"""
Direct database access for reading candle and annotation data.

This module provides read-only access to frontend tables (candles, annotations, 
span_annotations, charts) using SQLAlchemy table reflections or raw queries.
"""

import logging
from typing import List, Dict, Any, Optional
from datetime import datetime

import pandas as pd
from sqlalchemy import Table, MetaData, select, and_
from sqlalchemy.orm import Session

from app.db import engine, get_db

logger = logging.getLogger(__name__)


class DataAccess:
    """
    Provides read-only access to frontend database tables.
    
    Uses SQLAlchemy table reflection to access tables managed by Drizzle ORM
    without creating duplicate model definitions.
    """
    
    def __init__(self):
        """Initialize data access with table reflections."""
        self.metadata = MetaData()
        
        # Reflect frontend tables
        try:
            self.charts = Table('charts', self.metadata, autoload_with=engine)
            self.candles = Table('candles', self.metadata, autoload_with=engine)
            self.annotations = Table('annotations', self.metadata, autoload_with=engine)
            self.span_annotations = Table('span_annotations', self.metadata, autoload_with=engine)
            self.span_label_types = Table('span_label_types', self.metadata, autoload_with=engine)
            logger.info("Successfully reflected frontend tables")
        except Exception as e:
            logger.error(f"Error reflecting frontend tables: {e}")
            raise
    
    def get_chart_by_name(self, chart_name: str) -> Optional[Dict[str, Any]]:
        """
        Get chart by name.
        
        Args:
            chart_name: Name of the chart
            
        Returns:
            Chart dictionary or None if not found
        """
        with get_db() as db:
            stmt = select(self.charts).where(self.charts.c.name == chart_name)
            result = db.execute(stmt).fetchone()
            
            if result:
                return dict(result._mapping)
            return None
    
    def get_candles(
        self, 
        chart_id: int,
        start_time: Optional[datetime] = None,
        end_time: Optional[datetime] = None
    ) -> pd.DataFrame:
        """
        Get candle data for a chart.
        
        Args:
            chart_id: Chart ID
            start_time: Optional start time filter
            end_time: Optional end time filter
            
        Returns:
            DataFrame with columns: id, chart_id, time, open, high, low, close
        """
        with get_db() as db:
            # Build query
            stmt = select(self.candles).where(self.candles.c.chart_id == chart_id)
            
            if start_time:
                stmt = stmt.where(self.candles.c.time >= start_time)
            if end_time:
                stmt = stmt.where(self.candles.c.time <= end_time)
            
            stmt = stmt.order_by(self.candles.c.time)
            
            result = db.execute(stmt).fetchall()
            
            if not result:
                logger.warning(f"No candles found for chart_id={chart_id}")
                return pd.DataFrame()
            
            # Convert to DataFrame
            df = pd.DataFrame([dict(row._mapping) for row in result])
            logger.info(f"Loaded {len(df)} candles for chart_id={chart_id}")
            
            return df
    
    def get_span_annotations(
        self,
        chart_id: int,
        source: Optional[str] = None,
        min_confidence: Optional[int] = None
    ) -> pd.DataFrame:
        """
        Get span annotations for a chart.
        
        Args:
            chart_id: Chart ID
            source: Optional filter by source ('human', 'model', 'hybrid')
            min_confidence: Optional minimum confidence filter
            
        Returns:
            DataFrame with span annotations
        """
        with get_db() as db:
            # Build query
            stmt = select(self.span_annotations).where(
                self.span_annotations.c.chart_id == chart_id
            )
            
            if source:
                stmt = stmt.where(self.span_annotations.c.source == source)
            
            if min_confidence is not None:
                stmt = stmt.where(
                    and_(
                        self.span_annotations.c.confidence.isnot(None),
                        self.span_annotations.c.confidence >= min_confidence
                    )
                )
            
            stmt = stmt.order_by(self.span_annotations.c.start_time)
            
            result = db.execute(stmt).fetchall()
            
            if not result:
                logger.warning(f"No span annotations found for chart_id={chart_id}")
                return pd.DataFrame()
            
            # Convert to DataFrame
            df = pd.DataFrame([dict(row._mapping) for row in result])
            logger.info(f"Loaded {len(df)} span annotations for chart_id={chart_id}")
            
            return df
    
    def get_point_annotations(
        self,
        chart_id: int,
        label_type: Optional[str] = None
    ) -> pd.DataFrame:
        """
        Get point annotations for a chart.
        
        Args:
            chart_id: Chart ID
            label_type: Optional filter by label type
            
        Returns:
            DataFrame with point annotations
        """
        with get_db() as db:
            # Build query
            stmt = select(self.annotations).where(
                self.annotations.c.chart_id == chart_id
            )
            
            if label_type:
                stmt = stmt.where(self.annotations.c.label_type == label_type)
            
            stmt = stmt.order_by(self.annotations.c.timestamp)
            
            result = db.execute(stmt).fetchall()
            
            if not result:
                logger.warning(f"No point annotations found for chart_id={chart_id}")
                return pd.DataFrame()
            
            # Convert to DataFrame
            df = pd.DataFrame([dict(row._mapping) for row in result])
            logger.info(f"Loaded {len(df)} point annotations for chart_id={chart_id}")
            
            return df
    
    def get_training_data(
        self,
        chart_name: str,
        start_time: Optional[datetime] = None,
        end_time: Optional[datetime] = None,
        annotation_source: str = "human",
        min_confidence: Optional[int] = None
    ) -> tuple[pd.DataFrame, pd.DataFrame]:
        """
        Get complete training data for a chart (candles + span annotations).
        
        This is a convenience method that combines candle and annotation queries.
        
        Args:
            chart_name: Name of the chart
            start_time: Optional start time filter
            end_time: Optional end time filter
            annotation_source: Filter annotations by source (default: 'human')
            min_confidence: Optional minimum confidence filter
            
        Returns:
            Tuple of (candles_df, annotations_df)
        """
        # Get chart
        chart = self.get_chart_by_name(chart_name)
        if not chart:
            raise ValueError(f"Chart not found: {chart_name}")
        
        chart_id = chart['id']
        logger.info(f"Loading training data for chart: {chart_name} (id={chart_id})")
        
        # Get candles
        candles_df = self.get_candles(chart_id, start_time, end_time)
        
        # Get annotations
        annotations_df = self.get_span_annotations(
            chart_id, 
            source=annotation_source,
            min_confidence=min_confidence
        )
        
        return candles_df, annotations_df
    
    def get_all_charts(self) -> pd.DataFrame:
        """
        Get all available charts.
        
        Returns:
            DataFrame with all charts
        """
        with get_db() as db:
            stmt = select(self.charts).order_by(self.charts.c.created_at)
            result = db.execute(stmt).fetchall()
            
            if not result:
                return pd.DataFrame()
            
            df = pd.DataFrame([dict(row._mapping) for row in result])
            logger.info(f"Found {len(df)} charts")
            
            return df