app/data_visualizer.py

"""
Data Visualization Helper
Generate chart data for frontend visualization
"""

from typing import Dict, List, Any
from collections import Counter

class DataVisualizer:
    """Helper to prepare data for charts and graphs"""
    
    def prepare_chart_data(self, data: List[Dict], x_column: str, y_column: str, chart_type: str = 'bar') -> Dict:
        """Prepare data for chart visualization"""
        if not data:
            return {'ok': False, 'error': 'No data provided'}
        
        try:
            labels = [str(row.get(x_column, '')) for row in data]
            values = [row.get(y_column, 0) for row in data]
            
            return {
                'ok': True,
                'chart_type': chart_type,
                'labels': labels,
                'values': values,
                'x_label': x_column,
                'y_label': y_column
            }
        except Exception as e:
            return {'ok': False, 'error': str(e)}
    
    def analyze_column(self, data: List[Dict], column: str) -> Dict:
        """Analyze a column and return statistics"""
        if not data:
            return {'ok': False, 'error': 'No data'}
        
        values = [row.get(column) for row in data if row.get(column) is not None]
        
        if not values:
            return {'ok': False, 'error': 'No values in column'}
        
        # Determine data type
        sample = values[0]
        is_numeric = isinstance(sample, (int, float))
        
        result = {
            'ok': True,
            'column': column,
            'count': len(values),
            'null_count': len(data) - len(values),
            'unique_count': len(set(str(v) for v in values))
        }
        
        if is_numeric:
            result.update({
                'type': 'numeric',
                'min': min(values),
                'max': max(values),
                'avg': sum(values) / len(values),
                'sum': sum(values)
            })
        else:
            # Get most common values
            counter = Counter(str(v) for v in values)
            result.update({
                'type': 'categorical',
                'most_common': counter.most_common(5)
            })
        
        return result
    
    def get_distribution(self, data: List[Dict], column: str, bins: int = 10) -> Dict:
        """Get distribution of values for histogram"""
        if not data:
            return {'ok': False, 'error': 'No data'}
        
        values = [row.get(column) for row in data if row.get(column) is not None]
        
        if not values:
            return {'ok': False, 'error': 'No values'}
        
        # Check if numeric
        if not isinstance(values[0], (int, float)):
            # For categorical, return frequency
            counter = Counter(str(v) for v in values)
            return {
                'ok': True,
                'type': 'categorical',
                'distribution': dict(counter.most_common(bins))
            }
        
        # For numeric, create bins
        min_val = min(values)
        max_val = max(values)
        bin_size = (max_val - min_val) / bins
        
        distribution = {}
        for i in range(bins):
            bin_start = min_val + i * bin_size
            bin_end = bin_start + bin_size
            bin_label = f"{bin_start:.2f}-{bin_end:.2f}"
            count = sum(1 for v in values if bin_start <= v < bin_end)
            distribution[bin_label] = count
        
        return {
            'ok': True,
            'type': 'numeric',
            'distribution': distribution,
            'bins': bins
        }

data_visualizer = DataVisualizer()