Get credits remaining at startup and after changing the API key

KeywordsEverywhereClient/ClientForm.cs

@@ -20,6 +20,27 @@ public partial class ClientForm : Form
 
         this.clientFormConfiguration = this.clientFormConfigurationManager.Load();
         this.apiKeyTextBox.Text = this.clientFormConfiguration.ApiKey;
+
+        this.UpdateCreditBalanceAsync();
+    }
+
+    protected async void UpdateCreditBalanceAsync()
+    {
+        this.SetEnabled(false);
+
+        try
+        {
+            var creditBalance = await this.keywordsEverywhereApi.GetCreditBalanceAsync(this.clientFormConfiguration.ApiKey, default);
+            this.UpdateCreditsRemaining(creditBalance);
+        }
+        catch
+        {
+            creditsRemainingLabel.Text = "Credits remaining: TBD";
+        }
+        finally
+        {
+            this.SetEnabled(true);
+        }
     }
 
     protected override void OnShown(EventArgs e)
@@ -32,8 +53,13 @@ public partial class ClientForm : Form
 
     private void apiKeyTextBox_Leave(object sender, EventArgs e)
     {
-        this.clientFormConfiguration.ApiKey = this.apiKeyTextBox.Text;
-        this.clientFormConfigurationManager.Save(this.clientFormConfiguration);
+        if (this.clientFormConfiguration.ApiKey != this.apiKeyTextBox.Text)
+        {
+            this.clientFormConfiguration.ApiKey = this.apiKeyTextBox.Text;
+
+            this.clientFormConfigurationManager.Save(this.clientFormConfiguration);
+            this.UpdateCreditBalanceAsync();
+        }
     }
 
     private async void getResultsButton_Click(object sender, EventArgs e)
@@ -89,7 +115,12 @@ public partial class ClientForm : Form
 
         this.resultsDataGrid.DataSource = rows;
 
-        creditsRemainingLabel.Text = $"Credits remaining: {responseData.Credits}";
+        UpdateCreditsRemaining(responseData.Credits);
+    }
+
+    private void UpdateCreditsRemaining(long creditsRemaining)
+    {
+        creditsRemainingLabel.Text = $"Credits remaining: {creditsRemaining}";
     }
 
     private void HandleError(GetKeywordDataError errorData)

KeywordsEverywhereClient/KeywordsEverywhereApi.cs

@@ -14,6 +14,30 @@ internal class KeywordsEverywhereApi
         });
     }
 
+    public async Task<long> GetCreditBalanceAsync(string apiKey, CancellationToken cancellationToken)
+    {
+        HttpRequestMessage request = new(HttpMethod.Get, "https://api.keywordseverywhere.com/v1/account/credits");
+
+        request.Headers.Add("Accept", "application/json");
+        request.Headers.Add("Authorization", $"Bearer {apiKey}");
+
+        using var response = await this.httpClient.SendAsync(request, HttpCompletionOption.ResponseHeadersRead, cancellationToken);
+
+        var responseBody = await response.Content.ReadAsStringAsync(cancellationToken);
+
+        if (response.IsSuccessStatusCode)
+        {
+            var result = JsonSerializer.Deserialize<IReadOnlyList<long>>(responseBody)
+                ?? throw new InvalidOperationException("Success response is null.");
+
+            return result.Single();
+        }
+        else
+        {
+            throw new InvalidOperationException("Failed to get credit balance. " + responseBody);
+        }
+    }
+
     public async Task<GetKeywordResponseOrError> GetKeywordDataAsync(string apiKey, GetKeywordDataRequest requestData, CancellationToken cancellationToken)
     {
         HttpRequestMessage request = new(HttpMethod.Post, "https://api.keywordseverywhere.com/v1/get_keyword_data");