Add "Visual-Mode" (#192)

* Add "Visual-Mode"

This adds a "visual-mode" file selection feature where a range-selection follows the file-cursor.

Description of usage is added to the docs.

Also, the "normal" and the new "visual-mode-selection" are now preserved
when a `DirList` is reloaded.

Wrap-up of changes:
* Add command `toggle_visual`, mapped to `V`
* Add command `escape`, mapped to `ESCAPE`
* Add style `[visual_mode_selection]` for file entries which are
  "temporarily" selected by visual-mode
* For `JoshutoDirEntry`, the attribute `selected` has been renamed to
  `permanent_selected`, and a second selection-attribute
  `visual_mode_selected` has been added. "Setters" and "getters" have
  been adapted/added accordingly. The former "getter" for the `selecetd`
  attribute still exists and returns `True` for an entry which is
  "permanant selected" _or_ "visual-mode selected". So any higher logic
  which acts on selected files does not need to care about "how" and
  entry is selected.
* Each `JoshutoDirList` has an optional index of the file where
  visual-mode has been entered and re-calculates the "visual-mode
  selecetd" status for each entry any time the cursor-index changes.
* The footer has been extended so it shows a "VIS" marker when the user
  is in visual-mode.

This implementation of visual-mode is a bit different from the ranger
one, where the visual-selection is turned into a "normal selection" when
a command (like `copy-files`) is issued. This implementation keeps
both selections separate until the user toggles back to "normal mode".
Only then the visual-selection is taken over to the "normal selection".
The user also can withdraw the visual-selection with `escape`.

The `escape` command may be used also for other "reset"-actions in the
future.

* fix syntax for Rust stable

* cargo clippy

22 files changed, 198 insertions, 22 deletions

diff --git a/src/commands/escape.rs b/src/commands/escape.rs
new file mode 100644
index 0000000..1a507df
--- /dev/null
+++ b/src/commands/escape.rs
@@ -0,0 +1,9 @@
+use crate::context::AppContext;
+use crate::error::JoshutoResult;
+
+pub fn escape(context: &mut AppContext) -> JoshutoResult {
+    if let Some(curr_dir_list) = context.tab_context_mut().curr_tab_mut().curr_list_mut() {
+        curr_dir_list.visual_mode_cancel();
+    };
+    Ok(())
+}
diff --git a/src/commands/flat.rs b/src/commands/flat.rs
index c0e9dfb..b9d0a64 100644
--- a/src/commands/flat.rs
+++ b/src/commands/flat.rs
@@ -79,7 +79,14 @@ pub fn flatten(depth: usize, context: &mut AppContext) -> JoshutoResult {
     contents.sort_by(|f1, f2| sort_options.compare(f1, f2));
 
     let metadata = JoshutoMetadata::from(path.as_path())?;
-    let dirlist = JoshutoDirList::new(path.clone(), contents, index, viewport_index, metadata);
+    let dirlist = JoshutoDirList::new(
+        path.clone(),
+        contents,
+        index,
+        viewport_index,
+        None,
+        metadata,
+    );
     history.insert(path, dirlist);
 
     Ok(())
diff --git a/src/commands/mod.rs b/src/commands/mod.rs
index f4e0ee5..c7420e2 100644
--- a/src/commands/mod.rs
+++ b/src/commands/mod.rs
@@ -3,6 +3,7 @@ pub mod change_directory;
 pub mod command_line;
 pub mod cursor_move;
 pub mod delete_files;
+pub mod escape;
 pub mod file_ops;
 pub mod flat;
 pub mod line_nums;
@@ -28,4 +29,5 @@ pub mod sub_process;
 pub mod subdir_fzf;
 pub mod tab_ops;
 pub mod touch_file;
+pub mod uimodes;
 pub mod zoxide;
diff --git a/src/commands/quit.rs b/src/commands/quit.rs
index ccc9a8b..165f289 100644
--- a/src/commands/quit.rs
+++ b/src/commands/quit.rs
@@ -3,7 +3,7 @@ use std::io;
 use crate::context::AppContext;
 use crate::error::{JoshutoError, JoshutoErrorKind, JoshutoResult};
 
