"""
codegraph/extractor.py — V2 Multi-language metadata extractor.

V1 used Python's ast module → Python-only, returned empty object on SyntaxError.
V2 uses tree-sitter → Python + JS + TS + TSX with same API.
V2 also returns structured SyntaxError with line + message → agent can fix it.

tree-sitter is error-tolerant: returns a partial parse tree even for broken code,
so we always get *some* metadata even from syntactically broken submissions.
"""
import ast as pyast
from typing import Dict, Any

# ── tree-sitter setup ─────────────────────────────────────────────────────────
_PARSERS: Dict[str, Any] = {}


def _get_parser(ext: str):
    """Lazy-load language parser. Falls back to Python if grammar unavailable."""
    global _PARSERS
    if ext in _PARSERS:
        return _PARSERS[ext]
    try:
        from tree_sitter import Language, Parser
        if ext in (".py",):
            import tree_sitter_python as tspython
            lang = Language(tspython.language())
        elif ext in (".js", ".ts", ".tsx", ".jsx"):
            import tree_sitter_javascript as tsjavascript
            lang = Language(tsjavascript.language())
        else:
            import tree_sitter_python as tspython
            lang = Language(tspython.language())
        parser = Parser(lang)
        _PARSERS[ext] = parser
        return parser
    except Exception:
        # tree-sitter not installed → signal caller to use ast-only path
        _PARSERS[ext] = None
        return None


def extract_metadata(code: str, filename: str, step: int) -> Dict[str, Any]:
    """
    Extract structured metadata from agent code.

    Returns:
        dict with keys: status, functions, imports, conventions, language, created_at_step
        On syntax error: status='syntax_error', error, line, col, feedback

    V2 guarantee: always returns a dict, never raises.
    """
    ext = _get_ext(filename)

    # ── Python path: try ast for exact SyntaxError info ──────────────────────
    if ext == ".py":
        try:
            pyast.parse(code)
        except SyntaxError as e:
            return {
                "status": "syntax_error",
                "error": str(e.msg),
                "line": e.lineno,
                "col": e.offset,
                "feedback": f"SyntaxError line {e.lineno}: {e.msg}. Fix before grading.",
                "functions": [],
                "imports": [],
                "conventions": {},
                "created_at_step": step,
                "language": "py",
            }

    # ── tree-sitter parse (works even on broken JS/TS) ────────────────────────
    parser = _get_parser(ext)
    functions, imports = [], []

    if parser:
        try:
            tree = parser.parse(code.encode())

            def walk(node):
                if node.type in (
                    "function_definition", "function_declaration",
                    "arrow_function", "method_definition",
                ):
                    name_node = node.child_by_field_name("name")
                    if name_node:
                        functions.append({
                            "name": name_node.text.decode(),
                            "start_line": node.start_point[0],
                        })
                if node.type in (
                    "import_statement", "import_from_statement",
                    "import_declaration",
                ):
                    imports.append(node.text.decode()[:120])
                for child in node.children:
                    walk(child)

            walk(tree.root_node)
        except Exception:
            pass   # Partial results are fine

    # ── Fallback: pure ast for Python when tree-sitter unavailable ───────────
    if not functions and ext == ".py":
        try:
            tree = pyast.parse(code)
            for node in pyast.walk(tree):
                if isinstance(node, pyast.FunctionDef):
                    functions.append({"name": node.name, "start_line": node.lineno})
                if isinstance(node, pyast.Import):
                    imports += [a.name for a in node.names]
                if isinstance(node, pyast.ImportFrom) and node.module:
                    imports.append(node.module)
        except Exception:
            pass

    conventions = {
        "uses_try_catch": "try:" in code or "try {" in code,
        "uses_type_hints": (": " in code and " -> " in code) or ": str" in code or ": int" in code,
        "no_print_stmts": "print(" not in code,
        "uses_docstrings": '"""' in code or "'''" in code,
        "language": ext.lstrip("."),
    }

    return {
        "status": "ok",
        "functions": functions,
        "imports": imports,
        "conventions": conventions,
        "created_at_step": step,
        "language": ext.lstrip("."),
    }


def _get_ext(filename: str) -> str:
    if "." in filename:
        return "." + filename.rsplit(".", 1)[-1].lower()
    return ".py"