feat(News): refactor news service and add sentiment tracking

FinlyticNews/Services/N8nService.cs

@@ -0,0 +1,132 @@
+using System.Text.Json;
+using System.Text.Json.Serialization;
+using FinlyticCore.Util;
+using Microsoft.Extensions.Configuration;
+using Microsoft.Extensions.DependencyInjection;
+using Microsoft.Extensions.Logging;
+
+namespace FinlyticNews.Services;
+
+using FinlyticCore.Dtos.News;
+
+/// <summary>
+/// Defines integration operations with the external n8n AI workflow webhook.
+/// </summary>
+public interface IN8nService
+{
+    /// <summary>
+    /// Submits raw article content and pre-filtered assets to n8n, returning the parsed response metadata.
+    /// </summary>
+    Task<N8nResponsePayload?> AnalyzeArticleAsync(string content, List<FilteredAssetPayload> filteredAssets, CancellationToken ct = default);
+}
+
+/// <inheritdoc />
+public class N8nService : IN8nService
+{
+    private readonly HttpClient _httpClient;
+    private readonly IServiceScopeFactory _scopeFactory;
+    private readonly IConfiguration _configuration;
+    private readonly ILogger<N8nService> _logger;
+
+    /// <summary>
+    /// Initializes a new instance of the <see cref="N8nService"/> class.
+    /// </summary>
+    public N8nService(
+        HttpClient httpClient,
+        IServiceScopeFactory scopeFactory,
+        IConfiguration configuration,
+        ILogger<N8nService> logger)
+    {
+        _httpClient = httpClient;
+        _scopeFactory = scopeFactory;
+        _configuration = configuration;
+        _logger = logger;
+    }
+
+    /// <inheritdoc />
+    public async Task<N8nResponsePayload?> AnalyzeArticleAsync(string content, List<FilteredAssetPayload> filteredAssets, CancellationToken ct = default)
+    {
+        string? targetUrl = null;
+
+        // 1. Dynamic Settings Resolution (DB Scope -> AppSettings Fallback)
+        using (var scope = _scopeFactory.CreateScope())
+        {
+            var settingsDb = scope.ServiceProvider.GetService<ISettingsDbService>();
+            if (settingsDb != null)
+            {
+                var settings = await settingsDb.GetSettingsAsync();
+                targetUrl = settings?.N8nWebhookUrl;
+            }
+        }
+
+        if (string.IsNullOrWhiteSpace(targetUrl))
+        {
+            targetUrl = _configuration["N8N__WebhookUrl"] 
+                        ?? _configuration["N8N:WebhookUrl"];
+        }
+
+        if (string.IsNullOrWhiteSpace(targetUrl))
+        {
+            _logger.LogError("[{Channel}] N8nWebhookUrl is not configured in DB or application settings.", "NewsChannel");
+            return null;
+        }
+
+        _logger.LogInformation("[{Channel}] Posting article to n8n webhook pipeline at: {Url}", "NewsChannel", targetUrl);
+
+        var payload = new N8nRequestPayload(content, filteredAssets ?? []);
+
+        try
+        {
+            // Zero-Allocation / Source-Generated Request Serialization
+            var jsonContent = JsonSerializer.Serialize(payload, FinlyticJsonSerializerContext.Default.N8nRequestPayload);
+            using var requestContent = new StringContent(jsonContent, System.Text.Encoding.UTF8, "application/json");
+
+            using var response = await _httpClient.PostAsync(targetUrl, requestContent, ct);
+
+            if (!response.IsSuccessStatusCode)
+            {
+                var errorMsg = await response.Content.ReadAsStringAsync(ct);
+                _logger.LogError("[{Channel}] n8n webhook returned status code {StatusCode}. Error payload: {Error}", "NewsChannel", response.StatusCode, errorMsg);
+                return null;
+            }
+
+            using var responseStream = await response.Content.ReadAsStreamAsync(ct);
+            using var doc = await JsonDocument.ParseAsync(responseStream, cancellationToken: ct);
+            
+            var root = doc.RootElement;
+
+            // 2. Robust n8n Array-Unwrapping (Handles [{ "json": { ... } }])
+            if (root.ValueKind == JsonValueKind.Array)
+            {
+                if (root.GetArrayLength() == 0)
+                {
+                    _logger.LogWarning("[{Channel}] n8n webhook returned an empty array.", "NewsChannel");
+                    return null;
+                }
+                root = root[0];
+            }
+
+            // 3. Dynamic Node Wrapper Unwrapping ("json", "output", "data", "body")
+            if (root.ValueKind == JsonValueKind.Object)
+            {
+                if (root.TryGetProperty("json", out var jsonChild) && jsonChild.ValueKind == JsonValueKind.Object)
+                    root = jsonChild;
+                else if (root.TryGetProperty("output", out var outChild) && outChild.ValueKind == JsonValueKind.Object)
+                    root = outChild;
+                else if (root.TryGetProperty("data", out var dataChild) && dataChild.ValueKind == JsonValueKind.Object)
+                    root = dataChild;
+                else if (root.TryGetProperty("body", out var bodyChild) && bodyChild.ValueKind == JsonValueKind.Object)
+                    root = bodyChild;
+            }
+
+            // 4. Source-Generated Deserialization directly from JsonElement
+            var result = root.Deserialize(FinlyticJsonSerializerContext.Default.N8nResponsePayload);
+            return result;
+        }
+        catch (Exception ex)
+        {
+            _logger.LogError(ex, "[{Channel}] Failed to communicate with or parse response from n8n webhook workflow.", "NewsChannel");
+            return null;
+        }
+    }
+}