From b13b3a6a38ac3bbb8016f07ac3b5d9ca2aade85d Mon Sep 17 00:00:00 2001
From: ragsav <raghav227996399@gmail.com>
Date: Sun, 30 Apr 2023 15:03:59 +0530
Subject: [PATCH] added undo and redo

---
 js/hooks/useUndo.js      | 114 +++++++++++++++++++++++++++++++++++++++
 js/screens/TaskScreen.js |  56 +++++++++++++++----
 2 files changed, 161 insertions(+), 9 deletions(-)
 create mode 100644 js/hooks/useUndo.js

diff --git a/js/hooks/useUndo.js b/js/hooks/useUndo.js
new file mode 100644
index 0000000..b29daac
--- /dev/null
+++ b/js/hooks/useUndo.js
@@ -0,0 +1,114 @@
+import {useReducer, useCallback} from 'react';
+
+const ActionType = {
+  Undo: 'UNDO',
+  Redo: 'REDO',
+  Set: 'SET',
+  Reset: 'RESET',
+};
+
+const initialState = {
+  past: [],
+  present: null,
+  future: [],
+};
+
+export const useUndo = (initialPresent, opts = {}) => {
+  const {useCheckpoints} = {
+    useCheckpoints: false,
+    ...opts,
+  };
+
+  const reducer = (state, action) => {
+    const {past, present, future} = state;
+
+    switch (action.type) {
+      case ActionType.Undo: {
+        if (past.length === 0) {
+          return state;
+        }
+
+        const previous = past[past.length - 1];
+        const newPast = past.slice(0, past.length - 1);
+
+        return {
+          past: newPast,
+          present: previous,
+          future: [present, ...future],
+        };
+      }
+
+      case ActionType.Redo: {
+        if (future.length === 0) {
+          return state;
+        }
+        const next = future[0];
+        const newFuture = future.slice(1);
+
+        return {
+          past: [...past, present],
+          present: next,
+          future: newFuture,
+        };
+      }
+
+      case ActionType.Set: {
+        const isNewCheckpoint = useCheckpoints
+          ? !!action.historyCheckpoint
+          : true;
+        const {newPresent} = action;
+
+        if (newPresent === present) {
+          return state;
+        }
+
+        return {
+          past: isNewCheckpoint === false ? past : [...past, present],
+          present: newPresent,
+          future: [],
+        };
+      }
+
+      case ActionType.Reset: {
+        const {newPresent} = action;
+
+        return {
+          past: [],
+          present: newPresent,
+          future: [],
+        };
+      }
+    }
+  };
+
+  const [state, dispatch] = useReducer(reducer, {
+    ...initialState,
+    present: initialPresent,
+  });
+
+  const canUndo = state.past.length !== 0;
+  const canRedo = state.future.length !== 0;
+  const undo = useCallback(() => {
+    if (canUndo) {
+      dispatch({type: ActionType.Undo});
+    }
+  }, [canUndo]);
+  const redo = useCallback(() => {
+    if (canRedo) {
+      dispatch({type: ActionType.Redo});
+    }
+  }, [canRedo]);
+  const set = useCallback((newPresent, checkpoint = false) => {
+    dispatch({
+      type: ActionType.Set,
+      newPresent,
+      historyCheckpoint: checkpoint,
+    });
+  }, []);
+  const reset = useCallback(
+    newPresent => dispatch({type: ActionType.Reset, newPresent}),
+    [],
+  );
+
+  return [state, {set, reset, undo, redo, canUndo, canRedo}];
+};
diff --git a/js/screens/TaskScreen.js b/js/screens/TaskScreen.js
index ee08597..cea71f9 100644
--- a/js/screens/TaskScreen.js
+++ b/js/screens/TaskScreen.js
@@ -55,6 +55,7 @@ import {
 import {CONSTANTS} from '../../constants';
 import {NotePasswordInputScreen} from './NotePasswordInputScreen';
 import {Q} from '@nozbe/watermelondb';
+import {useUndo} from '../hooks/useUndo';
 
