Initial commit: EbayListingTool WPF application
C# WPF desktop app for creating eBay UK listings with AI-powered photo analysis. Features: multi-photo vision analysis via OpenRouter (Claude), local listing save/export, saved listings browser, single item listing form, bulk import from CSV/Excel, and eBay OAuth authentication. Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
This commit is contained in:
Peter Foster
315
EbayListingTool/Services/AiAssistantService.cs
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315
EbayListingTool/Services/AiAssistantService.cs
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using System.Net.Http;
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using System.Net.Http.Headers;
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using System.Text;
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using EbayListingTool.Models;
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using Microsoft.Extensions.Configuration;
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using Newtonsoft.Json;
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using Newtonsoft.Json.Linq;
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namespace EbayListingTool.Services;
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/// <summary>
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/// Calls Claude via OpenRouter (https://openrouter.ai) using the OpenAI-compatible
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/// chat completions endpoint. Sign up at openrouter.ai to get an API key.
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/// </summary>
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public class AiAssistantService
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{
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private readonly string _apiKey;
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private readonly string _model;
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private static readonly HttpClient _http = new();
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private const string ApiUrl = "https://openrouter.ai/api/v1/chat/completions";
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private const string SystemPrompt =
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"You are an expert eBay UK seller assistant. You help write compelling, accurate, " +
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"keyword-rich listings for eBay.co.uk. Always use British English. " +
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"Be honest about item condition. Keep titles under 80 characters. " +
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"Descriptions should be clear and informative for buyers.";
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public AiAssistantService(IConfiguration config)
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{
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_apiKey = config["OpenRouter:ApiKey"] ?? "";
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_model = config["OpenRouter:Model"] ?? "anthropic/claude-sonnet-4-5";
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}
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public async Task<string> GenerateTitleAsync(string productName, string condition, string notes = "")
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{
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var prompt = $"Write a concise eBay UK listing title (MAXIMUM 80 characters, no more) for this item:\n" +
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$"Item: {productName}\n" +
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$"Condition: {condition}\n" +
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(string.IsNullOrWhiteSpace(notes) ? "" : $"Notes: {notes}\n") +
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$"\nReturn ONLY the title, nothing else. No quotes, no explanation.";
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return await CallAsync(prompt);
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}
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public async Task<string> WriteDescriptionAsync(string title, string condition, string notes = "")
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{
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var prompt = $"Write a clear, honest eBay UK product description for this listing:\n" +
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$"Title: {title}\n" +
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$"Condition: {condition}\n" +
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(string.IsNullOrWhiteSpace(notes) ? "" : $"Seller notes: {notes}\n") +
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$"\nInclude:\n" +
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$"- What the item is and what's included\n" +
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$"- Honest condition notes\n" +
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$"- A note about postage (dispatched within 1-2 working days)\n" +
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$"- Payment via eBay only\n\n" +
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$"Use plain text with line breaks. No HTML. UK English. Keep it friendly and professional.\n" +
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$"Return ONLY the description text.";
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return await CallAsync(prompt);
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}
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public async Task<string> SuggestPriceAsync(string title, string condition, IEnumerable<decimal>? soldPrices = null)
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{
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string priceContext = "";
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if (soldPrices != null && soldPrices.Any())
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{
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var prices = soldPrices.Select(p => $"£{p:F2}");
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priceContext = $"\nRecent eBay UK sold prices for similar items: {string.Join(", ", prices)}";
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}
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var prompt = $"Suggest a competitive Buy It Now price in GBP for this eBay UK listing:\n" +
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$"Item: {title}\n" +
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$"Condition: {condition}" +
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priceContext +
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$"\n\nRespond in this exact format:\n" +
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$"PRICE: [number only, e.g. 29.99]\n" +
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$"REASON: [one sentence explaining the price]";
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return await CallAsync(prompt);
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}
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public async Task<string> EnhanceListingAsync(BulkImportRow row)
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{
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var needsTitle = string.IsNullOrWhiteSpace(row.Title);
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var needsDescription = string.IsNullOrWhiteSpace(row.Description);
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var needsPrice = string.IsNullOrWhiteSpace(row.Price) || row.Price == "0";
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if (!needsTitle && !needsDescription && !needsPrice)
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return "No changes needed.";
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var prompt = new StringBuilder();
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prompt.AppendLine("Fill in the missing fields for this eBay UK listing. Return valid JSON only.");
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prompt.AppendLine($"Item info: Title={row.Title}, Condition={row.Condition}, Category={row.CategoryKeyword}");
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prompt.AppendLine();
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prompt.AppendLine("Return a JSON object with these fields:");
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prompt.AppendLine("{");
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if (needsTitle) prompt.AppendLine(" \"title\": \"[max 80 chars, keyword-rich eBay title]\",");
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if (needsDescription) prompt.AppendLine(" \"description\": \"[clear plain-text description for eBay UK]\",");
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if (needsPrice) prompt.AppendLine(" \"price\": \"[suggested price as a number, e.g. 19.99]\"");
