--[[

Copyright 2018 Chrisgbk
Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

]]
-- MIT License, https://opensource.org/licenses/MIT

-- Hotpatch-MultiMod: a tool to load multiple scenarios side-by-side, with support for both static loading and dynamic loading, as well as run-time patching

log('Hotpatch runtime initializing...')
local util = require 'util'

local debug_levels = {['disabled'] = -1, ['severe'] = 1, ['error'] = 2, ['warning'] = 3, ['info'] = 4, ['verbose'] = 5, ['trace'] = 6}

-- configuration options; these should be exposed via API one day
local debug_level = (tonumber(_ENV.debug_settings.level) or debug_levels[_ENV.debug_settings.level]) or 0
local debug_log_to_console_only = _ENV.debug_settings.log_to_console_only
local debug_log_to_RCON = _ENV.debug_settings.log_to_RCON --only affects when log_to_console_only is in effect
local debug_log_on_tick = _ENV.debug_settings.log_on_tick

local compat_mode = false -- enable some compatibility settings, which can help some mods load
local strict_mode = false -- causes hotpatch to hard-stop on mods doing bad things

-- convenience object(rcon.print also prints to stdout when called from server console)
local console = {name = 'Console', admin = true, print = function(...) rcon.print(...) end, color = {1,1,1,1}}

-- these represent the mods as statically packaged with the scenario
local static_mods = {}
--      static_mods[i] = {}
--      static_mods[i].name = ''
--      static_mods[i].version = ''
--      static_mods[i].code = ''
--      static_mods[i].files = {}

-- installed mods are represented with:
--      global.mods = {}
--      global.mods[i] = {}
--      global.mods[i].name = ''
--      global.mods[i].version = ''
--      global.mods[i].code = ''
--      global.mods[i].files = {}
--      global.mods[i].global = {}

-- loaded/running mods are represented with:
local loaded_mods = {} -- this holds a reference to the mods internal object
--      loaded_mods[i] = mod_obj_template

-- internal mod object:
local mod_obj_template = {
    name = '', -- name of the current mod
    version = '',
    env = {}, -- environment of the mod
    loaded = false,
    running = false,
    on_init = nil, -- called once after first install, or when specifically requested to be re-ran (good practice is to never request a re-run)
    on_load = nil, -- called every time the scenario loads from disk
    on_configuration_changed = nil, -- called every time the external mod configuration changes, OR when the hotpatch mod configuration changes
    on_tick = nil, -- cache the on-tick event handler, because it is ID 0, which causes it to be stored in the hash part, which causes a 50% increase in access time
    on_event = {}, -- list of on_event handlers registered
    on_nth_tick = {}, -- list of on_nth_tick handlers registered
    loaded_files = {}, -- list of files loaded by require() that were installed into the virtual file system
}

-- this is for the core factorio libraries; hotpatch MUST load these now, as they cannot be dynamically loaded due to factorio limitation
local loaded_libraries = {} 

-- mod installation/uninstallation support functions
-- These take a mod NAME as a first argument
local install_mod
local find_installed_mod
local install_mod_file
local uninstall_mod

-- mod interaction functions
-- These take a LOADED INDEX as a first argument, except load_mod, which takes an INSTALLED INDEX
local load_mod
local find_loaded_mod
local run_mod
local reset_mod
local reset_mod_events
local register_mod_events
local unload_mod

-- internal callbacks when a mod registers events
local register_event
local register_nth_tick
local register_on_tick

-- mod bootstrap functions
-- These take a LOADED INDEX as a first argument
local mod_on_init
local mod_on_load
local mod_on_configuration_changed

-- local event handler to proxy to mods, these call the mods events
local on_event
local on_nth_tick

-- core handlers
local on_init -- installs static mods, loads, runs, and calls mod_on_init
local on_load -- loads, runs, and calls mod_on_load
local on_configuration_changed -- calls mod_on_configuration_changed

-- this is dual-purpose, handles core needs and mod on_tick
local on_tick

-- this installs a new mod statically, only installed during on_init
-- Installed mod will still be updatable
local function static_mod(name, version, code, files)
    local mod = {}
    mod.name = name
    mod.version = version
    mod.code = code
    mod.files = {}
    if files then
        for k, v in pairs(files) do
            mod.files[k] = v
        end
    end
    table.insert(static_mods, mod)
end

-- mapping of events to names for logging
local event_names = {}
for k,v in pairs(defines.events) do
    event_names[v] = k
end

-- This scenario contains an embedded locale, but it's unavailable until this file finishes loading
-- ie: calls to log{...} will fail right now, but will work in events
-- Rseding91 fixed it for 0.17 (https://forums.factorio.com/viewtopic.php?f=23&t=60767)
-- I'll make it work myself in 0.16 ¯\_(ツ)_/¯
local static_cfg = [[
[hotpatch]
log=@__1__:__2__] __3__
log-mod=@__1__:__2__][__4__] __3__
severe=SEVERE ERROR: __1__
error=ERROR: __1__
warning=WARNING: __1__
info=INFO: __1__
verbose=INFO: __1__
trace=TRACE: __1__

