fix: restore windows recent pane reads

refs #962

1 files changed, 336 insertions, 0 deletions

diff --git a/src/pane/terminal/windows_recent_fallback.rs b/src/pane/terminal/windows_recent_fallback.rs
new file mode 100644
index 00000000..c9a02f67
--- /dev/null
+++ b/src/pane/terminal/windows_recent_fallback.rs
@@ -0,0 +1,336 @@
+use super::{ghostty_line_from_cells, GhosttyPaneCore};
+
+const CACHE_LINES: usize = 2000;
+
+#[derive(Clone, Debug, Default, PartialEq, Eq)]
+pub(super) struct Cache {
+    rows: Vec<RenderedLine>,
+    last_snapshot: Vec<RenderedLine>,
+    usable: bool,
+}
+
+#[derive(Clone, Debug, PartialEq, Eq)]
+struct RenderedLine {
+    text: String,
+    soft_wrapped: bool,
+    wrap_continuation: bool,
+}
+
+pub(super) fn update(core: &mut GhosttyPaneCore) {
+    if !primary_screen_active(core) {
+        return;
+    }
+    if !viewport_is_at_bottom(core) {
+        core.recent_fallback.usable = false;
+        return;
+    }
+    let Ok(snapshot) = visible_render_lines(core) else {
+        core.recent_fallback.usable = false;
+        return;
+    };
+    if snapshot.is_empty() {
+        core.recent_fallback.rows.clear();
+        core.recent_fallback.last_snapshot.clear();
+        core.recent_fallback.usable = false;
+        return;
+    }
+    if snapshot == core.recent_fallback.last_snapshot {
+        core.recent_fallback.usable = true;
+        return;
+    }
+
+    merge_snapshot(&mut core.recent_fallback.rows, &snapshot);
+    core.recent_fallback.last_snapshot = snapshot;
+    core.recent_fallback.usable = true;
+}
+
+pub(super) fn recent_text(core: &GhosttyPaneCore, lines: usize, unwrap: bool) -> String {
+    if !primary_screen_active(core) {
+        return String::new();
+    }
+    if unwrap {
+        unwrapped_text(core, lines)
+    } else {
+        wrapped_text(core, lines)
+    }
+}
+
+fn primary_screen_active(core: &GhosttyPaneCore) -> bool {
+    matches!(
+        core.terminal.active_screen(),
+        Ok(crate::ghostty::ActiveScreen::Primary)
+    )
+}
+
+fn wrapped_text(core: &GhosttyPaneCore, lines: usize) -> String {
+    if !core.recent_fallback.usable {
+        return String::new();
+    }
+    let rows: Vec<&str> = core
+        .recent_fallback
+        .rows
+        .iter()
+        .map(|line| line.text.as_str())
+        .collect();
+    cache_text(&rows, lines)
+}
+
+fn unwrapped_text(core: &GhosttyPaneCore, lines: usize) -> String {
+    if !core.recent_fallback.usable {
+        return String::new();
+    }
+    let unwrapped = unwrap_render_lines(&core.recent_fallback.rows);
+    let rows: Vec<&str> = unwrapped.iter().map(String::as_str).collect();
+    cache_text(&rows, lines)
+}
+
+fn viewport_is_at_bottom(core: &GhosttyPaneCore) -> bool {
+    let Ok(scrollbar) = core.terminal.scrollbar() else {
+        return true;
+    };
+    scrollbar.offset.saturating_add(scrollbar.len) >= scrollbar.total
+}
+
+fn visible_render_lines(
+    core: &mut GhosttyPaneCore,
+) -> Result<Vec<RenderedLine>, crate::ghostty::Error> {
+    let GhosttyPaneCore {
+        terminal,
+        render_state,
+        ..
