"""
TextOverlayLib - Singleton class for managing text overlay content from Google Sheets
"""

import os
import pandas as pd
from typing import Optional

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 TextOverlayLib:
    """
    Singleton class that loads and manages text overlay content from Google Sheets.
    Uses round-robin auto-increment for text overlay selection.
    
    Usage:
        text_overlay_lib = get_text_overlay_lib()
        text = text_overlay_lib.select_text_overlay()
    """
    
    def __init__(self, gcloud_wrapper: Optional[GCloudWrapper] = None, initial_index: int = 0):
        self._gcloud_wrapper = gcloud_wrapper or get_default_wrapper()
        self._text_overlay_library: pd.DataFrame = self._load_from_gsheet()
        
        if len(self._text_overlay_library) == 0:
            raise ValueError("Text overlay library is empty! Check GSHEET_WORKSHEET_TEXT_OVERLAY env var and Google Sheet access.")
        
        self._current_index = initial_index % len(self._text_overlay_library)
        logger.debug(f"✓ TextOverlayLib initialized with {len(self._text_overlay_library)} text overlays, starting at index {self._current_index}")
    
    @property
    def text_overlay_library(self) -> pd.DataFrame:
        """Get the text overlay library DataFrame"""
        return self._text_overlay_library
    
    @property
    def current_index(self) -> int:
        """Get current text overlay index"""
        return self._current_index
    
    @current_index.setter
    def current_index(self, value: int) -> None:
        """Set current text overlay index (wraps around)"""
        if len(self._text_overlay_library) > 0:
            self._current_index = value % len(self._text_overlay_library)
    
    def _load_from_gsheet(self, account_id: str = "test_data") -> pd.DataFrame:
        """
        Load text overlay library from Google Sheet.
        
        Args:
            account_id: Which account to use ('final_data' or 'test_data')
        """
        try:
            worksheet_name = get_config_value("gsheet_worksheet_text_overlay")
            if not worksheet_name:
                logger.error("GSHEET_WORKSHEET_TEXT_OVERLAY env var not set!")
                return pd.DataFrame()
            
            logger.debug(f"Loading text overlay library using account: {account_id}")
            googleSheetReader = GoogleSheetReader(
                worksheet_name=worksheet_name,
                gcloud_wrapper=self._gcloud_wrapper,
                account_id=account_id,
            )
            text_df = googleSheetReader.get_filtered_dataframe()
            column_name = get_config_value("gsheet_worksheet_text_overlay_column")
            return clean_and_drop_empty(text_df, column_name)
        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() or "forbidden" in error_msg.lower():
                logger.error(f"❌ PERMISSION ERROR loading text overlay library: {error_msg}")
                logger.error("Share the Google Sheet with the service account email as Editor!")
            elif "404" in error_msg or "not found" in error_msg.lower():
                logger.error(f"❌ WORKSHEET NOT FOUND: '{get_config_value('GSHEET_WORKSHEET_TEXT_OVERLAY')}'")
            else:
                logger.error(f"Failed to load text overlay library from Google Sheet: {error_msg}")
            return pd.DataFrame()
    
    def inc_index(self) -> None:
        """Increment current text overlay index (wraps around)"""
        self._current_index = (self._current_index + 1) % len(self._text_overlay_library)
    
    def select_text_overlay(self) -> str:
        """
        Select text overlay SEQUENTIALLY (not random).
        Each call increments the index to ensure different text for each video.
        
        Returns:
            Text overlay string
        """
        if self._text_overlay_library.empty:
            logger.error("❌ Text overlay library is empty")
            return ""
        column_name = get_config_value("gsheet_worksheet_text_overlay_column")
        selected = self._text_overlay_library.iloc[self._current_index][column_name]
        
        logger.debug(
            f"📝 Selected text overlay #{self._current_index + 1}/{len(self._text_overlay_library)}: {selected}"
        )
        
        # Increment index for next call (loop back to start if needed)
        self._current_index = (self._current_index + 1) % len(self._text_overlay_library)
        
        return selected
    
    def reset_index(self) -> None:
        """Reset text overlay index to start from beginning (useful for batch processing)"""
        self._current_index = 0
        logger.debug("🔄 Reset text overlay index to 0")
    
    def __len__(self) -> int:
        return len(self._text_overlay_library)


# Module-level singleton instance
_text_overlay_lib: Optional[TextOverlayLib] = None


def get_text_overlay_lib(initial_index: int = 0) -> TextOverlayLib:
    """
    Get the singleton TextOverlayLib instance.
    
    Args:
        initial_index: Starting index for text overlay selection (only used on first call)
    
    Returns:
        TextOverlayLib: The singleton instance
    """
    global _text_overlay_lib
    if _text_overlay_lib is None:
        _text_overlay_lib = TextOverlayLib(initial_index=initial_index)
    return _text_overlay_lib


def reset_text_overlay_lib() -> None:
    """Reset the singleton (useful for testing)"""
    global _text_overlay_lib
    _text_overlay_lib = None