[hotpatch-info]
logging-enabled=Logging enabled
metatable-installed=_ENV metatable installed
complete=__1__ Complete!
on-init=initializing...
on-load=loading...
on-configuration-changed=mod configuration changed...
installing-included-mods=installing included mods...
loading-installed-mods=loading installed mods...
loading-libs=loading Factorio.data.core.lualib...
loading-library=loading library: __1__
uninstalling=Uninstalling mod...
installing=Installing version __1__...
installing-file=Installing file __1__...
script-shim=setting up mod script shim...
setting-env=setting up mod _ENV...
loading=loading...
unloading=unloading...
running=running...
must-be-admin=You must be an admin to run this command
remote-installing=installing remote interface

[hotpatch-trace]
nil-var-access=_ENV nil variable access: __1__
nil-var-assignment=_ENV variable assignment: __1__
event-registering=registering events...
on-tick-event-registered=registered on_tick event...
on-event-registered=registered event __1__...
on-nth-tick-event-registered=registered nth_tick event __1__...
event-running=running event __1__...
nth-tick-event-running=running nth_event __1__...
mod-on-init=running on_init...
mod-on-load=running on_load...
mod-on-configuration-changed=running on_configuration_changed...
adding-event=adding event __1__
adding-nth-tick-event=adding nth_tick event __1__
caching-event=caching event: __1__...
caching-nth-tick-event=caching nth_tick event: __1__...
event-processing=processing event __1__...
nth-tick-event-processing=processing nth_tick event __1__...
nth-tick-handler-added=added nth_tick handler: __1__
nth-tick-handler-removed=removed nth_tick handler: __1__
on-tick-handler-added=added on_tick handler
on-tick-handler-removed=removed on_tick handler
on-event-handler-added=added event handler: __1__
on-event-handler-removed=removed event handler: __1__
cached-load-require=loading cached require'd file: __1__...
load-require=loading require'd file: __1__...
load-core-lib=loading from Factorio.data.core.lualib: __1__...

[hotpatch-warning]
contains-comments=mod code contains comments!
contains-comments-no-lf=mod contains comments and no linefeed!
contains-comments-console=comments from console will comment out the entire code!
reset-events-not-running=tried to reset events for mod that isn't running!
remote-interface-exists=remote interface __1__ already exists, removing...
command-exists=command __1__ already exists, removing...
already-loaded=mod already loaded
reinitializing=reinitializing...
already-exists=mod already exists
reinstalling=reinstalling mod in-place

[hotpatch-error]
invalid-API-access=Invalid API access: __1__
not-installed=mod not installed, cannot install file for mod that does not exist
compilation-failed=compilation failed for mod
execution-failed=execution failed for mod

[test-pluralization]
test=__1:(^1$)=singular;(^[2-9]$)=plural single digit;([1-2][0-9]$)=plural ends with double digit <30;(.*)=fallback case%; plural with embedded %;;__
]]

local function build_locale(ini)
    local t = {}
    local section = ''
    local temp
    
    -- line must end with a linefeed - single line file with no LF will fail
    if not ini:match('[\r\n]+$') then
        ini = ini .. '\n'
    end
    
    -- for each non-empty line do
    local key, value
    for l in ini:gmatch('[\r\n]*(.-)[\r\n]+') do
        -- header?
        temp = l:match('^%[(.-)%].*$')
        if temp then
            section = temp
            temp = nil
        else
            --key=value
            key, value = l:match('^(.-)=(.+)$')
            t[table.concat{section, '.', key}] = value
        end
    end
    return t
end

local static_locale = build_locale(static_cfg)

local function escape(s)
    return (s:gsub('([%^%$%(%)%%%.%[%]%*%+%-%?])', '%%%1'))
end

local function unescape(s)
    return (s:gsub('(%%)', ''))
end

local function static_translate(t, recursive)
    -- only translate tables
    if type(t) ~= 'table' then return t end
    -- only translate tables that have a string as the first item
    local k = t[1]
    if type(k) ~= 'string' then return t end
    
    -- make a copy, don't destroy the original table, after we copy we can translate in place
    if not recursive then
        t = table.deepcopy(t)
    end
    -- translate any arguments as well
    local v
    for i = 2, #t do
        v = t[i]
        if type(v) == 'table' then
            t[i] = static_translate(v, true)
        end
    end
    -- special case: whitespace token causes concatenation with that token
    -- slightly better than factorio, where only '' is supported
    if k:find('^%s*$') then table.remove(t, 1) return table.concat(t, k) end
    local pattern = static_locale[k]
    -- if not translatable return normal table ref; factorio does following instead:
    -- if not pattern then return 'Unknown key: ' .. k end
    -- by returning the table we pass off to factorio runtime translation, where available
    if not pattern then return t end
    -- substitution of parameters: use literal value of parameter n
    -- __n__
    local result = (pattern:gsub('__(%d+)__', function(s) return tostring(t[tonumber(s)+1]) end))
       
