feat(compatibility): add support for osc 8 escape code (#822)

Resolve #645 

* add support for osc 8 escape code

* refactor, add links to CharacterStyles

* cleanup

* refactor, add minimal tests

5 files changed, 144 insertions, 2 deletions

diff --git a/zellij-server/src/panes/grid.rs b/zellij-server/src/panes/grid.rs
index c094701f..e3752fef 100644
--- a/zellij-server/src/panes/grid.rs
+++ b/zellij-server/src/panes/grid.rs
@@ -18,13 +18,13 @@ use zellij_tile::data::{Palette, PaletteColor};
 use zellij_utils::{consts::VERSION, shared::version_number};
 
 use crate::panes::alacritty_functions::{parse_number, xparse_color};
+use crate::panes::link_handler::LinkHandler;
+use crate::panes::selection::Selection;
 use crate::panes::terminal_character::{
     AnsiCode, CharacterStyles, CharsetIndex, Cursor, CursorShape, StandardCharset,
     TerminalCharacter, EMPTY_TERMINAL_CHARACTER,
 };
 
-use super::selection::Selection;
-
 fn get_top_non_canonical_rows(rows: &mut Vec<Row>) -> Vec<Row> {
     let mut index_of_last_non_canonical_row = None;
     for (i, row) in rows.iter().enumerate() {
@@ -394,6 +394,7 @@ pub struct Grid {
     pub selection: Selection,
     pub title: Option<String>,
     pub is_scrolled: bool,
+    pub link_handler: LinkHandler,
     scrollback_buffer_lines: usize,
 }
 
@@ -440,6 +441,7 @@ impl Grid {
             title: None,
             changed_colors: None,
             is_scrolled: false,
+            link_handler: Default::default(),
             scrollback_buffer_lines: 0,
         }
     }
@@ -1549,6 +1551,14 @@ impl Perform for Grid {
                 }
             }
 
+            // define hyperlink
+            b"8" => {
+                if params.len() < 3 {
+                    return;
+                }
+                self.cursor.pending_styles.link_anchor = self.link_handler.dispatch_osc8(params);
+            }
+
             // Get/set Foreground, Background, Cursor colors.
             b"10" | b"11" | b"12" => {
                 if params.len() >= 2 {
diff --git a/zellij-server/src/panes/link_handler.rs b/zellij-server/src/panes/link_handler.rs
new file mode 100644
index 00000000..4294dbed
--- /dev/null
+++ b/zellij-server/src/panes/link_handler.rs
@@ -0,0 +1,111 @@
+use std::collections::HashMap;
+
+use super::LinkAnchor;
+
+const TERMINATOR: &str = "\u{1b}\\";
+
+#[derive(Debug, Clone)]
+pub struct LinkHandler {
+    links: HashMap<u16, Link>,
+    link_index: u16,
+}
+#[derive(Debug, Clone)]
+struct Link {
+    id: Option<String>,
+    uri: String,
+}
+
+impl LinkHandler {
+    pub fn new() -> Self {
+        Self {
+            links: HashMap::new(),
+            link_index: 0,
+        }
+    }
+
+    pub fn dispatch_osc8(&mut self, params: &[&[u8]]) -> Option<LinkAnchor> {
+        let (link_params, uri) = (params[1], params[2]);
+        log::debug!(
+            "dispatching osc8, params: {:?}, uri: {:?}",
+            std::str::from_utf8(link_params),
+            std::str::from_utf8(uri)
+        );
+
+        if !uri.is_empty() {
+            // save the link, and the id if present to hashmap
+            String::from_utf8(uri.to_vec()).ok().map(|uri| {
+                let id = link_params
+                    .split(|&b| b == b':')
+                    .find(|kv| kv.starts_with(b"id="))
+                    .and_then(|kv| String::from_utf8(kv[3..].to_vec()).ok());
+                let anchor = LinkAnchor::Start(self.link_index);
+                self.links.insert(self.link_index, Link { id, uri });
+                self.link_index += 1;
+                anchor
+            })
+        } else {
+            // there is no link, so consider it a link end
+            Some(LinkAnchor::End)
+        }
+    }
+
+    pub fn output_osc8(&self, link_anchor: Option<LinkAnchor>) -> String {
+        link_anchor.map_or("".to_string(), |link| match link {
+            LinkAnchor::Start(index) => {
+                let link = self.links.get(&index).unwrap();
+                let id = link
+                    .id
+                    .as_ref()
+                    .map_or("".to_string(), |id| format!("id={}", id));
+                format!("\u{1b}]8;{};{}{}", id, link.uri, TERMINATOR)
+            }
+            LinkAnchor::End => format!("\u{1b}]8;;{}", TERMINATOR),
+        })
+    }
+}
+
+impl Default for LinkHandler {
+    fn default() -> Self {
+        Self::new()
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn dispatch_osc8_link_start() {
+        let mut link_handler = LinkHandler::default();
+        let link_params = "id=test";
+        let uri = "http://test.com";
+        let params = vec!["8".as_bytes(), link_params.as_bytes(), uri.as_bytes()];
+
+        let anchor = link_handler.dispatch_osc8(&params);
+
+        match anchor {
+            Some(LinkAnchor::Start(link_id)) => {
+                let link = link_handler.links.get(&link_id).expect("link was not some");
+                assert_eq!(link.id, Some("test".to_string()));
+                assert_eq!(link.uri, uri);
+            }
+            _ => panic!("pending link handler was not start"),
+        }
+
+        let expected = format!("\u{1b}]8;id=test;http://test.com{}", TERMINATOR);
+        assert_eq!(link_handler.output_osc8(anchor), expected);
+    }
+
+    #[test]
+    fn dispatch_osc8_link_end() {
+        let mut link_handler = LinkHandler::default();
+        let params = vec!["8".as_bytes(), &[], &[]];
+
+        let anchor = link_handler.dispatch_osc8(&params);
+
+        assert_eq!(anchor, Some(LinkAnchor::End));
+
+        let expected = format!("\u{1b}]8;;{}", TERMINATOR);
+        assert_eq!(link_handler.output_osc8(anchor), expected);
+    }
+}
diff --git a/zellij-server/src/panes/mod.rs b/zellij-server/src/panes/mod.rs
index c918f98f..7ee5ab62 100644
--- a/zellij-server/src/panes/mod.rs
+++ b/zellij-server/src/panes/mod.rs
@@ -1,5 +1,6 @@
 mod alacritty_functions;
 mod grid;
+mod link_handler;
 mod plugin_pane;
 mod selection;
 mod terminal_character;
diff --git a/zellij-server/src/panes/terminal_character.rs b/zellij-server/src/panes/terminal_character.rs
index f619b891..c9de3760 100644
--- a/zellij-server/src/panes/terminal_character.rs
+++ b/zellij-server/src/panes/terminal_character.rs
@@ -23,6 +23,7 @@ pub const RESET_STYLES: CharacterStyles = CharacterStyles {
     bold: Some(AnsiCode::Reset),
     dim: Some(AnsiCode::Reset),
     italic: Some(AnsiCode::Reset),
+    link_anchor: Some(LinkAnchor::End),
 };
 
