Give plugins the ability to read pane contents (#4465)

* initial implementation

* add Selection and better types

* event to plugins

* only send viewport diff

* simplify data structure sent over the wire

* cleanups

* rustfmt

* remove dead code and fix tests

* commit tests

* get pane scrollback plugin command without implementation

* add lines above and lines below to pane contents

* implement get scrollback plugin command

* selection => selected_text

* add convenience method to get the selected text

* move Selection back to zellij-server

* rustfmt

* bring back client id to get contents command

* rustfmt

* add pr

1 files changed, 32 insertions, 8 deletions

diff --git a/zellij-utils/src/plugin_api/plugin_command.rs b/zellij-utils/src/plugin_api/plugin_command.rs
index 4fc9d939..c1ba877e 100644
--- a/zellij-utils/src/plugin_api/plugin_command.rs
+++ b/zellij-utils/src/plugin_api/plugin_command.rs
@@ -12,14 +12,14 @@ pub use super::generated_api::api::{
         FixedOrPercent as ProtobufFixedOrPercent,
         FixedOrPercentValue as ProtobufFixedOrPercentValue, FloatMultiplePanesPayload,
         FloatingPaneCoordinates as ProtobufFloatingPaneCoordinates, GenerateWebLoginTokenPayload,
-        GroupAndUngroupPanesPayload, HidePaneWithIdPayload, HighlightAndUnhighlightPanesPayload,
-        HttpVerb as ProtobufHttpVerb, IdAndNewName, KeyToRebind, KeyToUnbind, KillSessionsPayload,
-        ListTokensResponse, LoadNewPluginPayload, MessageToPluginPayload,
-        MovePaneWithPaneIdInDirectionPayload, MovePaneWithPaneIdPayload, MovePayload,
-        NewPluginArgs as ProtobufNewPluginArgs, NewTabPayload, NewTabsWithLayoutInfoPayload,
-        OpenCommandPaneFloatingNearPluginPayload, OpenCommandPaneInPlaceOfPluginPayload,
-        OpenCommandPaneNearPluginPayload, OpenCommandPanePayload,
-        OpenFileFloatingNearPluginPayload, OpenFileInPlaceOfPluginPayload,
+        GetPaneScrollbackPayload, GroupAndUngroupPanesPayload, HidePaneWithIdPayload,
+        HighlightAndUnhighlightPanesPayload, HttpVerb as ProtobufHttpVerb, IdAndNewName,
+        KeyToRebind, KeyToUnbind, KillSessionsPayload, ListTokensResponse, LoadNewPluginPayload,
+        MessageToPluginPayload, MovePaneWithPaneIdInDirectionPayload, MovePaneWithPaneIdPayload,
+        MovePayload, NewPluginArgs as ProtobufNewPluginArgs, NewTabPayload,
+        NewTabsWithLayoutInfoPayload, OpenCommandPaneFloatingNearPluginPayload,
+        OpenCommandPaneInPlaceOfPluginPayload, OpenCommandPaneNearPluginPayload,
+        OpenCommandPanePayload, OpenFileFloatingNearPluginPayload, OpenFileInPlaceOfPluginPayload,
         OpenFileNearPluginPayload, OpenFilePayload, OpenTerminalFloatingNearPluginPayload,
         OpenTerminalInPlaceOfPluginPayload, OpenTerminalNearPluginPayload,
         PageScrollDownInPaneIdPayload, PageScrollUpInPaneIdPayload, PaneId as ProtobufPaneId,
@@ -1109,6 +1109,18 @@ impl TryFrom<ProtobufPluginCommand> for PluginCommand {
                 },
                 _ => Err("Mismatched payload for EditScrollback"),
             },
+            Some(CommandName::GetPaneScrollback) => match protobuf_plugin_command.payload {
+                Some(Payload::GetPaneScrollbackPayload(get_pane_scrollback_payload)) => {
+                    match get_pane_scrollback_payload.pane_id {
+                        Some(pane_id) => Ok(PluginCommand::GetPaneScrollback {
+                            pane_id: pane_id.try_into()?,
+                            get_full_scrollback: get_pane_scrollback_payload.get_full_scrollback,
+                        }),
+                        _ => Err("Malformed get_pane_scrollback_payload"),
+                    }
+                },
+                _ => Err("Mismatched payload for GetPaneScrollback"),
+            },
             Some(CommandName::WriteToPaneId) => match protobuf_plugin_command.payload {
                 Some(Payload::WriteToPaneIdPayload(write_to_pane_id_payload)) => {
                     match write_to_pane_id_payload.pane_id {
@@ -2373,6 +2385,18 @@ impl TryFrom<PluginCommand> for ProtobufPluginCommand {
                     },
                 )),
             }),
+            PluginCommand::GetPaneScrollback {
+                pane_id,
+                get_full_scrollback,
+            } => Ok(ProtobufPluginCommand {
+                name: CommandName::GetPaneScrollback as i32,
+                payload: Some(Payload::GetPaneScrollbackPayload(
+                    GetPaneScrollbackPayload {
+                        pane_id: Some(pane_id.try_into()?),
+                        get_full_scrollback,
+                    },
+                )),
+            }),
             PluginCommand::WriteToPaneId(bytes_to_write, pane_id) => Ok(ProtobufPluginCommand {
                 name: CommandName::WriteToPaneId as i32,
                 payload: Some(Payload::WriteToPaneIdPayload(WriteToPaneIdPayload {