    -- re-substitution engine: match value of parameter n to provide additional translation; use for pluralization
    -- __n:(pattern-1)=substitution-1;(pattern-2)=substitution-2;...(pattern-i)=substitution-i;__
    for n, p in result:gmatch('__(%d+)(:.-;)__') do
        for x, y in p:gmatch('%((.-)%)=(.-[^%%]);') do
            if t[tonumber(n)+1]:match(x) then 
                result = result:gsub(table.concat{'__', n, escape(p), '__'}, unescape(y))
                break
            end
        end
    end

    return result
end

-- override print to make it support our translation efforts
-- still doesn't support Factorio locales, because devs don't patch it like I do
-- this means unknown keys will be printed as 'table: 0x...'
local real_print = print
local print = function(...)
    if select('#', ...) == 1 then
        real_print(static_translate(...))
    else
        local t = table.pack(...)
        table.insert(t, 1, '\t')
        real_print(static_translate(t))
    end
end

-- override log to make it support our translation efforts
-- any unknown keys are passed to Factorio to translate

local hidden = load([===[
    local real_log = log; local static_translate = select(1, ...); local log = function(...); if select('#', ...) == 1 then real_log(static_translate(...)) else local t = table.pack(...); table.insert(t, 1, '\t'); real_log(static_translate(t)) end end return log
]===], '[HOTPATCH')
local hidden_log = hidden(static_translate)

-- logs localized data
local function debug_log(message, mod_name, stack_level)
    if debug_level > -1 then 
        if not stack_level then stack_level = 2 end
        local di = debug.getinfo(stack_level)
        local line = di.currentline
        local file = (di.source:gsub('%@.*/', ''))
        local class = 'hotpatch.info'
        local log_type = (mod_name and 'hotpatch.log-mod') or 'hotpatch.log'
        local severity
		if type(message) == 'table' then
            severity = message[1]:match('.-%-([^%-]*)%.')
            if not severity then
                severity = message[1]:match('.-%-.-%-(.*)%.')
                if not severity then
                    severity = 'always'
                end
            end
            class = table.concat{'hotpatch', '.', severity}
        else
            severity = 'always'
        end
		local level = ((severity == 'always') and 0) or debug_levels[severity]
        if debug_level >= level then
            if debug_log_to_console_only then
                if debug_log_to_RCON then
                    rcon.print{log_type, file, line, {class, message}, mod_name}
                end
                print{log_type, file, line, {class, message}, mod_name}

            else
                hidden_log{log_type, file, line, {class, message}, mod_name}
            end
        end
    end
end

debug_log({'hotpatch-info.logging-enabled'})

-- track _ENV accesses
setmetatable(_ENV, {
	__index = function(t, k)
		debug_log({'hotpatch-trace.nil-var-access', k}, nil, 3)
		return nil
	end,
	__newindex = function(t, k, v)
		debug_log({'hotpatch-trace.nil-var-assignment', k}, nil, 3)
		rawset(t,k,v)
	end,
	__metatable = false
})

debug_log({'hotpatch-info.metatable-installed'})

-- load all possible libraries
debug_log({'hotpatch-info.loading-libs'})

local libraries = {
    'camera',
    'flying_tags',
    'inspect',
    'math3d',
    'mod-gui',
    'noise',
    'production-score',
    'silo-script',
    'story',
    'util',
}

for k, v in pairs(libraries) do
    debug_log({'hotpatch-info.loading-library', v})
	loaded_libraries[k] = require(v)
end

debug_log({'hotpatch-info.complete', {'hotpatch-info.loading-libs'}})

find_installed_mod = function(mod_name)
    local mod
    local mods = global.mods
    for i = 1, #mods do
        mod = mods[i]
        if mod.name == mod_name then
            return i
        end
    end
    return nil
end

find_loaded_mod = function(mod_name)
    local mod
    for i = 1, #loaded_mods do
        mod = loaded_mods[i]
        if mod.name == mod_name then
            return i
        end
    end
    return nil
end

uninstall_mod = function(mod_name)
    local index = find_installed_mod(mod_name)
    if not index then
        -- TODO: notify that mod doesn't exist
        return
    end
    local loaded_index = find_loaded_mod(mod_name)
    
    if loaded_index then
        unload_mod(loaded_index)
    end
        

    debug_log({'hotpatch-info.uninstalling', mod_name})
    
    table.remove(global.mods, index)
end

install_mod_file = function(mod_name, mod_file, mod_file_code)
    local index = find_installed_mod(mod_name)
    if not index then
        debug_log({'hotpatch-error.not-installed'})
        return
    end
    local mod = global.mods[index]
    
    debug_log({'hotpatch-info.installing-file', mod_file}, mod_name)

    mod_file = mod_file:gsub('/', '.')
    mod_file = mod_file:gsub('\\', '.')
    mod_file_code = mod_file_code:gsub('\t', '  ')
    mod.files[mod_file] = mod_file_code
end

install_mod = function(mod_name, mod_version, mod_code, mod_files)
    local index = find_installed_mod(mod_name)
    local mod = {}
    if index then
        -- TODO: notify about installing over top of existing mod
        mod = global.mods[index]
    else
        --next free index
        table.insert(global.mods, mod)
    end
    debug_log({'hotpatch-info.installing', mod_version}, mod_name)
    if mod_code:find('--', 1, true) then

        debug_log({'hotpatch-warning.contains-comments'}, mod_name)
        if not mod_code:find("\n", 1, true) then
            debug_log({'hotpatch-warning.contains-comments-no-lf'}, mod_name)
        end
        debug_log({'hotpatch-warning.contains-comments-console'}, mod_name)
    end
    