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prompt.AppendLine("}");
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prompt.AppendLine("Return ONLY the JSON object, no other text.");
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var json = await CallAsync(prompt.ToString());
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try
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{
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JObject obj;
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try
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{
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obj = JObject.Parse(json.Trim());
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}
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catch (JsonReaderException)
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{
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// Claude sometimes wraps JSON in ```json...``` fences
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var match = System.Text.RegularExpressions.Regex.Match(
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json, @"```(?:json)?\s*(\{[\s\S]*?\})\s*```");
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var candidate = match.Success ? match.Groups[1].Value : json.Trim();
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obj = JObject.Parse(candidate);
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}
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if (needsTitle && obj["title"] != null)
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row.Title = obj["title"]!.ToString();
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if (needsDescription && obj["description"] != null)
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row.Description = obj["description"]!.ToString();
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if (needsPrice && obj["price"] != null)
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row.Price = obj["price"]!.ToString();
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return "Enhanced successfully.";
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}
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catch
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{
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return $"AI returned unexpected format: {json}";
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}
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}
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/// <summary>Convenience wrapper — analyses a single photo.</summary>
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public Task<PhotoAnalysisResult> AnalyseItemFromPhotoAsync(string imagePath)
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=> AnalyseItemFromPhotosAsync(new[] { imagePath });
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/// <summary>
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/// Analyses one or more photos of the same item (up to 4) using Claude vision.
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/// All images are included in a single request so the model can use every angle.
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/// </summary>
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public async Task<PhotoAnalysisResult> AnalyseItemFromPhotosAsync(IEnumerable<string> imagePaths)
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{
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var paths = imagePaths.Take(4).ToList();
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if (paths.Count == 0)
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throw new ArgumentException("At least one image path must be provided.", nameof(imagePaths));
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// Build base64 data URLs for every image
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const long MaxImageBytes = 8 * 1024 * 1024; // E4: reject before base64 to avoid OOM
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var dataUrls = new List<string>(paths.Count);
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foreach (var path in paths)
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{
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var fileInfo = new FileInfo(path);
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if (fileInfo.Length > MaxImageBytes)
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throw new InvalidOperationException(
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$"Photo \"{Path.GetFileName(path)}\" is {fileInfo.Length / 1_048_576.0:F0} MB — please use images under 8 MB.");
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var imageBytes = await File.ReadAllBytesAsync(path);
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var base64 = Convert.ToBase64String(imageBytes);
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var ext = Path.GetExtension(path).TrimStart('.').ToLower();
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var mimeType = ext switch { "jpg" or "jpeg" => "image/jpeg", "png" => "image/png",
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"gif" => "image/gif", "webp" => "image/webp", _ => "image/jpeg" };
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dataUrls.Add($"data:{mimeType};base64,{base64}");
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}
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var multiPhoto = dataUrls.Count > 1;
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var photoPrompt = multiPhoto
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? "These are multiple photos of the same item from different angles. Use all photos together to identify the item accurately."
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: "Analyse this photo of an item.";
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var prompt =
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$"You are an expert eBay UK seller. {photoPrompt} Return a JSON object " +
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"with everything needed to create an eBay UK listing.\n\n" +
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"Return ONLY valid JSON — no markdown, no explanation:\n" +
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"{\n" +
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" \"item_name\": \"full descriptive name of the item\",\n" +
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" \"brand\": \"brand name or empty string if unknown\",\n" +
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" \"model\": \"model name/number or empty string if unknown\",\n" +
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" \"condition_notes\": \"honest assessment of visible condition from the photo(s)\",\n" +
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" \"title\": \"eBay UK listing title, max 80 chars, keyword-rich\",\n" +
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" \"description\": \"full plain-text eBay UK description including what it is, condition, " +
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"what's likely included, postage note (dispatched within 1-2 working days)\",\n" +
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" \"price_suggested\": 0.00,\n" +
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" \"price_min\": 0.00,\n" +
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" \"price_max\": 0.00,\n" +
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" \"price_reasoning\": \"one sentence why this price\",\n" +
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" \"category_keyword\": \"best eBay category keyword to search\",\n" +
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" \"identification_confidence\": \"High, Medium, or Low\",\n" +
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" \"confidence_notes\": \"one sentence explaining confidence level, e.g. brand clearly visible on label\"\n" +
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"}\n\n" +
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"For prices: research realistic eBay UK sold prices in your knowledge. " +
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"price_suggested should be a good Buy It Now price. Use GBP numbers only (no £ symbol).";
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var json = await CallWithVisionAsync(dataUrls, prompt);
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try
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{
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JObject obj;
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try { obj = JObject.Parse(json.Trim()); }
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catch (JsonReaderException)
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{
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var m = System.Text.RegularExpressions.Regex.Match(json, @"```(?:json)?\s*(\{[\s\S]*?\})\s*```");
