Phase 8: Production readiness — failover tests, security hardening, sandboxing, deployment docs
- WP-1-3: Central/site failover + dual-node recovery tests (17 tests) - WP-4: Performance testing framework for target scale (7 tests) - WP-5: Security hardening (LDAPS, JWT key length, no secrets in logs) (11 tests) - WP-6: Script sandboxing adversarial tests (28 tests, all forbidden APIs) - WP-7: Recovery drill test scaffolds (5 tests) - WP-8: Observability validation (structured logs, correlation IDs, metrics) (6 tests) - WP-9: Message contract compatibility (forward/backward compat) (18 tests) - WP-10: Deployment packaging (installation guide, production checklist, topology) - WP-11: Operational runbooks (failover, troubleshooting, maintenance) 92 new tests, all passing. Zero warnings.
This commit is contained in:
Joseph Doherty
246
src/ScadaLink.ExternalSystemGateway/ExternalSystemClient.cs
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246
src/ScadaLink.ExternalSystemGateway/ExternalSystemClient.cs
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using System.Net;
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using System.Net.Http.Headers;
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using System.Text;
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using System.Text.Json;
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using Microsoft.Extensions.Logging;
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using ScadaLink.Commons.Entities.ExternalSystems;
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using ScadaLink.Commons.Interfaces.Repositories;
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using ScadaLink.Commons.Interfaces.Services;
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using ScadaLink.Commons.Types.Enums;
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using ScadaLink.StoreAndForward;
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namespace ScadaLink.ExternalSystemGateway;
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/// <summary>
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/// WP-6: HTTP/REST client that invokes external APIs.
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/// WP-7: Dual call modes — Call (synchronous) and CachedCall (S&F on transient failure).
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/// WP-8: Error classification applied to HTTP responses and exceptions.
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/// </summary>
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public class ExternalSystemClient : IExternalSystemClient
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{
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private readonly IHttpClientFactory _httpClientFactory;
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private readonly IExternalSystemRepository _repository;
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private readonly StoreAndForwardService? _storeAndForward;
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private readonly ILogger<ExternalSystemClient> _logger;
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public ExternalSystemClient(
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IHttpClientFactory httpClientFactory,
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IExternalSystemRepository repository,
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ILogger<ExternalSystemClient> logger,
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StoreAndForwardService? storeAndForward = null)
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{
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_httpClientFactory = httpClientFactory;
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_repository = repository;
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_logger = logger;
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_storeAndForward = storeAndForward;
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}
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/// <summary>
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/// WP-7: Synchronous call — all failures returned to caller.
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/// </summary>
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public async Task<ExternalCallResult> CallAsync(
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string systemName,
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string methodName,
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IReadOnlyDictionary<string, object?>? parameters = null,
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CancellationToken cancellationToken = default)
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{
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var (system, method) = await ResolveSystemAndMethodAsync(systemName, methodName, cancellationToken);
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if (system == null || method == null)
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{
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return new ExternalCallResult(false, null, $"External system '{systemName}' or method '{methodName}' not found");
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}
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try
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{
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var response = await InvokeHttpAsync(system, method, parameters, cancellationToken);
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return new ExternalCallResult(true, response, null);
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}
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catch (TransientExternalSystemException ex)
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{
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return new ExternalCallResult(false, null, $"Transient error: {ex.Message}");
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}
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catch (PermanentExternalSystemException ex)
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{
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return new ExternalCallResult(false, null, $"Permanent error: {ex.Message}");
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}
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}
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/// <summary>
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/// WP-7: CachedCall — attempt immediate, transient failure goes to S&F, permanent returned to script.
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/// </summary>
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public async Task<ExternalCallResult> CachedCallAsync(
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string systemName,
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string methodName,
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IReadOnlyDictionary<string, object?>? parameters = null,
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string? originInstanceName = null,
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CancellationToken cancellationToken = default)
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{
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var (system, method) = await ResolveSystemAndMethodAsync(systemName, methodName, cancellationToken);
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if (system == null || method == null)
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{
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return new ExternalCallResult(false, null, $"External system '{systemName}' or method '{methodName}' not found");
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}
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try
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{
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var response = await InvokeHttpAsync(system, method, parameters, cancellationToken);
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return new ExternalCallResult(true, response, null);
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}
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catch (PermanentExternalSystemException ex)
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{
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// Permanent failures returned to script, never buffered
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return new ExternalCallResult(false, null, $"Permanent error: {ex.Message}");
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}
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catch (TransientExternalSystemException)
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{
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// Transient failure — hand to S&F
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if (_storeAndForward == null)
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{
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return new ExternalCallResult(false, null, "Transient error and store-and-forward not available");
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}
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var payload = JsonSerializer.Serialize(new
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{
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SystemName = systemName,
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MethodName = methodName,
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Parameters = parameters
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});
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var sfResult = await _storeAndForward.EnqueueAsync(
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StoreAndForwardCategory.ExternalSystem,
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systemName,
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payload,
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originInstanceName,
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system.MaxRetries > 0 ? system.MaxRetries : null,
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system.RetryDelay > TimeSpan.Zero ? system.RetryDelay : null);
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return new ExternalCallResult(true, null, null, WasBuffered: true);
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}
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}
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/// <summary>
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/// WP-6: Executes the HTTP request against the external system.
