loc-rs 0.2.2

// Author: kelexine (https://github.com/kelexine)
// extractors/python.rs — Python function/class extraction via Tree-sitter

use super::{estimate_complexity, Extractor};
use crate::models::FunctionInfo;
use tree_sitter::Node;

pub struct PythonExtractor;

impl Extractor for PythonExtractor {
    fn extract(&self, content: &str) -> Vec<FunctionInfo> {
        super::with_parsed_tree(tree_sitter_python::LANGUAGE.into(), content, |tree| {
            let lines: Vec<&str> = content.lines().collect();
            let mut functions = Vec::new();
            traverse(tree.root_node(), content, &lines, &mut functions, false, Vec::new());
            functions.sort_by_key(|f| f.line_start);
            functions
        })
        .unwrap_or_default()
    }
}

fn traverse(
    node: Node,
    content: &str,
    lines: &[&str],
    functions: &mut Vec<FunctionInfo>,
    in_class: bool,
    mut pending_decorators: Vec<String>,
) {
    let kind = node.kind();

    if kind == "decorator" {
        let dec_text = node.utf8_text(content.as_bytes()).unwrap_or("");
        pending_decorators.push(dec_text.trim_start_matches('@').to_string());
        return;
    } else if kind == "decorated_definition" {
        // Collect all decorator children, then parse the function/class child
        // with those decorators.  We cannot use the sibling-based pending_decorators
        // mechanism here because siblings have independent call frames.
        let mut decorators: Vec<String> = Vec::new();
        let mut def_node = None;

        let mut cursor = node.walk();
        for child in node.children(&mut cursor) {
            match child.kind() {
                "decorator" => {
                    let dec_text = child.utf8_text(content.as_bytes()).unwrap_or("");
                    decorators.push(dec_text.trim_start_matches('@').to_string());
                }
                "function_definition" | "class_definition" => {
                    def_node = Some(child);
                }
                _ => {}
            }
        }

        if let Some(def) = def_node {
            if def.kind() == "function_definition" {
                functions.push(parse_function(def, content, lines, in_class, decorators));
            } else {
                functions.push(parse_class(def, content, lines, decorators));
            }
        }
        return;
    }

    if kind == "function_definition" {
        functions.push(parse_function(node, content, lines, in_class, pending_decorators.clone()));
        pending_decorators.clear();
    } else if kind == "class_definition" {
        functions.push(parse_class(node, content, lines, pending_decorators.clone()));
        pending_decorators.clear();
    }

    let is_class_body = kind == "class_definition";

    let mut cursor = node.walk();
    for child in node.children(&mut cursor) {
        traverse(child, content, lines, functions, in_class || is_class_body, Vec::new());
    }
}

fn parse_function(
    node: Node,
    content: &str,
    lines: &[&str],
    is_method: bool,
    decorators: Vec<String>,
) -> FunctionInfo {
    let mut name = String::new();
    let mut is_async = false;
    let mut params_str = String::new();
    let mut docstring = None;

    let mut cursor = node.walk();
    for child in node.children(&mut cursor) {
        let kind = child.kind();
        if kind == "identifier" && name.is_empty() {
            name = child.utf8_text(content.as_bytes()).unwrap_or("").to_string();
        } else if kind == "async" {
            is_async = true;
        } else if kind == "parameters" {
            params_str = child.utf8_text(content.as_bytes()).unwrap_or("").to_string();
        } else if kind == "block" && child.child_count() > 0 {
            let first_stmt = child.child(0).unwrap();
            if first_stmt.kind() == "expression_statement" && first_stmt.child_count() > 0 {
                let expr = first_stmt.child(0).unwrap();
                if expr.kind() == "string" {
                    let doc = expr.utf8_text(content.as_bytes()).unwrap_or("");
                    docstring = Some(clean_docstring(doc));
                }
            }
        }
    }

    if name.is_empty() {
        name = "?".to_string();
    }

    let start_line = node.start_position().row + 1;
    let end_line = node.end_position().row + 1;

    let block = &lines[start_line.saturating_sub(1)..end_line.min(lines.len())];
    let complexity = estimate_complexity(block);

    let mut parameters = Vec::new();
    let trimmed_params = params_str.trim_start_matches('(').trim_end_matches(')');
    if !trimmed_params.is_empty() {
        for p in trimmed_params.split(',') {
            let p_trim = p.trim();
            if !p_trim.is_empty() {
                parameters.push(p_trim.to_string());
            }
        }
    }

    let actual_is_method = is_method
        || parameters
            .first()
            .map(|p| p.starts_with("self") || p.starts_with("cls"))
            .unwrap_or(false);

