chat_formspec/show-receive.lua

-- https://rubenwardy.com/minetest_modding_book/en/players/formspecs.html#contexts
local _contexts = {}
local function get_context(name)
    local context = _contexts[name] or {}
    _contexts[name] = context
    return context
end

local function clear_context(name)
    _contexts[name] = nil
end

minetest.register_on_leaveplayer(function(player)
    clear_context(player:get_player_name())
end)


-- show a formspec to a player
function chat_formspec.show_to_target(sendername, targetname, fs)
    if not targetname then
        minetest.chat_send_player(sendername, "please provide a playername to whom the formspec shall be shown")
    end
    local target = minetest.get_player_by_name(targetname)
    if not target then
        minetest.chat_send_player(sendername, targetname .. " is not online")
        return
    end
    if target:get_hp() == 0 then
        minetest.chat_send_player(sendername, targetname .. " is dead. We cannot send them a formspec without removing their respawn-formspec. Please try again later")
        return
    end
    minetest.show_formspec(targetname, "chat_formspec:target_fs", fs)
    local context = get_context(targetname)
    context.sender = sendername
    context.fs = fs
    minetest.chat_send_player(sendername, "formspec send to " .. targetname)
end

minetest.register_on_player_receive_fields(function(player, formname, fields)
    if formname ~= "chat_formspec:target_fs" then return false end
    local name = player:get_player_name()
    local context = get_context(name)
    local sendername = context.sender
    if fields.chat_help then
        chat_formspec.show_misc(name, "chat_help")
    elseif fields.replant_help then
        chat_formspec.show_misc(name, "replant_help")
    elseif minetest.get_player_by_name(sendername) then
        local answer = fields.answer or ""
        minetest.chat_send_player(sendername, "chat formspec: " .. name .. " answered with \"" .. answer .. "\"")
    end
    if fields.quit then
        clear_context(name)
    end
    return true
end)


-- creating new formspecs
function chat_formspec.show_create_new(name)
    minetest.show_formspec(name, "chat_formspec:create_new", chat_formspec.create_new)
end

minetest.register_on_player_receive_fields(function(player, formname, fields)
    if formname ~= "chat_formspec:create_new" then return false end
    local name = player:get_player_name()
    if not fields.c_fs then
        minetest.chat_send_player(name, "Please provide a formspec")
        return
    end
    if not minetest.check_player_privs(name, chat_formspec.create_new_priv) then return true end
    chat_formspec.show_to_target(name, fields.target, fields.c_fs)
    return true
end)


-- show predefined formspecs
function chat_formspec.show_predefined(name, id)
    minetest.show_formspec(name, "chat_formspec:predefined", chat_formspec.get_predefined_template(id, nil))
end

minetest.register_on_player_receive_fields(function(player, formname, fields)
    if formname ~= "chat_formspec:predefined" then return false end
    local name = player:get_player_name()
    local context = get_context(name)
    if fields.back then
        clear_context(name)
        chat_formspec.show_select_predefined(name)
    elseif fields.change_text then
        context.replacement = minetest.formspec_escape(fields.change_text_field or "")
        minetest.show_formspec(name, "chat_formspec:predefined", chat_formspec.get_predefined_template(context.id, context.replacement))
    elseif fields.send then
        if not minetest.check_player_privs(name, chat_formspec.predefined_priv) then return true end
        local fs = chat_formspec.create_targest_fs(context.id, context.replacement)
        chat_formspec.show_to_target(name, fields.target, fs)
    end
    if fields.quit then
        clear_context(name)
    end
    return true
end)


-- show the formspec to select a predefined formspec
function chat_formspec.show_select_predefined(name)
    minetest.show_formspec(name, "chat_formspec:select_predefined", chat_formspec.selection_fs)
end

minetest.register_on_player_receive_fields(function(player, formname, fields)
    if formname ~= "chat_formspec:select_predefined" then return end
    local name = player:get_player_name()
    local context = get_context(name)
    if fields.select then
        context.id = fields.select
    end
    if fields.template then
        chat_formspec.show_predefined(name, context.id)
    end
    return true
end)


-- help formspecs (how to chat / replant)
function chat_formspec.show_misc(name, id)
    minetest.show_formspec(name, "chat_formspec:misc", chat_formspec.misc_fs[id])
end

minetest.register_on_player_receive_fields(function(player, formname, fields)
    if formname ~= "chat_formspec:misc" then return end
    local name = player:get_player_name()
    local context = get_context(name)
    if fields.quit then     -- for whatever reason it doesn't work to send another formspec (maybe side effect of quit?)
        minetest.after(1, function()  -- for whatever reason it doesn't work to use 0 (or 0.1)
            if minetest.get_player_by_name(name) then
                minetest.show_formspec(name, "chat_formspec:target_fs", context.fs)
            end
        end)
    else
        minetest.show_formspec(name, "chat_formspec:target_fs", context.fs)
    end
    return true
end)