    mod_code = mod_code:gsub('\t', '  ')

    mod.name = mod_name
    mod.files = mod.files or {}
    mod.code = mod_code
    mod.version = mod_version
    mod.global = mod.global or {}
    
    if mod_files then
        for k,v in pairs(mod_files) do
            install_mod_file(mod_name, k, v)
        end
    end
end

load_mod = function(installed_index)
    local mod = global.mods[installed_index]
    local mod_name = mod.name
    if mod.code then
        -- TODO: integrity check, verify each mods global table to detect guaranteed desync mods
        local loaded_index = find_loaded_mod(mod_name)
        if loaded_index then
            --TODO notify that mod was already loaded
            unload_mod(loaded_index)
        end
        
        local mod_obj = {
            name = mod_name, -- name of the current mod
            version = mod.version,
            env = {}, -- environment of the mod
            loaded = false,
            running = false,
            on_init = nil, -- called once after first install, or when specifically requested to be re-ran (good practice is to never request a re-run)
            on_load = nil, -- called every time the scenario loads from disk
            on_configuration_changed = nil, -- called every time the external mod configuration changes, OR when the hotpatch mod configuration changes
            on_tick = nil, -- cache the on-tick event handler, because it is ID 0, which causes it to be stored in the hash part, which causes a 50% increase in access time
            on_event = {}, -- list of on_event handlers registered
            on_nth_tick = {}, -- list of on_nth_tick handlers registered
            loaded_files = {}, -- list of files loaded by require() that were installed into the virtual file system
        }
        
        debug_log({'hotpatch-info.script-shim'}, mod_name)
        --mods private script table/shim
        local mod_script = {}

        mod_script.on_init = function(f)
            mod_obj.on_init = f
        end
        mod_script.on_load = function(f)
            mod_obj.on_load = f
        end
        mod_script.on_configuration_changed = function(f)
            mod_obj.on_configuration_changed = f
        end
        if not compat_mode then
            mod_script.on_event = function(event, f)
                if event == defines.events.on_tick then
                    mod_obj.on_tick = f
                else
                    mod_obj.on_event[event] = f
                end
            end
            mod_script.on_nth_tick = function(tick, f)
                if tick then
                    if type(tick) == 'table' then
                        for k, v in pairs(tick) do
                            mod_script.on_nth_tick(v, f)
                        end
                        return
                    end
                    mod_obj.on_nth_tick[tick] = f
                else
                    mod_obj.on_nth_tick = {}
                end
            end
        else   
            mod_script.on_event = function(event, f)
                if event == defines.events.on_tick then
                    mod_obj.on_tick = f
                    if mod_obj.running then
                        register_on_tick(mod_name, event)
                    end
                else
                    mod_obj.on_event[event] = f
                    if mod_obj.running then
                        register_event(mod_name, event)
                    end
                end
            end
            mod_script.on_nth_tick = function(tick, f)
                if tick then
                    if type(tick) == 'table' then
                        for k, v in pairs(tick) do
                            mod_script.on_nth_tick(v, f)
                        end
                        return
                    end
                    mod_obj.on_nth_tick[tick] = f
                    if mod_obj.running then
                        register_nth_tick(mod_name, tick)
                    end
                else
                    local on_nth_tick = mod_obj.on_nth_tick
                    mod_obj.on_nth_tick = {}
                    if mod_obj.running then
                        for k, v in pairs(on_nth_tick) do
                            register_nth_tick(mod_name, tick)
                        end
                    end
                end
            end
        end
        mod_script.generate_event_name = function()
            return script.generate_event_name()
        end
        mod_script.get_event_handler = function(event)
            return mod_obj.on_event[event]
        end
        mod_script.raise_event = function(event, table)
            script.raise_event(event, table)
        end
        --TODO: replace these with mod-provided versions, so multi-mod aware softmods can easily detect other loaded softmods
        mod_script.get_event_order = function()
            return script.get_event_order()
        end
        mod_script.mod_name = function()
            return script.mod_name()
        end
        
        debug_log({'hotpatch-info.setting-env'}, mod_name)
        -- mods private env
        local env = mod_obj.env
        -- mods private package
        local pack = {}
        -- mods private package.loaded
        local loaded = {}
        -- copy the current environment
		for k,v in pairs(_ENV) do
			env[k] = v
		end
        -- copy package.loaded
        for k,v in pairs(_ENV.package.loaded) do
			loaded[k] = v
		end
        loaded._G = env
        
        -- so many ways to escape sandboxes...
        
