Add hud_events mod (#825)

* Add hud_events

Reuses the HUD API provided by hud_scores

* Fix luacheck

mods/other/hud_events/README.md

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+# `hud_events`
+
+Forked and edited from `hud_score` by ANAND (ClobberXD), licensed under the LGPLv2.1+ license.  
+
+`hud_events` provides an API to display HUD event elements which can be used to
+display various hints and messages.
+
+## Methods
+
+- `hud_event.new(name, event_def)`: Adds a new HUD event element to player `name`.
+  - `name` [string]: Player name
+  - `event_def` [table]: HUD event element definition. See below.
+
+## HUD event element definition
+
+HUD event element definition table, passed to `hud_event.new`.
+
+Example definition:
+
+```lua
+{
+    name  = "ctf_bandages:healing", -- Can be any arbitrary string
+    color = "0x00FF00",             -- Should be compatible with Minetest's HUD def
+    value = "x has healed y",                     -- The actual event to be displayed
+    -- Field `time` is automatically added by `hud_event.new`
+    -- to keep track of element expiry
+}
+```
+
+## `players` table
+
+This is a table of tables, indexed by player names. This table holds the HUD
+data of all online players. Each sub-table is a list of HUD event elements,
+which are added by `hud_event.new`.
+
+```lua
+local players = {
+    ["name"] = {
+        [1] = <hud_event_element>,
+        [2] = <hud_event_element>,
+        [3] = <hud_event_element>
+        ...
+    },
+    ["name2"] = {
+        ...
+    },
+    ...
+}
+```
+
+## Changes
+
+Changes that have been made compared to the original `hud_score` mod. Lines mentioned underneath refer to the lines in the `hud_events`' init.lua file.  
+- replaced all occurences of `score` with `event` (10th March 2021)
+- changed variables and arguments in the lines 5, 6 and 36 (10th march 2021)
+- edited and added arguments in line 39 and 40 (10th march 2021)
+- deleted an `if` statement after line 28 (10th march 2021)

mods/other/hud_events/init.lua

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+hud_event = {}
+local hud = hudkit()
+
+local players = {}
+local duration = 7
+local max = 3
+local next_check = 10000000
+
+local function update(name)
+	local player = minetest.get_player_by_name(name)
+	if not player then
+		return
+	end
+
+	-- Handle all elements marked for deletion
+	-- and rebuild table
+	local temp = {}
+	for _, def in ipairs(players[name]) do
+		if def.delete then
+			if hud:exists(player, def.name) then
+				hud:remove(player, def.name)
+			end
+		else
+			table.insert(temp, def)
+		end
+	end
+
+	for i, def in ipairs(temp) do
+		local text = tostring(def.value)
+		if hud:exists(player, def.name) then
+			hud:change(player, def.name, "text", text)
+			hud:change(player, def.name, "offset", {x = 0, y = i * 20})
+		else
+			hud:add(player, def.name, {
+				hud_elem_type = "text",
+				alignment = {x = 0, y = 0},
+				position = {x = 0.5, y = 0.7},
+				offset = {x = 0, y = i * 20},
+				number = tonumber(def.color),
+				text = text,
+				z_index = -200
+			})
+		end
+	end
+	players[name] = temp
+end
+
+function hud_event.new(name, def)
+	-- Verify HUD event element def
+	if not name or not def or type(def) ~= "table" or
+			not def.name or not def.value or not def.color then
+		error("hud_event: Invalid HUD event element definition", 2)
+	end
+
+	local player = minetest.get_player_by_name(name)
+	if not player then
+		return
+	end
+
+	-- Store element expiration time in def.time
+	-- and append event element def to players[name]
+	def.time = os.time() + duration
+	if next_check > duration then
+		next_check = duration
+	end
+
+	-- If a HUD event element with the same name exists already,
+	-- reuse it instead of creating a new element
+	local is_new = true
+	for i, hud_event_spec in ipairs(players[name]) do
+		if hud_event_spec.name == def.name then
+			is_new = false
+			players[name][i] = def
+			break
+		end
+	end
+
+	if is_new then
+		table.insert(players[name], def)
+	end
+
+	-- If more than `max` active elements, mark oldest element for deletion
+	if #players[name] > max then
+		players[name][1].delete = true
+	end
+
+	update(name)
+end
+
+minetest.register_globalstep(function(dtime)
+	next_check = next_check - dtime
+	if next_check > 0 then
+		return
+	end
+
+	next_check = 10000000
+
+	-- Loop through HUD score elements of all players
+	-- and remove them if they've expired
+	for name, hudset in pairs(players) do
+		local modified = false
+		for i, def in pairs(hudset) do
+			local rem = def.time - os.time()
+			if rem <= 0 then
+				def.delete = true
+				modified = true
+			elseif rem < next_check then
+				next_check = rem
+			end
+		end
+
+		-- If a player's hudset was modified, update player's HUD
+		if modified then
+			update(name)
+		end
+	end
+end)
+
+minetest.register_on_joinplayer(function(player)
+	players[player:get_player_name()] = {}
+end)
+
+minetest.register_on_leaveplayer(function(player)
+	players[player:get_player_name()] = nil
+end)

mods/other/hud_events/mod.conf

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+name = hud_events
+description = API for displaying events on HUD
+depends = hudkit