limit the number of panels to 2

Can be changed in conf with `max_panels_count`.

Fix #345

14 files changed, 181 insertions, 112 deletions

diff --git a/src/app/app.rs b/src/app/app.rs
index da6f057..f30fc60 100644
--- a/src/app/app.rs
+++ b/src/app/app.rs
@@ -103,8 +103,18 @@ impl App {
         })
     }
 
+    fn panel_ref_to_idx(&self, panel_ref: PanelReference) -> Option<usize> {
+        match panel_ref {
+            PanelReference::Active => Some(self.active_panel_idx),
+            PanelReference::Leftest => Some(0),
+            PanelReference::Rightest => Some(self.panels.len().get() - 1),
+            PanelReference::Id(id) => self.panel_id_to_idx(id),
+            PanelReference::Preview => self.preview.and_then(|id| self.panel_id_to_idx(id)),
+        }
+    }
+
     /// return the current index of the panel whith given id
-    fn panel_idx(&self, id: PanelId) -> Option<usize> {
+    fn panel_id_to_idx(&self, id: PanelId) -> Option<usize> {
         self.panels.iter().position(|panel| panel.id == id)
     }
 
@@ -249,7 +259,7 @@ impl App {
             con,
         )? {
             ApplyOnPanel { id } => {
-                if let Some(idx) = self.panel_idx(id) {
+                if let Some(idx) = self.panel_id_to_idx(id) {
                     if let DisplayError(txt) = self.panels[idx].apply_command(
                         w,
                         &cmd,
@@ -269,12 +279,11 @@ impl App {
                     warn!("no panel found for ApplyOnPanel");
                 }
             }
-            ClosePanel { validate_purpose, id } => {
+            ClosePanel { validate_purpose, panel_ref } => {
                 if is_input_invocation {
                     self.mut_panel().clear_input_invocation();
                 }
-                let close_idx = id
-                    .and_then(|id| self.panel_idx(id))
+                let close_idx = self.panel_ref_to_idx(panel_ref)
                     .unwrap_or_else(||
                         // when there's a preview panel, we close it rather than the app
                         if self.panels.len().get()==2 && self.preview.is_some() {
@@ -320,11 +329,26 @@ impl App {
             }
             HandleInApp(internal) => {
                 let new_active_panel_idx = match internal {
-                    Internal::panel_left if self.active_panel_idx > 0 => {
-                        Some(self.active_panel_idx - 1)
+                    Internal::panel_left => {
+                        // we're not here to create a panel, this is handled in the state
+                        // we're here because the state wants us to either move to the panel
+                        // to the left, or close the rightest one
+                        if self.active_panel_idx == 0 {
+                            self.close_panel(self.panels.len().get()-1);
+                            None
+                        } else {
+                            Some(self.active_panel_idx - 1)
+                        }
                     }
-                    Internal::panel_right if self.active_panel_idx + 1 < self.panels.len().get() => {
-                        Some(self.active_panel_idx + 1)
+                    Internal::panel_right => {
+                        // we're not here to create panels (it's done in the state).
+                        // So we either move to the right or close the leftes panel
+                        if self.active_panel_idx + 1 == self.panels.len().get() {
+                            self.close_panel(0);
+                            None
+                        } else {
+                            Some(self.active_panel_idx + 1)
+                        }
                     }
                     _ => {
                         debug!("unhandled propagated internal. cmd={:?}", &cmd);
@@ -456,7 +480,7 @@ impl App {
 
     /// update the state of the preview, if there's some
     fn update_preview(&mut self, con: &AppContext) {
-        let preview_idx = self.preview.and_then(|id| self.panel_idx(id));
+        let preview_idx = self.preview.and_then(|id| self.panel_id_to_idx(id));
         if let Some(preview_idx) = preview_idx {
             let path = self.state().selected_path();
             let old_path = self.panels[preview_idx].state().selected_path();
diff --git a/src/app/cmd_result.rs b/src/app/cmd_result.rs
index 528bf6f..9c822a0 100644
--- a/src/app/cmd_result.rs
+++ b/src/app/cmd_result.rs
@@ -17,6 +17,16 @@ pub enum HDir {
     Right,
 }
 
