from typing import Any, Optional
from datetime import datetime
import re


class FlowContext:
    """Manages variables and state during flow execution"""

    def __init__(
        self,
        contact: dict,
        conversation: dict,
        message: dict,
        session_vars: dict = None
    ):
        self.contact = contact
        self.conversation = conversation
        self.message = message
        self.variables = session_vars or {}
        self._system = {
            "date": datetime.now().strftime("%Y-%m-%d"),
            "time": datetime.now().strftime("%H:%M"),
            "day_of_week": datetime.now().strftime("%A"),
        }

    def get(self, key: str) -> Any:
        """Get variable by dot notation: contact.name, variables.email"""
        parts = key.split(".")

        if parts[0] == "contact":
            return self._get_nested(self.contact, parts[1:])
        elif parts[0] == "conversation":
            return self._get_nested(self.conversation, parts[1:])
        elif parts[0] == "message":
            return self._get_nested(self.message, parts[1:])
        elif parts[0] == "system":
            return self._get_nested(self._system, parts[1:])
        elif parts[0] == "variables":
            return self._get_nested(self.variables, parts[1:])
        else:
            return self.variables.get(key)

    def set(self, key: str, value: Any):
        """Set a session variable"""
        self.variables[key] = value

    def _get_nested(self, obj: dict, keys: list) -> Any:
        for key in keys:
            if isinstance(obj, dict):
                obj = obj.get(key)
            else:
                return None
        return obj

    def interpolate(self, text: str) -> str:
        """Replace {{variable}} with actual values"""
        pattern = r'\{\{([^}]+)\}\}'

        def replace(match):
            key = match.group(1).strip()
            value = self.get(key)
            return str(value) if value is not None else ""

        return re.sub(pattern, replace, text)

    def to_dict(self) -> dict:
        return self.variables.copy()