Sort trades in vaguely-recent order

This logic is copied from DTI 2020! Though I didn't include the part
where we highlight trade matches yet!

app/helpers/item_trades_helper.rb

@@ -1,2 +1,26 @@
 module ItemTradesHelper
+	def vague_trade_timestamp(last_trade_activity_at)
+		if last_trade_activity_at >= 1.week.ago
+			translate "item_trades.index.table.last_active.this_week"
+		else
+			last_trade_activity_at.strftime("%b %Y")
+		end
+	end
+
+	def sorted_vaguely_by_trade_activity(trades)
+		# First, sort the list in ascending order.
+		trades_ascending = trades.sort_by do |trade|
+			if trade.user.last_trade_activity_at >= 1.week.ago
+				# Sort recent trades in a random order, but still collectively as the
+				# most recent. (This discourages spamming updates to game the system!)
+				[1, rand]
+			else
+				# Sort older trades by last trade activity.
+				[0, trade.user.last_trade_activity_at]
+			end
+		end
+
+		# Then, reverse it!
+		trades_ascending.reverse!
+	end
 end

app/views/item_trades/index.html.haml

@@ -13,13 +13,10 @@
 				%th= t(".table.headings.user.#{@type}")
 				%th= t(".table.headings.lists")
 		%tbody
-			- @trades.each do |trade|
+			- sorted_vaguely_by_trade_activity(@trades).each do |trade|
 				%tr
 					%td
-						-# TODO: Replace this with the coarse-grained version from 2020,
-						-# and translate it!
-						= time_ago_in_words trade.user.last_trade_activity_at
-						ago
+						= vague_trade_timestamp trade.user.last_trade_activity_at
 					%td= trade.user.name
 					%td
 						- if trade.lists.present?

config/locales/en.yml

@@ -381,6 +381,8 @@ en:
             offering: Owner
             seeking: Seeker
           lists: Lists
+        last_active:
+          this_week: This week
         not_in_a_list: Not in a list
       no_trades_yet:
         No trades yet! To add your name to this page, add this item to one of