        for k,v in pairs(_ENV.package) do
			pack[k] = v
		end
        pack.loaded = loaded
        env.package = pack
        loaded.package = pack
        
        env.script = mod_script
        env.global = mod.global
        env._G = env
        
        env['remote'] = {
            add_interface = function(name, functions)
                if remote.interfaces[name] then
                    debug_log({'hotpatch-warning.remote-interface-exists', name}, mod_name)
                    remote.remove_interface(name)
                end
                remote.add_interface(name, functions)
            end,
            remove_interface = function(name)
                return remote.remove_interface(name)
            end,
            call = function(...)
                return remote.call(...)
            end,
            interfaces = setmetatable({}, {
                __index = function(t, k) return remote.interfaces[k] end,
                __pairs = function(t) local function iter(t, k) local v; k, v = next(remote.interfaces, k); if v then return k, t[k] end; end; return iter, t, nil end
            })
        }
        env['commands'] = {
            add_command = function(name, help, func)
                if commands.commands[name] then
                    debug_log({'hotpatch-warning.command-exists', name}, mod_name)
                    commands.remove_command(name)
                end
                commands.add_command(name, help, func)
            end,
            remove_command = function(name)
                return commands.remove_command(name)
            end,
            commands = setmetatable({}, {
                __index = function(t, k) return commands.commands[k] end,
                __pairs = function(t) local function iter(t, k) local v; k, v = next(commands.commands, k); if v then return k, t[k] end; end; return iter, t, nil end
            }),
            game_commands = setmetatable({}, {
                __index = function(t, k) return commands.game_commands[k] end,
                __pairs = function(t) local function iter(t, k) local v; k, v = next(commands.game_commands, k); if v then return k, t[k] end; end; return iter, t, nil end
            })
        }
        
        
        env.require = function(path)
            -- I blame Nexela for this
            path = path:gsub('/', '.')
            path = path:gsub('\\', '.')
			local alt_path = ''
            if env.package._current_path_in_package then
                alt_path = env.package._current_path_in_package .. path
            end
            if mod_obj.loaded_files[path] then
                debug_log({'hotpatch-trace.cached-load-require', path}, mod_name)
                return mod_obj.loaded_files[path]
			elseif mod_obj.loaded_files[alt_path] then
				debug_log({'hotpatch-trace.cached-load-require', alt_path}, mod_name)
                return mod_obj.loaded_files[alt_path]
            else
                local oldbase = env.package._current_path_in_package
                env.package._current_path_in_package = path:match('.+%..+%.')
                if not env.package._current_path_in_package then
                     env.package._current_path_in_package = path:match('.+%.')
                end
                local file = global.mods[installed_index].files[path]
                if file then
                    debug_log({'hotpatch-trace.load-require', path}, mod_name)
                    local code, err = load(file, '[' .. mod_name .. '] ' .. path .. '.lua', 'bt', env)
                    if code then
                        local result = code()
                        mod_obj.loaded_files[path] = result or true
                        env.package._current_path_in_package = oldbase
                        return mod_obj.loaded_files[path]
                    else
                        debug_log(err, nil, 3)
                        error(err)
                    end
                end
				local file = global.mods[installed_index].files[alt_path]
                if file then
                    debug_log({'hotpatch-trace.load-require', alt_path}, mod_name)
                    local code, err = load(file, '[' .. mod_name .. '] ' .. alt_path .. '.lua', 'bt', env)
                    if code then
                        local result = code()
                        mod_obj.loaded_files[alt_path] = result or true
                        env.package._current_path_in_package = oldbase
                        return mod_obj.loaded_files[alt_path]
                    else
                        debug_log(err, nil, 3)
                        error(err)
                    end
                end
				
                debug_log({'hotpatch-trace.load-core-lib', path}, mod_name)
                env.package._current_path_in_package = oldbase
				local lib = package.loaded[path]
				if not lib then 
					debug_log(path .. ' not found', nil, 3)
                    error(path .. ' not found')
				end
                return lib
            end
        end
        
        env['load'] = function(l, s, m, e)
            return load(l, s, m, e or env)
        end
        env['loadstring'] = env['load']
        
        
        env['game'] = setmetatable({}, {
            __index = function(t, k) return game[k] end,
            __pairs = function(t) local function iter(t, k) local v; k, v = next(game, k); if v then return k, t[k] end; end; return iter, t, nil end
        })
        
        local mt = {}
        mt.__index = function(t, k)
            debug_log({'hotpatch-trace.nil-var-access', k}, nil, 3)
            return nil
        end
        mt.__newindex = function(t, k, v)
            debug_log({'hotpatch-trace.nil-var-assignment', k}, nil, 3)
            rawset(t,k,v)
        end
        -- Don't let mods break this
        mt.__metatable = false
        setmetatable(env, mt)

        --load/run code
        debug_log({'hotpatch-info.loading'}, mod_name)
        
        local mod_code, message = load(mod.code, '[' .. mod_name .. '] control.lua', 'bt', env)
        if not mod_code then
            debug_log({'hotpatch-error.compilation-failed'}, mod_name)
            if game and game.player then
                game.player.print(message)
            end
            debug_log(message, mod_name)
            return false
        end

        mod_obj.code = mod_code
        mod_obj.loaded = true
        table.insert(loaded_mods, mod_obj)
        return true
    end
    return false
end

unload_mod = function(loaded_index)
    local mod = loaded_mods[loaded_index]
    if not mod then
        --TODO notify that mod isn't loaded
        return
    end
    local mod_name = mod.name
    -- TODO
    -- stop mod running, unregister handlers from being called
    debug_log({'hotpatch-info.unloading'}, mod_name)
    -- TODO:
    mod.loaded = false
    mod.running = false
    table.remove(loaded_mods, loaded_index)
end


