docs: Source code for Noogler Project - Todo App

issues/Charlotte Y - Noogler Project/TodoFunctions/AbstractTodoFunction.cs

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+// Copyright 2025 Google Inc. All Rights Reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+using FirebaseAdmin;
+using FirebaseAdmin.Auth;
+using Google.Apis.Auth.OAuth2;
+using Google.Cloud.Firestore;
+using Google.Cloud.Functions.Framework;
+using Microsoft.AspNetCore.Http;
+using System;
+using System.IO;
+using System.Text.Json;
+using System.Text.Json.Serialization;
+using System.Threading.Tasks;
+
+namespace TodoFunctions;
+
+/// <summary>
+/// Abstract parent class for CRUD functions on the Todo application.
+/// </summary>
+public abstract class AbstractTodoFunction : IHttpFunction
+{
+    private const string ProjectId = "REDACTED";
+    private const string DatabaseId = "todo-application";
+    private const string CollectionId = "todo-items";
+    private const FirebaseAuth FirebaseAuth = FirebaseAuth.GetAuth(FirebaseApp.Create(new AppOptions()
+    {
+        Credential = GoogleCredential.GetApplicationDefault(),
+        ProjectId = ProjectId,
+    }));
+    private const FirestoreDb FirebaseDb = new FirestoreDbBuilder { ProjectId = ProjectId, DatabaseId = DatabaseId }.Build();
+    protected const CollectionReference TodoItemsCollection = FirebaseDb.Collection(CollectionId);
+    protected const JsonSerializerOptions SerializerOptions = new()
+    {
+        DefaultIgnoreCondition = JsonIgnoreCondition.WhenWritingNull,
+        Converters = { new JsonStringEnumConverter(), new FirestoreTimestampConverter() }
+    };
+
+    /// <summary>
+    /// Main method for the CRUD operations. Authenticates user, validates the inputs, executes the DB operation, and prints results in the response.
+    /// </summary>
+    /// <param name="context">Object for the HTTP Request</param>
+    /// <returns>void</returns>
+    public async Task HandleAsync(HttpContext context)
+    {
+
+        // authenticate and parse request
+        TodoData todoData = await AuthenticateAndParseRequest(context);
+
+        // validate request
+        bool isValid = ValidateRequest(todoData);
+        if (!isValid)
+        {
+            await context.Response.WriteAsync("Request is not valid\n");
+            return;
+        }
+
+        // perform operation
+        try
+        {
+            string output = await PerformOperation(todoData);
+            await context.Response.WriteAsync(output);
+        }
+        catch (Exception e)
+        {
+            await context.Response.WriteAsync($"{e.Message}\n");
+        }
+    }
+
+    /// <summary>
+    /// Authenticates user and deserializes the request body into TodoData object and returns it
+    /// </summary>
+    /// <param name="context">Object for the HTTP Request</param>
+    /// <returns>TodoData object</returns>
+    private static async Task<TodoData> AuthenticateAndParseRequest(HttpContext context)
+    {
+
+        using var reader = new StreamReader(context.Request.Body);
+        try
+        {
+            // deserialize request body
+            string body = await reader.ReadToEndAsync();
+            TodoData todoData = JsonSerializer.Deserialize<TodoData>(body, SerializerOptions);
+
+            // authenticate user and get user email
+            FirebaseToken token = await FirebaseAuth.VerifyIdTokenAsync(todoData.IdToken);
+            UserRecord userRecord = await FirebaseAuth.GetUserAsync(token.Uid);
+            todoData.UserId = userRecord.Email;
+
+            // set IdToken to null to avoid printing it out or storing it
+            todoData.IdToken = null;
+
+            await context.Response.WriteAsync($"Request Body: {JsonSerializer.Serialize(todoData, SerializerOptions)}\n");
+            return todoData;
+        }
+        catch (Exception ex)
+        {
+            await context.Response.WriteAsync($"{ex.Message}\n");
+            throw;
+        }
+    }
+
+    /// <summary>
+    /// Performs validation on inputs
+    /// </summary>
+    /// <param name="todoData">TodoData object</param>
+    /// <returns>true if valid, false otherwise</returns>
+    protected abstract bool ValidateRequest(TodoData todoData);
+
+    /// <summary>
+    /// Calls the Firestore client to perform DB operations
+    /// </summary>
+    /// <param name="todoData">TodoData object</param>
+    /// <returns>Result string</returns>
+    protected abstract Task<string> PerformOperation(TodoData todoData);
+}

issues/Charlotte Y - Noogler Project/TodoFunctions/CreateTodo.cs

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+// Copyright 2025 Google Inc. All Rights Reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+using System.Threading.Tasks;
+
+namespace TodoFunctions;
+
+/// <summary>
+/// Cloud Function to create a todo item in the Todo Application.
+/// </summary>
+public class CreateTodo : AbstractTodoFunction
+{
+    protected override bool ValidateRequest(TodoData todoData)
+    {
+        string userId = todoData.UserId;
+        string title = todoData.Title;
+        string description = todoData.Description;
+        int? priority = todoData.Priority;
+
+        // UserID, title, and description must not be null or empty. Priority must be an integer between 1 to 5.
+        return userId is not null
+            && title is not null
+            && description is not null
+            && userId != ""
+            && title != ""
+            && description != ""
+            && (priority is null || (1 <= priority && priority <= 5));
+    }
+    protected override async Task<string> PerformOperation(TodoData todoData)
+    {
+        // prepare the object before creating
+        todoData.Prepare(Operation.Create);
+
+        // create the document
+        string documentId = $"{todoData.UserId}-{todoData.TaskId}";
+        await todoItemsCollection.Document(documentId).CreateAsync(todoData.ToDictionary());
+
+        return $"Successfully created new task {documentId}\n";
+    }
+}

