIndex) {
-                    currDate = prevMonthStart + cur;
-                    day.setTextColor(lightGrey);
-                } else if (currDate <= currMonthDays) {
-                    if (targetDate.withDayOfMonth(thisMonthDays).toString(DATE_PATTERN).equals(today)) {
-                        day.setTextSize(todayTextSize);
-                    }
-
-                    thisMonthDays++;
-                    day.setTextColor(darkGrey);
             } else {
-                    currDate = nextMonthsDay++;
+                dayTV.setTextColor(lightGrey);
-                    day.setTextColor(lightGrey);
             }
 
-                day.setText(String.valueOf(currDate));
+            if (day.getIsToday()) {
-                cur++;
+                dayTV.setTextSize(todayTextSize);
+            } else {
+                dayTV.setTextSize(dayTextSize);
             }
         }
     }
 
     @OnClick(R.id.left_arrow)
     public void leftArrowClicked() {
-        targetDate = targetDate.minusMonths(1);
+        calendar.getPrevMonth();
-        fillCalendar();
     }
 
     @OnClick(R.id.right_arrow)
     public void rightArrowClicked() {
-        targetDate = targetDate.plusMonths(1);
+        calendar.getNextMonth();
-        fillCalendar();
     }
 
     @OnClick(R.id.table_month)
     public void pickMonth() {
         final MyDatePickerDialog dialog = new MyDatePickerDialog();
         final Bundle bundle = new Bundle();
-        bundle.putString(DATE, targetDate.toString());
+        bundle.putString(DATE, calendar.getTargetDate().toString());
         dialog.setArguments(bundle);
         dialog.show(getSupportFragmentManager(), "datepicker");
     }
 
-    private String getMonthName() {
+    @Override
-        final String[] months = new DateFormatSymbols().getMonths();
+    public void onDatePicked(DateTime dateTime) {
-        final StringBuilder sb = new StringBuilder();
+        calendar.updateCalendar(dateTime);
-        sb.append(months[targetDate.getMonthOfYear() - 1]);
-
-        final String targetYear = targetDate.toString(YEAR_PATTERN);
-        if (!targetYear.equals(new DateTime().toString(YEAR_PATTERN))) {
-            sb.append(" ");
-            sb.append(targetYear);
-        }
-        return sb.toString();
     }
 
     @Override
-    public void onDatePicked(DateTime dateTime) {
+    public void updateDays(List<Day> days) {
-        targetDate = dateTime;
+        fillCalendar(days);
-        fillCalendar();
+    }
+
+    @Override
+    public void updateMonth(String month) {
+        monthTV.setText(month);
+    }
+
+    private void setupLabelSizes() {
+        for (int i = 0; i < 7; i++) {
+            final TextView dayTV = (TextView) findViewById(res.getIdentifier("label_" + i, "id", packageName));
+            dayTV.setTextSize(dayTextSize);
+        }
     }
 }

app/src/main/res/values/dimens.xml

@@ -1,5 +1,5 @@
 <resources>
     <dimen name="activity_margin">16dp</dimen>
     <dimen name="day_text_size">16sp</dimen>
-    <dimen name="today_text_size">22sp</dimen>
+    <dimen name="today_text_size">30sp</dimen>
 </resources>