+/// the symbolic reference to the panel to close
+#[derive(Debug, Clone, Copy, PartialEq)]
+pub enum PanelReference {
+    Active,
+    Leftest,
+    Rightest,
+    Id(PanelId),
+    Preview,
+}
+
 /// Result of applying a command to a state
 pub enum AppStateCmdResult {
     ApplyOnPanel {
@@ -24,7 +34,7 @@ pub enum AppStateCmdResult {
     },
     ClosePanel {
         validate_purpose: bool,
-        id: Option<PanelId>, // None if current panel
+        panel_ref: PanelReference,
     },
     DisplayError(String),
     ExecuteSequence {
diff --git a/src/app/context.rs b/src/app/context.rs
index 1d429d9..55bf296 100644
--- a/src/app/context.rs
+++ b/src/app/context.rs
@@ -61,6 +61,10 @@ pub struct AppContext {
     pub modal: bool,
 
     pub mouse_capture_disabled: bool,
+
+    /// max number of panels (including preview) that can be
+    /// open. Guaranteed to be at least 2.
+    pub max_panels_count: usize,
 }
 
 impl AppContext {
@@ -89,6 +93,9 @@ impl AppContext {
             .transpose()?
             .unwrap_or_default();
         let ext_colors = ExtColorMap::try_from(&config.ext_colors)?;
+        let max_panels_count = config.max_panels_count
+            .unwrap_or(2)
+            .clamp(2, 100);
         Ok(Self {
             config_paths,
             launch_args,
@@ -103,6 +110,7 @@ impl AppContext {
             icons,
             modal: config.modal.unwrap_or(false),
             mouse_capture_disabled: config.disable_mouse_capture.unwrap_or(false),
+            max_panels_count,
         })
     }
 }
diff --git a/src/app/state.rs b/src/app/state.rs
index 29a4579..ed911c4 100644
--- a/src/app/state.rs
+++ b/src/app/state.rs
@@ -127,11 +127,11 @@ pub trait AppState {
             }
             Internal::close_panel_ok => AppStateCmdResult::ClosePanel {
                 validate_purpose: true,
-                id: None,
+                panel_ref: PanelReference::Active,
             },
             Internal::close_panel_cancel => AppStateCmdResult::ClosePanel {
                 validate_purpose: false,
-                id: None,
+                panel_ref: PanelReference::Active,
             },
             #[cfg(unix)]
             Internal::filesystems => {
@@ -283,27 +283,17 @@ pub trait AppState {
                 if let Some(id) = cc.preview {
                     AppStateCmdResult::ClosePanel {
                         validate_purpose: false,
-                        id: Some(id),
+                        panel_ref: PanelReference::Id(id),
                     }
                 } else {
                     AppStateCmdResult::Keep
                 }
             }
             Internal::panel_left => {
-                if cc.areas.is_first() {
-                    AppStateCmdResult::Keep
-                } else {
-                    // we ask the app to focus the panel to the left
-                    AppStateCmdResult::HandleInApp(Internal::panel_left)
-                }
+                AppStateCmdResult::HandleInApp(Internal::panel_left)
             }
             Internal::panel_right => {
-                if cc.areas.is_last() {
-                    AppStateCmdResult::Keep
-                } else {
-                    // we ask the app to focus the panel to the left
-                    AppStateCmdResult::HandleInApp(Internal::panel_right)
-                }
+                AppStateCmdResult::HandleInApp(Internal::panel_right)
             }
             Internal::print_path => {
                 print::print_path(self.selected_path(), con)?
@@ -431,7 +421,7 @@ pub trait AppState {
             if close_if_open {
                 AppStateCmdResult::ClosePanel {
                     validate_purpose: false,
-                    id: Some(id),
+                    panel_ref: PanelReference::Id(id),
                 }
             } else {
                 if prefered_mode.is_some() {
diff --git a/src/browser/browser_state.rs b/src/browser/browser_state.rs
index 91110a3..9dae74c 100644
--- a/src/browser/browser_state.rs
+++ b/src/browser/browser_state.rs
@@ -346,30 +346,23 @@ impl AppState for BrowserState {
                 AppStateCmdResult::Keep
             }
             Internal::panel_left => {
-                if cc.areas.is_first() {
-                    if cc.preview.is_some() && cc.areas.nb_pos == 2 {
-                        AppStateCmdResult::ClosePanel {
-                            validate_purpose: false,
-                            id: cc.preview,
-                        }
-                    } else {
-                        // we ask for the creation of a panel to the left
-                        internal_focus::new_panel_on_path(
-                            self.selected_path().to_path_buf(),
-                            screen,
-                            self.displayed_tree().options.clone(),
-                            PanelPurpose::None,
-                            con,
-                            HDir::Left,
-                        )
-                    }
+                if cc.areas.is_first() && cc.areas.nb_pos < cc.con.max_panels_count  {
+                    // we ask for the creation of a panel to the left
+                    internal_focus::new_panel_on_path(
+                        self.selected_path().to_path_buf(),
+                        screen,
+                        self.displayed_tree().options.clone(),
+                        PanelPurpose::None,
+                        con,
+                        HDir::Left,
+                    )
                 } else {