-#[derive(Clone, Copy, Debug, PartialEq)]
+#[derive(Clone, Copy, Debug, PartialEq, Eq)]
 pub enum QuitAction {
     DoNot,
     Noop,
diff --git a/src/commands/selection.rs b/src/commands/selection.rs
index a4d26c4..3bfa227 100644
--- a/src/commands/selection.rs
+++ b/src/commands/selection.rs
@@ -23,11 +23,11 @@ fn select_without_pattern(context: &mut AppContext, options: &SelectOption) -> J
         if let Some(curr_list) = context.tab_context_mut().curr_tab_mut().curr_list_mut() {
             curr_list.iter_mut().for_each(|e| {
                 if options.reverse {
-                    e.set_selected(false);
+                    e.set_permanent_selected(false);
                 } else if options.toggle {
-                    e.set_selected(!e.is_selected());
+                    e.set_permanent_selected(!e.is_selected());
                 } else {
-                    e.set_selected(true);
+                    e.set_permanent_selected(true);
                 }
             });
         }
@@ -38,11 +38,11 @@ fn select_without_pattern(context: &mut AppContext, options: &SelectOption) -> J
         .and_then(|s| s.curr_entry_mut())
     {
         if options.reverse {
-            entry.set_selected(false);
+            entry.set_permanent_selected(false);
         } else if options.toggle {
-            entry.set_selected(!entry.is_selected());
+            entry.set_permanent_selected(!entry.is_selected());
         } else {
-            entry.set_selected(true);
+            entry.set_permanent_selected(true);
         }
         cursor_move::down(context, 1)?;
     }
@@ -64,11 +64,11 @@ fn select_with_pattern(
             .for_each(|e| {
                 found += 1;
                 if options.reverse {
-                    e.set_selected(false);
+                    e.set_permanent_selected(false);
                 } else if options.toggle {
-                    e.set_selected(!e.is_selected());
+                    e.set_permanent_selected(!e.is_selected());
                 } else {
-                    e.set_selected(true);
+                    e.set_permanent_selected(true);
                 }
             });
         context
diff --git a/src/commands/uimodes.rs b/src/commands/uimodes.rs
new file mode 100644
index 0000000..480cc75
--- /dev/null
+++ b/src/commands/uimodes.rs
@@ -0,0 +1,9 @@
+use crate::context::AppContext;
+use crate::error::JoshutoResult;
+
+pub fn toggle_visual_mode(context: &mut AppContext) -> JoshutoResult {
+    if let Some(curr_dir_list) = context.tab_context_mut().curr_tab_mut().curr_list_mut() {
+        curr_dir_list.toggle_visual_mode()
+    };
+    Ok(())
+}
diff --git a/src/config/option/sort_type.rs b/src/config/option/sort_type.rs
index 442eb45..a00ad29 100644
--- a/src/config/option/sort_type.rs
+++ b/src/config/option/sort_type.rs
@@ -8,7 +8,7 @@ use serde_derive::Deserialize;
 use crate::config::option::SortOption;
 use crate::fs::JoshutoDirEntry;
 
-#[derive(Clone, Copy, Debug, Deserialize, PartialEq)]
+#[derive(Clone, Copy, Debug, Deserialize, PartialEq, Eq)]
 pub enum SortType {
     Lexical,
     Mtime,
diff --git a/src/config/theme/app_theme.rs b/src/config/theme/app_theme.rs
index 651b2fd..6e3dfec 100644
--- a/src/config/theme/app_theme.rs
+++ b/src/config/theme/app_theme.rs
@@ -13,6 +13,8 @@ pub struct AppThemeRaw {
     #[serde(default)]
     pub selection: AppStyleRaw,
     #[serde(default)]
+    pub visual_mode_selection: AppStyleRaw,
+    #[serde(default)]
     pub directory: AppStyleRaw,
     #[serde(default)]
     pub executable: AppStyleRaw,
@@ -29,6 +31,7 @@ pub struct AppThemeRaw {
 impl From<AppThemeRaw> for AppTheme {
     fn from(crude: AppThemeRaw) -> Self {
         let selection = crude.selection.to_style_theme();
+        let visual_mode_selection = crude.visual_mode_selection.to_style_theme();
         let executable = crude.executable.to_style_theme();
         let regular = crude.regular.to_style_theme();
         let directory = crude.directory.to_style_theme();
@@ -46,6 +49,7 @@ impl From<AppThemeRaw> for AppTheme {
 