issues/Charlotte Y - Noogler Project/TodoFunctions/DeleteTodo.cs

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+// Copyright 2025 Google Inc. All Rights Reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+using Google.Cloud.Firestore;
+using System.Threading.Tasks;
+
+namespace TodoFunctions;
+
+/// <summary>
+/// Cloud Function to delete a todo item in the Todo Application
+/// </summary>
+public class DeleteTodo : AbstractTodoFunction
+{
+
+    protected override bool ValidateRequest(TodoData todoData)
+    {
+        string userId = todoData.UserId;
+        string taskId = todoData.TaskId;
+
+        // UserID and taskId must not be null or empty.
+        return userId is not null
+            && taskId is not null
+            && userId != ""
+            && taskId != "";
+    }
+
+    protected override async Task<string> PerformOperation(TodoData todoData)
+    {
+        // delete the document
+        string documentId = $"{todoData.UserId}-{todoData.TaskId}";
+        await todoItemsCollection.Document(documentId).DeleteAsync(Precondition.MustExist);
+
+        return $"Successfully deleted task {documentId}\n";
+    }
+}

issues/Charlotte Y - Noogler Project/TodoFunctions/FirestoreTimestampConverter.cs

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+// Copyright 2025 Google Inc. All Rights Reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+using Google.Cloud.Firestore;
+using System;
+using System.Text.Json;
+using System.Text.Json.Serialization;
+
+namespace TodoFunctions
+{
+    public class FirestoreTimestampConverter : JsonConverter<Timestamp>
+    {
+        private const string TimestampFormat = "yyyy-MM-ddTHH:mm:ss.ffffffZ"; // ISO 8601 format
+
+        public override void Write(Utf8JsonWriter writer, Timestamp value, JsonSerializerOptions options)
+        {
+            if (value is null)
+            {
+                writer.WriteNullValue();
+                return;
+            }
+
+            // Convert Timestamp to ISO 8601 string (UTC)
+            DateTime dateTime = value.ToDateTime();
+            string isoString = dateTime.ToUniversalTime().ToString(TimestampFormat);
+            writer.WriteStringValue(isoString);
+        }
+
+        public override Timestamp Read(ref Utf8JsonReader reader, Type typeToConvert, JsonSerializerOptions options)
+        {
+            if (reader.TokenType == JsonTokenType.String)
+            {
+                string dateString = reader.GetString();
+                if (DateTime.TryParse(dateString, out DateTime dateTime))
+                {
+                    return Timestamp.FromDateTime(dateTime.ToUniversalTime());
+                }
+                else
+                {
+                    throw new JsonException($"Could not parse DateTime from string: {dateString}");
+                }
+            }
+
+            throw new JsonException($"Unexpected token type: {reader.TokenType}.  Expected String.");
+        }
+    }
+
+    public class FirestoreTimestampConverterFactory : JsonConverterFactory
+    {
+        public override bool CanConvert(Type typeToConvert)
+        {
+            return typeToConvert == typeof(Timestamp);
+        }
+
+        public override JsonConverter CreateConverter(Type typeToConvert, JsonSerializerOptions options)
+        {
+            return new FirestoreTimestampConverter();
+        }
+    }
+}

issues/Charlotte Y - Noogler Project/TodoFunctions/ReadTodos.cs

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+// Copyright 2025 Google Inc. All Rights Reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+using Google.Cloud.Firestore;
+using System.Collections.Generic;
+using System.Text;
+using System.Text.Json;
+using System.Threading.Tasks;
+
+namespace TodoFunctions;
+
+/// <summary>
+/// Cloud Function to read todo items in the Todo Application
+/// </summary>
+public class ReadTodos : AbstractTodoFunction
+{
+    protected override bool ValidateRequest(TodoData todoData)
+    {
+        string userId = todoData.UserId;
+        string taskId = todoData.TaskId;
+        int? priority = todoData.Priority;
+
+        // UserId should not be null or empty. TaskId, if provided, should not be empty. Priority should be an integer between 1 to 5.
+        return userId is not null
+            && userId != ""
+            && (taskId is null || taskId != "")
+            && (priority is null || (1 <= priority && priority <= 5));
+    }
+
+    protected override async Task<string> PerformOperation(TodoData todoData)
+    {
+
+        // Create a filter for the query based on the request
+        List<Filter> filterList = new() {
+            Filter.EqualTo("userId", todoData.UserId)
+        };
+        if (todoData.TaskId != null)
+        {
+            filterList.Add(Filter.EqualTo("taskId", todoData.TaskId));
+        }
+        if (todoData.Priority != null)
+        {
+            filterList.Add(Filter.EqualTo("priority", todoData.Priority));
+        }
+        if (todoData.Status != null)
+        {
+            filterList.Add(Filter.EqualTo("status", todoData.Status.ToString()));
+        }
+
+        // Query the collection
+        Query query = todoItemsCollection.Where(Filter.And(filterList.ToArray()));
+        QuerySnapshot querySS = await query.GetSnapshotAsync();
+
+        // Serialize the results
+        StringBuilder output = new();
+        foreach (DocumentSnapshot document in querySS.Documents)
+        {
+            output.Append(JsonSerializer.Serialize(document.ToDictionary(), SERIALIZER_OPTIONS));
+            output.Append('\n');
+        }
+
+        // Build the results into a string and return
+        return output.ToString();
+    }
+}