+    } = core;
+    render_state.update(terminal)?;
+    let mut row_iterator = crate::ghostty::RowIterator::new()?;
+    let mut row_cells = crate::ghostty::RowCells::new()?;
+    let mut rows = render_state.populate_row_iterator(&mut row_iterator)?;
+    let mut lines = Vec::new();
+    while rows.next() {
+        let (soft_wrapped, wrap_continuation) = rows.wrap_state().unwrap_or((false, false));
+        let mut cells = rows.populate_cells(&mut row_cells)?;
+        let text = ghostty_line_from_cells(&mut cells)?;
+        if !text.is_empty() {
+            lines.push(RenderedLine {
+                text,
+                soft_wrapped,
+                wrap_continuation,
+            });
+        }
+    }
+    Ok(lines)
+}
+
+fn unwrap_render_lines(snapshot: &[RenderedLine]) -> Vec<String> {
+    let mut unwrapped = Vec::new();
+    let mut current = String::new();
+    for line in snapshot {
+        if line.wrap_continuation && current.is_empty() {
+            continue;
+        }
+        current.push_str(&line.text);
+        if !line.soft_wrapped {
+            unwrapped.push(std::mem::take(&mut current));
+        }
+    }
+    if !current.is_empty() {
+        unwrapped.push(current);
+    }
+    unwrapped
+}
+
+fn merge_snapshot(cache: &mut Vec<RenderedLine>, snapshot: &[RenderedLine]) {
+    if snapshot.is_empty() {
+        return;
+    }
+
+    let max_overlap = cache.len().min(snapshot.len());
+    let overlap = (0..=max_overlap)
+        .rev()
+        .find(|count| *count == 0 || cache[cache.len() - count..] == snapshot[..*count])
+        .unwrap_or(0);
+    cache.extend(snapshot[overlap..].iter().cloned());
+    let overflow = cache.len().saturating_sub(CACHE_LINES);
+    if overflow > 0 {
+        cache.drain(0..overflow);
+    }
+}
+
+fn cache_text(cache: &[&str], lines: usize) -> String {
+    if lines == 0 || cache.is_empty() {
+        return String::new();
+    }
+    let start = cache.len().saturating_sub(lines);
+    let text = cache[start..].join("\n");
+    if text.is_empty() {
+        text
+    } else {
+        format!("{text}\n")
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use tokio::sync::mpsc;
+
+    use super::*;
+    use crate::layout::PaneId;
+    use crate::pane::terminal::GhosttyPaneTerminal;
+
+    fn rendered_line(
+        text: impl Into<String>,
+        soft_wrapped: bool,
+        wrap_continuation: bool,
+    ) -> RenderedLine {
+        RenderedLine {
+            text: text.into(),
+            soft_wrapped,
+            wrap_continuation,
+        }
+    }
+
+    #[test]
+    fn merges_overlapping_snapshots() {
+        let mut cache = Vec::new();
+
+        merge_snapshot(
+            &mut cache,
+            &[
+                rendered_line("one", false, false),
+                rendered_line("two", false, false),
+            ],
+        );
+        merge_snapshot(
+            &mut cache,
+            &[
+                rendered_line("two", false, false),
+                rendered_line("three", false, false),
+                rendered_line("four", false, false),
+            ],
+        );
+        merge_snapshot(
+            &mut cache,
+            &[
+                rendered_line("three", false, false),
+                rendered_line("four", false, false),
+                rendered_line("five", false, false),
+            ],
+        );
+
+        let text: Vec<&str> = cache.iter().map(|line| line.text.as_str()).collect();
+        assert_eq!(text, vec!["one", "two", "three", "four", "five"]);
+    }
+
+    #[test]
+    fn unwraps_soft_wrapped_rows() {
+        let snapshot = vec![
+            rendered_line("ABCDE", true, false),
+            rendered_line("FGHIJ", false, true),
+            rendered_line("next", false, false),
+        ];
+
+        assert_eq!(unwrap_render_lines(&snapshot), vec!["ABCDEFGHIJ", "next"]);
