Steps

Source/ProofOfConcept/Models/Token.cs

@@ -9,5 +9,5 @@ public record Token
     public string TokenType { get; init; } = String.Empty;
 
     //For JSON deserialization
-    public int ExpiresIn { get => (int)DateTimeOffset.Now.Subtract(Expires).TotalSeconds; init => Expires = DateTimeOffset.Now.AddSeconds(value); }
+    public int ExpiresIn { get => (int)Expires.Subtract(DateTimeOffset.Now).TotalSeconds; init => Expires = DateTimeOffset.Now.AddSeconds(value); }
 }

Source/ProofOfConcept/Services/TeslaAuthenticatorService.cs

@@ -1,5 +1,6 @@
 using System.Net.Http.Headers;
 using System.Text.Json;
+using System.Text.Json.Nodes;
 using Microsoft.Extensions.Caching.Memory;
 using Microsoft.Extensions.Options;
 using ProofOfConcept.Models;
@@ -18,20 +19,12 @@ public class TeslaAuthenticatorService
     const string authEndpointURL = "https://fleet-auth.prd.vn.cloud.tesla.com/oauth2/v3/token";
     const string euBaseURL = "https://fleet-api.prd.eu.vn.cloud.tesla.com";
 
-    private JsonSerializerOptions serializerOptions;
-    
     public TeslaAuthenticatorService(ILogger<TeslaAuthenticatorService> logger, IOptions<TeslaAuthenticatorServiceConfiguration> options, IHttpClientFactory httpClientFactory, IMemoryCache memoryCache)
     {
         this.logger = logger;
         this.httpClientFactory = httpClientFactory;
         this.memoryCache = memoryCache;
         this.configuration = options.Value;
-
-        serializerOptions = new JsonSerializerOptions()
-        {
-            PropertyNameCaseInsensitive = true,
-            PropertyNamingPolicy = JsonNamingPolicy.SnakeCaseLower
-        };
     }
 
     /// Asynchronously retrieves an authentication token from the Tesla partner API.
@@ -39,7 +32,7 @@ public class TeslaAuthenticatorService
     /// OAuth2 access token that grants access to Tesla partner services.
     /// <return>Returns a string containing the authentication token received from the API.</return>
     /// <exception cref="HttpRequestException">Thrown when the HTTP request to the API fails.</exception>
-    public async Task<Token> AcquirePartnerAuthenticationTokenAsync()
+    public async Task<Result<Token>> AcquirePartnerAuthenticationTokenAsync()
     {
         this.logger.LogTrace("Acquiring authentication token from Tesla partner API...");
         
@@ -60,6 +53,9 @@ public class TeslaAuthenticatorService
 
         FormUrlEncodedContent content = new FormUrlEncodedContent(formData);
 
+        string json = "";
+        try
+        {
             // Send POST request
             HttpResponseMessage response = await client.PostAsync(authEndpointURL, content);
             this.logger.LogTrace("Response status code: {0}", response.StatusCode);
@@ -68,22 +64,54 @@ public class TeslaAuthenticatorService
             response.EnsureSuccessStatusCode();
 
             // Read the response body as a string
-        string json = await response.Content.ReadAsStringAsync();
-        
-        // Deserialize
-        try
-        {
-            Token? result = JsonSerializer.Deserialize<Token>(json);
-        
-            if (result is null)
-                throw new FormatException("Response could not be deserialized (null).");
-            
-            // Return the token response
-            return result;
+            json = await response.Content.ReadAsStringAsync();
         }
+
+        catch (HttpRequestException httpRequestException)
+        {
+            this.logger.LogError(httpRequestException, "HTTP Request error while acquiring partner authentication token from Tesla API");
+            return new Result<Token>(httpRequestException);
+        }
+
         catch (Exception e)
         {
-            throw new AggregateException($"Could not deserialize token response: {json}", e);
+            this.logger.LogError(e, "Unexpected communication error while acquiring partner authentication token from Tesla API");
+            return new Result<Token>(e);
+        }
+
+        try
+        {
+            // Check if the response is empty
+            if (String.IsNullOrWhiteSpace(json))
+                throw new JsonException("Response could not be deserialized (empty).");
+            
+            // Deserializer options: {"access_token":"999 random chars including some special characters","expires_in":28800,"token_type":"Bearer"}
+            JsonSerializerOptions serializerOptions = new JsonSerializerOptions()
+            {
+                PropertyNameCaseInsensitive = true,
+                PropertyNamingPolicy = JsonNamingPolicy.SnakeCaseLower
+            };
+
+            // Deserialize the JSON response
+            Token? result = JsonSerializer.Deserialize<Token>(json, serializerOptions);
+
+            if (result is null)
+                throw new JsonException("Response could not be deserialized (null).");
+            
+            this.logger.LogInformation("Authentication token acquired from Tesla partner API");
+            return new Result<Token>(result);
+        }
+
+        catch (JsonException jsonException)
+        {
+            this.logger.LogError(jsonException, "JSON deserialization error while acquiring partner authentication token from Tesla API");
+            return new Result<Token>(jsonException);
+        }
+        
+        catch (Exception e)
+        {
+            this.logger.LogError(e, "Unexpected serialization error while acquiring partner authentication token from Tesla API");
+            return new Result<Token>(e);
         }
     }
 
