Backport WC2 fixes

This fixes:
- "Destruction mechanic line 73 bug"
- [traits] in artifacts not working
- custom effects being lost in next scenario
- artifacts reduce HP
- Promoted commander have the wrong id

The fixed are not exactly pretty, in particular the one that uses a
preload event to workaround and engine bug.

Since we are already replacing artifacts.give_item We could in theory
also explicitly fix certain Items here, should we really need to.

data/campaigns/World_Conquest/config.cfg

@@ -13,3 +13,24 @@
 #enddef
 #endif
 #endif
+
+#define WC_REPLACE_FILE FILE ORIG_FILE VARIABLE
+    [lua]
+        code = <<
+		local args = ...
+		args.orig_file_name = filesystem.canonical_path(args.orig_file_name)
+		if wesnoth.package[args.orig_file_name] == nil then
+			local result = load(args.file_content)()
+			wesnoth.package[args.orig_file_name] = result
+		end
+		if args.variable and args.variable ~= "" then
+			_G[args.variable] = wesnoth.package[args.orig_file_name]
+		end
+	>>
+        [args]
+            file_content = {{FILE}}
+            orig_file_name = {ORIG_FILE}
+            variable = {VARIABLE}
+        [/args]
+    [/lua]
+#enddef

data/campaigns/World_Conquest/era/era.cfg

@@ -36,6 +36,7 @@
     ## this is needed in both the era and the campaign, in particular in the campaign this data is used to generate the deserters and the ai sides.
     [resource]
         id = "wc2_era_res"
+        {WC_REPLACE_FILE campaigns/World_Conquest/lua/shared_utils/wml_converter_updated.lua campaigns/World_Conquest/lua/shared_utils/wml_converter.lua wc2_convert}
         [lua]
             code = " wesnoth.dofile('campaigns/World_Conquest//lua/era_main.lua') "
         [/lua]

