#!/usr/bin/env python
"""
Log Reader Utility

This script provides a convenient way to read and filter log files during
development.
"""

import os
import sys
import time
import argparse
from datetime import datetime

def parse_args():
    """Parse command line arguments"""
    parser = argparse.ArgumentParser(description='Read and filter log files')
    parser.add_argument('--file', type=str, help='Log file to read (defaults to most recent .log file)')
    parser.add_argument('--tail', type=int, default=50, help='Number of lines to show from the end')
    parser.add_argument('--follow', '-f', action='store_true', help='Follow the file as it grows')
    parser.add_argument('--filter', type=str, help='Only show lines containing this string')
    parser.add_argument('--list', action='store_true', help='List all log files sorted by modification time')
    return parser.parse_args()

def get_most_recent_log():
    """Find the most recently modified log file"""
    log_files = [f for f in os.listdir('.') if f.endswith('.log')]
    if not log_files:
        print("No log files found in current directory.")
        sys.exit(1)
    
    # Sort by modification time (newest first)
    log_files.sort(key=lambda x: os.path.getmtime(x), reverse=True)
    return log_files[0]

def list_log_files():
    """List all log files sorted by modification time"""
    log_files = [f for f in os.listdir('.') if f.endswith('.log')]
    if not log_files:
        print("No log files found in current directory.")
        sys.exit(1)
    
    # Sort by modification time (newest first)
    log_files.sort(key=lambda x: os.path.getmtime(x), reverse=True)
    
    print(f"{'LAST MODIFIED':<20} {'SIZE':<10} FILENAME")
    print("-" * 60)
    for log_file in log_files:
        mtime = datetime.fromtimestamp(os.path.getmtime(log_file))
        size = os.path.getsize(log_file)
        size_str = f"{size / 1024:.1f} KB" if size > 1024 else f"{size} B"
        print(f"{mtime.strftime('%Y-%m-%d %H:%M:%S'):<20} {size_str:<10} {log_file}")

def read_log_tail(file_path, num_lines, filter_text=None):
    """Read the last N lines of a file"""
    try:
        with open(file_path, 'r', encoding='utf-8') as f:
            # Read all lines (inefficient but simple)
            lines = f.readlines()
            
            # Filter if needed
            if filter_text:
                lines = [line for line in lines if filter_text in line]
            
            # Get the last N lines
            last_lines = lines[-num_lines:] if len(lines) > num_lines else lines
            return last_lines
    except Exception as e:
        print(f"Error reading file: {str(e)}")
        sys.exit(1)

def follow_log(file_path, filter_text=None):
    """Follow the log file as it grows (like tail -f)"""
    try:
        with open(file_path, 'r', encoding='utf-8') as f:
            # Go to the end of the file
            f.seek(0, 2)
            
            while True:
                line = f.readline()
                if line:
                    if not filter_text or filter_text in line:
                        # Remove newlines at the end to avoid double spacing
                        print(line.rstrip())
                else:
                    time.sleep(0.1)  # Sleep briefly to avoid consuming CPU
    except KeyboardInterrupt:
        print("\nLog reading stopped.")
    except Exception as e:
        print(f"Error following file: {str(e)}")
        sys.exit(1)

def main():
    """Main function"""
    args = parse_args()
    
    # List all log files if requested
    if args.list:
        list_log_files()
        return
    
    # Determine which file to read
    file_path = args.file
    if not file_path:
        file_path = get_most_recent_log()
        print(f"Reading most recent log file: {file_path}")
    
    # Follow mode (like tail -f)
    if args.follow:
        print(f"Following {file_path} (Press Ctrl+C to stop)...")
        # First print the tail
        for line in read_log_tail(file_path, args.tail, args.filter):
            print(line.rstrip())
        print("-" * 80)
        print("Waiting for new content...")
        # Then follow
        follow_log(file_path, args.filter)
    else:
        # Just print the tail
        for line in read_log_tail(file_path, args.tail, args.filter):
            print(line.rstrip())

if __name__ == "__main__":
    main()