Display diff

src/tui/tool_display.rs

@@ -0,0 +1,133 @@
+//! Formatting functions for tool-specific display in the TUI.
+//!
+//! Each tool type has a structured [`ToolDisplay`] variant carrying the data
+//! needed for rich rendering. These functions turn that data into the
+//! user-facing strings shown in the conversation pane.
+
+use similar::{ChangeTag, TextDiff};
+
+use crate::core::types::ToolDisplay;
+
+/// Format a tool that is currently executing (or awaiting approval).
+pub fn format_executing(name: &str, display: &ToolDisplay) -> String {
+    match display {
+        ToolDisplay::WriteFile {
+            path,
+            old_content,
+            new_content,
+        } => {
+            let mut out = format!("write {path}\n");
+            out.push_str(&unified_diff(
+                old_content.as_deref().unwrap_or(""),
+                new_content,
+            ));
+            out
+        }
+        ToolDisplay::ShellExec { command } => format!("$ {command}"),
+        ToolDisplay::ListDirectory { path } => format!("ls {path}"),
+        ToolDisplay::ReadFile { path } => format!("read {path}"),
+        ToolDisplay::Generic { summary } => format!("[{name}] {summary}"),
+    }
+}
+
+/// Format a tool result after execution completes.
+pub fn format_result(name: &str, display: &ToolDisplay, is_error: bool) -> String {
+    let prefix = if is_error { "error" } else { "result" };
+    match display {
+        ToolDisplay::WriteFile {
+            path,
+            old_content,
+            new_content,
+        } => {
+            let mut out = format!("write {path}\n");
+            out.push_str(&unified_diff(
+                old_content.as_deref().unwrap_or(""),
+                new_content,
+            ));
+            out.push_str(&format!("\nWrote {} bytes", new_content.len()));
+            out
+        }
+        ToolDisplay::ShellExec { command } => {
+            // For results, the command field carries "command\nstdout\nstderr".
+            format!("$ {command}")
+        }
+        ToolDisplay::ListDirectory { path } => format!("ls {path}"),
+        ToolDisplay::ReadFile { path } => format!("read {path}"),
+        ToolDisplay::Generic { summary } => format!("[{name} {prefix}] {summary}"),
+    }
+}
+
+/// Produce a unified diff between `old` and `new` text.
+///
+/// Uses the `similar` crate to compute line-level changes and formats them
+/// with the conventional `+`/`-`/` ` prefix markers.
+fn unified_diff(old: &str, new: &str) -> String {
+    let diff = TextDiff::from_lines(old, new);
+    let mut out = String::new();
+    for change in diff.iter_all_changes() {
+        let marker = match change.tag() {
+            ChangeTag::Delete => "-",
+            ChangeTag::Insert => "+",
+            ChangeTag::Equal => " ",
+        };
+        out.push_str(marker);
+        out.push_str(change.as_str().unwrap_or(""));
+        if !change.as_str().unwrap_or("").ends_with('\n') {
+            out.push('\n');
+        }
+    }
+    out
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn format_executing_shell() {
+        let display = ToolDisplay::ShellExec {
+            command: "cargo test".to_string(),
+        };
+        assert_eq!(format_executing("shell_exec", &display), "$ cargo test");
+    }
+
+    #[test]
+    fn format_executing_write_with_diff() {
+        let display = ToolDisplay::WriteFile {
+            path: "src/lib.rs".to_string(),
+            old_content: Some("fn hello() {\n    println!(\"hello\");\n}\n".to_string()),
+            new_content: "fn hello() {\n    println!(\"hello world\");\n}\n".to_string(),
+        };
+        let output = format_executing("write_file", &display);
+        assert!(output.starts_with("write src/lib.rs\n"));
+        assert!(output.contains("-    println!(\"hello\");"));
+        assert!(output.contains("+    println!(\"hello world\");"));
+    }
+
+    #[test]
+    fn format_result_write_shows_byte_count() {
+        let display = ToolDisplay::WriteFile {
+            path: "foo.txt".to_string(),
+            old_content: None,
+            new_content: "hello".to_string(),
+        };
+        let output = format_result("write_file", &display, false);
+        assert!(output.contains("Wrote 5 bytes"));
+    }
+
+    #[test]
+    fn format_result_generic_error() {
+        let display = ToolDisplay::Generic {
+            summary: "something failed".to_string(),
+        };
+        let output = format_result("unknown_tool", &display, true);
+        assert_eq!(output, "[unknown_tool error] something failed");
+    }
+
+    #[test]
+    fn unified_diff_empty_old() {
+        let diff = unified_diff("", "line1\nline2\n");
+        assert!(diff.contains("+line1"));
+        assert!(diff.contains("+line2"));
+    }
+}