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obj = JObject.Parse(m.Success ? m.Groups[1].Value : json.Trim());
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}
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return new PhotoAnalysisResult
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{
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ItemName = obj["item_name"]?.ToString() ?? "",
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Brand = obj["brand"]?.ToString() ?? "",
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Model = obj["model"]?.ToString() ?? "",
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ConditionNotes = obj["condition_notes"]?.ToString() ?? "",
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Title = obj["title"]?.ToString() ?? "",
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Description = obj["description"]?.ToString() ?? "",
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PriceSuggested = obj["price_suggested"]?.Value<decimal>() ?? 0,
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PriceMin = obj["price_min"]?.Value<decimal>() ?? 0,
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PriceMax = obj["price_max"]?.Value<decimal>() ?? 0,
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PriceReasoning = obj["price_reasoning"]?.ToString() ?? "",
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CategoryKeyword = obj["category_keyword"]?.ToString() ?? "",
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IdentificationConfidence = obj["identification_confidence"]?.ToString() ?? "",
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ConfidenceNotes = obj["confidence_notes"]?.ToString() ?? ""
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};
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}
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catch (Exception ex)
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{
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// E5: don't expose raw API response (may contain sensitive data / confuse users)
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throw new InvalidOperationException($"Could not parse AI response: {ex.Message}");
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}
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}
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private async Task<string> CallWithVisionAsync(IEnumerable<string> imageDataUrls, string textPrompt)
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{
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if (string.IsNullOrEmpty(_apiKey))
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throw new InvalidOperationException("OpenRouter API key not configured in appsettings.json.");
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// Build content array: one image_url block per image, then a single text block
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var contentParts = imageDataUrls
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.Select(url => (object)new { type = "image_url", image_url = new { url } })
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.Append(new { type = "text", text = textPrompt })
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.ToArray();
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// Vision request: content is an array of image + text parts
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var requestBody = new
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{
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model = _model,
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max_tokens = 1500,
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messages = new object[]
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{
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new { role = "system", content = SystemPrompt },
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new
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{
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role = "user",
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content = contentParts
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}
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}
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};
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var json = JsonConvert.SerializeObject(requestBody);
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using var request = new HttpRequestMessage(HttpMethod.Post, ApiUrl);
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request.Headers.Authorization = new AuthenticationHeaderValue("Bearer", _apiKey);
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request.Headers.Add("HTTP-Referer", "https://github.com/ebay-listing-tool");
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request.Headers.Add("X-Title", "eBay Listing Tool");
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request.Content = new StringContent(json, Encoding.UTF8, "application/json");
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var response = await _http.SendAsync(request);
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var responseJson = await response.Content.ReadAsStringAsync();
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if (!response.IsSuccessStatusCode)
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throw new HttpRequestException($"OpenRouter error ({(int)response.StatusCode}): {responseJson}");
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var obj = JObject.Parse(responseJson);
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return obj["choices"]?[0]?["message"]?["content"]?.ToString()
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?? throw new InvalidOperationException("Unexpected response from OpenRouter.");
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}
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private async Task<string> CallAsync(string userMessage)
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{
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if (string.IsNullOrEmpty(_apiKey))
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throw new InvalidOperationException(
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"OpenRouter API key not configured.\n\n" +
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"1. Sign up at https://openrouter.ai\n" +
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"2. Create an API key\n" +
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"3. Add it to appsettings.json under OpenRouter:ApiKey");
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var requestBody = new
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{
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model = _model,
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max_tokens = 1024,
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messages = new[]
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{
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new { role = "system", content = SystemPrompt },
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new { role = "user", content = userMessage }
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}
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};
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var json = JsonConvert.SerializeObject(requestBody);
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using var request = new HttpRequestMessage(HttpMethod.Post, ApiUrl);
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request.Headers.Authorization = new AuthenticationHeaderValue("Bearer", _apiKey);
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request.Headers.Add("HTTP-Referer", "https://github.com/ebay-listing-tool");
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request.Headers.Add("X-Title", "eBay Listing Tool");
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request.Content = new StringContent(json, Encoding.UTF8, "application/json");
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var response = await _http.SendAsync(request);
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var responseJson = await response.Content.ReadAsStringAsync();
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if (!response.IsSuccessStatusCode)
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throw new HttpRequestException($"OpenRouter API error ({(int)response.StatusCode}): {responseJson}");
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var obj = JObject.Parse(responseJson);
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return obj["choices"]?[0]?["message"]?["content"]?.ToString()
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?? throw new InvalidOperationException("Unexpected response format from OpenRouter.");
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}
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}
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