         Self {
             selection,
+            visual_mode_selection,
             executable,
             regular,
             directory,
@@ -61,6 +65,7 @@ impl From<AppThemeRaw> for AppTheme {
 pub struct AppTheme {
     pub regular: AppStyle,
     pub selection: AppStyle,
+    pub visual_mode_selection: AppStyle,
     pub directory: AppStyle,
     pub executable: AppStyle,
     pub link: AppStyle,
diff --git a/src/context/app_context.rs b/src/context/app_context.rs
index 364b5b1..66ffbc6 100644
--- a/src/context/app_context.rs
+++ b/src/context/app_context.rs
@@ -17,7 +17,7 @@ use crate::Args;
 use notify::{RecursiveMode, Watcher};
 use std::path;
 
-#[derive(Clone, Debug, PartialEq)]
+#[derive(Clone, Debug, PartialEq, Eq)]
 pub struct UiContext {
     pub layout: Vec<Rect>,
 }
diff --git a/src/fs/dirlist.rs b/src/fs/dirlist.rs
index 096c9a0..567b8eb 100644
--- a/src/fs/dirlist.rs
+++ b/src/fs/dirlist.rs
@@ -15,6 +15,8 @@ pub struct JoshutoDirList {
     index: Option<usize>,
     /// The index in this dir list to start with when rendering the list
     viewport_index: usize,
+    /// The index in this dir list where visual mode has started or None if not in visual mode
+    visual_mode_anchor_index: Option<usize>,
     _need_update: bool,
 }
 
@@ -24,6 +26,7 @@ impl JoshutoDirList {
         contents: Vec<JoshutoDirEntry>,
         index: Option<usize>,
         viewport_index: usize,
+        visual_mode_anchor_index: Option<usize>,
         metadata: JoshutoMetadata,
     ) -> Self {
         Self {
@@ -32,6 +35,7 @@ impl JoshutoDirList {
             metadata,
             index,
             viewport_index,
+            visual_mode_anchor_index,
             _need_update: false,
         }
     }
@@ -55,6 +59,7 @@ impl JoshutoDirList {
             _need_update: false,
             index,
             viewport_index: if let Some(ix) = index { ix } else { 0 },
+            visual_mode_anchor_index: None,
         })
     }
 
@@ -62,6 +67,62 @@ impl JoshutoDirList {
         self.index
     }
 
+    pub fn get_visual_mode_anchor_index(&self) -> Option<usize> {
+        self.visual_mode_anchor_index
+    }
+
+    fn update_visual_mode_selection(&mut self) {
+        //! To be invoked any time the cursor index, the visual mode anchor index,
+        //! or the shown sub-set of entries changes.
+        if let Some(vmix) = self.visual_mode_anchor_index {
+            if let Some(cix) = self.index {
+                self.iter_mut().enumerate().for_each(|(i, entry)| {
+                    entry.set_visual_mode_selected(
+                        (if vmix > cix {
+                            cix..vmix + 1
+                        } else {
+                            vmix..cix + 1
+                        })
+                        .contains(&i),
+                    )
+                })
+            }
+        } else {
+            self.iter_mut()
+                .for_each(|entry| entry.set_visual_mode_selected(false))
+        }
+    }
+
+    fn visual_mode_enable(&mut self) {
+        if let Some(ix) = self.index {
+            self.visual_mode_anchor_index = Some(ix)
+        };
+        self.update_visual_mode_selection();
+    }
+
+    fn visual_mode_disable(&mut self) {
+        self.visual_mode_anchor_index = None;
+        self.iter_mut().for_each(|entry| {
+            if entry.is_visual_mode_selected() {
+                entry.set_permanent_selected(true)
+            }
+        });
+        self.update_visual_mode_selection();
+    }
+
+    pub fn visual_mode_cancel(&mut self) {
+        self.visual_mode_anchor_index = None;
+        self.update_visual_mode_selection();
+    }
+
+    pub fn toggle_visual_mode(&mut self) {
+        if self.get_visual_mode_anchor_index().is_none() {
+            self.visual_mode_enable()
+        } else {
+            self.visual_mode_disable()
+        }
+    }
+
     fn update_viewport(&mut self, ui_context: &UiContext, options: &DisplayOption) {
         if let Some(ix) = self.index {
             let height = ui_context.layout[0].height as usize;
@@ -106,6 +167,7 @@ impl JoshutoDirList {
         if !ui_context.layout.is_empty() {
             self.update_viewport(ui_context, options);
         }
+        self.update_visual_mode_selection();
     }
 
