"""File-system helpers for the ChemGraph Streamlit UI.

Functions for resolving output paths, finding XYZ files, checking file
recency, and extracting directory paths from agent messages.
"""

import os
import re
from datetime import datetime, timedelta, timezone
from pathlib import Path
from typing import Any, Optional


def resolve_output_path(path: str) -> str:
    """Resolve output paths relative to CHEMGRAPH_LOG_DIR when set.

    Parameters
    ----------
    path : str
        Absolute or relative output path.

    Returns
    -------
    str
        Resolved output path.
    """
    if not path:
        return path
    if os.path.isabs(path):
        return path
    log_dir = os.environ.get("CHEMGRAPH_LOG_DIR")
    if log_dir:
        return os.path.join(log_dir, path)
    return path


def changed_recently(path: str = "ir_spectrum.png", window_seconds: int = 300) -> bool:
    """Return True if a file was modified within a recent time window.

    Parameters
    ----------
    path : str, optional
        File path to inspect.
    window_seconds : int, optional
        Recency window in seconds.

    Returns
    -------
    bool
        ``True`` when the file exists and is recent.
    """
    p = Path(resolve_output_path(path))
    if not p.exists():
        return False

    mtime = datetime.fromtimestamp(p.stat().st_mtime, tz=timezone.utc)
    now = datetime.now(timezone.utc)
    return (now - mtime) <= timedelta(seconds=window_seconds)


def find_latest_xyz_file() -> Optional[str]:
    """Find the most recently modified ``.xyz`` file in the log dir or cwd."""
    search_dirs: list[str] = []
    log_dir = os.environ.get("CHEMGRAPH_LOG_DIR")
    if log_dir:
        search_dirs.append(log_dir)
    search_dirs.append(os.getcwd())

    latest_path: Optional[str] = None
    latest_mtime = -1.0
    for base in search_dirs:
        if not base or not os.path.isdir(base):
            continue
        for path in Path(base).rglob("*.xyz"):
            try:
                mtime = path.stat().st_mtime
            except OSError:
                continue
            if mtime > latest_mtime:
                latest_mtime = mtime
                latest_path = str(path)
    return latest_path


def find_latest_xyz_file_in_dir(directory: str) -> Optional[str]:
    """Find the most recently modified ``.xyz`` file under a directory.

    Parameters
    ----------
    directory : str
        Directory to search recursively.

    Returns
    -------
    str or None
        Latest XYZ file path, or ``None`` when none is found.
    """
    if not directory or not os.path.isdir(directory):
        return None
    latest_path: Optional[str] = None
    latest_mtime = -1.0
    for path in Path(directory).rglob("*.xyz"):
        try:
            mtime = path.stat().st_mtime
        except OSError:
            continue
        if mtime > latest_mtime:
            latest_mtime = mtime
            latest_path = str(path)
    return latest_path


def extract_log_dir_from_messages(messages: Any) -> Optional[str]:
    """Extract a log directory from messages that reference output files.

    Parameters
    ----------
    messages : Any
        Message object, dictionary, list, or text to scan.

    Returns
    -------
    str or None
        Parent directory of a referenced output file, or ``None``.
    """
    if not messages:
        return None
    patterns = [
        r"(/[^\s'\"`]+?\.json)",
        r"(/[^\s'\"`]+?\.xyz)",
        r"(/[^\s'\"`]+?\.html)",
        r"(/[^\s'\"`]+?\.csv)",
    ]

    def _scan_value(value: Any) -> Optional[str]:
        """Recursively scan a value for absolute output-file references.

        Parameters
        ----------
        value : Any
            Message content, mapping, list, or scalar to scan.

        Returns
        -------
        str or None
            Parent directory of a referenced file, or ``None``.
        """
        if isinstance(value, str):
            for pattern in patterns:
                match = re.search(pattern, value)
                if match:
                    path = match.group(1)
                    if os.path.isabs(path):
                        return str(Path(path).parent)
        elif isinstance(value, dict):
            for v in value.values():
                found = _scan_value(v)
                if found:
                    return found
        elif isinstance(value, list):
            for v in value:
                found = _scan_value(v)
                if found:
                    return found
        return None

    for message in reversed(messages):
        content = ""
        if hasattr(message, "content"):
            content = getattr(message, "content", "")
        elif isinstance(message, dict):
            content = message.get("content", "")
        elif isinstance(message, str):
            content = message
        else:
            content = str(message)
        if not content:
            continue
        found = _scan_value(content)
        if found:
            return found

        # Also scan structured tool outputs if present
        if hasattr(message, "additional_kwargs"):
            found = _scan_value(message.additional_kwargs)
            if found:
                return found
        if isinstance(message, dict):
            found = _scan_value(message)
            if found:
                return found
    return None