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/// </summary>
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internal async Task<string?> InvokeHttpAsync(
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ExternalSystemDefinition system,
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ExternalSystemMethod method,
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IReadOnlyDictionary<string, object?>? parameters,
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CancellationToken cancellationToken)
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{
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var client = _httpClientFactory.CreateClient($"ExternalSystem_{system.Name}");
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var url = BuildUrl(system.EndpointUrl, method.Path, parameters, method.HttpMethod);
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var request = new HttpRequestMessage(new HttpMethod(method.HttpMethod), url);
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// Apply authentication
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ApplyAuth(request, system);
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// For POST/PUT/PATCH, send parameters as JSON body
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if (method.HttpMethod.Equals("POST", StringComparison.OrdinalIgnoreCase) ||
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method.HttpMethod.Equals("PUT", StringComparison.OrdinalIgnoreCase) ||
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method.HttpMethod.Equals("PATCH", StringComparison.OrdinalIgnoreCase))
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{
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if (parameters != null && parameters.Count > 0)
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{
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request.Content = new StringContent(
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JsonSerializer.Serialize(parameters),
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Encoding.UTF8,
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"application/json");
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}
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}
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HttpResponseMessage response;
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try
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{
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response = await client.SendAsync(request, cancellationToken);
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}
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catch (Exception ex) when (ErrorClassifier.IsTransient(ex))
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{
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throw ErrorClassifier.AsTransient($"Connection error to {system.Name}: {ex.Message}", ex);
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}
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if (response.IsSuccessStatusCode)
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{
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return await response.Content.ReadAsStringAsync(cancellationToken);
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}
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var errorBody = await response.Content.ReadAsStringAsync(cancellationToken);
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if (ErrorClassifier.IsTransient(response.StatusCode))
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{
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throw ErrorClassifier.AsTransient(
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$"HTTP {(int)response.StatusCode} from {system.Name}: {errorBody}");
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}
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throw new PermanentExternalSystemException(
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$"HTTP {(int)response.StatusCode} from {system.Name}: {errorBody}",
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(int)response.StatusCode);
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}
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private static string BuildUrl(string baseUrl, string path, IReadOnlyDictionary<string, object?>? parameters, string httpMethod)
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{
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var url = baseUrl.TrimEnd('/') + "/" + path.TrimStart('/');
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// For GET/DELETE, append parameters as query string
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if ((httpMethod.Equals("GET", StringComparison.OrdinalIgnoreCase) ||
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httpMethod.Equals("DELETE", StringComparison.OrdinalIgnoreCase)) &&
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parameters != null && parameters.Count > 0)
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{
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var queryString = string.Join("&",
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parameters.Where(p => p.Value != null)
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.Select(p => $"{Uri.EscapeDataString(p.Key)}={Uri.EscapeDataString(p.Value?.ToString() ?? "")}"));
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url += "?" + queryString;
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}
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return url;
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}
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private static void ApplyAuth(HttpRequestMessage request, ExternalSystemDefinition system)
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{
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if (string.IsNullOrEmpty(system.AuthConfiguration))
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return;
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switch (system.AuthType.ToLowerInvariant())
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{
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case "apikey":
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// Auth config format: "HeaderName:KeyValue" or just "KeyValue" (default header: X-API-Key)
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var parts = system.AuthConfiguration.Split(':', 2);
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if (parts.Length == 2)
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{
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request.Headers.TryAddWithoutValidation(parts[0], parts[1]);
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}
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else
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{
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request.Headers.TryAddWithoutValidation("X-API-Key", system.AuthConfiguration);
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}
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break;
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case "basic":
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// Auth config format: "username:password"
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var basicParts = system.AuthConfiguration.Split(':', 2);
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if (basicParts.Length == 2)
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{
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var encoded = Convert.ToBase64String(
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Encoding.UTF8.GetBytes($"{basicParts[0]}:{basicParts[1]}"));
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request.Headers.Authorization = new AuthenticationHeaderValue("Basic", encoded);
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}
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break;
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}
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}
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private async Task<(ExternalSystemDefinition? system, ExternalSystemMethod? method)> ResolveSystemAndMethodAsync(
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string systemName,
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string methodName,
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CancellationToken cancellationToken)
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{
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var systems = await _repository.GetAllExternalSystemsAsync(cancellationToken);
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var system = systems.FirstOrDefault(s => s.Name.Equals(systemName, StringComparison.OrdinalIgnoreCase));
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if (system == null)
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return (null, null);
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var methods = await _repository.GetMethodsByExternalSystemIdAsync(system.Id, cancellationToken);
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var method = methods.FirstOrDefault(m => m.Name.Equals(methodName, StringComparison.OrdinalIgnoreCase));
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return (system, method);
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}
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}
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