--TODO: pretty much all of this routine
-- This should unregister events and clear the globals
reset_mod = function(loaded_index)
    local new_global = {}
    local mod = loaded_mods[loaded_index]
    mod.mod_env.global = new_global
    local install_index = find_installed_mod(mod.name)
    mod = global.mods[install_index]
    mod.global = new_global
    --local mod_global = global.mod_global[mod_name]
    --for k, v in pairs(mod_global) do
    --    mod_global[k] = nil
    --end

    reset_mod_events(loaded_index)
end

reset_mod_events = function(loaded_index)
    local loaded_index = find_loaded_mod(mod_name)
    
    if not loaded_index then
        debug_log({'hotpatch-warning.reset-events-not-running'}, mod_name)
    else 
        local loaded_mod = loaded_mods[loaded_index]
        loaded_mod.on_event = {}
        loaded_mod.on_nth_tick = {}
        loaded_mod.on_init = nil
        loaded_mod.on_load = nil
        loaded_mod.on_configuration_changed = nil
        loaded_mod.on_tick = nil
        register_all_events()
    end
end

run_mod = function(loaded_index)
    local mod = loaded_mods[loaded_index]
    if mod then
        local mod_name = mod.name
        local old_global = table.deepcopy(mod.env.global)

        if strict_mode then
           --mod.env.global = {}
        end
        debug_log({'hotpatch-info.running'}, mod_name)
        
        local success, result = xpcall(mod.code, debug.traceback)
        if not success then
            debug_log({'hotpatch-error.execution-failed'}, mod_name)
            debug_log(result, mod_name)
            --local caller = (game and game.player) or console
            if game and game.player then
                game.player.print(result)
            end
            
            return false
        end
            
        if strict_mode then
            --if mod.env.global ~= {} then
                --TODO: error, mod touched global inappropriately during load
            --end
           --mod.env.global = old_global
		   
        end
		
		-- if a mod is being loaded that already has global data, it must be restored after
		-- running control.lua, discarding any changes made
		if not table.compare(old_global, {}) then
			for k,v in pairs(mod.env.global) do
				mod.env.global[k] = nil
			end
			for k,v in pairs(old_global) do
				mod.env.global[k] = v
			end
			--mod.env.global = old_global
		end
		old_global = nil
		
        mod.running = true
        debug_log({'hotpatch-info.complete', {'hotpatch-info.running'}}, mod_name)
        
        --load complete, start notifying on event subscriptions
        if not compat_mode then
            mod.env.script.on_event = function(event, f)
                if event == defines.events.on_tick then
                    mod.on_tick = f
                    register_on_tick(mod_name, event)
                else
                    mod.on_event[event] = f
                    register_event(mod_name, event)
                end
            end
            mod.env.script.on_nth_tick = function(tick, f)
                if tick then
                    if type(tick) == 'table' then
                        for k, v in pairs(tick) do
                            mod_script.on_nth_tick(v, f)
                        end
                        return
                    end
                    mod.on_nth_tick[tick] = f
                    register_nth_tick(mod_name, tick)
                else
                    local on_nth_tick = mod.on_nth_tick
                    mod.on_nth_tick = {}
                    for k, v in pairs(on_nth_tick) do
                        register_nth_tick(mod_name, tick)
                    end
                end
            end
        end
        return true
    end
    return false
end

-- Note: might be able to optimize this a bit
-- event handlers to call into mods requested event handlers
on_event = function(event)
    local event_name = (event_names[event.name] or event.name)
    local f
    debug_log({'hotpatch-trace.event-processing', event_name})
    local mod
    for i = 1, #loaded_mods do
        mod = loaded_mods[i]
        f = mod.on_event[event.name]
        if f then 
            debug_log({'hotpatch-trace.event-running', event_name}, mod.name)
            f(event)
        end
    end
end

if debug_log_on_tick then
    on_nth_tick = function(event)
        local tick = event.nth_tick
        local f
        debug_log({'hotpatch-trace.nth-tick-event-processing', tick})
        local mod
        for i = 1, #loaded_mods do
            mod = loaded_mods[i]
            f = mod.on_nth_tick[event.nth_tick]
            if f then 
                debug_log({'hotpatch-trace.nth-tick-event-running', tick}, mod.name)
                f(event)
            end
        end
    end
else
    on_nth_tick = function(event)
        local tick = event.nth_tick
        local f
        local mod
        for i = 1, #loaded_mods do
            mod = loaded_mods[i]
            f = mod.on_nth_tick[event.nth_tick]
            if f then 
                debug_log({'hotpatch-trace.nth-tick-event-running', tick}, mod.name)
                f(event)
            end
        end
    end
end

local register_all_events = function()
    --unregister all events
    script.on_event(defines.events, nil)
    script.on_nth_tick(nil, nil)
    --re-register all mod events
    for i = 1, #loaded_mods do
        register_mod_events(i)
    end
end

register_mod_events = function(loaded_index)

