"""
ast_check.py — P45: AST syntax check pre-esecuzione codice.

Usa ast.parse() stdlib Python (zero dipendenze) per Python.
Per JS/TS: esprima se disponibile, fallback balanced-bracket heuristic.
Integra P17-B1: sostituisce routing regex E2B per validazione sintattica.

Utilizzo:
    from tools.ast_check import check_code_syntax
    result = check_code_syntax(code, "python")
    if not result.ok:
        return f"SyntaxError: {result.error}"
"""
import ast
import re
import logging
from dataclasses import dataclass

_logger = logging.getLogger("tools.ast_check")


@dataclass
class SyntaxCheckResult:
    ok: bool
    error: str | None = None
    language: str = ""
    line: int | None = None
    col: int | None = None

    def __str__(self):
        if self.ok:
            return f"[AST] {self.language}: OK"
        loc = f" (line {self.line})" if self.line else ""
        return f"[AST] {self.language}{loc}: {self.error}"


def check_python_syntax(code):
    """AST check Python con ast.parse() stdlib. Zero dipendenze."""
    try:
        ast.parse(code, mode="exec")
        return SyntaxCheckResult(ok=True, language="python")
    except SyntaxError as e:
        return SyntaxCheckResult(
            ok=False, language="python",
            error=f"{type(e).__name__}: {e.msg}",
            line=e.lineno, col=e.offset,
        )
    except Exception as e:
        return SyntaxCheckResult(ok=False, language="python", error=str(e))


def _balanced_brackets(code):
    """Heuristica bilanciamento parentesi — fallback JS senza esprima."""
    stack = []
    pairs = {")": "(", "}": "{", "]": "["}
    in_str = None
    i = 0
    while i < len(code):
        ch = code[i]
        if in_str:
            if ch == "\\" and i + 1 < len(code):
                i += 2
                continue
            if ch == in_str:
                in_str = None
        elif ch in ('"', "'", '`'):
            in_str = ch
        elif ch in "({[":
            stack.append(ch)
        elif ch in ")}]":
            if not stack or stack[-1] != pairs[ch]:
                return SyntaxCheckResult(ok=False, language="js/ts", error=f"Unmatched '{ch}' at pos {i}")
            stack.pop()
        i += 1
    if stack:
        return SyntaxCheckResult(ok=False, language="js/ts", error=f"Unclosed '{stack[-1]}'")
    return SyntaxCheckResult(ok=True, language="js/ts")


def check_js_syntax(code):
    """AST check JS/TS: esprima se disponibile, fallback balanced-bracket."""
    try:
        import esprima
        esprima.parseScript(code, tolerant=False)
        return SyntaxCheckResult(ok=True, language="js/ts")
    except ImportError:
        pass
    except Exception as e:
        msg = str(e)
        m = re.search(r"Line (\d+)", msg)
        line = int(m.group(1)) if m else None
        return SyntaxCheckResult(ok=False, language="js/ts", error=msg[:200], line=line)
    return _balanced_brackets(code)


_LANG_MAP = {
    "python": "python", "py": "python",
    "javascript": "js", "js": "js", "jsx": "js",
    "typescript": "js", "ts": "js", "tsx": "js",
}


def check_code_syntax(code, language):
    """
    Dispatch AST check per linguaggio. Fail-open su linguaggi non supportati.
    Returns SyntaxCheckResult(ok, error, language, line, col).
    """
    if not code or not code.strip():
        return SyntaxCheckResult(ok=True, language=language)
    lang = _LANG_MAP.get(language.lower().strip(), "")
    if lang == "python":
        result = check_python_syntax(code)
    elif lang == "js":
        result = check_js_syntax(code)
    else:
        return SyntaxCheckResult(ok=True, language=language)
    if not result.ok:
        _logger.warning("[AST-P45] %s syntax error: %s", language, result.error)
    return result


def extract_code_blocks(text):
    """Estrae blocchi codice da markdown. Ritorna list[(language, code)]."""
    blocks = []
    pattern = re.compile(r'```(\w+)?\n([\s\S]*?)```')
    for m in pattern.finditer(text):
        lang = (m.group(1) or "").strip()
        code = m.group(2)
        blocks.append((lang, code))
    return blocks


def check_all_code_blocks(text):
    """Verifica tutti i blocchi codice in markdown. Ritorna solo errori."""
    errors = []
    for lang, code in extract_code_blocks(text):
        result = check_code_syntax(code, lang)
        if not result.ok:
            errors.append(result)
    return errors