 /**
  *
@@ -72,6 +73,8 @@ const TaskScreen = ({
   route,
 }) => {
   // ref
+  const titleRef = useRef();
+  const descriptionRef = useRef();
 
   // variables
   const theme = useTheme();
@@ -85,21 +88,29 @@ const TaskScreen = ({
     error: null,
   });
   const [title, setTitle] = useState('');
-  const [description, setDescription] = useState('');
-  const titleRef = useRef();
-  const descriptionRef = useRef();
+
+  const [
+    descriptionUndoRedoState,
+    {
+      set: setDescription,
+      reset: resetDescription,
+      undo: undoDescription,
+      redo: redoDescription,
+      canUndo,
+      canRedo,
+    },
+  ] = useUndo('');
+  const {present: presentDescription} = descriptionUndoRedoState;
   const [error, setError] = useState(null);
   const [isDeleteDialogOpen, setIsDeleteDialogOpen] = useState(false);
   const [dueDateString, setDueDateString] = useState('date');
   const [isMenuOpen, setIsMenuOpen] = useState(false);
   const [isDueDateTimePickerVisible, setIsDueDateTimePickerVisible] =
     useState(false);
-
   const [reminderDateString, setReminderDateString] = useState('time');
   const [isReminderDateTimePickerVisible, setIsReminderDateTimePickerVisible] =
     useState(false);
   const [urls, setURLs] = useState([]);
-
   const [isImagePickerOpen, setIsImagePickerOpen] = useState(false);
   const [imageToView, setImageToView] = useState({
     images: [],
@@ -166,9 +177,9 @@ const TaskScreen = ({
 
   useEffect(() => {
     if (descriptionRef) {
-      descriptionRef.current = description;
+      descriptionRef.current = presentDescription;
     }
-  }, [description, descriptionRef, descriptionRef.current]);
+  }, [presentDescription, descriptionRef, descriptionRef.current]);
 
   useEffect(() => {
     if (titleRef) {
@@ -339,7 +350,7 @@ const TaskScreen = ({
     try {
       const result = await Share.share({
         title: title,
-        message: description,
+        message: presentDescription,
       });
       if (result.action === Share.sharedAction) {
         if (result.activityType) {
@@ -595,12 +606,13 @@ const TaskScreen = ({
             textAlignVertical: 'top',
             padding: 12,
             paddingHorizontal: 18,
+            paddingBottom: 30,
           }}
           onBlur={_handleDescriptionSave}
           onChangeText={_handleDescriptionChange}
           placeholder="Add some here..."
           placeholderTextColor={theme?.colors.onSurfaceDisabled}
-          value={description}
+          value={presentDescription}
           multiline={true}
         />
 
@@ -623,6 +635,32 @@ const TaskScreen = ({
         presentationStyle="fullScreen"
         onRequestClose={() => setImageToView({...imageToView, visible: false})}
       />
+      <Appbar.Header
+        style={{
+          backgroundColor: theme?.colors.surface,
+        }}>
+        <Appbar.Content />
+        <Appbar.Action
+          isLeading={false}
+          icon={'undo-variant'}
+          disabled={!canUndo}
+          // iconColor={theme?.colors.onPrimary}
+          onPress={undoDescription}
+        />
+        <Appbar.Action
+          isLeading={false}
+          icon={'redo-variant'}
+          disabled={!canRedo}
+          // iconColor={theme?.colors.onPrimary}
+          onPress={redoDescription}
+        />
+        <Appbar.Action
+          isLeading={false}
+          icon={'restore'}
+          // iconColor={theme?.colors.onPrimary}
+          onPress={resetDescription}
+        />
+      </Appbar.Header>
     </SafeAreaView>
   ) : (
     <NotePasswordInputScreen