add trade validation to prevent accepting invalid trades and update UI accordingly

supabase/migrations/20250127000001_add_trade_validation.sql

@@ -0,0 +1,101 @@
+-- Add is_valid column to trades table
+ALTER TABLE public.trades
+ADD COLUMN IF NOT EXISTS is_valid BOOLEAN DEFAULT true;
+
+-- Create index for filtering by validity
+CREATE INDEX IF NOT EXISTS idx_trades_is_valid ON public.trades(is_valid);
+
+-- Function to validate if a trade can still be executed based on current collections
+CREATE OR REPLACE FUNCTION public.validate_trade(p_trade_id uuid)
+RETURNS boolean
+LANGUAGE plpgsql
+SECURITY DEFINER
+AS $$
+DECLARE
+  v_item RECORD;
+  v_collection_quantity integer;
+BEGIN
+  -- Check each item in the trade
+  FOR v_item IN
+    SELECT owner_id, card_id, quantity
+    FROM public.trade_items
+    WHERE trade_id = p_trade_id
+  LOOP
+    -- Get the quantity of this card in the owner's collection
+    SELECT COALESCE(quantity, 0) INTO v_collection_quantity
+    FROM public.collections
+    WHERE user_id = v_item.owner_id
+    AND card_id = v_item.card_id;
+
+    -- If owner doesn't have enough of this card, trade is invalid
+    IF v_collection_quantity < v_item.quantity THEN
+      RETURN false;
+    END IF;
+  END LOOP;
+
+  -- All items are available, trade is valid
+  RETURN true;
+END;
+$$;
+
+-- Function to check and update validity of affected trades when collections change
+CREATE OR REPLACE FUNCTION public.update_affected_trades_validity()
+RETURNS TRIGGER
+LANGUAGE plpgsql
+SECURITY DEFINER
+AS $$
+DECLARE
+  v_user_id uuid;
+  v_card_id text;
+  v_trade RECORD;
+  v_is_valid boolean;
+BEGIN
+  -- Get the user_id and card_id from the changed row
+  IF (TG_OP = 'DELETE') THEN
+    v_user_id := OLD.user_id;
+    v_card_id := OLD.card_id;
+  ELSE
+    v_user_id := NEW.user_id;
+    v_card_id := NEW.card_id;
+  END IF;
+
+  -- Find all pending trades that involve this card from this user
+  FOR v_trade IN
+    SELECT DISTINCT t.id
+    FROM public.trades t
+    JOIN public.trade_items ti ON ti.trade_id = t.id
+    WHERE t.status = 'pending'
+    AND ti.owner_id = v_user_id
+    AND ti.card_id = v_card_id
+  LOOP
+    -- Validate the trade
+    v_is_valid := public.validate_trade(v_trade.id);
+
+    -- Update the trade's validity
+    UPDATE public.trades
+    SET is_valid = v_is_valid,
+        updated_at = now()
+    WHERE id = v_trade.id;
+  END LOOP;
+
+  IF (TG_OP = 'DELETE') THEN
+    RETURN OLD;
+  ELSE
+    RETURN NEW;
+  END IF;
+END;
+$$;
+
+-- Create trigger to auto-update trade validity when collections change
+CREATE TRIGGER update_trades_on_collection_change
+AFTER UPDATE OR DELETE ON public.collections
+FOR EACH ROW
+EXECUTE FUNCTION public.update_affected_trades_validity();
+
+-- Add comment
+COMMENT ON COLUMN public.trades.is_valid IS 'Indicates if the trade can still be executed based on current collections. Auto-updated when collections change.';
+
+-- Initial validation: set is_valid for all existing pending trades
+UPDATE public.trades
+SET is_valid = public.validate_trade(id)
+WHERE status = 'pending';