Implement preview pane

Display preview in the selection pane when selection is empty.

Adds:

- xplr.util.preview
- xplr.fn.builtin.fmt_general_preview_renderer

docs/en/src/configuration.md

@@ -47,6 +47,20 @@ that can be overwritten.
 
 Tries to auto complete the path in the input buffer
 
+#### xplr.fn.builtin.fmt_general_selection_item
+
+Formats each node in the selection
+
+#### xplr.fn.builtin.fmt_general_preview_renderer
+
+Renders the focused node in preview pane
+
+See: [xplr.util.preview](https://xplr.dev/en/xplr.util#xplrutilpreview)
+
+The focused node is passed as the node value, and layout_hight is passed
+dynamically.
+When there is no item under focus, the node value will be nil.
+
 #### xplr.fn.builtin.fmt_general_table_row_cols_0
 
 Renders the first column in the table

docs/en/src/general-config.md

@@ -193,6 +193,18 @@ Style for each item in the selection list.
 
 Type: [Style](https://xplr.dev/en/style)
 
+#### xplr.config.general.preview.renderer.format
+
+Preview renderer for the path under focus.
+
+Type: nullable string
+
+#### xplr.config.general.preview.renderer.style
+
+Style for preview panel.
+
+Type: [Style](https://xplr.dev/en/style)
+
 #### xplr.config.general.search.algorithm
 
 The default search algorithm

docs/en/src/xplr.util.md

@@ -110,12 +110,12 @@ xplr.util.path_split(".././foo")
 
 ### xplr.util.node
 
-Get [Node][5] information of a given path.
+Get [Node][2] information of a given path.
 Doesn't check if the path exists.
 Returns nil if the path is "/".
 Errors out if absolute path can't be obtained.
 
-Type: function( path:string ) -> [Node][5]|nil
+Type: function( path:string ) -> [Node][2]|nil
 
 Example:
 
@@ -129,9 +129,9 @@ xplr.util.node("/")
 
 ### xplr.util.node_type
 
-Get the configured [Node Type][6] of a given [Node][5].
+Get the configured [Node Type][6] of a given [Node][2].
 
-Type: function( [Node][5], [xplr.config.node_types][7]|nil ) -> [Node Type][6]
+Type: function( [Node][2], [xplr.config.node_types][7]|nil ) -> [Node Type][6]
 
