feat(ui): initial mouse support (#448)

* Initial mouse support

* enable mouse support (termion MouseTerminal)
* handle scroll up and down events

* Allow enabling/disabling of mouse reporting

Store the mouse terminal on OsInputOutput

* WIP: switch pane focus with mouse

* testing to get mouse character selection

* wip mouse selection

* wip: mouse selection

- initial handling of mouse events for
  text selection within a pane
- wide characters currently problematic
- selection is not highlighted

* highlight currently selected text

* improve get currently selected text from TerminalPane

* copy selection to clipboard (wayland only for now)

* Add missing set_should_render on selection update

* Improve text selection

- Strip whitespace from end of lines
- Insert newlines when selection spans multiple lines

* Simplify selection logic

- Remove Range struct
- Selection is not an Option anymore, it's empty when start == end

* copy selection to clipboard with OSC-52 sequence

* Improve text selection with multiple panes

- Constrain mouse hold and release events to currently active pane
- Fix calculation of columns with side by side panes

* fix for PositionAndSize changes

* Fix mouse selection with full screen pane.

- Transform mouse event positions to relative when passing to pane.

* Move selection to grid, rework highlighting.

- Mark selected lines for update in grid output buffer, for now in the
  simplest way possible, but can be made more efficient by calculating
  changed lines only.
- Clear selection on pane resize.
- Re-add logic to forward mouse hold and release events only to
  currently active pane.

* Tidy up selection

- add method to get selection line range
- add method to sort the current selection

* Grid: move current selection up/down when scrolling

- Make the selection work with lines in lines_above and lines_below
- Todo: update selection end when scrolling with mouse button being held
- Todo: figure out how to move selection when new characters are added.

* Grid: move selection when new lines are added

* Keep track of selection being active

- Handle the selection growing/shrinking when scrolling with mouse
  button held down but not yet released.

* Improve selection end with multiple panes

* Tidying up

- remove logging statements, unused code

* Add some unit tests for selection, move position to zellij-utils

* Change Position::new to take i32 for line

* Grid: add unit tests for copy from selection

* add basic integration test for mouse pane focus

* Add basic integration test for mouse scroll

* Use color from palette for selection rendering

* Improve performance of selection render

- Try to minimize lines to update on selection start/update/end

* fixes for updated start method

* fix lines not in viewport being marked for rendering

- the previous optimization to grid selection rendering was always
adding the lines at the extremes of previous selection, causing problems
when scrolling up or down
- make sure to only add lines in viewport

* Disable mouse mode on exit

* use saturating_sub for usize subtractions

* copy selection to clipboard on mouse release

* disable mouse on exit after error

* remove left-over comments

* remove copy keybinding

* add default impl for selection methods in Pane

- remove the useless methods from Impl Pane in PluginPane

* move line diff between selections to selection

* add option to disable mouse mode

* Allow scrolling with mouse while selecting.

* move action repeater to os_input_output, change timeout to 10ms

- change repeater to take an action instead of a position with hardcoded
action

* replace mouse mode integration tests with e2e tests

* cleanup

* cleanup

* check if mouse mode is disabled from merged options

* fix missing changes in tests, cleanup

3 files changed, 211 insertions, 1 deletions

diff --git a/src/tests/e2e/cases.rs b/src/tests/e2e/cases.rs
index 69233f25..8d41d44f 100644
--- a/src/tests/e2e/cases.rs
+++ b/src/tests/e2e/cases.rs
@@ -1,7 +1,7 @@
 #![allow(unused)]
 
 use ::insta::assert_snapshot;
-use zellij_utils::pane_size::PositionAndSize;
+use zellij_utils::{pane_size::PositionAndSize, position::Position};
 
 use rand::Rng;
 
@@ -54,6 +54,17 @@ pub const BRACKETED_PASTE_START: [u8; 6] = [27, 91, 50, 48, 48, 126]; // \u{1b}[
 pub const BRACKETED_PASTE_END: [u8; 6] = [27, 91, 50, 48, 49, 126]; // \u{1b}[201
 pub const SLEEP: [u8; 0] = [];
 
+// simplified, slighty adapted version of alacritty mouse reporting code
+pub fn normal_mouse_report(position: Position, button: u8) -> Vec<u8> {
+    let Position { line, column } = position;
+
+    let mut command = vec![b'\x1b', b'[', b'M', 32 + button];
+    command.push(32 + 1 + column.0 as u8);
+    command.push(32 + 1 + line.0 as u8);
+
+    command
+}
+
 // All the E2E tests are marked as "ignored" so that they can be run separately from the normal
 // tests
 
