#!/usr/bin/env python3
"""
Archive old Done tasks to monthly archive files.
Run periodically (heartbeat) to keep tasks.json small.
"""

import json
import os
from datetime import datetime, timedelta
from pathlib import Path

TASKS_FILE = Path(__file__).parent / "tasks.json"
ARCHIVE_DIR = Path(__file__).parent / "archive"
DAYS_TO_KEEP = 7  # Keep Done tasks for 7 days before archiving

def archive_old_tasks():
    if not TASKS_FILE.exists():
        print("No tasks.json found")
        return
    
    with open(TASKS_FILE, 'r') as f:
        data = json.load(f)
    
    # Find Done column
    done_col = None
    for col in data['columns']:
        if col['id'] == 'done':
            done_col = col
            break
    
    if not done_col:
        print("No Done column found")
        return
    
    # Calculate cutoff date
    cutoff = (datetime.now() - timedelta(days=DAYS_TO_KEEP)).strftime('%Y-%m-%d')
    
    # Separate old and recent tasks
    old_tasks = []
    recent_tasks = []
    
    for task in done_col['tasks']:
        completed = task.get('completed', task.get('created', ''))
        if completed and completed < cutoff:
            old_tasks.append(task)
        else:
            recent_tasks.append(task)
    
    if not old_tasks:
        print(f"No tasks older than {DAYS_TO_KEEP} days to archive")
        return
    
    # Create archive directory
    ARCHIVE_DIR.mkdir(exist_ok=True)
    
    # Group old tasks by month
    by_month = {}
    for task in old_tasks:
        completed = task.get('completed', task.get('created', ''))[:7]  # YYYY-MM
        if completed not in by_month:
            by_month[completed] = []
        by_month[completed].append(task)
    
    # Write to monthly archive files
    for month, tasks in by_month.items():
        archive_file = ARCHIVE_DIR / f"tasks-{month}.json"
        
        # Load existing archive
        if archive_file.exists():
            with open(archive_file, 'r') as f:
                archive = json.load(f)
        else:
            archive = {"month": month, "tasks": []}
        
        # Add new tasks (avoid duplicates by ID)
        existing_ids = {t['id'] for t in archive['tasks']}
        for task in tasks:
            if task['id'] not in existing_ids:
                archive['tasks'].append(task)
        
        # Save archive
        with open(archive_file, 'w') as f:
            json.dump(archive, f, indent=2, ensure_ascii=False)
        
        print(f"Archived {len(tasks)} tasks to {archive_file.name}")
    
    # Update tasks.json with only recent Done tasks
    done_col['tasks'] = recent_tasks
    data['lastUpdated'] = datetime.now().isoformat()
    
    with open(TASKS_FILE, 'w') as f:
        json.dump(data, f, indent=2, ensure_ascii=False)
    
    print(f"Kept {len(recent_tasks)} recent Done tasks, archived {len(old_tasks)}")

if __name__ == "__main__":
    archive_old_tasks()