Minetest Lua Mainmenu API Reference 5.4.0
=========================================

Introduction
-------------

The main menu is defined as a formspec by Lua in builtin/mainmenu/
Description of formspec language to show your menu is in lua_api.txt


Callbacks
---------

core.button_handler(fields): called when a button is pressed.
^ fields = {name1 = value1, name2 = value2, ...}
core.event_handler(event)
^ event: "MenuQuit", "KeyEnter", "ExitButton" or "EditBoxEnter"


Gamedata
--------

The "gamedata" table is read when calling core.start(). It should contain:
{
    playername     = <name>,
    password       = <password>,
    address        = <IP/adress>,
    port           = <port>,
    selected_world = <index>, -- 0 for client mode
    singleplayer   = <true/false>,
}


Functions
---------

core.start()
core.close()
core.get_min_supp_proto()
^ returns the minimum supported network protocol version
core.get_max_supp_proto()
^ returns the maximum supported network protocol version
core.open_url(url)
^ opens the URL in a web browser, returns false on failure.
^ Must begin with http:// or https://
core.open_dir(path)
^ opens the path in the system file browser/explorer, returns false on failure.
^ Must be an existing directory.
core.get_version() (possible in async calls)
^ returns current core version



Filesystem
----------

core.get_builtin_path()
^ returns path to builtin root
core.create_dir(absolute_path) (possible in async calls)
^ absolute_path to directory to create (needs to be absolute)
^ returns true/false
core.delete_dir(absolute_path) (possible in async calls)
^ absolute_path to directory to delete (needs to be absolute)
^ returns true/false
core.copy_dir(source,destination,keep_soure) (possible in async calls)
^ source folder
^ destination folder
^ keep_source DEFAULT true --> if set to false source is deleted after copying
^ returns true/false
core.is_dir(path) (possible in async calls)
^ returns true if path is a valid dir
core.extract_zip(zipfile,destination) [unzip within path required]
^ zipfile to extract
^ destination folder to extract to
^ returns true/false
core.sound_play(spec, looped) -> handle
^ spec = SimpleSoundSpec (see lua-api.txt)
^ looped = bool
core.sound_stop(handle)
core.get_video_drivers()
^ get list of video drivers supported by engine (not all modes are guaranteed to work)
^ returns list of available video drivers' settings name and 'friendly' display name
^ e.g. { {name="opengl", friendly_name="OpenGL"}, {name="software", friendly_name="Software Renderer"} }
^ first element of returned list is guaranteed to be the NULL driver
core.get_mapgen_names([include_hidden=false]) -> table of map generator algorithms
    registered in the core (possible in async calls)
core.get_cache_path() -> path of cache


HTTP Requests
-------------

* core.download_file(url, target) (possible in async calls)
    * url to download, and target to store to
    * returns true/false
* `minetest.get_http_api()` (possible in async calls)
    * returns `HTTPApiTable` containing http functions.
    * The returned table contains the functions `fetch_sync`, `fetch_async` and
      `fetch_async_get` described below.
    * Function only exists if minetest server was built with cURL support.
* `HTTPApiTable.fetch_sync(HTTPRequest req)`: returns HTTPRequestResult
    * Performs given request synchronously
* `HTTPApiTable.fetch_async(HTTPRequest req)`: returns handle
    * Performs given request asynchronously and returns handle for
      `HTTPApiTable.fetch_async_get`
* `HTTPApiTable.fetch_async_get(handle)`: returns HTTPRequestResult
    * Return response data for given asynchronous HTTP request

### `HTTPRequest` definition

Used by `HTTPApiTable.fetch` and `HTTPApiTable.fetch_async`.

    {
        url = "http://example.org",

        timeout = 10,
        -- Timeout for connection in seconds. Default is 3 seconds.

        post_data = "Raw POST request data string" OR {field1 = "data1", field2 = "data2"},
        -- Optional, if specified a POST request with post_data is performed.
        -- Accepts both a string and a table. If a table is specified, encodes
        -- table as x-www-form-urlencoded key-value pairs.
        -- If post_data is not specified, a GET request is performed instead.

        user_agent = "ExampleUserAgent",
        -- Optional, if specified replaces the default minetest user agent with
        -- given string

        extra_headers = { "Accept-Language: en-us", "Accept-Charset: utf-8" },
        -- Optional, if specified adds additional headers to the HTTP request.
        -- You must make sure that the header strings follow HTTP specification
        -- ("Key: Value").

        multipart = boolean
        -- Optional, if true performs a multipart HTTP request.
        -- Default is false.
    }

### `HTTPRequestResult` definition

Passed to `HTTPApiTable.fetch` callback. Returned by
`HTTPApiTable.fetch_async_get`.

    {
        completed = true,
        -- If true, the request has finished (either succeeded, failed or timed
        -- out)

        succeeded = true,
        -- If true, the request was successful

        timeout = false,
        -- If true, the request timed out

        code = 200,
        -- HTTP status code

        data = "response"
    }


Formspec
--------

core.update_formspec(formspec)
core.get_table_index(tablename) -> index
^ can also handle textlists
core.formspec_escape(string) -> string
^ escapes characters [ ] \ , ; that can not be used in formspecs
core.explode_table_event(string) -> table
^ returns e.g. {type="CHG", row=1, column=2}
^ type: "INV" (no row selected), "CHG" (selected) or "DCL" (double-click)
core.explode_textlist_event(string) -> table
^ returns e.g. {type="CHG", index=1}
^ type: "INV" (no row selected), "CHG" (selected) or "DCL" (double-click)
core.set_formspec_prepend(formspec)
^ string to be added to every mainmenu formspec, to be used for theming.