-                    // we ask the app to focus the panel to the left
+                    // we let the app handle other cases
                     AppStateCmdResult::HandleInApp(Internal::panel_left)
                 }
             }
             Internal::panel_right => {
-                if cc.areas.is_last() {
+                if cc.areas.is_last() && cc.areas.nb_pos < cc.con.max_panels_count {
                     let purpose = if self.selected_path().is_file() && cc.preview.is_none() {
                         PanelPurpose::Preview
                     } else {
@@ -385,7 +378,8 @@ impl AppState for BrowserState {
                         HDir::Right,
                     )
                 } else {
-                    // we ask the app to focus the panel to the right
+                    // we ask the app to handle other cases :
+                    // focus the panel to the right or close the leftest one
                     AppStateCmdResult::HandleInApp(Internal::panel_right)
                 }
             }
@@ -415,7 +409,7 @@ impl AppState for BrowserState {
                     debug!("start_end understood as end");
                     AppStateCmdResult::ClosePanel {
                         validate_purpose: true,
-                        id: None,
+                        panel_ref: PanelReference::Active,
                     }
                 } else {
                     debug!("start_end understood as start");
diff --git a/src/cli/app_launch_args.rs b/src/cli/app_launch_args.rs
new file mode 100644
index 0000000..59be3fe
--- /dev/null
+++ b/src/cli/app_launch_args.rs
@@ -0,0 +1,25 @@
+
+use {
+    crate::{
+        tree::TreeOptions,
+    },
+    std::{
+        path::PathBuf,
+    },
+};
+
+
+/// the parsed program launch arguments which are kept for the
+/// life of the program
+pub struct AppLaunchArgs {
+    pub root: PathBuf,                    // what should be the initial root
+    pub file_export_path: Option<String>, // where to write the produced path (if required with --out)
+    pub cmd_export_path: Option<String>,  // where to write the produced command (if required with --outcmd)
+    pub tree_options: TreeOptions,        // initial tree options
+    pub commands: Option<String>,         // commands passed as cli argument, still unparsed
+    pub height: Option<u16>,              // an optional height to replace the screen's one
+    pub no_style: bool,                   // whether to remove all styles (including colors)
+
+    #[cfg(feature = "client-server")]
+    pub listen: Option<String>,
+}
diff --git a/src/clap.rs b/src/cli/clap_args.rs
index 765a8bf..765a8bf 100644
--- a/src/clap.rs
+++ b/src/cli/clap_args.rs
diff --git a/src/cli/install_launch_args.rs b/src/cli/install_launch_args.rs
new file mode 100644
index 0000000..5b8ef39
--- /dev/null
+++ b/src/cli/install_launch_args.rs
@@ -0,0 +1,54 @@
+
+
+use {
+    crate::{
+        errors::ProgramError,
+        shell_install::ShellInstallState,
+    },
+    clap::{self, ArgMatches},
+    std::{
+        env,
+        str::FromStr,
+    },
+};
+
+
+/// launch arguments related to installation
+/// (not used by the application after the first step)
+pub struct InstallLaunchArgs {
+    pub install: Option<bool>,                        // installation is required
+    pub set_install_state: Option<ShellInstallState>, // the state to set
+    pub print_shell_function: Option<String>,         // shell function to print on stdout
+}
+impl InstallLaunchArgs {
+    pub fn from(cli_args: &ArgMatches<'_>) -> Result<Self, ProgramError> {
+        let mut install = None;
+        if let Ok(s) = env::var("BR_INSTALL") {
+            if s == "yes" {
+                install = Some(true);
+            } else if s == "no" {
+                install = Some(false);
+            } else {
+                warn!("Unexpected value of BR_INSTALL: {:?}", s);
+            }
+        }
+        // the cli arguments may override the env var value
+        if cli_args.is_present("install") {
+            install = Some(true);
+        } else if cli_args.value_of("cmd-export-path").is_some() {
+            install = Some(false);
+        }
+        let print_shell_function = cli_args
+            .value_of("print-shell-function")
+            .map(str::to_string);
+        let set_install_state = cli_args
+            .value_of("set-install-state")
+            .map(ShellInstallState::from_str)
+            .transpose()?;
+        Ok(Self {
+            install,
+            set_install_state,
+            print_shell_function,
+        })
+    }
+}
diff --git a/src/cli.rs b/src/cli/mod.rs
index 8bed34d..c92d41f 100644
--- a/src/cli.rs
+++ b/src/cli/mod.rs
@@ -1,5 +1,15 @@
-/// this module manages reading and translating
-/// the arguments passed on launch of the application.
+//! this module manages reading and translating
+//! the arguments passed on launch of the application.
+
+pub mod clap_args;
+mod app_launch_args;
+mod install_launch_args;
+
+pub use {
+    app_launch_args::*,
+    install_launch_args::*,
+};
+
 use {
     crate::{
         app::{App, AppContext},
@@ -7,7 +17,7 @@ use {
         display,
         errors::{ProgramError, TreeBuildError},
         launchable::Launchable,
-        shell_install::{ShellInstall, ShellInstallState},
+        shell_install::ShellInstall,
         tree::TreeOptions,
         verb::VerbStore,
     },
@@ -23,65 +33,9 @@ use {
         env,
         io::{self, Write},
         path::{Path, PathBuf},
-        str::FromStr,
     },
 };
 