 If the second argument is missing, global config `xplr.config.node_types`
 will be used.
@@ -501,11 +501,33 @@ xplr.util.permissions_octal(app.focused_node.permission)
 -- { 0, 7, 5, 4 }
 ```
 
+### xplr.util.preview
+
+Renders a preview of the given node as string.
+
+You probably want to use it inside the function mentioned in
+[xplr.config.general.preview.renderer.format][9], or inside a
+[custom dynamic layout][10].
+
+Type: function( { node:[Node][2]|nil, layout_size:[Size][5] } ) -> string
+
+Example:
+
+```lua
+xplr.util.preview({
+    node = xplr.util.node("/foo"),
+    layout_size = { x = 0, y = 0, height = 10, width = 10 },
+})
+-- "..."
+```
+
 [1]: https://xplr.dev/en/lua-function-calls#explorer-config
 [2]: https://xplr.dev/en/lua-function-calls#node
 [3]: https://xplr.dev/en/style
 [4]: https://xplr.dev/en/layout
-[5]: https://xplr.dev/en/lua-function-calls#node
+[5]: https://xplr.dev/en/layout#size
 [6]: https://xplr.dev/en/node-type
 [7]: https://xplr.dev/en/node_types
 [8]: https://xplr.dev/en/column-renderer#permission
+[9]: https://xplr.dev/en/general-config#xplrconfiggeneralpreviewrendererformat
+[10]: https://xplr.dev/en/layout#dynamic

src/config.rs

@@ -189,6 +189,13 @@ pub struct SelectionConfig {
     pub item: UiElement,
 }
 
+#[derive(Debug, Clone, Default, Serialize, Deserialize)]
+#[serde(deny_unknown_fields)]
+pub struct PreviewConfig {
+    #[serde(default)]
+    pub renderer: UiElement,
+}
+
 #[derive(Debug, Clone, Default, Serialize, Deserialize)]
 #[serde(deny_unknown_fields)]
 pub struct SearchConfig {
@@ -318,6 +325,9 @@ pub struct GeneralConfig {
     #[serde(default)]
     pub selection: SelectionConfig,
 
+    #[serde(default)]
+    pub preview: PreviewConfig,
+
     #[serde(default)]
     pub search: SearchConfig,
 

src/init.lua

@@ -256,6 +256,16 @@ xplr.config.general.selection.item.format = "builtin.fmt_general_selection_item"
 -- Type: [Style](https://xplr.dev/en/style)
 xplr.config.general.selection.item.style = {}
 
+--  Preview renderer for the path under focus.
+--
+--  Type: nullable string
+xplr.config.general.preview.renderer.format = "builtin.fmt_general_preview_renderer"
+
+-- Style for preview panel.
+--
+-- Type: [Style](https://xplr.dev/en/style)
+xplr.config.general.preview.renderer.style = {}
+
 -- The default search algorithm
 --
 -- Type: [Search Algorithm](https://xplr.dev/en/searching#algorithm)
@@ -2948,6 +2958,7 @@ xplr.fn.builtin.try_complete_path = function(m)
   end
 end
 
+-- Formats each node in the selection
 xplr.fn.builtin.fmt_general_selection_item = function(n)
   local nl = xplr.util.paint("\\n", { add_modifiers = { "Italic", "Dim" } })
   local sh_config = { with_prefix_dots = true, without_suffix_dots = true }
@@ -2961,6 +2972,15 @@ xplr.fn.builtin.fmt_general_selection_item = function(n)
   return xplr.util.paint(shortened:gsub("\n", nl), style)
 end
 
+-- Renders the focused node in preview pane
+--
+-- See: [xplr.util.preview](https://xplr.dev/en/xplr.util#xplrutilpreview)
+--
+-- The focused node is passed as the node value, and layout_hight is passed
+-- dynamically.
+-- When there is no item under focus, the node value will be nil.
+xplr.fn.builtin.fmt_general_preview_renderer = xplr.util.preview
+
 -- Renders the first column in the table
 xplr.fn.builtin.fmt_general_table_row_cols_0 = function(m)
   local r = ""

src/lua/util.rs

@@ -10,6 +10,7 @@ use crate::permissions::Octal;
 use crate::permissions::Permissions;
 use crate::ui;
 use crate::ui::Layout;
+use crate::ui::PreviewRendererArgs;
 use crate::ui::Style;
 use crate::ui::WrapOptions;
 use anyhow::Result;
@@ -195,12 +196,12 @@ pub fn path_split<'a>(util: Table<'a>, lua: &Lua) -> Result<Table<'a>> {
     Ok(util)
 }
 
-/// Get [Node][5] information of a given path.
+/// Get [Node][2] information of a given path.
 /// Doesn't check if the path exists.
 /// Returns nil if the path is "/".
 /// Errors out if absolute path can't be obtained.
 ///
-/// Type: function( path:string ) -> [Node][5]|nil
+/// Type: function( path:string ) -> [Node][2]|nil
 ///
 /// Example:
 ///
@@ -230,9 +231,9 @@ pub fn node<'a>(util: Table<'a>, lua: &Lua) -> Result<Table<'a>> {
     Ok(util)
 }
 
-/// Get the configured [Node Type][6] of a given [Node][5].
+/// Get the configured [Node Type][6] of a given [Node][2].
 ///
-/// Type: function( [Node][5], [xplr.config.node_types][7]|nil ) -> [Node Type][6]
+/// Type: function( [Node][2], [xplr.config.node_types][7]|nil ) -> [Node Type][6]
