recursive-agent 0.6.0

//! Standalone helper functions for rendering / display.
//!
//! These are pure functions (no `&mut self`) used by event_loop and the
//! terminal UI to format tool arguments, parse diffs, etc.

use serde_json::Value;

use super::{DiffHunk, DiffLine, DiffLineKind};

// ── Argument preview ─────────────────────────────────────────────────

/// Produce a short preview of a JSON-encoded arguments string.
///
/// Picks up to two top-level fields, formats them as `k=v`, and clamps
/// to ~60 characters with an ellipsis.
pub fn preview_args(arguments: &str) -> String {
    let parsed: Result<Value, _> = serde_json::from_str(arguments);
    let Ok(Value::Object(map)) = parsed else {
        // Not JSON-y; just clamp the raw string.
        return clamp(arguments, 60);
    };

    let mut parts = Vec::new();
    for (k, v) in map.iter().take(2) {
        let v_str = match v {
            Value::String(s) => format!("\"{}\"", clamp(s, 30)),
            other => clamp(&other.to_string(), 30),
        };
        parts.push(format!("{k}={v_str}"));
    }
    clamp(&parts.join(" "), 60)
}

fn clamp(s: &str, max: usize) -> String {
    if s.chars().count() <= max {
        s.to_string()
    } else {
        let head: String = s.chars().take(max.saturating_sub(1)).collect();
        format!("{head}…")
    }
}

// ── Spinner verb ─────────────────────────────────────────────────────

/// Pick a spinner verb based on the tool name.
pub fn verb_for_tool(name: &str) -> &'static str {
    match name {
        "read_file" | "list_dir" | "search_files" => "Reading",
        "apply_patch" | "write_file" => "Editing",
        "run_shell" => "Running",
        _ => "Calling tool",
    }
}

// ── V4A patch parser ─────────────────────────────────────────────────

/// Parse a V4A patch envelope from an `apply_patch` arguments JSON.
///
/// Returns `(path, hunks)` for the first `*** Update File:` /
/// `*** Add File:` block found, or `None` if the input is not parseable
/// as a V4A patch.
pub fn parse_apply_patch_input(arguments: &str) -> Option<(String, Vec<DiffHunk>)> {
    let v: Value = serde_json::from_str(arguments).ok()?;
    let input = v.get("input")?.as_str()?;
    parse_v4a_patch(input)
}

/// Pure parser for a V4A patch string.
pub fn parse_v4a_patch(input: &str) -> Option<(String, Vec<DiffHunk>)> {
    let mut path: Option<String> = None;
    let mut current = Vec::new();
    let mut hunks: Vec<DiffHunk> = Vec::new();

    for line in input.lines() {
        if let Some(rest) = line
            .strip_prefix("*** Update File: ")
            .or_else(|| line.strip_prefix("*** Add File: "))
        {
            if path.is_some() {
                // Multiple update sections — only the first is used,
                // per goal scope.
                break;
            }
            path = Some(rest.trim().to_string());
            continue;
        }
        if line.starts_with("*** Begin Patch")
            || line.starts_with("*** End Patch")
            || line.starts_with("*** End of File")
        {
            continue;
        }
        if path.is_none() {
            continue;
        }
        // @@ anchor lines start a new hunk.
        if let Some(stripped) = line.strip_prefix("@@") {
            if !current.is_empty() {
                hunks.push(DiffHunk {
                    lines: std::mem::take(&mut current),
                });
            }
            let text = stripped.trim_start().to_string();
            if !text.is_empty() {
                current.push(DiffLine {
                    kind: DiffLineKind::Context,
                    text,
                });
            }
            continue;
        }
        if let Some(rest) = line.strip_prefix('+') {
            current.push(DiffLine {
                kind: DiffLineKind::Add,
                text: rest.to_string(),
            });
        } else if let Some(rest) = line.strip_prefix('-') {
            current.push(DiffLine {
                kind: DiffLineKind::Remove,
                text: rest.to_string(),
            });
        } else if let Some(rest) = line.strip_prefix(' ') {
            current.push(DiffLine {
                kind: DiffLineKind::Context,
                text: rest.to_string(),
            });
        }
    }
    if !current.is_empty() {
        hunks.push(DiffHunk { lines: current });
    }

    let path = path?;
    if hunks.is_empty() {
        return None;
    }
    Some((path, hunks))
}

// ── write_file path extractor ────────────────────────────────────────

/// Best-effort path extraction from a write_file ToolResult output.
///
/// The `WriteFile` tool emits something like
/// `"Wrote 42 bytes to crates/foo/bar.rs"`. We parse that pattern and
/// fall back to `None` if it doesn't match.
pub(crate) fn extract_write_file_path_from_result(output: &str) -> Option<String> {
    let trimmed = output.trim();
    if let Some(idx) = trimmed.rfind(" to ") {
        let candidate = &trimmed[idx + 4..];
        if !candidate.is_empty() {
            return Some(candidate.to_string());
        }
    }
    None
}

// ──────────────────────────────────────────────────────────────────────
// Tests
// ──────────────────────────────────────────────────────────────────────

#[cfg(test)]
mod tests {
    use super::*;
    use crate::tui::app::DiffLineKind;

    #[test]
    fn tool_call_args_preview_extracts_path() {
        let preview = preview_args(r#"{"path":"src/agent.rs"}"#);
        assert!(preview.contains("path"));
        assert!(preview.contains("src/agent.rs"));
    }

    #[test]
    fn verb_for_tool_categorises_tools() {
        assert_eq!(verb_for_tool("read_file"), "Reading");
        assert_eq!(verb_for_tool("apply_patch"), "Editing");
        assert_eq!(verb_for_tool("run_shell"), "Running");
        assert_eq!(verb_for_tool("custom_xyz"), "Calling tool");
    }

    #[test]
    fn parse_v4a_patch_extracts_path_and_pm_lines() {
        let patch = "*** Begin Patch\n*** Update File: src/foo.rs\n@@ pub fn bar()\n pub fn bar() {\n-    let x = 1;\n+    let x = 2;\n }\n*** End Patch";
        let (path, hunks) = parse_v4a_patch(patch).unwrap();
        assert_eq!(path, "src/foo.rs");
        assert!(!hunks.is_empty());
        let kinds: Vec<_> = hunks
            .iter()
            .flat_map(|h| h.lines.iter().map(|l| l.kind.clone()))
            .collect();
        assert!(kinds.contains(&DiffLineKind::Add));
        assert!(kinds.contains(&DiffLineKind::Remove));
    }
}