RedMew/features/train_saviour.lua

local Event = require 'utils.event'
local market_items = require 'resources.market_items'
local Global = require 'utils.global'
local DonatorPerks = require 'resources.donator_perks'
local Donator = require 'features.donator'
local train_perk_flag = DonatorPerks.train

local saviour_token_name = 'small-plane' -- item name for what saves players
local saviour_timeout = 180 -- number of ticks players are train immune after getting hit (roughly)

table.insert(market_items, 3, {
    price = 100,
    name = saviour_token_name,
    name_label = 'Train Immunity (1x use)',
    description = 'Each ' .. saviour_token_name .. ' in your inventory will save you from being killed by a train once.',
})

local remove_stack = {name = saviour_token_name, count = 1}
local saved_players = {}

Global.register(saved_players, function(tbl)
    saved_players = tbl
end)

local train_names = {
    ['locomotive'] = true,
    ['cargo-wagon'] = true,
    ['fluid-wagon'] = true,
    ['artillery-wagon'] = true
}

local function save_player(player)
    player.character.health = 1

    local pos = player.surface.find_non_colliding_position('player', player.position, 100, 2)
    if not pos then
        return
    end

    player.teleport(pos, player.surface)
end

local function on_pre_death(event)
    local cause = event.cause
    if not cause or not cause.valid then
        return
    end

    if not train_names[cause.name] then
        return
    end

    local player_index = event.player_index
    local player = game.get_player(player_index)
    if not player or not player.valid then
        return
    end

    local tick = saved_players[player_index]
    local game_tick = game.tick
    if tick and game_tick - tick <= saviour_timeout then
        save_player(player)
        return
    end

    local player_name = player.name

    if Donator.player_has_donator_perk(player_name, train_perk_flag) then
        saved_players[player_index] = game_tick
        save_player(player)

        game.print(player_name .. ' has been saved from a train death as a perk of donating to the server.')

        return
    end

    local saviour_tokens = player.get_item_count(saviour_token_name)
    if saviour_tokens < 1 then
        return
    end

    player.remove_item(remove_stack)
    saved_players[player_index] = game_tick
    save_player(player)
    game.print(player_name .. ' has been saved from a train death. One of their Train Immunity items has been consumed.')
end

Event.add(defines.events.on_pre_player_died, on_pre_death)