dtmt/crates/dtmm/assets/mod_main.lua

local _G = _G
local rawget = rawget
local rawset = rawset

local log = function(category, format, ...)
    local Log = rawget(_G, "Log")
    if Log then
        Log.info(category, format, ...)
    else
        print(string.format("[%s] %s", category or "", string.format(format or "", ...)))
    end
end

log("mod_main", "Initializing mods...")

local require_store = {}

-- This token is treated as a string template and filled by DTMM during deployment.
-- This allows hiding unsafe I/O functions behind a setting.
-- It's also a valid table definition, thereby degrading gracefully when not replaced.
local is_io_enabled = {{ is_io_enabled }} -- luacheck: ignore 113
local lua_libs = {
    debug = debug,
    os = {
        date = os.date,
        time = os.time,
        clock = os.clock,
        getenv = os.getenv,
        difftime = os.difftime,
    },
    load = load,
    loadfile = loadfile,
    loadstring = loadstring,
}

if is_io_enabled then
    lua_libs.io = io
    lua_libs.os = os
    lua_libs.ffi = require("ffi")
end

Mods = {
    -- Keep a backup of certain system libraries before
    -- Fatshark's code scrubs them.
    -- The loader can then decide to pass them on to mods, or ignore them
    lua = setmetatable({}, { __index = lua_libs }),
    require_store = require_store,
    original_require = require,
}

local can_insert = function(filepath, new_result)
    local store = require_store[filepath]
    if not store or #store then
        return true
    end

    if store[#store] ~= new_result then
        return true
    end
end

local original_require = require
require = function(filepath, ...)
    local result = original_require(filepath, ...)
    if result and type(result) == "table" then
        if can_insert(filepath, result) then
            require_store[filepath] = require_store[filepath] or {}
            local store = require_store[filepath]

            table.insert(store, result)

            if Mods.hook then
                Mods.hook.enable_by_file(filepath, #store)
            end
        end
    end

    return result
end

require("scripts/boot_init")
require("scripts/foundation/utilities/class")

-- The `__index` metamethod maps a proper identifier `CLASS.MyClassName` to the
-- stringified version of the key: `"MyClassName"`.
-- This allows using LuaCheck for the stringified class names in hook parameters.
_G.CLASS = setmetatable({}, {
    __index = function(_, key)
        return key
    end
})

local original_class = class
class = function(class_name, super_name, ...)
    local result = original_class(class_name, super_name, ...)
    if not rawget(_G, class_name) then
        rawset(_G, class_name, result)
    end
    if not rawget(_G.CLASS, class_name) then
        rawset(_G.CLASS, class_name, result)
    end
    return result
end

require("scripts/main")
log("mod_main", "'scripts/main' loaded")

-- Inject our state into the game. The state needs to run after `StateGame._init_managers`,
-- since some parts of DMF, and presumably other mods, depend on some of those managers to exist.
local function patch_mod_loading_state()
    local StateBootSubStateBase = require("scripts/game_states/boot/state_boot_sub_state_base")
    local StateBootLoadDML = class("StateBootLoadDML", "StateBootSubStateBase")
    local StateGameLoadMods = class("StateGameLoadMods")

    StateBootLoadDML.on_enter = function(self, parent, params)
        log("StateBootLoadDML", "Entered")
        StateBootLoadDML.super.on_enter(self, parent, params)

        local state_params = self:_state_params()
        local package_manager = state_params.package_manager

        self._package_manager = package_manager
        self._package_handles = {
            ["packages/mods"] = package_manager:load("packages/mods", "StateBootDML", nil),
            ["packages/dml"] = package_manager:load("packages/dml", "StateBootDML", nil),
        }
    end

    StateBootLoadDML._state_update = function(self, dt)
        local package_manager = self._package_manager

        if package_manager:update() then
            local DML = require("scripts/mods/dml/init")
            local mod_data = require("scripts/mods/mod_data")
            local mod_loader = DML.create_loader(mod_data)
            Managers.mod = mod_loader
            log("StateBootLoadDML", "DML loaded, exiting")
            return true, false
        end

        return false, false
    end


    function StateGameLoadMods:on_enter(_, params)
        log("StateGameLoadMods", "Entered")
        self._next_state = require("scripts/game_states/game/state_splash")
        self._next_state_params = params
    end

    function StateGameLoadMods:update(main_dt)
        local state = self._loading_state

        -- We're relying on the fact that DML internally makes sure
        -- that `Managers.mod:update()` is being called appropriately.
        -- The implementation as of this writing is to hook `StateGame.update`.
        if Managers.mod:all_mods_loaded() then
            Log.info("StateGameLoadMods", "Mods loaded, exiting")
            return self._next_state, self._next_state_params
        end
    end

    local GameStateMachine = require("scripts/foundation/utilities/game_state_machine")
    local GameStateMachine_init = GameStateMachine.init
    GameStateMachine.init = function(self, parent, start_state, params, creation_context, state_change_callbacks, name)
        if name == "Main" then
            log("mod_main", "Injecting StateBootLoadDML")

            -- Hardcoded position after `StateRequireScripts`.
            -- We need to wait until then to even begin most of our stuff,
            -- so that most of the game's core systems are at least loaded and can be hooked,
            -- even if they aren't running, yet.
            local pos = 4
            table.insert(params.states, pos, {
                StateBootLoadDML,
                {
                    package_manager = params.package_manager,
                },
            })

            GameStateMachine_init(self, parent, start_state, params, creation_context, state_change_callbacks, name)
        elseif name == "Game" then
            log("mod_main", "Injection StateGameLoadMods")
            -- The second time around, we want to be the first, so we pass our own
            -- 'start_state'.
            -- We can't just have the state machine be initialized and then change its `_next_state`, as by the end of
            -- `init`, a bunch of stuff will already be initialized.
            GameStateMachine_init(self, parent, StateGameLoadMods, params, creation_context, state_change_callbacks, name)
            -- And since we're done now, we can revert the function to its original
            GameStateMachine.init = GameStateMachine_init

            return
        else
            -- In all other cases, simply call the original
            GameStateMachine_init(self, parent, start_state, params, creation_context, state_change_callbacks, name)
        end
    end
end

-- Override `init` to run our injection
function init()
    patch_mod_loading_state()

    -- As requested by Fatshark
    local StateRequireScripts = require("scripts/game_states/boot/state_require_scripts")
    StateRequireScripts._get_is_modded = function() return true end

    Main:init()
end