    local mod = loaded_mods[loaded_index]
    local mod_name = mod.name
    debug_log({'hotpatch-trace.event-registering'}, mod_name)
    if mod.on_tick then
        debug_log({'hotpatch-trace.on-tick-event-registered'}, mod_name)
        script.on_event(defines.events.on_tick, on_tick)
    end
    for k,v in pairs(mod.on_event) do 
        local event_name = (event_names[k] or k)
        debug_log({'hotpatch-trace.on-event-registered', event_name}, mod_name)
        script.on_event(k, on_event)
    end
    for k,v in pairs(mod.on_nth_tick) do 
        debug_log({'hotpatch-trace.on-nth-tick-event-registered', k}, mod_name)
        script.on_nth_tick(k, on_nth_tick)
    end
end

mod_on_init = function(loaded_index)
    local mod = loaded_mods[loaded_index]
    
    if mod then
        debug_log({'hotpatch-trace.mod-on-init'}, mod.name)
        if mod.on_init then 
            local success, result = xpcall(mod.on_init, debug.traceback)
            if not success then
                debug_log('on_init failed for ' .. mod.name)
                debug_log(result)
                return false
            end
        end
        register_mod_events(loaded_index)
        return true
    end
    return false
end

mod_on_load = function(loaded_index)
    local mod = loaded_mods[loaded_index]
    
    if mod then
        debug_log({'hotpatch-trace.mod-on-load'}, mod.name)
        if mod.on_load then 
			--local old_global = table.deepcopy(mod.env.global)
            local success, result = xpcall(mod.on_load, debug.traceback)
            if not success then
                debug_log('on_load failed for ' .. mod.name)
                debug_log(result)
                return false
            end
        end
        register_mod_events(loaded_index)
        return true
    end
    return false
end

mod_on_configuration_changed = function(loaded_index, config)
    local mod = loaded_mods[loaded_index]
    
    if mod then
        debug_log({'hotpatch-trace.mod-on-configuration-changed'}, mod.name)
        if mod.on_configuration_changed then 
            local success, result = xpcall(mod.on_configuration_changed, debug.traceback, config)
            if not success then
                debug_log('on_configuration_changed failed for ' .. mod.name)
                debug_log(result)
                return false
            end
        end
        return true
    end
    return false
end

-- callbacks from mods to tell hotpatch when to enable handlers

register_on_tick = function(mod_name)
    local found_event
    --
    local mod
    for i = 1, #loaded_mods do
        mod = loaded_mods[i]
        local f = mod.on_tick
        if f then 
            found_event = true 
            break 
        end
    end
    debug_log({'hotpatch-trace.on-tick-event-registered'}, mod_name)
    if found_event then
        debug_log({'hotpatch-trace.on-tick-handler-added'})
    else
        debug_log({'hotpatch-trace.on-tick-handler-removed'})
    end
end

register_nth_tick = function(mod_name, nth_tick)
    local found_event
    --
    local mod
    for i = 1, #loaded_mods do
        mod = loaded_mods[i]
        local f = mod.on_nth_tick[nth_tick]
        if f then 
            found_event = true 
            break 
        end
    end
    debug_log({'hotpatch-trace.on-nth-tick-event-registered', nth_tick}, mod_name)
    if found_event then
        debug_log({'hotpatch-trace.nth-tick-handler-added', nth_tick})
        script.on_nth_tick(nth_tick, on_nth_tick)
    else
        debug_log({'hotpatch-trace.nth-tick-handler-removed', nth_tick})
        script.on_nth_tick(nth_tick, nil)
    end
end

register_event = function(mod_name, event_name)
    local found_event
    local mod
    for i = 1, #loaded_mods do
        mod = loaded_mods[i]
        local f = mod.on_event[event_name]
        if f then found_event = true break end
    end
    debug_log({'hotpatch-trace.on-event-registered', (event_names[event_name] or event_name)}, mod_name)
    if found_event then
        if script.get_event_handler(event_name) then
            -- handler already installed
            return
        else
           debug_log({'hotpatch-trace.on-event-handler-added', (event_names[event_name] or event_name)})
           script.on_event(event_name, on_event)
        end
    else
        debug_log({'hotpatch-trace.on-event-handler-removed', (event_names[event_name] or event_name)})
        script.on_event(event_name, nil)
    end
end

-- Core registration

on_init = function()
    hidden = load([===[
        return function(...) log(...) end
    ]===], '[HOTPATCH')
    hidden_log = hidden()
    debug_log({'hotpatch-info.on-init'})
    --juuuuust in case
    global.mods = global.mods or {}
    
    debug_log({'hotpatch-info.installing-included-mods'})
    local mod
    for i = 1, #static_mods do
        mod = static_mods[i]
        install_mod(mod.name, mod.version, mod.code, mod.files)
    end
    -- TODO: fix mod error loading behaviours
    for i = 1, #global.mods do
        load_mod(i)
    end
    
    for i = 1, #loaded_mods do
        run_mod(i)
        mod_on_init(i)
    end
    debug_log({'hotpatch-info.complete', {'hotpatch-info.installing-included-mods'}})
    debug_log({'hotpatch-info.complete', {'hotpatch-info.on-init'}})
end

on_load = function()
    hidden = load([===[
        return function(...) log(...) end
    ]===], '[HOTPATCH')
    hidden_log = hidden()
    debug_log({'hotpatch-info.on-load'})
    debug_log({'hotpatch-info.loading-installed-mods'})
    
    if global.globals then
        error('Upgrading from Hotpatch 1.0.X to 1.1.0 is not currently supported!')
        