-/// launch arguments related to installation
-/// (not used by the application after the first step)
-struct InstallLaunchArgs {
-    install: Option<bool>,                        // installation is required
-    set_install_state: Option<ShellInstallState>, // the state to set
-    print_shell_function: Option<String>,         // shell function to print on stdout
-}
-impl InstallLaunchArgs {
-    fn from(cli_args: &ArgMatches<'_>) -> Result<Self, ProgramError> {
-        let mut install = None;
-        if let Ok(s) = env::var("BR_INSTALL") {
-            if s == "yes" {
-                install = Some(true);
-            } else if s == "no" {
-                install = Some(false);
-            } else {
-                warn!("Unexpected value of BR_INSTALL: {:?}", s);
-            }
-        }
-        // the cli arguments may override the env var value
-        if cli_args.is_present("install") {
-            install = Some(true);
-        } else if cli_args.value_of("cmd-export-path").is_some() {
-            install = Some(false);
-        }
-        let print_shell_function = cli_args
-            .value_of("print-shell-function")
-            .map(str::to_string);
-        let set_install_state = cli_args
-            .value_of("set-install-state")
-            .map(ShellInstallState::from_str)
-            .transpose()?;
-        Ok(Self {
-            install,
-            set_install_state,
-            print_shell_function,
-        })
-    }
-}
-
-/// the parsed program launch arguments which are kept for the
-/// life of the program
-pub struct AppLaunchArgs {
-    pub root: PathBuf,                    // what should be the initial root
-    pub file_export_path: Option<String>, // where to write the produced path (if required with --out)
-    pub cmd_export_path: Option<String>,  // where to write the produced command (if required with --outcmd)
-    pub tree_options: TreeOptions,        // initial tree options
-    pub commands: Option<String>,         // commands passed as cli argument, still unparsed
-    pub height: Option<u16>,              // an optional height to replace the screen's one
-    pub no_style: bool,                   // whether to remove all styles (including colors)
-
-    #[cfg(feature = "client-server")]
-    pub listen: Option<String>,
-}
-
 #[cfg(not(windows))]
 fn canonicalize_root(root: &Path) -> io::Result<PathBuf> {
     root.canonicalize()
@@ -138,7 +92,7 @@ fn is_no_style(cli_matches: &ArgMatches) -> bool {
 /// run the application, and maybe return a launchable
 /// which must be run after broot
 pub fn run() -> Result<Option<Launchable>, ProgramError> {
-    let clap_app = crate::clap::clap_app();
+    let clap_app = clap_args::clap_app();
 
