Implemented phase 6 for the POC prototype in the Website service.

Services/Website/Sources/Library/Public/Controllers/TradeController.swift

@@ -20,6 +20,9 @@ public struct TradeController<Context: RequestContext> {
     /// The repository listings and shops are read through.
     private let catalogue: CatalogueRepository
 
+    /// The repository the events a shop trades at are read and set through, or `nil` to leave them out.
+    private let collecting: CollectingRepository?
+
     /// Told whenever the controller changes what is for sale, so pages cached elsewhere can catch up.
     private let onCatalogueChange: @Sendable () async -> Void
 
@@ -36,6 +39,7 @@ public struct TradeController<Context: RequestContext> {
     ///   - trade: the repository conversations, offers, and sales are read and written through.
     ///   - catalogue: the repository listings and shops are read through.
     ///   - sessions: the store the signed-in account is read from.
+    ///   - collecting: the repository the events a shop trades at are read and set through, or `nil` (the default) to leave them out.
     ///   - assetVersion: the version token appended to the pages' asset URLs, or `nil` (the default) to leave them unversioned.
     ///   - analytics: the analytics tracker the pages embed, or `nil` (the default) to omit it.
     ///   - onCatalogueChange: told whenever the controller changes what is for sale; does nothing by default.
@@ -43,6 +47,7 @@ public struct TradeController<Context: RequestContext> {
         trade: TradeRepository,
         catalogue: CatalogueRepository,
         sessions: SessionStore,
+        collecting: CollectingRepository? = nil,
         assetVersion: String? = nil,
         analytics: Analytics? = nil,
         onCatalogueChange: @escaping @Sendable () async -> Void = {}
@@ -51,6 +56,7 @@ public struct TradeController<Context: RequestContext> {
         self.onCatalogueChange = onCatalogueChange
         self.assetVersion = assetVersion
         self.catalogue = catalogue
+        self.collecting = collecting
         self.sessions = sessions
         self.trade = trade
     }
@@ -78,6 +84,7 @@ extension TradeController: RouterController {
         routes.post(.Trade.sale, use: takeStep)
         routes.get(.Trade.dashboard, use: dashboard)
         routes.post(.Trade.answer, use: answer)
+        routes.post(.init("\(String.Route.sellerDashboard)/events"), use: setEvents)
 
         return routes
     }
@@ -429,6 +436,26 @@ private extension TradeController {
         )
     }
 
+    /// Handles the events a seller ticked on the dashboard. A form with no box ticked posts no field at all.
+    @Sendable
+    func setEvents(
+        request: Request,
+        context: Context
+    ) async throws -> Response {
+        guard let (user, _) = await account(of: request) else {
+            return .redirect(to: .Route.signIn, type: .normal)
+        }
+
+        let body = try await request.body.collect(upTo: 16 * 1_024)
+        let slugs = SearchParameters(query: String(buffer: body)).items
+            .filter { $0.name == "events" }
+            .map(\.value)
+
+        try await collecting?.setEvents(slugs, forShopOwnedBy: user)
+
+        return .redirect(to: .Route.sellerDashboard, type: .normal)
+    }
+
     /// Handles a request for the seller dashboard; an account without a shop is led to where one is opened.
     @Sendable
     func dashboard(
@@ -446,6 +473,7 @@ private extension TradeController {
         let offers = try await trade.openOffers(for: user)
         let sales = try await trade.sales(for: user).filter { $0.seller.id == user.id }
         let listings = try await catalogue.listings(matching: .init(shop: shop.slug))
+        let events = try await collecting?.upcomingEvents() ?? []
 
         return HTMLResponse(additionalHeaders: .perViewer) { [analytics, assetVersion] in
             SellerDashboardPage(
@@ -453,6 +481,7 @@ private extension TradeController {
                 offers: offers,
                 sales: sales,
                 listings: listings,
+                events: events,
                 viewer: viewer,
                 assetVersion: assetVersion,
                 analytics: analytics