add some methods into TodoItemManager

app/src/main/java/org/cutem/cutecalendar/model/TodoItemManager.java

@@ -1,20 +1,25 @@
 package org.cutem.cutecalendar.model;
 
 import com.google.gson.GsonBuilder;
+import org.cutem.cutecalendar.util.CalendarUtil;
 import org.jetbrains.annotations.NotNull;
 
-import java.util.HashMap;
-import java.util.HashSet;
+import java.util.*;
 
 public class TodoItemManager {
     private static final String TODO_LIST_SAVE_NAME = "todo-list.json";
 
 
     private static TodoItemManager ourInstance;
+
     private long idCount;
+
     private HashSet<TodoItem> items = new HashSet<>();
+
     private HashMap<Long, TodoItem> idCache = new HashMap<>();
 
+    private HashMap<String, List<TodoItem>> dateCache = new HashMap<>();
+
     private TodoItemManager() {
     }
 
@@ -25,6 +30,7 @@ public class TodoItemManager {
         return ourInstance;
     }
 
+
     public long getNextId() {
         while (idCache.containsKey(idCount)) {
             ++idCount;
@@ -32,29 +38,96 @@ public class TodoItemManager {
         return idCount++;
     }
 
+    private static boolean isIntersectedDuring(@NotNull TodoItem item, @NotNull Calendar from, @NotNull Calendar to) {
+        return !from.after(item.getEnd()) && !to.before(item.getBgn());
+    }
 
     public void add(@NotNull TodoItem item) {
         if (idCache.containsKey(item.getId())) {
-            items.remove(
-                    idCache.get(item.getId())
-            );
+            remove(item.getId());
         }
-        items.add(item);
         idCache.put(item.getId(), item);
-    }
-
-
-    public void remove(long id) {
-        if (idCache.containsKey(id)) {
-            items.remove(idCache.get(id));
-            idCache.remove(id);
-        }
+        items.add(item);
+        addDateCache(item);
     }
 
     public void remove(@NotNull TodoItem item) {
         remove(item.getId());
     }
 
+    public void remove(long id) {
+        if (idCache.containsKey(id)) {
+            TodoItem item = idCache.remove(id);
+            items.remove(item);
+            removeDateCache(item);
+        }
+    }
+
+    private void addDateCache(@NotNull TodoItem item) {
+        Calendar from = CalendarUtil.getWholeDayPeriod(item.getBgn())[0];
+        Calendar to = CalendarUtil.getWholeDayPeriod(item.getEnd())[1];
+
+        while (!from.after(to)) {
+            String date = CalendarUtil.getDatePartString(from);
+
+            if (!dateCache.containsKey(date)) {
+                dateCache.put(date, new ArrayList<>());
+            }
+            List<TodoItem> list = dateCache.get(date);
+
+            if (!list.contains(item)) {
+                list.add(item);
+            }
+
+            from.add(Calendar.DAY_OF_MONTH, 1);
+        }
+    }
+
+    private void removeDateCache(@NotNull TodoItem item) {
+        Calendar from = CalendarUtil.getWholeDayPeriod(item.getBgn())[0];
+        Calendar to = CalendarUtil.getWholeDayPeriod(item.getEnd())[1];
+
+        while (!from.after(to)) {
+            String date = CalendarUtil.getDatePartString(from);
+            List<TodoItem> list = dateCache.getOrDefault(date, Collections.emptyList());
+
+            list.remove(item);
+
+            from.add(Calendar.DAY_OF_MONTH, 1);
+        }
+    }
+
+    public List<TodoItem> queryTodoItemsDuring(@NotNull Calendar from, @NotNull Calendar to) {
+        ArrayList<TodoItem> result = new ArrayList<>();
+
+        Calendar c1 = CalendarUtil.getWholeDayPeriod(from)[0];
+        Calendar c2 = CalendarUtil.getWholeDayPeriod(to)[1];
+
+        while (!c1.after(c2)) {
+            String date = CalendarUtil.getDatePartString(c1);
+            List<TodoItem> list = dateCache.getOrDefault(date, Collections.emptyList());
+
+            list.forEach(item -> {
+                if (isIntersectedDuring(item, from, to)
+                        && !result.contains(item)) {
+                    result.add(item);
+                }
+            });
+
+            c1.add(Calendar.DAY_OF_MONTH, 1);
+        }
+
+        return result;
+    }
+
+    public boolean haveTodoItemOnSomeday(@NotNull Calendar someday) {
+        String date = CalendarUtil.getDatePartString(someday);
+        List<TodoItem> items = dateCache.getOrDefault(date, Collections.emptyList());
+
+        return !items.isEmpty();
+    }
+
+
 
     String toJson() {
         GsonBuilder gson = new GsonBuilder();
@@ -62,4 +135,5 @@ public class TodoItemManager {
         return gson.create().toJson(items);
     }
 
+
 }