     // parse the launch arguments we got from cli
     let cli_matches = clap_app.get_matches();
diff --git a/src/conf/conf.rs b/src/conf/conf.rs
index 2ac0399..51a40ce 100644
--- a/src/conf/conf.rs
+++ b/src/conf/conf.rs
@@ -82,6 +82,8 @@ pub struct Conf {
 
     pub modal: Option<bool>,
 
+    pub max_panels_count: Option<usize>,
+
 }
 
 impl Conf {
@@ -145,6 +147,7 @@ impl Conf {
         overwrite!(self, cols_order, conf);
         overwrite!(self, skin, conf);
         overwrite!(self, search_modes, conf);
+        overwrite!(self, max_panels_count, conf);
         overwrite!(self, modal, conf);
         self.verbs.append(&mut conf.verbs);
         // the following maps are "additive": we can add entries from several
diff --git a/src/conf/default_conf.rs b/src/conf/default_conf.rs
index df1868b..b8a21e4 100644
--- a/src/conf/default_conf.rs
+++ b/src/conf/default_conf.rs
@@ -327,5 +327,12 @@ pub const DEFAULT_CONF_FILE: &str = r#"
 	# 	rs: yellow
 	# }
 
+
+	###############################################################
+	# Max Panels Count
+        #
+	# Change this if you sometimes want to have more than 2 panels
+        # open
+        # max_panels_count: 2
 }
 "#;
diff --git a/src/filesystems/filesystems_state.rs b/src/filesystems/filesystems_state.rs
index fa990a5..22d57e1 100644
--- a/src/filesystems/filesystems_state.rs
+++ b/src/filesystems/filesystems_state.rs
@@ -496,7 +496,7 @@ impl AppState for FilesystemState {
                 )
             }
             Internal::panel_left => {
-                if cc.areas.is_first() {
+                if cc.areas.is_first() && cc.areas.nb_pos < cc.con.max_panels_count {
                     // we ask for the creation of a panel to the left
                     internal_focus::new_panel_on_path(
                         self.selected_path().to_path_buf(),
@@ -512,7 +512,7 @@ impl AppState for FilesystemState {
                 }
             }
             Internal::panel_right => {
-                if cc.areas.is_last() {
+                if cc.areas.is_last() && cc.areas.nb_pos < cc.con.max_panels_count {
                     // we ask for the creation of a panel to the right
                     internal_focus::new_panel_on_path(
                         self.selected_path().to_path_buf(),
diff --git a/src/lib.rs b/src/lib.rs
index d552adb..61a5738 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -9,7 +9,6 @@
 
 pub mod app;
 pub mod browser;
-pub mod clap;
 pub mod cli;
 pub mod command;
 pub mod conf;
diff --git a/src/tree/tree_options.rs b/src/tree/tree_options.rs
index 862b8f9..636b9c8 100644
--- a/src/tree/tree_options.rs
+++ b/src/tree/tree_options.rs
@@ -1,6 +1,7 @@
 use {
     super::Sort,
     crate::{
+        cli::clap_args,
         conf::Conf,
         display::{Cols, DEFAULT_COLS},
         errors::ConfError,
@@ -76,7 +77,7 @@ impl TreeOptions {
     /// change tree options according to configuration
     pub fn apply_config(&mut self, config: &Conf) -> Result<(), ConfError> {
         if let Some(default_flags) = &config.default_flags {
-            let clap_app = crate::clap::clap_app().setting(clap::AppSettings::NoBinaryName);
+            let clap_app = clap_args::clap_app().setting(clap::AppSettings::NoBinaryName);
             let flags_args = format!("-{}", default_flags);
             let conf_matches = clap_app.get_matches_from(vec![&flags_args]);
             self.apply_launch_args(&conf_matches);