GUI
---

core.set_background(type, texturepath,[tile],[minsize])
^ type: "background", "overlay", "header" or "footer"
^ tile: tile the image instead of scaling (background only)
^ minsize: minimum tile size, images are scaled to at least this size prior
^   doing tiling (background only)
core.set_clouds(<true/false>)
core.set_topleft_text(text)
core.show_keys_menu()
core.show_path_select_dialog(formname, caption, is_file_select)
^ shows a path select dialog
^ formname is base name of dialog response returned in fields
^     -if dialog was accepted "_accepted"
^        will be added to fieldname containing the path
^     -if dialog was canceled "_cancelled"
^        will be added to fieldname value is set to formname itself
^ if `is_file_select` is `true`, a file and not a folder will be selected
^ returns nil or selected file/folder
core.get_screen_info()
^ returns {
    density         = <screen density 0.75,1.0,2.0,3.0 ... (dpi)>,
    display_width   = <width of display>,
    display_height  = <height of display>,
    window_width    = <current window width>,
    window_height   = <current window height>
    }


Content and Packages
--------------------

Content - an installed mod, modpack, game, or texture pack (txt)
Package - content which is downloadable from the content db, may or may not be installed.

* core.get_user_path() (possible in async calls)
    * returns path to global user data,
      the directory that contains user-provided mods, worlds, games, and texture packs.
* core.get_modpath() (possible in async calls)
    * returns path to global modpath
* core.get_clientmodpath() (possible in async calls)
    * returns path to global client-side modpath
* core.get_gamepath() (possible in async calls)
    * returns path to global gamepath
* core.get_texturepath() (possible in async calls)
    * returns path to default textures
* core.get_game(index)
    * returns:

        {
            id               = <id>,
            path             = <full path to game>,
            gamemods_path    = <path>,
            name             = <name of game>,
            menuicon_path    = <full path to menuicon>,
            author           = "author",
            DEPRECATED:
            addon_mods_paths = {[1] = <path>,},
        }

* core.get_games() -> table of all games in upper format (possible in async calls)
* core.get_content_info(path)
    * returns

        {
            name             = "name of content",
            type             = "mod" or "modpack" or "game" or "txp",
            description      = "description",
            author           = "author",
            path             = "path/to/content",
            depends          = {"mod", "names"}, -- mods only
            optional_depends = {"mod", "names"}, -- mods only
        }


Logging
-------

core.debug(line) (possible in async calls)
^ Always printed to stderr and logfile (print() is redirected here)
core.log(line) (possible in async calls)
core.log(loglevel, line) (possible in async calls)
^ loglevel one of "error", "action", "info", "verbose"


Settings
--------

core.settings:set(name, value)
core.settings:get(name) -> string or nil (possible in async calls)
core.settings:set_bool(name, value)
core.settings:get_bool(name) -> bool or nil (possible in async calls)
core.settings:save() -> nil, save all settings to config file

For a complete list of methods of the Settings object see
[lua_api.txt](https://github.com/minetest/minetest/blob/master/doc/lua_api.txt)


Worlds
------

core.get_worlds() -> list of worlds (possible in async calls)
^ returns {
    [1] = {
    path   = <full path to world>,
    name   = <name of world>,
    gameid = <gameid of world>,
    },
}
core.create_world(worldname, gameid)
core.delete_world(index)


Helpers
-------

core.get_us_time()
^ returns time with microsecond precision
core.gettext(string) -> string
^ look up the translation of a string in the gettext message catalog
fgettext_ne(string, ...)
^ call core.gettext(string), replace "$1"..."$9" with the given
^ extra arguments and return the result
fgettext(string, ...) -> string
^ same as fgettext_ne(), but calls core.formspec_escape before returning result
core.parse_json(string[, nullvalue]) -> something (possible in async calls)
^ see core.parse_json (lua_api.txt)
dump(obj, dumped={})
^ Return object serialized as a string
string:split(separator)
^ eg. string:split("a,b", ",") == {"a","b"}
string:trim()
^ eg. string.trim("\n \t\tfoo bar\t ") == "foo bar"
core.is_yes(arg) (possible in async calls)
^ returns whether arg can be interpreted as yes
minetest.encode_base64(string) (possible in async calls)
^ Encodes a string in base64.
minetest.decode_base64(string) (possible in async calls)
^ Decodes a string encoded in base64.


Async
-----

core.handle_async(async_job,parameters,finished)
^ execute a function asynchronously
^ async_job is a function receiving one parameter and returning one parameter
^ parameters parameter table passed to async_job
^ finished function to be called once async_job has finished
^    the result of async_job is passed to this function

Limitations of Async operations
 -No access to global lua variables, don't even try
 -Limited set of available functions
    e.g. No access to functions modifying menu like core.start,core.close,
    core.show_path_select_dialog


Background music
----------------

The main menu supports background music.
It looks for a `main_menu` sound in `$USER_PATH/sounds`. The same naming
conventions as for normal sounds apply.
This means the player can add a custom sound.
It will be played in the main menu (gain = 1.0), looped.
