Chloe

Todo-Challenge/Todo-Challenge/CommandHandler.cs

@@ -0,0 +1,22 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace Todo_Challenge
+{
+    internal class CommandHandler
+    {
+        public static char GetCommandRefNum(string line)
+        {
+            return line[0];
+        }
+        public static string GetTodoItemName(string line)
+        {
+            string lineWithoutRefNum = line.Remove(0, 1);
+            string name = lineWithoutRefNum.Trim();
+            return name;
+        }
+    }
+}

Todo-Challenge/Todo-Challenge/Menu.cs

@@ -0,0 +1,25 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace Todo_Challenge
+{
+    class Menu
+    {
+        public static void DisplayOptions()
+        {
+            Console.WriteLine("Your current todo list is:");
+            Console.WriteLine();
+            Console.WriteLine("To edit it, use the options below");
+            Console.WriteLine();
+            Console.WriteLine("OPTIONS");
+            Console.WriteLine("input:               action:");
+            Console.WriteLine("  1 <todo name> ->     create a new todo");
+            Console.WriteLine("  2 <todo name> ->     delete a todo");
+            Console.WriteLine("  3 <todo name> ->     toggle an item's completion status");
+            Console.WriteLine("  exit          ->     stop running this app");
+        }
+    }
+}

Todo-Challenge/Todo-Challenge/Program.cs

@@ -1,2 +1,30 @@
-// See https://aka.ms/new-console-template for more information
-Console.WriteLine("Hello, World!");
+using System.Text;
+using Todo_Challenge;
+
+new Menu();
+Menu.DisplayOptions();
+
+string? line = Console.ReadLine();
+
+var list = new TodoList("Todo list");
+
+while (line != "exit")
+{
+    if (line == null) break;
+    char refNum = CommandHandler.GetCommandRefNum(line);
+    string itemName = CommandHandler.GetTodoItemName(line);
+    switch (refNum)
+    {
+        case '1':
+            new TodoItem(itemName, list);
+            break;
+        case '2':
+            TodoList.DeleteItemWhereNameIs(itemName, list);
+            break;
+        case '3':
+            TodoList.ToggleItemCompletionStatusWhereNameIs(itemName, list);
+            break;
+    }
+    TodoList.View(list);
+    line = Console.ReadLine();
+}

Todo-Challenge/Todo-Challenge/TodoItem.cs

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+using System;
+using System.Collections;
+using System.Collections.Generic;
+using System.Linq;
+using System.Runtime.InteropServices;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace Todo_Challenge
+{
+    internal class TodoItem
+    {
+        public int Id { get; set; }
+        public string? Name { get; set; }
+        public bool Completed { get; set; } = false;
+        public TodoItem? NextTodoItem { get; set; } = null;
+
+        private readonly TodoList _list;
+
+        private void LinkToPreviousItem()
+        {
+            if (_list.DoesNotContainFirstTodoItem())
+            {
+                _list.Head = this;
+                return;
+            } 
+            if (_list.Tail != null)
+            {
+                _list.Tail.NextTodoItem = this;
+            }
+        }
+
+        public string ReadCompletionStatus()
+        {
+            return Completed ? "done" : "to do";
+        }
+
+        public TodoItem(string name, TodoList todoList)
+        {
+            Id = todoList.NextId;
+            Name = name;
+            _list = todoList;
+            todoList.IncreaseNextIdByOne();
+            LinkToPreviousItem();
+            todoList.Tail = this;
+        }
+    }
+}

Todo-Challenge/Todo-Challenge/TodoList.cs

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+using System;
+using System.Collections;
+using System.Collections.Generic;
+using System.Linq;
+using System.Runtime.CompilerServices;
+using System.Text;
+using System.Threading.Tasks;
+using System.Xml.Linq;
+
+namespace Todo_Challenge
+{
+    internal class TodoList : IEnumerable
+    {
+        public string Name;
+        public TodoItem? Head { get; set; }
+        public TodoItem? Tail { get; set; }
+        public TodoItem? Current { get; set; }
+        public int NextId { get; set; }
+
+        IEnumerator IEnumerable.GetEnumerator()
+        {
+            Current = Head;
+
+            while (Current != null)
+            {
+                yield return Current;
+                Current = Current.NextTodoItem;
+            }
+        }
+
+
+        // private retrieval operations executed prior to modifying the list
+        private static TodoItem? GetTodoItemByName(string name, TodoList todoList)
+        {
+            foreach (TodoItem item in todoList)
+            {
+                if (item != null && item.Name == name)
+                {
+                    return item;
+                }
+            }
+            return null;
+        }
+
+        private static TodoItem? GetPreviousTodoItemByName(string name, TodoList todoList)
+        {
+            if (todoList.Head != null && todoList.Head.Name == name)
+            {
+                return null;
+            }
+
+            foreach (TodoItem item in todoList)
+            {
+                if (item != null && item.NextTodoItem != null && item.NextTodoItem.Name == name)
+                {
+                    return item;
+                }
+            }
+            return null;
+        }
+
+        // is ran upon the start of the application
+        public TodoList(string name)
+        {
+            Name = name;
+            Head = null;
+            Tail = null;
+            Current = null;
+            NextId = 1;
+        }
+
+        // methods ran when a todo item is created
+        public void IncreaseNextIdByOne()
+        {
+            NextId++;
+        }
+
+        public bool DoesNotContainFirstTodoItem() { return Head == null; }
+
+        // method ran after each list modification so the user may visualise the result
+        public static void View(TodoList todoList)
+        {
+            Console.WriteLine();
+            Console.WriteLine("TODO LIST");
+            Console.WriteLine();
+
+            foreach (TodoItem item in todoList)
+            {
+                var isComplete = item.ReadCompletionStatus();
+                Console.WriteLine(item.Name + " completion status: " + isComplete);
+            }
+        }
+
+        // list modification operations triggered by commands
+        public static void DeleteItemWhereNameIs(string name, TodoList todoList)
+        {
+            var item = GetTodoItemByName(name, todoList);
+            if (item == null)
+            {
+                Console.WriteLine($"failed to delete ${name}, no such item found");
+                return;
+            }
+            var previousItem = GetPreviousTodoItemByName(name, todoList);
+            if (previousItem == null)
+            {
+                todoList.Head = item.NextTodoItem;
+                return;
+            }
+            else
+            {
+                // if I got this right redirecting the pointer is enough to remove 
+                // any references to said item, and set it up for garbage collection (since it becomes unreachable)
+                previousItem.NextTodoItem = item.NextTodoItem;
+            }
+        }
+
+        public static void ToggleItemCompletionStatusWhereNameIs(string name, TodoList todoList)
+        {
+            var item = GetTodoItemByName(name, todoList);
+            if (item == null)
+            {
+                Console.WriteLine($"failed to toggle completion status of {name}, no such item found");
+                return;
+            }
+            item.Completed = !item.Completed;
+        }
+
+    }
+}