    FunctionInfo {
        name,
        line_start: start_line,
        line_end: end_line,
        parameters,
        is_async,
        is_method: actual_is_method,
        is_class: false,
        docstring,
        decorators,
        complexity,
    }
}

fn parse_class(
    node: Node,
    content: &str,
    _lines: &[&str],
    decorators: Vec<String>,
) -> FunctionInfo {
    let mut name = String::new();
    let mut params_str = String::new();

    let mut cursor = node.walk();
    for child in node.children(&mut cursor) {
        let kind = child.kind();
        if kind == "identifier" && name.is_empty() {
            name = child.utf8_text(content.as_bytes()).unwrap_or("").to_string();
        } else if kind == "argument_list" {
            params_str = child.utf8_text(content.as_bytes()).unwrap_or("").to_string();
        }
    }

    if name.is_empty() {
        name = "?".to_string();
    }

    let start_line = node.start_position().row + 1;
    let end_line = node.end_position().row + 1;

    let mut parameters = Vec::new();
    let trimmed_params = params_str.trim_start_matches('(').trim_end_matches(')');
    if !trimmed_params.is_empty() {
        for p in trimmed_params.split(',') {
            let p_trim = p.trim();
            if !p_trim.is_empty() {
                parameters.push(p_trim.to_string());
            }
        }
    }

    FunctionInfo {
        name,
        line_start: start_line,
        line_end: end_line,
        parameters,
        is_async: false,
        is_method: false,
        is_class: true,
        docstring: None,
        decorators,
        complexity: 1,
    }
}

fn clean_docstring(doc: &str) -> String {
    let s = doc.trim();
    if (s.starts_with("\"\"\"") && s.ends_with("\"\"\"") && s.len() >= 6)
        || (s.starts_with("'''") && s.ends_with("'''") && s.len() >= 6)
    {
        s[3..s.len() - 3].trim().to_string()
    } else if (s.starts_with('"') && s.ends_with('"') && s.len() >= 2)
        || (s.starts_with('\'') && s.ends_with('\'') && s.len() >= 2)
    {
        s[1..s.len() - 1].trim().to_string()
    } else {
        s.to_string()
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn test_extract_python_functions() {
        let content = r#"
def plain(x, y):
    pass

async def fetch(url):
    pass

@staticmethod
def decorated():
    pass

class MyClass:
    def method(self):
        pass
"#;
        let extractor = PythonExtractor;
        let mut fns = extractor.extract(content);
        fns.sort_by(|a, b| a.name.cmp(&b.name));

        // decorated, fetch, method, MyClass, plain
        assert_eq!(fns.len(), 5);

        let fetch = fns.iter().find(|f| f.name == "fetch").unwrap();
        assert!(fetch.is_async);

        let dec = fns.iter().find(|f| f.name == "decorated").unwrap();
        assert!(dec.decorators.contains(&"staticmethod".to_string()));

        let cls = fns.iter().find(|f| f.name == "MyClass").unwrap();
        assert!(cls.is_class);

        let meth = fns.iter().find(|f| f.name == "method").unwrap();
        assert!(meth.is_method);
    }

    #[test]
    fn test_python_docstring_extraction() {
        let content = r#"
def greet(name):
    """Say hello."""
    return f"hello {name}"
"#;
        let extractor = PythonExtractor;
        let fns = extractor.extract(content);
        assert_eq!(fns.len(), 1);
        assert_eq!(fns[0].docstring.as_deref(), Some("Say hello."));
    }
}