feat: create fulfillment policies on-demand per postage option and cost

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

EbayListingTool/Services/EbayListingService.cs

@@ -22,27 +22,56 @@ public class EbayListingService
     private string? _returnPolicyId;
     private string? _merchantLocationKey;
 
+    private readonly Dictionary<string, string> _policyCache = new();
+    private static readonly string PolicyCacheFile =
+        Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.ApplicationData),
+                     "EbayListingTool", "fulfillment_policies.json");
+
     public EbayListingService(EbayAuthService auth, EbayCategoryService categoryService)
     {
         _auth = auth;
         _categoryService = categoryService;
+        LoadPolicyCacheFromDisk();
     }
 
     /// <summary>Call when the user disconnects so stale IDs are not reused after re-login.</summary>
     public void ClearCache()
     {
-        _fulfillmentPolicyId = null;
         _paymentPolicyId     = null;
         _returnPolicyId      = null;
         _merchantLocationKey = null;
     }
 
+    private void LoadPolicyCacheFromDisk()
+    {
+        try
+        {
+            if (!File.Exists(PolicyCacheFile)) return;
+            var json = File.ReadAllText(PolicyCacheFile);
+            var dict = JsonConvert.DeserializeObject<Dictionary<string, string>>(json);
+            if (dict != null)
+                foreach (var kv in dict) _policyCache[kv.Key] = kv.Value;
+        }
+        catch { /* ignore corrupt cache */ }
+    }
+
+    private void SavePolicyCacheToDisk()
+    {
+        try
+        {
+            Directory.CreateDirectory(Path.GetDirectoryName(PolicyCacheFile)!);
+            File.WriteAllText(PolicyCacheFile, JsonConvert.SerializeObject(_policyCache));
+        }
+        catch { /* non-critical */ }
+    }
+
     public async Task<string> PostListingAsync(ListingDraft draft)
     {
         var token = await _auth.GetValidAccessTokenAsync();
 
         // Resolve business policies and merchant location before touching inventory/offers
         await EnsurePoliciesAndLocationAsync(token, draft.Postcode);
+        _fulfillmentPolicyId = await GetOrCreateFulfillmentPolicyAsync(draft.Postage, draft.ShippingCost, token);
 
         // 1. Upload photos and get eBay-hosted URLs
         var imageUrls = await UploadPhotosAsync(draft.PhotoPaths, token);
@@ -73,6 +102,94 @@ public class EbayListingService
         return draft.EbayListingUrl;
     }
 
+    // ---- Fulfillment policy: on-demand creation ----
+
+    private static string ToShippingServiceCode(PostageOption option) => option switch
+    {
+        PostageOption.RoyalMailFirstClass  => "UK_RoyalMailFirstClassStandard",
+        PostageOption.RoyalMailSecondClass => "UK_RoyalMailSecondClassStandard",
+        PostageOption.RoyalMailTracked24   => "UK_RoyalMailTracked24",
+        PostageOption.RoyalMailTracked48   => "UK_RoyalMailTracked48",
+        PostageOption.CollectionOnly       => "UK_CollectInPerson",
+        PostageOption.FreePostage          => "UK_RoyalMailSecondClassStandard",
+        _ => "UK_RoyalMailSecondClassStandard"
+    };
+
+    private async Task<string> GetOrCreateFulfillmentPolicyAsync(
+        PostageOption postage, decimal shippingCost, string token)
+    {
+        var free     = postage == PostageOption.FreePostage || postage == PostageOption.CollectionOnly;
+        var cost     = free ? 0m : shippingCost;
+        var cacheKey = $"{postage}_{cost:F2}";
+
+        if (_policyCache.TryGetValue(cacheKey, out var cached)) return cached;
+
+        var serviceCode = ToShippingServiceCode(postage);
+        var policyName  = $"ELT_{postage}_{cost:F2}".Replace(" ", "");
+
+        object shippingServiceObj;
+        if (postage == PostageOption.CollectionOnly)
+        {
+            shippingServiceObj = new
+            {
+                shippingServiceCode         = serviceCode,
+                shippingCost                = new { value = "0.00", currency = "GBP" },
+                freeShipping                = false,
+                buyerResponsibleForShipping = true,
+                sortOrder                   = 1
+            };
+        }
+        else
+        {
+            shippingServiceObj = new
+            {
+                shippingCarrierCode = "RoyalMail",
+                shippingServiceCode = serviceCode,
+                shippingCost        = new { value = cost.ToString("F2"), currency = "GBP" },
+                freeShipping        = free,
+                sortOrder           = 1
+            };
+        }
+
+        var body = new
+        {
+            name            = policyName,
+            marketplaceId   = "EBAY_GB",
+            categoryTypes   = new[] { new { name = "ALL_EXCLUDING_MOTORS_VEHICLES" } },
+            handlingTime    = new { value = 2, unit = "DAY" },
+            shippingOptions = new[]
+            {
+                new
+                {
+                    optionType       = "DOMESTIC",
+                    costType         = postage == PostageOption.CollectionOnly ? "NOT_SPECIFIED" : "FLAT_RATE",
+                    shippingServices = new[] { shippingServiceObj }
+                }
+            }
+        };
+
+        var json = JsonConvert.SerializeObject(body,
+            new JsonSerializerSettings { NullValueHandling = NullValueHandling.Ignore });
+
+        using var req = MakeRequest(HttpMethod.Post,
+            $"{_auth.BaseUrl}/sell/account/v1/fulfillment_policy", token);
+        req.Content = new StringContent(json, Encoding.UTF8, "application/json");
+
+        var res     = await _http.SendAsync(req);
+        var resJson = await res.Content.ReadAsStringAsync();
+
+        if (!res.IsSuccessStatusCode)
+            throw new HttpRequestException(
+                $"Could not create fulfillment policy ({(int)res.StatusCode}): {resJson}");
+
+        var policyId = JObject.Parse(resJson)["fulfillmentPolicyId"]?.ToString()
+            ?? throw new InvalidOperationException("No fulfillmentPolicyId in response.");
+
+        _policyCache[cacheKey] = policyId;
+        SavePolicyCacheToDisk();
+        return policyId;
+    }
+
     // ---- Setup: policies + location ----
 
     /// <summary>
@@ -84,28 +201,6 @@ public class EbayListingService
     {
         var baseUrl = _auth.BaseUrl;
 
-        if (_fulfillmentPolicyId == null)
-        {
-            using var req = MakeRequest(HttpMethod.Get,
-                $"{baseUrl}/sell/account/v1/fulfillment_policy?marketplace_id=EBAY_GB", token);
-            var res  = await _http.SendAsync(req);
-            var json = await res.Content.ReadAsStringAsync();
-
-            if (!res.IsSuccessStatusCode)
-                throw new HttpRequestException(
-                    $"Could not fetch fulfillment policies ({(int)res.StatusCode}): {json}");
-
-            var arr = JObject.Parse(json)["fulfillmentPolicies"] as JArray;
-            _fulfillmentPolicyId = arr?.Count > 0
-                ? arr[0]["fulfillmentPolicyId"]?.ToString()
-                : null;
-
-            if (_fulfillmentPolicyId == null)
-                throw new InvalidOperationException(
-                    "No fulfillment policy found on your eBay account.\n\n" +
-                    "Please set one up in My eBay → Account → Business policies, then try again.");
-        }
-
         if (_paymentPolicyId == null)
         {
             using var req = MakeRequest(HttpMethod.Get,