data/campaigns/World_Conquest/lua/game_mechanics/artifacts_updated.lua

@@ -0,0 +1,262 @@
+--<<
+print("artifacts_updated loaded")
+
+local on_event = wesnoth.require("on_event")
+local helper = wesnoth.require("helper")
+
+local _ = wesnoth.textdomain 'wesnoth-wc'
+
+local artifacts = {}
+artifacts.list = {}
+
+function artifacts.add_artifact_data(a)
+	table.insert(artifacts.list, a)
+end
+
+function artifacts.read_wml_data(cfg)
+	for i, artifact in ipairs(wc2_convert.wml_to_lon(wml.literal(cfg), "wct_artifact_list").artifact or {}) do
+		artifacts.add_artifact_data(artifact)
+	end
+end
+
+function artifacts.init_data()
+	local cfg = wc2_utils.get_wc2_data("artifact")
+	for i, a in ipairs(wc2_convert.wml_to_lon(cfg, "wct_artifact_list").artifact or {}) do
+		artifacts.add_artifact_data(a)
+	end
+end
+
+
+function artifacts.get_artifact(id)
+	return artifacts.list[id]
+end
+
+function artifacts.get_artifact_list()
+	return artifacts.list
+end
+
+
+function artifacts.drop_message(index)
+	local aftifact_data = artifacts.get_artifact(index)
+	wesnoth.wml_actions.message {
+		speaker = "narrator",
+		caption = aftifact_data.name,
+		message = aftifact_data.info .. "\n" .. wc2_color.bonus_text(aftifact_data.description),
+		image = aftifact_data.icon,
+	}
+end
+
+function wc2_artifact_needs_compensation(side)
+	return not wc2_scenario.is_human_side(side.side)
+end
+
+
+-- place an artifact with id @a index on the map at position @a x, y.
+-- can be used from the bug console as `lua wc2_artifacts.place_item(30,20,1)`
+function artifacts.place_item(x, y, index)
+	wesnoth.wml_actions.item {
+		x = x,
+		y = y,
+		image = artifacts.get_artifact(index).icon,
+		z_order = 20,
+		wml.tag.variables { wc2_atrifact_id = index },
+	}
+end
+
+-- give te item with id @a index to unit @a unit, set @a visualize=true, to show the item pickup animation.
+function artifacts.give_item(unit, index, visualize)
+	local aftifact_data = artifacts.get_artifact(index)
+	if visualize then
+		-- play visual/sound effects if item have any
+		wesnoth.wml_actions.sound {
+			name = aftifact_data.sound or ""
+		}
+		if unit.gender == "male" then
+			wesnoth.wml_actions.sound {
+				name = aftifact_data.sound_male or ""
+			}
+		else
+			wesnoth.wml_actions.sound {
+				name = aftifact_data.sound_female or ""
+			}
+		end
+		for i, animate_unit in ipairs(aftifact_data.animate_unit) do
+			wesnoth.wml_actions.animate_unit(animate_unit)
+		end
+	end
+	local make_holder_loyal = wml.variables["wc2_config_items_make_loyal"] ~= false
+	-- is_commander or is_hero imples unit.upkeep == "loyal"
+	-- note that the following `unit.upkeep` does not match normal
+	-- level 0 (which have still 'full' upkeep) only units with upkeep=0 explicitly set
+	if make_holder_loyal and (not unit.canrecruit) and (unit.upkeep ~= 0) and (unit.upkeep ~= "loyal") then
+		unit:add_modification("object", { wml.tag.effect { apply_to = "wc2_overlay", add = "misc/loyal-icon.png" }})
+	end
+
+	local object = {
+		wc2_atrifact_id = index,
+		-- cannot filter on wc2_artifact_id being empty so we also need wc2_is_artifact
+		wc2_is_artifact = true,
+	}
+	if make_holder_loyal then
+		table.insert(object, wml.tag.effect { apply_to= "loyal" })
+	end
+
+
+	-- IDEA: i _could_ replace the follwing with a 'apply_to=wc2_artifact' effect that
+	--       basicially applies all effects in the [artifact]s definition. The obvious
+	--       advantage would be a smaller savefile size. Also this would change how savefiles
+	--       would behave if an artifacts effect has changed, i am currently not sure
+	--       whether that'd be good or bad
+	--
+	--       One of the reasons why i currently won't do this is to make the artifacts list
+	--       more flexible: the suggested approach requires that artifacts are loaded before
+	--       units are created which means artifacts must be loaded at toplevel [lua] tags
+	for i, effect in ipairs(aftifact_data.effect) do
+		table.insert(object, wml.tag.effect (effect) )
+	end
+	for i, trait in ipairs(aftifact_data.trait) do
+		if not unit:matches { wml.tag.filter_wml { wml.tag.modifications { wml.tag.trait { id = trait.id } } } } then
+			unit:add_modification("trait", trait)
+		end
+	end
+	unit:add_modification("object", object)
+	local unit_initial_hp = unit.hitpoints
+	--rebuild unit, to reduce savefile size.
+	unit:transform(unit.type)
+	-- restore unit hitpoints to before they picked up the artifact
+	unit.hitpoints = unit_initial_hp
+	-- the artifact might reduce the max xp.
+	unit:advance(true, true)
+end
+
+-- unit picking up artifacts
+on_event("wc2_drop_pickup", function(ec)
+	local item = wc2_dropping.current_item
+	local unit = wesnoth.units.get(ec.x1, ec.y1)
+	if not item.variables.wc2_atrifact_id then
+		return
+	end
+
+	if not unit then 
+		return
+	end
+
+	local side_num = unit.side
+	local is_human = wc2_scenario.is_human_side(side_num)
+	if not wml.variables["wc2_config_experimental_pickup"] and not is_human  then
+		return
+	end
+
+
+	local index = item.variables.wc2_atrifact_id
+	local filter = artifacts.get_artifact(index).filter
+	if filter and not unit:matches(filter) then
+		if is_human then
+			wesnoth.wml_actions.message {
+				id = unit.id,
+				message = _"I cannot pick up that item.",
+			}
+		end
+		return
+	end
+
+	if is_human and not wml.variables["wc2_config_disable_pickup_confirm"] then
+		if not wc2_pickup_confirmation_dialog.promt_synced(unit, artifacts.get_artifact(index).icon) then
+			return
+		end
+	end
+
+
+	wc2_dropping.item_taken = true
+	artifacts.give_item(unit, index, true)
+	wesnoth.allow_undo(false)
+end)
+
+-- returns a list of artifact ids, suitable for  the give type ('enemy' for example).
+function artifacts.fresh_artifacts_list(for_type)
+	local res = {} 
+	for i,v in ipairs(artifacts.get_artifact_list()) do
+		if not for_type or not stringx.map_split(v.not_available or "")[for_type] then
+			table.insert(res, i)
+		end
+	end
+	return res
+end
+
+
+-- drop all items a dying unit carries.
+on_event("die", function(event_context)
+	local unit = wesnoth.units.get(event_context.x1, event_context.y1)
+	if not unit then
+		return
+	end
+	if not wml.variables["wc2_config_experimental_pickup"] and wc2_scenario.is_human_side(unit.side) then
+		return
+	end
+	for object in wml.child_range(wml.get_child(unit.__cfg, "modifications") or {}, "object") do
+		if object.wc2_atrifact_id then
+			artifacts.place_item(unit.x, unit.y, object.wc2_atrifact_id)
+			artifacts.drop_message(object.wc2_atrifact_id)
+			wesnoth.allow_undo(false)
+		end
+	end
+
+	-- remove the item from the unit, just in case the unit is somehow brought back to life by another addons code. (for example 'besieged druid' can do such a thing)
+	unit:remove_modifications { wc2_is_artifact = true }
+end)
+
+-- returns true if there is an item in the map at the given position,
+-- used to determine whether to show the artifact info menu at that position. 
+function artifacts.is_item_at(x,y)
+	for i,item in ipairs(wesnoth.interface.get_items(x,y)) do
+		if item.variables.wc2_atrifact_id then
+			return true
+		end
+	end
+	return false
+end
+
+-- shows an information [message] about the item laying at position 
+-- @a cfg.x, cfg.y
+function wesnoth.wml_actions.wc2_show_item_info(cfg)
+	local x = cfg.x
+	local y = cfg.y
+	for i,item in ipairs(wesnoth.interface.get_items(x,y)) do
+		if item.variables.wc2_atrifact_id then
+			local artifact_info = artifacts.get_artifact(item.variables.wc2_atrifact_id)
+			wesnoth.wml_actions.message {
+				scroll = false,
+				image = artifact_info.icon,
+				caption = artifact_info.name,
+				message= artifact_info.info .. "\n" .. wc2_color.help_text(artifact_info.description),
+			}
+		end
+	end
+end
+
+wc2_utils.menu_item {
+	id="4_WCT_Item_Info_Option",
+	description = _ "Remind me what this item does",
+	image = "icons/terrain/terrain_type_info.png",
+	synced = false,
+	filter = artifacts.is_item_at,
+	handler = function(cx)
+		wesnoth.wml_actions.wc2_show_item_info {
+			x = cx.x1,
+			y = cx.y1,
+		}
+	end
+}
+
+function wesnoth.wml_actions.wc2_place_item(cfg)
+	artifacts.place_item(cfg.x, cfg.y, cfg.item_index)
+	if cfg.message then
+		artifacts.drop_message(cfg.item_index)
+	end
+end
+
+artifacts.init_data()
+
+return artifacts
+
+-->>