From 887bf0a744646c6d9cfb361ba0c929d4a4342337 Mon Sep 17 00:00:00 2001
From: sigoden <sigoden@gmail.com>
Date: Fri, 3 Nov 2023 18:36:17 +0800
Subject: fix: fix rendering markdown in REPL (#207)

---
 src/render/markdown.rs | 4 +++-
 src/render/repl.rs     | 9 ++++++++-
 2 files changed, 11 insertions(+), 2 deletions(-)

(limited to 'src/render')

diff --git a/src/render/markdown.rs b/src/render/markdown.rs
index f491fc1..f300854 100644
--- a/src/render/markdown.rs
+++ b/src/render/markdown.rs
@@ -205,7 +205,9 @@ impl MarkdownRender {
 
 fn wrap(text: &str, width: usize) -> String {
     let indent: usize = text.chars().take_while(|c| *c == ' ').count();
-    let wrap_options = textwrap::Options::new(width).initial_indent(&text[0..indent]);
+    let wrap_options = textwrap::Options::new(width)
+        .wrap_algorithm(textwrap::WrapAlgorithm::FirstFit)
+        .initial_indent(&text[0..indent]);
     textwrap::wrap(&text[indent..], wrap_options).join("\n")
 }
 
diff --git a/src/render/repl.rs b/src/render/repl.rs
index 31c597e..34212c3 100644
--- a/src/render/repl.rs
+++ b/src/render/repl.rs
@@ -70,7 +70,9 @@ fn repl_render_stream_inner(
                             cursor::MoveTo(0, 0),
                         )?;
                     }
-                    queue!(writer, terminal::Clear(terminal::ClearType::UntilNewLine))?;
+
+                    // No guarantee that text returned by render will not be re-layouted, so it is better to clear it.
+                    queue!(writer, terminal::Clear(terminal::ClearType::FromCursorDown))?;
 
                     if text.contains('\n') {
                         let text = format!("{buffer}{text}");
@@ -79,6 +81,9 @@ fn repl_render_stream_inner(
                         let output = render.render(head);
                         print_block(writer, &output, columns)?;
                         queue!(writer, style::Print(&buffer),)?;
+
+                        // No guarantee the buffer width of the buffer will not exceed the number of columns.
+                        // So we calcuate the number of rows needed, rather than setting it directly to 1.
                         buffer_rows = need_rows(&buffer, columns);
                     } else {
                         buffer = format!("{buffer}{text}");
@@ -87,6 +92,8 @@ fn repl_render_stream_inner(
                             let (head, tail) = split_line_tail(&output);
                             buffer_rows = print_block(writer, head, columns)?;
                             queue!(writer, style::Print(&tail),)?;
+
+                            // Same as above.
                             buffer_rows += need_rows(tail, columns);
                         } else {
                             queue!(writer, style::Print(&output))?;
-- 
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