@@ -785,3 +796,144 @@ pub fn accepts_basic_layout() {
         .run_all_steps();
     assert_snapshot!(last_snapshot);
 }
+
+#[test]
+#[ignore]
+fn focus_pane_with_mouse() {
+    let fake_win_size = PositionAndSize {
+        cols: 120,
+        rows: 24,
+        x: 0,
+        y: 0,
+        ..Default::default()
+    };
+
+    let last_snapshot = RemoteRunner::new("split_terminals_vertically", fake_win_size, None)
+        .add_step(Step {
+            name: "Split pane to the right",
+            instruction: |mut remote_terminal: RemoteTerminal| -> bool {
+                let mut step_is_complete = false;
+                if remote_terminal.status_bar_appears() && remote_terminal.cursor_position_is(2, 2)
+                {
+                    remote_terminal.send_key(&PANE_MODE);
+                    remote_terminal.send_key(&SPLIT_RIGHT_IN_PANE_MODE);
+                    // back to normal mode after split
+                    remote_terminal.send_key(&ENTER);
+                    step_is_complete = true;
+                }
+                step_is_complete
+            },
+        })
+        .add_step(Step {
+            name: "Click left pane",
+            instruction: |mut remote_terminal: RemoteTerminal| -> bool {
+                let mut step_is_complete = false;
+                if remote_terminal.cursor_position_is(63, 2) && remote_terminal.tip_appears() {
+                    remote_terminal.send_key(&normal_mouse_report(Position::new(5, 2), 0));
+                    step_is_complete = true;
+                }
+                step_is_complete
+            },
+        })
+        .add_step(Step {
+            name: "Wait for left pane to be focused",
+            instruction: |remote_terminal: RemoteTerminal| -> bool {
+                let mut step_is_complete = false;
+                if remote_terminal.cursor_position_is(2, 2) && remote_terminal.tip_appears() {
+                    // cursor is in the newly opened second pane
+                    step_is_complete = true;
+                }
+                step_is_complete
+            },
+        })
+        .run_all_steps();
+    assert_snapshot!(last_snapshot);
+}
+
+#[test]
+#[ignore]
+pub fn scrolling_inside_a_pane_with_mouse() {
+    let fake_win_size = PositionAndSize {
+        cols: 120,
+        rows: 24,
+        x: 0,
+        y: 0,
+        ..Default::default()
+    };
+    let last_snapshot =
+        RemoteRunner::new("scrolling_inside_a_pane_with_mouse", fake_win_size, None)
+            .add_step(Step {
+                name: "Split pane to the right",
+                instruction: |mut remote_terminal: RemoteTerminal| -> bool {
+                    let mut step_is_complete = false;
+                    if remote_terminal.status_bar_appears()
+                        && remote_terminal.cursor_position_is(2, 2)
+                    {
+                        remote_terminal.send_key(&PANE_MODE);
+                        remote_terminal.send_key(&SPLIT_RIGHT_IN_PANE_MODE);
+                        // back to normal mode after split
+                        remote_terminal.send_key(&ENTER);
+                        step_is_complete = true;
+                    }
+                    step_is_complete
+                },
+            })
+            .add_step(Step {
+                name: "Fill terminal with text",
+                instruction: |mut remote_terminal: RemoteTerminal| -> bool {
+                    let mut step_is_complete = false;
+                    if remote_terminal.cursor_position_is(63, 2) && remote_terminal.tip_appears() {
+                        // cursor is in the newly opened second pane
+                        remote_terminal.send_key(&format!("{:0<57}", "line1 ").as_bytes());
+                        remote_terminal.send_key(&format!("{:0<59}", "line2 ").as_bytes());
+                        remote_terminal.send_key(&format!("{:0<59}", "line3 ").as_bytes());
+                        remote_terminal.send_key(&format!("{:0<59}", "line4 ").as_bytes());
+                        remote_terminal.send_key(&format!("{:0<59}", "line5 ").as_bytes());
+                        remote_terminal.send_key(&format!("{:0<59}", "line6 ").as_bytes());
+                        remote_terminal.send_key(&format!("{:0<59}", "line7 ").as_bytes());
+                        remote_terminal.send_key(&format!("{:0<59}", "line8 ").as_bytes());
+                        remote_terminal.send_key(&format!("{:0<59}", "line9 ").as_bytes());
+                        remote_terminal.send_key(&format!("{:0<59}", "line10 ").as_bytes());
+                        remote_terminal.send_key(&format!("{:0<59}", "line11 ").as_bytes());
+                        remote_terminal.send_key(&format!("{:0<59}", "line12 ").as_bytes());
+                        remote_terminal.send_key(&format!("{:0<59}", "line13 ").as_bytes());
+                        remote_terminal.send_key(&format!("{:0<59}", "line14 ").as_bytes());
+                        remote_terminal.send_key(&format!("{:0<59}", "line15 ").as_bytes());
+                        remote_terminal.send_key(&format!("{:0<59}", "line16 ").as_bytes());
+                        remote_terminal.send_key(&format!("{:0<59}", "line17 ").as_bytes());
+                        remote_terminal.send_key(&format!("{:0<59}", "line18 ").as_bytes());
+                        remote_terminal.send_key(&format!("{:0<59}", "line19 ").as_bytes());
+                        remote_terminal.send_key(&format!("{:0<58}", "line20 ").as_bytes());
+                        step_is_complete = true;
+                    }
+                    step_is_complete
+                },
+            })
+            .add_step(Step {
+                name: "Scroll up inside pane",
+                instruction: |mut remote_terminal: RemoteTerminal| -> bool {
+                    let mut step_is_complete = false;
+                    if remote_terminal.cursor_position_is(119, 20) {
+                        // all lines have been written to the pane
+                        remote_terminal.send_key(&normal_mouse_report(Position::new(2, 64), 64));
+                        step_is_complete = true;
+                    }
+                    step_is_complete
+                },
+            })
+            .add_step(Step {
+                name: "Wait for scroll to finish",
+                instruction: |remote_terminal: RemoteTerminal| -> bool {
+                    let mut step_is_complete = false;
+                    if remote_terminal.cursor_position_is(119, 20)
+                        && remote_terminal.snapshot_contains("line1 ")
+                    {
+                        // scrolled up one line
+                        step_is_complete = true;
+                    }