     pub fn iter(&self) -> Iter<JoshutoDirEntry> {
diff --git a/src/fs/entry.rs b/src/fs/entry.rs
index 8337bc4..f7dae32 100644
--- a/src/fs/entry.rs
+++ b/src/fs/entry.rs
@@ -12,7 +12,10 @@ pub struct JoshutoDirEntry {
     label: String,
     path: path::PathBuf,
     pub metadata: JoshutoMetadata,
-    selected: bool,
+    /// Directly selected by the user, _not_ by a current visual mode selection
+    permanent_selected: bool,
+    /// Temporarily selected by the visual mode range
+    visual_mode_selected: bool,
     _marked: bool,
 }
 
@@ -63,11 +66,23 @@ impl JoshutoDirEntry {
     }
 
     pub fn is_selected(&self) -> bool {
-        self.selected
+        self.permanent_selected || self.visual_mode_selected
     }
 
-    pub fn set_selected(&mut self, selected: bool) {
-        self.selected = selected;
+    pub fn is_permanent_selected(&self) -> bool {
+        self.permanent_selected
+    }
+
+    pub fn is_visual_mode_selected(&self) -> bool {
+        self.visual_mode_selected
+    }
+
+    pub fn set_permanent_selected(&mut self, selected: bool) {
+        self.permanent_selected = selected;
+    }
+
+    pub fn set_visual_mode_selected(&mut self, visual_mode_selected: bool) {
+        self.visual_mode_selected = visual_mode_selected;
     }
 
     pub fn get_ext(&self) -> &str {
@@ -102,7 +117,8 @@ impl JoshutoDirEntry {
             label,
             path,
             metadata,
-            selected: false,
+            permanent_selected: false,
+            visual_mode_selected: false,
             _marked: false,
         })
     }
diff --git a/src/fs/metadata.rs b/src/fs/metadata.rs
index fd192cc..616e09c 100644
--- a/src/fs/metadata.rs
+++ b/src/fs/metadata.rs
@@ -1,6 +1,6 @@
 use std::{fs, io, path, time};
 
-#[derive(Clone, Debug, PartialEq)]
+#[derive(Clone, Debug, PartialEq, Eq)]
 pub enum FileType {
     Directory,
     File,
diff --git a/src/history.rs b/src/history.rs
index 42c5b0a..162c3bd 100644
--- a/src/history.rs
+++ b/src/history.rs
@@ -156,6 +156,8 @@ pub fn create_dirlist_with_history(
 ) -> io::Result<JoshutoDirList> {
     let filter_func = options.filter_func();
     let mut contents = read_directory(path, filter_func, options)?;
+
+    // re-use directory size information on reload
     for entry in contents.iter_mut() {
         if entry.metadata.is_dir() {
             if let Some(lst) = history.get(entry.file_path()) {
@@ -164,6 +166,19 @@ pub fn create_dirlist_with_history(
         }
     }
 
+    // preserve selection status of entries on reload
+    if let Some(former_dir_list) = history.get(path) {
+        let former_entries_by_file_name = HashMap::<&str, &JoshutoDirEntry>::from_iter(
+            former_dir_list.contents.iter().map(|e| (e.file_name(), e)),
+        );
+        for entry in contents.iter_mut() {
+            if let Some(former_entry) = former_entries_by_file_name.get(entry.file_name()) {
+                entry.set_permanent_selected(former_entry.is_permanent_selected());
+                entry.set_visual_mode_selected(former_entry.is_visual_mode_selected());
+            }
+        }
+    }
+
     let sort_options = tab_options.sort_options_ref();
     contents.sort_by(|f1, f2| sort_options.compare(f1, f2));
 