 #[derive(Clone, Copy, Debug, PartialEq, Eq)]
@@ -110,6 +111,7 @@ pub struct CharacterStyles {
     pub bold: Option<AnsiCode>,
     pub dim: Option<AnsiCode>,
     pub italic: Option<AnsiCode>,
+    pub link_anchor: Option<LinkAnchor>,
 }
 
 impl Default for CharacterStyles {
@@ -126,6 +128,7 @@ impl Default for CharacterStyles {
             bold: None,
             dim: None,
             italic: None,
+            link_anchor: None,
         }
     }
 }
@@ -178,6 +181,10 @@ impl CharacterStyles {
         self.strike = strike_code;
         self
     }
+    pub fn link_anchor(mut self, link_anchor: Option<LinkAnchor>) -> Self {
+        self.link_anchor = link_anchor;
+        self
+    }
     pub fn clear(&mut self) {
         self.foreground = None;
         self.background = None;
@@ -190,6 +197,7 @@ impl CharacterStyles {
         self.bold = None;
         self.dim = None;
         self.italic = None;
+        self.link_anchor = None;
     }
     pub fn update_and_return_diff(
         &mut self,
@@ -241,6 +249,9 @@ impl CharacterStyles {
         if self.italic != new_styles.italic {
             diff.italic = new_styles.italic;
         }
+        if self.link_anchor != new_styles.link_anchor {
+            diff.link_anchor = new_styles.link_anchor;
+        }
 
         // apply new styles
         *self = *new_styles;
@@ -556,6 +567,12 @@ impl Display for CharacterStyles {
     }
 }
 
+#[derive(Clone, Copy, Debug, PartialEq)]
+pub enum LinkAnchor {
+    Start(u16),
+    End,
+}
+
 #[derive(Clone, Copy, Debug)]
 pub enum CharsetIndex {
     G0,
diff --git a/zellij-server/src/panes/terminal_pane.rs b/zellij-server/src/panes/terminal_pane.rs
index 66a8a3dd..f2974cee 100644
--- a/zellij-server/src/panes/terminal_pane.rs
+++ b/zellij-server/src/panes/terminal_pane.rs
@@ -236,7 +236,10 @@ impl Pane for TerminalPane {
                         .update_and_return_diff(&t_character.styles, self.grid.changed_colors)
                     {
                         vte_output.push_str(&new_styles.to_string());
+                        vte_output
+                            .push_str(&self.grid.link_handler.output_osc8(new_styles.link_anchor))
                     }
+
                     vte_output.push(t_character.character);
                 }
                 character_styles.clear();