@@ -94,7 +122,7 @@ public class TeslaAuthenticatorService
     /// <return>Returns a Token object containing the authentication token and its expiration details.</return>
     /// <exception cref="HttpRequestException">Thrown when the HTTP request to acquire a new partner token fails.</exception>
     /// <exception cref="Exception">Thrown for any unexpected errors during the token retrieval or caching process.</exception>
-    public async Task<Token> GetPartnerAuthenticationTokenAsync()
+    public async Task<Result<Token>> GetPartnerAuthenticationTokenAsync()
     {
         this.logger.LogTrace("Getting partner authentication token...");
         
@@ -102,17 +130,25 @@ public class TeslaAuthenticatorService
         if (this.memoryCache.TryGetValue(Keys.TeslaPartnerToken, out Token? token) && token is not null)
         {
             this.logger.LogInformation("Partner authentication token provided from cache");
-            return token;
+            return Result.Success(token);
         }
 
         //Acquire token
-        token = await AcquirePartnerAuthenticationTokenAsync();
+        Result<Token> aquirationResult = await AcquirePartnerAuthenticationTokenAsync();
         
         //Save to cache
+        if (aquirationResult.IsSuccessful)
+        {
+            token = aquirationResult.Value;
             this.memoryCache.Set(Keys.TeslaPartnerToken, token, token.Expires.Subtract(this.configuration.MemoryCacheDelta));
 
-        this.logger.LogInformation("Partner authentication token provided provided by acquiring from API");
-        return token;
+            this.logger.LogInformation("Partner authentication token provided by acquiring from API");
+        }
+
+        else
+            this.logger.LogError("Failed to get partner authentication token");
+
+        return aquirationResult;
     }
 
     public async Task<Result> RegisterApplicationAsync(CancellationToken cancellationToken = default(CancellationToken))
@@ -121,7 +157,13 @@ public class TeslaAuthenticatorService
 
         //Create client and get partner token
         HttpClient httpClient = httpClientFactory.CreateClient();
-        Token partnerToken = await GetPartnerAuthenticationTokenAsync();
+        Result<Token> partnerTokenResult = await GetPartnerAuthenticationTokenAsync();
+
+        if (!partnerTokenResult.IsSuccessful)
+            return Result.Fail(partnerTokenResult.Exception ?? new Exception("Partner authentication token not found"));
+
+        //Set partner token
+        Token partnerToken = partnerTokenResult.Value;
         
         //Set headers
         httpClient.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));
@@ -135,7 +177,29 @@ public class TeslaAuthenticatorService
         bool success = response.IsSuccessStatusCode;
         
         logger.LogInformation("Application registration result: {Success}", success ? "Success" : "Failed");
-        return new Result(success);
+        
+        //Load response from server
+        string json = await response.Content.ReadAsStringAsync(cancellationToken);
+        this.logger.LogTrace("Registration response from server: {Response}", json);
+        
+        //{"isSuccessful":true,"isFailed":false,"exceptions":[],"exception":null}
+        //Parse JSON
+        JsonNode? root = JsonNode.Parse(json);
+        bool isSuccessful = root?["isSuccessful"]?.GetValue<bool>() ?? false;
+        bool isFailed     = root?["isFailed"]?.GetValue<bool>() ?? false;
+
+        if (success && isSuccessful && !isFailed)
+        {
+            logger.LogInformation("Application registered successfully");
+            return Result.Success();
+        }
+        
+        else
+        {
+            logger.LogError("Application registration failed");
+            
+            return Result.Fail(new AggregateException(new Exception(root?["exception"]?.ToJsonString()), new Exception(root?["exceptions"]?.ToJsonString())));
+        }
     }
 
     public async Task<Result<bool>> CheckApplicationRegistrationAsync(CancellationToken cancellationToken = default(CancellationToken))
@@ -144,14 +208,20 @@ public class TeslaAuthenticatorService
         
         //Create client and get partner token
         HttpClient httpClient = httpClientFactory.CreateClient();
-        Token partnerToken = await GetPartnerAuthenticationTokenAsync();
+        Result<Token> partnerTokenResult = await GetPartnerAuthenticationTokenAsync();
+        
+        if (!partnerTokenResult.IsSuccessful)
+            return Result.Fail(partnerTokenResult.Exception ?? new Exception("Partner authentication token not found"));
+
+        //Set partner token
+        Token partnerToken = partnerTokenResult.Value;
         
         //Set headers
         httpClient.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));
         httpClient.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Bearer", partnerToken.AccessToken);
 
         //Send request
-        HttpResponseMessage response = await httpClient.GetAsync($"{euBaseURL}/api/1/partner_accounts", cancellationToken);
+        HttpResponseMessage response = await httpClient.GetAsync($"{euBaseURL}/api/1/partner_accounts/public_key?domain={this.configuration.Domain}", cancellationToken);
         string responseBody = await response.Content.ReadAsStringAsync(cancellationToken);
         
         logger.LogInformation("Application registration result: {Result}", responseBody);