+                    step_is_complete
+                },
+            })
+            .run_all_steps();
+    assert_snapshot!(last_snapshot);
+}
diff --git a/src/tests/e2e/snapshots/zellij__tests__e2e__cases__focus_pane_with_mouse.snap b/src/tests/e2e/snapshots/zellij__tests__e2e__cases__focus_pane_with_mouse.snap
new file mode 100644
index 00000000..79e84810
--- /dev/null
+++ b/src/tests/e2e/snapshots/zellij__tests__e2e__cases__focus_pane_with_mouse.snap
@@ -0,0 +1,29 @@
+---
+source: src/tests/e2e/cases.rs
+expression: last_snapshot
+
+---
+ Zellij  Tab #1                                                                                                       
+                                                                                                                        
+$ █                                                         │$                                                          
+                                                            │                                                           
+                                                            │                                                           
+                                                            │                                                           
+                                                            │                                                           
+                                                            │                                                           
+                                                            │                                                           
+                                                            │                                                           
+                                                            │                                                           
+                                                            │                                                           
+                                                            │                                                           
+                                                            │                                                           
+                                                            │                                                           
+                                                            │                                                           
+                                                            │                                                           
+                                                            │                                                           
+                                                            │                                                           
+                                                            │                                                           
+                                                            │                                                           
+                                                                                                                        
+ Ctrl + <g> LOCK  <p> PANE  <t> TAB  <r> RESIZE  <s> SCROLL  <o> SESSION  <q> QUIT                       
+ Tip: Alt + n => open new pane. Alt + [] or hjkl => navigate between panes.                                             
diff --git a/src/tests/e2e/snapshots/zellij__tests__e2e__cases__scrolling_inside_a_pane_with_mouse.snap b/src/tests/e2e/snapshots/zellij__tests__e2e__cases__scrolling_inside_a_pane_with_mouse.snap
new file mode 100644
index 00000000..bff40376
--- /dev/null
+++ b/src/tests/e2e/snapshots/zellij__tests__e2e__cases__scrolling_inside_a_pane_with_mouse.snap
@@ -0,0 +1,29 @@
+---
+source: src/tests/e2e/cases.rs
+expression: last_snapshot
+
+---
+ Zellij  Tab #1                                                                                                       
+                                                                                                                        
+$                                                           │$ line1 000000000000000000000000000000000000000000000000000
+                                                            │line2 00000000000000000000000000000000000000000000000000000
+                                                            │line3 00000000000000000000000000000000000000000000000000000
+                                                            │line4 00000000000000000000000000000000000000000000000000000
+                                                            │line5 00000000000000000000000000000000000000000000000000000
+                                                            │line6 00000000000000000000000000000000000000000000000000000
+                                                            │line7 00000000000000000000000000000000000000000000000000000
+                                                            │line8 00000000000000000000000000000000000000000000000000000
+                                                            │line9 00000000000000000000000000000000000000000000000000000
+                                                            │line10 0000000000000000000000000000000000000000000000000000
+                                                            │line11 0000000000000000000000000000000000000000000000000000
+                                                            │line12 0000000000000000000000000000000000000000000000000000
+                                                            │line13 0000000000000000000000000000000000000000000000000000
+                                                            │line14 0000000000000000000000000000000000000000000000000000
+                                                            │line15 0000000000000000000000000000000000000000000000000000
+                                                            │line16 0000000000000000000000000000000000000000000000000000
+                                                            │line17 0000000000000000000000000000000000000000000000000000
+                                                            │line18 0000000000000000000000000000000000000000000000000000
+                                                            │line19 000000000000000000000000000000000000000000000000000█
+                                                                                                                        
+ Ctrl + <g> LOCK  <p> PANE  <t> TAB  <r> RESIZE  <s> SCROLL  <o> SESSION  <q> QUIT                       
+ Tip: Alt + n => open new pane. Alt + [] or hjkl => navigate between panes.