Initial commit

README.md

@@ -23,6 +23,94 @@ https://developers.google.com/identity/protocols/OAuth2UserAgent
 
 2. Add `builder.Services.AddScoped<IReminders,Reminders>();`
 
+3. Use it:
+
+        @page "/"
+
+        @using System.Text.RegularExpressions;
+
+        @inject NavigationManager navigationManager
+        @inject IReminders googleReminders
+
+        <h1>Reminders:</h1>
+
+        <div>@((MarkupString)innerHTML)</div>
+
+        @code {
+            private const string YOUR_CLIENT_ID = "REPLACE_THIS_VALUE";
+            private const string YOUR_REDIRECT_URI = "REPLACE_THIS_VALUE";
+
+            Dictionary<string, string> oauth2Params = new Dictionary<string, string>();
+            string innerHTML = "";
+
+            protected override async Task OnInitializedAsync()
+            {
+                string fragment = new Uri(navigationManager.Uri).Fragment;
+
+                if (fragment.Length > 0)
+                {
+                    string fragmentString = fragment.Substring(1);
+
+                    // Parse query string to see if page request is coming from OAuth 2.0 server.
+                    Regex regex = new Regex("([^&=]+)=([^&]*)");
+
+                    foreach (Match match in regex.Matches(fragmentString))
+                    {
+                        oauth2Params[Uri.UnescapeDataString(match.Groups[1].Value)] = Uri.UnescapeDataString(match.Groups[2].Value);
+                    }
+                }
+
+                    await SendRequest();
+                }
+
+            async Task SendRequest()
+            {
+                if (oauth2Params != null && oauth2Params.TryGetValue("access_token", out string? accessToken))
+                {
+                    List<Reminder>? reminders = await googleReminders.ListReminders(accessToken, 10);
+
+                    if (reminders != null)
+                    {
+                        foreach (Reminder reminder in reminders)
+                        {
+                            innerHTML += "<p>" + reminder + "</p>";
+                        }
+                    }
+                    else
+                    {
+                        // Token invalid, so prompt for user permission.
+                        OAuth2SignIn();
+                    }
+                }
+                else
+                {
+                    OAuth2SignIn();
+                }
+            }
+
+            void OAuth2SignIn()
+            {
+                // Google's OAuth 2.0 endpoint for requesting an access token
+                string oauth2Endpoint = "https://accounts.google.com/o/oauth2/v2/auth";
+
+                // Parameters to pass to OAuth 2.0 endpoint.
+                Dictionary<string, string> queryParams = new Dictionary<string, string>
+                {
+                    { "client_id", YOUR_CLIENT_ID },
+                    { "redirect_uri", YOUR_REDIRECT_URI },
+                    { "scope", "https://www.googleapis.com/auth/reminders" },
+                    { "include_granted_scopes", "true" },
+                    { "response_type", "token" }
+                };
+
+                // Build the query string from the parameters
+                string queryString = string.Join("&", queryParams.Select(p => $"{p.Key}={Uri.EscapeDataString(p.Value)}"));
+
+                // Navigate to the OAuth 2.0 endpoint in a new window.
+                navigationManager.NavigateTo($"{oauth2Endpoint}?{queryString}", true);
+            }
+        }
+
 ## Version history:
 
 - 0.0.0.1