feat(attach): Support `--index` option to choose specific session by provided number in active sessions ordered by creation date, resolve #823

feat(attach): Support `--first` option for `attach` sub-command to let zellij choose the alphabetically first session; resolve #823

fix(attach-first): Fix `--first` option to choose the first created session in the existent sessions

feat(attach): Support `--index` option to choose the session indexed by provided number like -t option of tmux

feat(attach): Support listing active sessions with index when a provided number is not found in the active sessions

feat(attach): Support listing active sessions with index when a provided number is not found in the active sessions

feat: Add anyhow to uniformly treat error types and avoid panics

6 files changed, 36 insertions, 22 deletions

diff --git a/zellij-utils/src/cli.rs b/zellij-utils/src/cli.rs
index 7ac9e958c..78615d929 100644
--- a/zellij-utils/src/cli.rs
+++ b/zellij-utils/src/cli.rs
@@ -85,6 +85,10 @@ pub enum Sessions {
         #[structopt(short, long)]
         create: bool,
 
+        /// Number of the session index in the active sessions ordered creation date.
+        #[structopt(long)]
+        index: Option<usize>,
+
         /// Change the behaviour of zellij
         #[structopt(subcommand, name = "options")]
         options: Option<SessionCommand>,
diff --git a/zellij-utils/src/errors.rs b/zellij-utils/src/errors.rs
index be75e4add..401cdc10b 100644
--- a/zellij-utils/src/errors.rs
+++ b/zellij-utils/src/errors.rs
@@ -258,6 +258,7 @@ pub enum ScreenContext {
     TerminalResize,
     ChangeMode,
     LeftClick,
+    RightClick,
     MouseRelease,
     MouseHold,
     Copy,
diff --git a/zellij-utils/src/input/actions.rs b/zellij-utils/src/input/actions.rs
index 8446bf0d8..9dd259580 100644
--- a/zellij-utils/src/input/actions.rs
+++ b/zellij-utils/src/input/actions.rs
@@ -28,6 +28,8 @@ pub enum Action {
     Quit,
     /// Write to the terminal.
     Write(Vec<u8>),
+    /// Write Characters to the terminal.
+    WriteChars(String),
     /// Switch to the specified input mode.
     SwitchToMode(InputMode),
     /// Resize focus pane in specified direction.
@@ -85,6 +87,7 @@ pub enum Action {
     /// Detach session and exit
     Detach,
     LeftClick(Position),
+    RightClick(Position),
     MouseRelease(Position),
     MouseHold(Position),
     Copy,
diff --git a/zellij-utils/src/input/config.rs b/zellij-utils/src/input/config.rs
index ecfe64c7c..66104016c 100644
--- a/zellij-utils/src/input/config.rs
+++ b/zellij-utils/src/input/config.rs
@@ -5,7 +5,7 @@ use std::fs::File;
 use std::io::{self, Read};
 use std::path::{Path, PathBuf};
 
-use serde::{Deserialize, Serialize};
+use serde::Deserialize;
 use std::convert::{TryFrom, TryInto};
 
 use super::keybinds::{Keybinds, KeybindsFromYaml};
@@ -20,7 +20,7 @@ const DEFAULT_CONFIG_FILE_NAME: &str = "config.yaml";
 type ConfigResult = Result<Config, ConfigError>;
 
 /// Intermediate deserialization config struct
-#[derive(Debug, Deserialize)]
+#[derive(Clone, Debug, Deserialize)]
 pub struct ConfigFromYaml {
     #[serde(flatten)]
     pub options: Option<Options>,
@@ -31,7 +31,7 @@ pub struct ConfigFromYaml {
 }
 
 /// Main configuration.
-#[derive(Debug, Clone, PartialEq, Deserialize, Serialize)]
+#[derive(Debug, Clone, PartialEq, Deserialize)]
 pub struct Config {
     pub keybinds: Keybinds,
     pub options: Options,
@@ -106,7 +106,8 @@ impl TryFrom<&CliArgs> for Config {
 impl Config {
     /// Uses defaults, but lets config override them.
     pub fn from_yaml(yaml_config: &str) -> ConfigResult {
-        let config_from_yaml: Option<ConfigFromYaml> = match serde_yaml::from_str(yaml_config) {
+        let maybe_config_from_yaml: Option<ConfigFromYaml> = match serde_yaml::from_str(yaml_config)
+        {
             Err(e) => {
                 // needs direct check, as `[ErrorImpl]` is private
                 // https://github.com/dtolnay/serde-yaml/issues/121
@@ -118,20 +119,9 @@ impl Config {
             Ok(config) => config,
         };
 
-        match config_from_yaml {
+        match maybe_config_from_yaml {
             None => Ok(Config::default()),
-            Some(config) => {
-                let keybinds = Keybinds::get_default_keybinds_with_config(config.keybinds);
-                let options = Options::from_yaml(config.options);
-                let themes = config.themes;
-                let plugins = PluginsConfig::get_plugins_with_default(config.plugins.try_into()?);
-                Ok(Config {
-                    keybinds,
-                    options,
-                    plugins,
-                    themes,
-                })
-            }
+            Some(config) => config.try_into(),
         }
     }
 
@@ -157,6 +147,23 @@ impl Config {
     }
 }
 
+impl TryFrom<ConfigFromYaml> for Config {
+    type Error = ConfigError;
+
+    fn try_from(config_from_yaml: ConfigFromYaml) -> ConfigResult {
+        let keybinds = Keybinds::get_default_keybinds_with_config(config_from_yaml.keybinds);
+        let options = Options::from_yaml(config_from_yaml.options);
+        let themes = config_from_yaml.themes;
+        let plugins = PluginsConfig::get_plugins_with_default(config_from_yaml.plugins.try_into()?);
+        Ok(Self {
+            keybinds,
+            options,
+            plugins,
+            themes,
+        })
+    }
+}
+
 // TODO: Split errors up into separate modules
 #[derive(Debug, Clone)]
 pub struct LayoutNameInTabError;
diff --git a/zellij-utils/src/ipc.rs b/zellij-utils/src/ipc.rs
index 995b89fb4..b27a097a1 100644
--- a/zellij-utils/src/ipc.rs
+++ b/zellij-utils/src/ipc.rs
@@ -104,7 +104,7 @@ impl Display for ExitReason {
                 f,
                 "Session attached to another client. Use --force flag to force connect."
             ),
-            Self::Error(e) => write!(f, "Error occured in server:\n{}", e),
+            Self::Error(e) => write!(f, "Error occurred in server:\n{}", e),
         }
     }
 }
diff --git a/zellij-utils/src/shared.rs b/zellij-utils/src/shared.rs
index 06d1378db..37dfc3be2 100644
--- a/zellij-utils/src/shared.rs
+++ b/zellij-utils/src/shared.rs
@@ -2,7 +2,7 @@
 
 use std::{iter, str::from_utf8};
 
-use colors_transform::{Color, Rgb};
+use colorsys::Rgb;
 use std::os::unix::fs::PermissionsExt;
 use std::path::Path;
 use std::{fs, io};
@@ -52,10 +52,9 @@ pub mod colors {
 }
 
 pub fn _hex_to_rgb(hex: &str) -> (u8, u8, u8) {
-    let rgb = Rgb::from_hex_str(hex)
+    Rgb::from_hex_str(hex)
         .expect("The passed argument must be a valid hex color")
-        .as_tuple();
-    (rgb.0 as u8, rgb.1 as u8, rgb.2 as u8)
+        .into()
 }
 
 pub fn default_palette() -> Palette {