        -- untested migration: use a tick to do the migration
        script.on_event(defines.events.on_tick, function(e)
            global.mods = {}
            local mod
            for k, v in pairs(global.mod_version) do
                mod = {}
                mod.name = k
                mod.version = v
                mod.code = global.mod_code[k]
                mod.files = global.mod_files[k]
                mod.global = global.globals[k]
                table.insert(global.mods, mod)
            end
            global.mod_version = nil
            global.mod_code = nil
            global.mod_files = nil
            global.globals = nil
            
            on_load() -- jump back into loading
            on_tick(e) -- need to test if factorio auto calls this or not after assigning the handler
            script.on_event(defines.events.on_tick, on_tick) -- restore old on_tick handler
        end)
        return
    end
    
    -- load installed mods
    for i = 1, #global.mods do
        load_mod(i)
    end
    
    -- run mods which loaded successfully
	local failed_mods = {}
    for i = 1, #loaded_mods do
        if run_mod(i) then
			if not mod_on_load(i) then
				table.insert(failed_mods, i)
			end
		else
			table.insert(failed_mods, i)
		end
    end
	
	-- unload mods which failed to run
	for i = 1, #failed_mods do
		unload_mod(failed_mods[i])
	end
    
    debug_log({'hotpatch-info.complete', {'hotpatch-info.loading-installed-mods'}})
    debug_log({'hotpatch-info.complete', {'hotpatch-info.on-load'}})
end

on_configuration_changed = function(config)
    debug_log({'hotpatch-info.on-configuration-changed'})
	local failed_mods = {}
    for i = 1, #loaded_mods do
        if not mod_on_configuration_changed(i) then
			table.insert(failed_mods, i)
		end
    end
	
	for i = 1, #failed_mods do
		unload_mod(failed_mods[i])
	end
    debug_log({'hotpatch-info.complete', {'hotpatch-info.on-configuration-changed'}})
end

if debug_log_on_tick then
    on_tick = function(e)
        debug_log({'hotpatch-trace.event-processing', 'on_tick'})
        local mod
        local f
        for i = 1, #loaded_mods do
            mod = loaded_mods[i]
            f = mod.on_tick
            if f then 
                debug_log({'hotpatch-trace.event-running', 'on_tick'}, mod.name)
                f(e)
            end
        end
    end
else
    on_tick = function(e)
        local mod
        local f
        for i = 1, #loaded_mods do
            mod = loaded_mods[i]
            f = mod.on_tick
            if f then 
                f(e)
            end
        end
    end
end


script.on_init(on_init)
script.on_load(on_load)
script.on_configuration_changed(on_configuration_changed)
script.on_event(defines.events.on_tick, on_tick)

--private API, don't use this
local mod_tools_internal = setmetatable({
    -- mod installation/uninstallation support functions
    -- These take a mod NAME as a first argument
    install_mod = install_mod,
    find_installed_mod = find_installed_mod,
    install_mod_file = install_mod_file,
    uninstall_mod = uninstall_mod,

    -- mod interaction functions
    -- These take a LOADED INDEX as a first argument, except load_mod, which takes an INSTALLED INDEX
    load_mod = load_mod,
    find_loaded_mod = find_loaded_mod,
    run_mod = run_mod,
    reset_mod = reset_mod,
    reset_mod_events = reset_mod_events,
    register_mod_events = register_mod_events,
    unload_mod = unload_mod,

    -- internal callbacks when a mod registers events
    register_event = register_event,
    register_nth_tick = register_nth_tick,
    register_on_tick = register_on_tick,

    -- mod bootstrap functions
    -- These take a LOADED INDEX as a first argument
    mod_on_init = mod_on_init,
    mod_on_load = mod_on_load,
    mod_on_configuration_changed = mod_on_configuration_changed,
    
    static_mods = static_mods,
    console = console,
    debug_log = debug_log,
    loaded_mods = loaded_mods,
    loaded_libraries = loaded_libraries,
    installed_mods = setmetatable({}, {
        __index = function(t, k)
            return global.mods[k]
        end,
        __newindex = function(t, k, v)
        -- do nothing
        end,
        __len = function(t)
            return #global.mods
        end,
        __pairs = function(t) local function iter(t, k) local v; v = global.mods[k+1]; if v then return k+1, v end; end; return iter, t, 0 end,
        __ipairs = function(t) local function iter(t, k) local v; v = global.mods[k+1]; if v then return k+1, v end; end; return iter, t, 0 end,
        __metatable = false,
    })
},{
    __index = function(t, k)
        debug_log({'hotpatch-error.invalid-API-access', k}, nil, 3)
    end,
    __newindex = function(t, k, v)
        -- do nothing
    end,
    -- Don't let mods muck around
    __metatable = false,
})

--public API
local mod_tools = setmetatable({
    -- most code should use static_mod
    static_mod = static_mod, -- (name, version, code, files)
    set_debug_level = function(level)
        debug_level = tonumber(_ENV.debug_settings.level) or debug_levels[_ENV.debug_settings.level]
    end,
},{
    __index = mod_tools_internal,
    __newindex = function(t, k, v)
        -- do nothing, read-only table
    end,
    -- Don't let mods muck around
    __metatable = false,
})


return mod_tools