@@ -199,6 +214,20 @@ pub fn create_dirlist_with_history(
             None => 0,
         }
     };
+    let visual_mode_anchor_index = match history.get(path) {
+        None => None,
+        Some(dirlist) => {
+            dirlist
+                .get_visual_mode_anchor_index()
+                .map(|old_visual_mode_anchor_index| {
+                    if old_visual_mode_anchor_index < contents_len {
+                        old_visual_mode_anchor_index
+                    } else {
+                        contents_len - 1
+                    }
+                })
+        }
+    };
 
     let metadata = JoshutoMetadata::from(path)?;
     let dirlist = JoshutoDirList::new(
@@ -206,6 +235,7 @@ pub fn create_dirlist_with_history(
         contents,
         index,
         viewport_index,
+        visual_mode_anchor_index,
         metadata,
     );
 
diff --git a/src/key_command/command.rs b/src/key_command/command.rs
index 9ffbe5c..6c698ea 100644
--- a/src/key_command/command.rs
+++ b/src/key_command/command.rs
@@ -7,6 +7,8 @@ use crate::io::FileOperationOptions;
 #[derive(Clone, Debug)]
 #[allow(clippy::enum_variant_names)]
 pub enum Command {
+    Escape,
+    ToggleVisualMode,
     BulkRename,
 
     ChangeDirectory(path::PathBuf),
diff --git a/src/key_command/constants.rs b/src/key_command/constants.rs
index 8dd60ed..68b99d2 100644
--- a/src/key_command/constants.rs
+++ b/src/key_command/constants.rs
@@ -69,6 +69,7 @@ cmd_constants![
     (CMD_TAB_SWITCH, "tab_switch"),
     (CMD_TAB_SWITCH_INDEX, "tab_switch_index"),
     (CMD_TOGGLE_HIDDEN, "toggle_hidden"),
+    (CMD_TOGGLE_VISUAL, "toggle_visual"),
     (CMD_SWITCH_LINE_NUMBERS, "line_nums"),
     (CMD_TOUCH_FILE, "touch"),
     (CMD_HELP, "help"),
@@ -77,6 +78,7 @@ cmd_constants![
     (CMD_ZOXIDE, "z"),
     (CMD_ZOXIDE_INTERACTIVE, "zi"),
     (CMD_FLAT, "flat"),
+    (CMD_ESCAPE, "escape"),
 ];
 
 pub fn complete_command(partial_command: &str) -> Vec<Pair> {
diff --git a/src/key_command/impl_appcommand.rs b/src/key_command/impl_appcommand.rs
index fe7dbc2..f942d82 100644
--- a/src/key_command/impl_appcommand.rs
+++ b/src/key_command/impl_appcommand.rs
@@ -8,6 +8,9 @@ impl AppCommand for Command {
 
             Self::Quit(_) => CMD_QUIT,
 
+            Self::ToggleVisualMode => CMD_TOGGLE_VISUAL,
+            Self::Escape => CMD_ESCAPE,
+
             Self::BulkRename => CMD_BULK_RENAME,
 
             Self::ChangeDirectory(_) => CMD_CHANGE_DIRECTORY,
diff --git a/src/key_command/impl_appexecute.rs b/src/key_command/impl_appexecute.rs
index cd7aacc..65ef504 100644
--- a/src/key_command/impl_appexecute.rs
+++ b/src/key_command/impl_appexecute.rs
@@ -13,7 +13,10 @@ impl AppExecute for Command {
         backend: &mut AppBackend,
         keymap_t: &AppKeyMapping,
     ) -> JoshutoResult {
-        match &*self {
+        match self {
+            Self::Escape => escape::escape(context),
+            Self::ToggleVisualMode => uimodes::toggle_visual_mode(context),
+
             Self::BulkRename => bulk_rename::bulk_rename(context, backend),
 
             Self::ChangeDirectory(p) => {
diff --git a/src/key_command/impl_comment.rs b/src/key_command/impl_comment.rs
index 36697c0..6f56c78 100644
--- a/src/key_command/impl_comment.rs
+++ b/src/key_command/impl_comment.rs
@@ -7,8 +7,11 @@ impl CommandComment for Command {
     // These comments are displayed at the help page
     fn comment(&self) -> &'static str {
         match self {
+            Self::Escape => "Escape from visual mode (cancel)",
             Self::BulkRename => "Bulk rename",
 
