"""
ContentStrategyLib - Singleton class for managing content strategies from Google Sheets
"""

import os
import pandas as pd
from typing import Optional, List

from src.logger_config import logger
from src.utils import clean_and_drop_empty
from google_src.google_sheet import GoogleSheetReader
from google_src import get_default_wrapper, GCloudWrapper
from src.config import get_config_value



class ContentStrategyLib:
    """
    Singleton class that loads and manages content strategies from Google Sheets.
    Replaces the legacy CSV-based loading.
    
    Usage:
        lib = get_content_strategy_lib()
        df = lib.strategies  # Auto-loads if empty
    """
    
    def __init__(self, gcloud_wrapper: Optional[GCloudWrapper] = None):
        self._gcloud_wrapper = gcloud_wrapper or get_default_wrapper()
        self._strategies_df: pd.DataFrame = pd.DataFrame()
        self._worksheet_name = get_config_value("content_strategy_worksheet")
        
        if not self._worksheet_name:
            logger.warning("content_strategy_worksheet env var not set. Content strategies will be empty.")
        
    def load_strategies(self, account_id: str = "test_data") -> pd.DataFrame:
        """
        Load content strategies from Google Sheet.
        
        Args:
            account_id: Which account to use ('final_data' or 'test_data')
        """
        if not self._worksheet_name:
            return pd.DataFrame()
            
        try:
            logger.debug(f"Loading content strategies from Google Sheet: {self._worksheet_name} ({account_id})")
            googleSheetReader = GoogleSheetReader(
                worksheet_name=self._worksheet_name,
                gcloud_wrapper=self._gcloud_wrapper,
                account_id=account_id,
            )
            df = googleSheetReader.get_filtered_dataframe()
            
            # Validate required columns similar to the old CSV method
            if get_config_value("ON_SCREEN_TEXT", "false").lower() == "true":
                required_cols = ["On-Screen Text"]
            else:
                required_cols = [
                    "Gemini Imagen4 Ultra Prompt (specific)",
                    "TTS Script (AI Avatar)",
                    "Runway Prompt Gen4 Turbo",
                    "Captions",
                ]
            
            missing_cols = [col for col in required_cols if col not in df.columns]
            if missing_cols:
                logger.error(f"❌ Google Sheet missing columns: {', '.join(missing_cols)}")
                # We return empty or partial? Let's return what we have but warn
                
            self._strategies_df = df
            logger.debug(f"✓ Loaded {len(df)} content strategies")
            return df
            
        except Exception as e:
            error_msg = str(e) if str(e) else type(e).__name__
            if "403" in error_msg or "permission" in error_msg.lower():
                logger.error(f"❌ PERMISSION ERROR loading strategies: {error_msg}")
            elif "404" in error_msg or "not found" in error_msg.lower():
                logger.error(f"❌ WORKSHEET NOT FOUND: '{self._worksheet_name}'")
            else:
                logger.error(f"Failed to load content strategies: {error_msg}")
            return pd.DataFrame()

    @property
    def strategies(self) -> pd.DataFrame:
        """Get the cached strategies DataFrame. Loads if empty."""
        if self._strategies_df.empty:
            return self.load_strategies()
        return self._strategies_df
        
    def reload(self):
        """Force reload from Google Sheets"""
        return self.load_strategies()


# Module-level singleton instance
_content_strategy_lib: Optional[ContentStrategyLib] = None


def get_content_strategy_lib() -> ContentStrategyLib:
    """
    Get the singleton ContentStrategyLib instance.
    """
    global _content_strategy_lib
    if _content_strategy_lib is None:
        _content_strategy_lib = ContentStrategyLib()
    return _content_strategy_lib