import matplotlib.pyplot as plt
import pandas as pd
import os
import logging
import time

class ChartGenerator:
    def __init__(self, data=None):
        logging.info("Initializing ChartGenerator")
        if data is not None:
            self.data = data
        else:
            self.data = pd.read_excel(os.path.join(os.path.dirname(os.path.dirname(__file__)), 'data', 'sample_data.xlsx'))

    def generate_chart(self, plot_args):
        start_time = time.time()
        logging.info(f"Generating chart with arguments: {plot_args}")
        
        # Validate columns before plotting
        x_col = plot_args['x']
        y_cols = plot_args['y']
        missing_cols = []
        if x_col not in self.data.columns:
            missing_cols.append(x_col)
        for y in y_cols:
            if y not in self.data.columns:
                missing_cols.append(y)
        if missing_cols:
            logging.error(f"Missing columns in data: {missing_cols}")
            logging.info(f"Available columns: {list(self.data.columns)}")
            raise ValueError(f"Missing columns in data: {missing_cols}")
        
        # Clear any existing plots
        plt.clf()
        plt.close('all')
        
        fig, ax = plt.subplots(figsize=(10, 6))
        
        for y in y_cols:
            color = plot_args.get('color', None)
            if plot_args.get('chart_type', 'line') == 'bar':
                ax.bar(self.data[x_col], self.data[y], label=y, color=color)
            else:
                ax.plot(self.data[x_col], self.data[y], label=y, color=color, marker='o')
        
        ax.set_xlabel(x_col)
        ax.set_ylabel('Value')
        ax.set_title(f'{plot_args.get("chart_type", "line").title()} Chart')
        ax.legend()
        ax.grid(True, alpha=0.3)
        
        # Rotate x-axis labels if needed
        if len(self.data[x_col]) > 5:
            plt.xticks(rotation=45)

        chart_filename = 'chart.png'
        output_dir = os.path.join(os.path.dirname(os.path.dirname(__file__)), 'static', 'images')
        if not os.path.exists(output_dir):
            os.makedirs(output_dir)
            logging.info(f"Created output directory: {output_dir}")
        
        full_path = os.path.join(output_dir, chart_filename)
        
        if os.path.exists(full_path):
            os.remove(full_path)
            logging.info(f"Removed existing chart file: {full_path}")
        
        # Save with high DPI for better quality
        plt.savefig(full_path, dpi=300, bbox_inches='tight', facecolor='white')
        plt.close(fig)
        
        # Verify file was created
        if os.path.exists(full_path):
            file_size = os.path.getsize(full_path)
            logging.info(f"Chart generated and saved to {full_path} (size: {file_size} bytes)")
        else:
            logging.error(f"Failed to create chart file at {full_path}")
            raise FileNotFoundError(f"Chart file was not created at {full_path}")
        
        return os.path.join('static', 'images', chart_filename)