+            Self::ToggleVisualMode => "Toggle visual mode",
+
             Self::ChangeDirectory(_) => "Change directory",
             Self::ParentDirectory => "CD to parent directory",
             Self::PreviousDirectory => "CD to the last dir in history",
diff --git a/src/key_command/impl_display.rs b/src/key_command/impl_display.rs
index 9c9a7b4..c414486 100644
--- a/src/key_command/impl_display.rs
+++ b/src/key_command/impl_display.rs
@@ -2,7 +2,7 @@ use super::{AppCommand, Command};
 
 impl std::fmt::Display for Command {
     fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
-        match &*self {
+        match self {
             Self::ChangeDirectory(p) => write!(f, "{} {:?}", self.command(), p),
             Self::CommandLine(s, p) => write!(f, "{} {} {}", self.command(), s, p),
             Self::CursorMoveUp(i) => write!(f, "{} {}", self.command(), i),
diff --git a/src/key_command/impl_from_str.rs b/src/key_command/impl_from_str.rs
index 2c9fc96..f358e3e 100644
--- a/src/key_command/impl_from_str.rs
+++ b/src/key_command/impl_from_str.rs
@@ -34,6 +34,10 @@ impl std::str::FromStr for Command {
             None => (s, ""),
         };
 
+        simple_command_conversion_case!(command, CMD_ESCAPE, Self::Escape);
+
+        simple_command_conversion_case!(command, CMD_TOGGLE_VISUAL, Self::ToggleVisualMode);
+
         simple_command_conversion_case!(command, CMD_NEW_TAB, Self::NewTab);
         simple_command_conversion_case!(command, CMD_CLOSE_TAB, Self::CloseTab);
 
diff --git a/src/ui/widgets/tui_footer.rs b/src/ui/widgets/tui_footer.rs
index 1cc0995..d4fbef7 100644
--- a/src/ui/widgets/tui_footer.rs
+++ b/src/ui/widgets/tui_footer.rs
@@ -26,6 +26,7 @@ impl<'a> Widget for TuiFooter<'a> {
             Some(i) if i < self.dirlist.len() => {
                 let entry = &self.dirlist.contents[i];
 
+                let visual_mode_style = Style::default().fg(Color::Black).bg(Color::LightRed);
                 let mode_style = Style::default().fg(Color::Cyan);
                 let mode_str = unix::mode_to_string(entry.metadata.permissions_ref().mode());
 
@@ -33,6 +34,19 @@ impl<'a> Widget for TuiFooter<'a> {
                 let size_str = format::file_size_to_string(entry.metadata.len());
 
                 let mut text = vec![
+                    Span::styled(
+                        if self.dirlist.get_visual_mode_anchor_index().is_none() {
+                            ""
+                        } else {
+                            "VIS"
+                        },
+                        visual_mode_style,
+                    ),
+                    Span::raw(if self.dirlist.get_visual_mode_anchor_index().is_none() {
+                        ""
+                    } else {
+                        " "
+                    }),
                     Span::styled(mode_str, mode_style),
                     Span::raw("  "),
                     Span::raw(format!("{}/{}", i + 1, self.dirlist.len())),
diff --git a/src/util/style.rs b/src/util/style.rs
index 4312425..6715f50 100644
--- a/src/util/style.rs
+++ b/src/util/style.rs
@@ -10,7 +10,12 @@ pub fn entry_style(entry: &JoshutoDirEntry) -> Style {
     let filetype = &metadata.file_type();
     let linktype = &metadata.link_type();
 
-    if entry.is_selected() {
+    if entry.is_visual_mode_selected() {
+        Style::default()
+            .fg(THEME_T.visual_mode_selection.fg)
+            .bg(THEME_T.visual_mode_selection.bg)
+            .add_modifier(THEME_T.visual_mode_selection.modifier)
+    } else if entry.is_permanent_selected() {
         Style::default()
             .fg(THEME_T.selection.fg)
             .bg(THEME_T.selection.bg)