 ///
 /// If the second argument is missing, global config `xplr.config.node_types`
 /// will be used.
@@ -824,15 +825,59 @@ pub fn permissions_octal<'a>(util: Table<'a>, lua: &Lua) -> Result<Table<'a>> {
     Ok(util)
 }
 
+/// Renders a preview of the given node as string.
+///
+/// You probably want to use it inside the function mentioned in
+/// [xplr.config.general.preview.renderer.format][9], or inside a
+/// [custom dynamic layout][10].
+///
+/// Type: function( { node:[Node][2]|nil, layout_size:[Size][5] } ) -> string
+///
+/// Example:
+///
+/// ```lua
+/// xplr.util.preview({
+///     node = xplr.util.node("/foo"),
+///     layout_size = { x = 0, y = 0, height = 10, width = 10 },
+/// })
+/// -- "..."
+/// ```
+pub fn preview<'a>(util: Table<'a>, lua: &Lua) -> Result<Table<'a>> {
+    let func = lua.create_function(|lua, args: Table| {
+        let args: PreviewRendererArgs = lua.from_value(Value::Table(args))?;
+        let Some(node) = args.node else {
+            return Ok("".into());
+        };
+
+        let size = args.layout_size;
+
+        let preview = if node.is_dir {
+            "Directory".to_string()
+        } else if node.is_file {
+            "File".to_string()
+        } else if node.is_symlink {
+            "Symlink".to_string()
+        } else {
+            "Unknown".to_string()
+        };
+
+        Ok(preview)
+    })?;
+    util.set("preview", func)?;
+    Ok(util)
+}
+
 ///
 /// [1]: https://xplr.dev/en/lua-function-calls#explorer-config
 /// [2]: https://xplr.dev/en/lua-function-calls#node
 /// [3]: https://xplr.dev/en/style
 /// [4]: https://xplr.dev/en/layout
-/// [5]: https://xplr.dev/en/lua-function-calls#node
+/// [5]: https://xplr.dev/en/layout#size
 /// [6]: https://xplr.dev/en/node-type
 /// [7]: https://xplr.dev/en/node_types
 /// [8]: https://xplr.dev/en/column-renderer#permission
+/// [9]: https://xplr.dev/en/general-config#xplrconfiggeneralpreviewrendererformat
+/// [10]: https://xplr.dev/en/layout#dynamic
 
 pub(crate) fn create_table(lua: &Lua) -> Result<Table> {
     let mut util = lua.create_table()?;
@@ -867,6 +912,7 @@ pub(crate) fn create_table(lua: &Lua) -> Result<Table> {
     util = layout_replace(util, lua)?;
     util = permissions_rwx(util, lua)?;
     util = permissions_octal(util, lua)?;
+    util = preview(util, lua)?;
 
     Ok(util)
 }

src/ui.rs

@@ -853,6 +853,53 @@ fn draw_table(
     f.render_widget(table, layout_size);
 }
 
+#[derive(Debug, Clone, Default, Serialize, Deserialize, PartialEq, Eq)]
+#[serde(deny_unknown_fields)]
+pub struct PreviewRendererArgs {
+    pub node: Option<Node>,
+    pub layout_size: TuiRect,
+}
+
+fn draw_preview(
+    f: &mut Frame,
+    _screen_size: TuiRect,
+    layout_size: TuiRect,
+    app: &app::App,
+    lua: &Lua,
+) {
+    let panel_config = &app.config.general.panel_ui;
+    let config = panel_config
+        .default
+        .to_owned()
+        .extend(&panel_config.selection);
+
+    let renderer = app
+        .config
+        .general
+        .preview
+        .renderer
+        .format
+        .clone()
+        .unwrap_or_default();
+
+    let preview = if let Some(node) = app.focused_node() {
+        let args = PreviewRendererArgs {
+            node: Some(node.to_owned()),
+            layout_size,
+        };
+        lua::serialize::<PreviewRendererArgs>(lua, &args)
+            .and_then(|args| lua::call(lua, &renderer, args))
+            .unwrap_or_else(|e| format!("{e:?}"))
+    } else {
+        String::new()
+    };
+
+    let preview =
+        Paragraph::new(string_to_text(preview)).block(block(config, " Preview ".into()));
+
+    f.render_widget(preview, layout_size);
+}
+
 fn draw_selection(
     f: &mut Frame,
     _screen_size: TuiRect,
@@ -1360,7 +1407,13 @@ pub fn draw_layout(
             draw_sort_n_filter(f, screen_size, layout_size, app, lua)
         }
         Layout::HelpMenu => draw_help_menu(f, screen_size, layout_size, app, lua),
-        Layout::Selection => draw_selection(f, screen_size, layout_size, app, lua),
+        Layout::Selection => {
+            if app.selection.is_empty() {
+                draw_preview(f, screen_size, layout_size, app, lua);
+            } else {
+                draw_selection(f, screen_size, layout_size, app, lua);
+            }
+        }
         Layout::InputAndLogs => {
             if app.input.buffer.is_some() {
                 draw_input_buffer(f, screen_size, layout_size, app, lua);