+    }
+
+    #[test]
+    fn suppresses_leading_wrap_continuation() {
+        let snapshot = vec![
+            rendered_line("suffix", false, true),
+            rendered_line("next", false, false),
+        ];
+
+        assert_eq!(unwrap_render_lines(&snapshot), vec!["next"]);
+    }
+
+    #[test]
+    fn clears_on_blank_snapshot() {
+        let (tx, _rx) = mpsc::channel(4);
+        let terminal = crate::ghostty::Terminal::new(40, 3, 1024).unwrap();
+        let pane = GhosttyPaneTerminal::new(terminal, tx.clone()).unwrap();
+        let pane_id = PaneId::from_raw(1);
+
+        pane.process_pty_bytes(pane_id, 0, b"old\r\n", &tx);
+        assert!(pane.recent_text(3).contains("old"));
+
+        pane.process_pty_bytes(pane_id, 0, b"\x1b[2J\x1b[H", &tx);
+        assert_eq!(pane.recent_text(3).trim(), "");
+    }
+
+    #[test]
+    fn ignores_alternate_screen_snapshots() {
+        let (tx, _rx) = mpsc::channel(4);
+        let terminal = crate::ghostty::Terminal::new(40, 3, 1024).unwrap();
+        let pane = GhosttyPaneTerminal::new(terminal, tx.clone()).unwrap();
+        let pane_id = PaneId::from_raw(1);
+
+        for line in 0..20 {
+            pane.process_pty_bytes(pane_id, 0, format!("{line:06}\r\n").as_bytes(), &tx);
+        }
+        {
+            let core = pane.core.lock().unwrap();
+            assert!(core
+                .recent_fallback
+                .rows
+                .iter()
+                .any(|line| line.text.contains("000000")));
+        }
+
+        pane.process_pty_bytes(pane_id, 0, b"\x1b[?1049h\x1b[2J\x1b[H", &tx);
+
+        let core = pane.core.lock().unwrap();
+        assert!(core
+            .recent_fallback
+            .rows
+            .iter()
+            .any(|line| line.text.contains("000000")));
+    }
+
+    #[test]
+    fn invalidates_fallback_when_output_arrives_while_scrolled_up() {
+        let (tx, _rx) = mpsc::channel(4);
+        let terminal = crate::ghostty::Terminal::new(40, 3, 1024).unwrap();
+        let pane = GhosttyPaneTerminal::new(terminal, tx.clone()).unwrap();
+        let pane_id = PaneId::from_raw(1);
+
+        for line in 0..20 {
+            pane.process_pty_bytes(pane_id, 0, format!("{line:06}\r\n").as_bytes(), &tx);
+        }
+        let before = pane.scroll_metrics().expect("scroll metrics before scroll");
+        pane.set_scroll_offset_from_bottom(before.max_offset_from_bottom);
+        pane.process_pty_bytes(pane_id, 0, b"new output\r\n", &tx);
+
+        let core = pane.core.lock().unwrap();
+        assert_eq!(recent_text(&core, 3, false), "");
+        assert_eq!(recent_text(&core, 3, true), "");
+    }
+
+    #[test]
+    fn seed_history_updates_fallback() {
+        let (tx, _rx) = mpsc::channel(4);
+        let terminal = crate::ghostty::Terminal::new(40, 3, 1024).unwrap();
+        let pane = GhosttyPaneTerminal::new(terminal, tx).unwrap();
+
+        pane.seed_history_ansi("seeded history\r\n");
+
+        let core = pane.core.lock().unwrap();
+        assert!(recent_text(&core, 3, false).contains("seeded history"));
+        assert!(recent_text(&core, 3, true).contains("seeded history"));
+    }
+
+    #[test]
+    fn recent_ansi_unwrapped_uses_unwrapped_render_cache() {
+        let (tx, _rx) = mpsc::channel(4);
+        let terminal = crate::ghostty::Terminal::new(40, 3, 1024).unwrap();
+        let pane = GhosttyPaneTerminal::new(terminal, tx).unwrap();
+
+        {
+            let mut core = pane.core.lock().unwrap();
+            core.recent_fallback.rows = vec![
+                rendered_line("wrapped", true, false),
+                rendered_line("rows", false, true),
+            ];
+            core.recent_fallback.usable = true;
+        }
+
+        assert_eq!(pane.recent_ansi(2), "wrapped\nrows\n");
+        assert_eq!(pane.recent_unwrapped_ansi(2), "wrappedrows\n");
+    }
+}