feat: Show intro message (#1980)

* Show intro message

* Rename INTRO_MESSAGE to INTRO_MESSAGE_LUA

* Initialize the lua random seed

lua/intro.lua

@@ -0,0 +1,150 @@
+local function show_intro()
+    -- Don't show the intro if a buffer is loaded
+    if vim.api.nvim_buf_line_count(0) > 1 or vim.api.nvim_buf_get_name(0) ~= "" then
+        return
+    end
+
+    -- Create a new unlisted buffer
+    local buf = vim.api.nvim_create_buf(false, true)
+    local version_string = vim.api.nvim_exec2("version", { output = true }).output
+    -- we only need the first line of the version
+    version_string = version_string:sub(2, version_string:find("\n", 2) - 1)
+    local version = vim.version()
+
+    local lines = {
+        version_string,
+        "",
+        "Nvim is open source and freely distributable",
+        "https://neovim.io/#chat",
+        "",
+        "type  :help nvim<Enter>       if you are new! ",
+        "type  :checkhealth<Enter>     to optimize Nvim",
+        "type  :q<Enter>               to exit         ",
+        "type  :help<Enter>            for help        ",
+        "",
+        string.format("type  :help news<Enter> to see changes in v%d.%d", version.major, version.minor),
+        "",
+    }
+
+    local help_messages = {
+        {
+            "Sponsor Vim development!",
+            "type  :help sponsor<Enter>    for information ",
+        },
+        {
+            "Become a registered Vim user!",
+            "type  :help register<Enter>   for information ",
+        },
+        {
+            "Help poor children in Uganda!",
+            "type  :help iccf<Enter>       for information ",
+        },
+    }
+
+    -- Show the sponsor and register message one out of four times, the Uganda
+    -- message two out of four times.
+    math.randomseed(os.time())
+    local help_type = math.random(4)
+    if help_type <= 2 then
+        vim.list_extend(lines, help_messages[help_type])
+    else
+        vim.list_extend(lines, help_messages[3])
+    end
+
+    local longest_line = 0
+    for i, line in ipairs(lines) do
+        if line:len() > 0 then
+            -- translate
+            line = vim.fn.gettext(line)
+        end
+        longest_line = math.max(longest_line, line:len())
+        lines[i] = line
+    end
+
+    -- add padding to the lines
+    for i, line in ipairs(lines) do
+        local padding = math.floor((longest_line - line:len()) / 2) + 1
+        lines[i] = string.rep(" ", padding) .. line
+    end
+
+    -- add highlight to the special keys
+    vim.api.nvim_buf_set_lines(buf, 0, -1, false, lines)
+    for i, line in ipairs(lines) do
+        local s, e = line:find("<.*>")
+        if s ~= nil then
+            vim.api.nvim_buf_add_highlight(buf, -1, "SpecialKey", i - 1, s - 1, e)
+        end
+    end
+
+    local width = longest_line + 2
+    local height = #lines
+
+    local function get_config()
+        return {
+            relative = "editor",
+            width = width,
+            height = height,
+            col = math.max(0, math.ceil((vim.o.columns - width) / 2)),
+            row = math.max(0, math.ceil((vim.o.lines - height) / 2)),
+            style = "minimal",
+            border = "none"
+        }
+    end
+
+    local win = vim.api.nvim_open_win(buf, false, get_config())
+    vim.api.nvim_win_set_option(win, "winhighlight", "NormalFloat:Normal")
+
+    local win_autogroup = vim.api.nvim_create_augroup("neovide_intro_win", { clear = true })
+
+    local function close()
+        vim.api.nvim_del_augroup_by_id(win_autogroup)
+        if vim.api.nvim_buf_is_valid(buf) then
+            vim.api.nvim_buf_delete(buf, { force = true })
+        end
+        if vim.api.nvim_win_is_valid(win) then
+            vim.api.nvim_win_close(win, true)
+        end
+    end
+
+    vim.api.nvim_create_autocmd({ "VimResized" }, {
+        pattern = "*",
+        group = win_autogroup,
+        callback = function()
+            vim.api.nvim_win_set_config(win, get_config())
+        end
+    })
+
+    local first_cursor_move = false
+
+    vim.api.nvim_create_autocmd(
+        {
+            "BufEnter",
+            "ModeChanged",
+            "CursorMoved", "CursorMovedI",
+            "TextChanged", "TextChangedI", "TextChangedP", "TextChangedT"
+        },
+        {
+            pattern = "*",
+            group = win_autogroup,
+            callback = function(param)
+                -- Allow changing from and to command mode
+                if param.event == "ModeChanged" and param.match:find("c") ~= nil then
+                    return
+                end
+                -- The first cursor move is ignored, since it happens after the message is shown
+                if not first_cursor_move and param.event == "CursorMoved" then
+                    first_cursor_move = true
+                    return
+                end
+                close()
+            end
+        })
+end
+
+
+local autogroup = vim.api.nvim_create_augroup("neovide_intro", { clear = true })
+vim.api.nvim_create_autocmd({ "VimEnter" }, {
+    pattern = "*",
+    group = autogroup,
+    callback = show_intro
+})

src/bridge/setup.rs

@@ -30,6 +30,8 @@ const REGISTER_CLIPBOARD_PROVIDER_LUA: &str = r"
         cache_enabled = 0
     }";
 
+const INTRO_MESSAGE_LUA: &str = include_str!("../../lua/intro.lua");
+
 pub async fn setup_neovide_remote_clipboard(nvim: &Neovim<NeovimWriter>, neovide_channel: u64) {
     // Users can opt-out with
     // vim: `let g:neovide_no_custom_clipboard = v:true`
@@ -144,6 +146,8 @@ pub async fn setup_neovide_specific_state(
     nvim.command("autocmd VimLeave * call rpcnotify(1, 'neovide.quit', v:exiting)")
         .await
         .ok();
+
+    nvim.exec_lua(INTRO_MESSAGE_LUA, Vec::new()).await.ok();
 }
 
 #[cfg(windows)]