Only log a rocket as fired when its ammo count drops

Factorio has no fired event, so the log was written on every ammo
inventory change, which includes loading rockets for the first time and
swapping between rocket types. The last seen name and count of each ammo
slot is now kept per player, and a shot is only logged when a slot holds
the same ammo with one fewer, or empties from a single round. Only the
three configured ammo types are logged, rather than every ammo change.

Fixes #242

exp_scenario/module/control/deconstruction_log.lua

@@ -3,6 +3,7 @@ Log certain actions into a file when events are triggered
 ]]
 
 local ExpUtil = require("modules/exp_util")
+local Storage = require("modules/exp_util/storage")
 local Roles = require("modules/exp_roles")
 local config = require("modules.exp_legacy.config.deconlog")
 
@@ -130,29 +131,63 @@ local function on_player_mined_entity(event)
     add_log_line(player, "mined_entity", format_entity(event.entity))
 end
 
---- Log when rocket is fired
+--- Ammo which is logged when fired
+local logged_ammo = {
+    ["rocket"] = config.fired_rocket,
+    ["explosive-rocket"] = config.fired_explosive_rocket,
+    ["atomic-bomb"] = config.fired_nuke,
+}
+
+--- @class ExpScenario_DeconstructionLog.AmmoSlot
+--- @field name string
+--- @field count number
+
+--- The last seen contents of each ammo slot, keyed by player index then slot index
+local ammo_slots = {} --- @type table<uint, table<uint, ExpScenario_DeconstructionLog.AmmoSlot>>
+Storage.register(ammo_slots, function(tbl)
+    ammo_slots = tbl
+end)
+
+--- Log a shot, there is no fired event so a slot losing one of the same ammo is taken as a shot
 --- @param event EventData.on_player_ammo_inventory_changed
 local function on_player_ammo_inventory_changed(event)
     local player = get_log_player(event)
     if not player or not player.character then return end
 
+    local slots = ammo_slots[player.index]
+    if not slots then
+        slots = {}
+        ammo_slots[player.index] = slots
+    end
+
     local character_ammo = assert(player.get_inventory(defines.inventory.character_ammo))
-    local gun_index = player.character.selected_gun_index --[[@as uint]]
-    local item = character_ammo[gun_index]
-    if not item or not item.valid or not item.valid_for_read then
-        return
+    for index = 1, #character_ammo do
+        local stack = character_ammo[index --[[@as uint]]]
+        local previous = slots[index]
+        local fired = nil --- @type string?
+
+        if stack.valid_for_read then
+            if previous and previous.name == stack.name and previous.count == stack.count + 1 then
+                fired = stack.name
+            end
+            slots[index] = { name = stack.name, count = stack.count }
+        else
+            if previous and previous.count == 1 then
+                fired = previous.name
+            end
+            slots[index] = nil
         end
 
-    local action_name = "shot-" .. item.name
-    if not config.fired_rocket and action_name == "shot-rocket" then
-        return
-    elseif not config.fired_explosive_rocket and action_name == "shot-explosive-rocket" then
-        return
-    elseif not config.fired_nuke and action_name == "shot-atomic-bomb" then
-        return
+        if fired and logged_ammo[fired] then
+            add_log_line(player, "shot-" .. fired, format_position(player.physical_position), format_position(player.shooting_state.position))
+        end
+    end
 end
 
-    add_log_line(player, action_name, format_position(player.physical_position), format_position(player.shooting_state.position))
+--- Forget the ammo of a player who left, their slots are read again on the next change
+--- @param event EventData.on_player_left_game
+local function on_player_left_game(event)
+    ammo_slots[event.player_index] = nil
 end
 
 
@@ -175,6 +210,7 @@ end
 
 if config.fired_rocket or config.fired_explosive_rocket or config.fired_nuke then
     events[e.on_player_ammo_inventory_changed] = on_player_ammo_inventory_changed
+    events[e.on_player_left_game] = on_player_left_game
 end
 
 return {