"""
Common utilities and constants
Stable functions that rarely change
"""

import os
import time
from pathlib import Path
from typing import Dict, Any, List, Set

# Constants
IMG_EXTS: Set[str] = {'.jpg', '.jpeg', '.png', '.bmp', '.webp'}
VID_EXTS: Set[str] = {'.mp4', '.avi', '.mov', '.mkv'}

ASPECT: Dict[str, str] = {
    'youtube': '1920:1080',
    'reels': '1080:1920', 
    'tiktok': '1080:1920',
    'square': '1080:1080',
    'widescreen': '1920:1080'
}

QUALITY: Dict[str, Dict[str, str]] = {
    'fast': {'preset': 'ultrafast', 'crf': '28'},
    'balanced': {'preset': 'fast', 'crf': '23'},
    'quality': {'preset': 'medium', 'crf': '20'}, 
    'best': {'preset': 'slow', 'crf': '18'}
}

# Utility functions
def is_image(file_path: str) -> bool:
    """Check if file is supported image format"""
    return Path(file_path).suffix.lower() in IMG_EXTS

def is_video(file_path: str) -> bool:
    """Check if file is supported video format"""
    return Path(file_path).suffix.lower() in VID_EXTS

def is_media(file_path: str) -> bool:
    """Check if file is supported media format"""
    return is_image(file_path) or is_video(file_path)

def size_mb(file_path: str) -> float:
    """Get file size in MB"""
    if not os.path.exists(file_path):
        return 0.0
    return round(os.path.getsize(file_path) / (1024 * 1024), 2)

def unique_name(prefix: str, extension: str = '.mp4') -> str:
    """Generate unique filename with timestamp and PID"""
    return f"{prefix}_{int(time.time())}_{os.getpid()}{extension}"

def safe_filename(name: str) -> str:
    """Make filename safe for filesystem"""
    invalid_chars = '<>:"/\\|?*'
    for char in invalid_chars:
        name = name.replace(char, '_')
    return name[:100]  # Limit length

def format_duration(seconds: int) -> str:
    """Format seconds to human readable duration"""
    if seconds < 60:
        return f"{seconds}s"
    elif seconds < 3600:
        return f"{seconds // 60}m {seconds % 60}s"
    else:
        h = seconds // 3600
        m = (seconds % 3600) // 60
        return f"{h}h {m}m"

def estimate_output(input_files: List[str], duration_per_file: int = 4) -> Dict[str, Any]:
    """Estimate output video characteristics"""
    total_files = len(input_files)
    total_duration = total_files * duration_per_file
    
    # Rough size estimation (varies greatly by content)
    estimated_size_mb = total_duration * 2  # ~2MB per second for balanced quality
    
    return {
        'files': total_files,
        'duration': total_duration,
        'duration_fmt': format_duration(total_duration),
        'size_mb': round(estimated_size_mb, 1)
    }

def valid_template(template: Dict[str, Any]) -> bool:
    """Validate motion template structure"""
    required_fields = ['name', 'scale', 'pan', 'rotate', 'duration']
    
    if not all(field in template for field in required_fields):
        return False
    
    # Validate data types and ranges
    if not isinstance(template['duration'], (int, float)) or template['duration'] <= 0:
        return False
        
    if not (isinstance(template['scale'], list) and len(template['scale']) == 2):
        return False
        
    if not (isinstance(template['pan'], list) and len(template['pan']) == 4):
        return False
        
    if not (isinstance(template['rotate'], list) and len(template['rotate']) == 2):
        return False
    
    return True

def get_platform_info(aspect_key: str) -> Dict[str, str]:
    """Get platform information and recommendations"""
    platform_info = {
        'youtube': {
            'name': 'YouTube',
            'ratio': '16:9',
            'optimal_duration': '15-60s',
            'description': 'Horizontal format for YouTube Shorts and regular videos'
        },
        'reels': {
            'name': 'Instagram Reels',
            'ratio': '9:16', 
            'optimal_duration': '15-30s',
            'description': 'Vertical format optimized for mobile viewing'
        },
        'tiktok': {
            'name': 'TikTok',
            'ratio': '9:16',
            'optimal_duration': '15-60s', 
            'description': 'Vertical format for TikTok content'
        },
        'square': {
            'name': 'Instagram Post',
            'ratio': '1:1',
            'optimal_duration': '15-30s',
            'description': 'Square format for Instagram feed posts'
        },
        'widescreen': {
            'name': 'Widescreen',
            'ratio': '16:9',
            'optimal_duration': '30-120s',
            'description': 'Standard widescreen format for presentations'
        }
    }
    
    return platform_info.get(aspect_key, {
        'name': 'Custom',
        'ratio': 'Custom',
        'optimal_duration': 'Variable',
        'description': 'Custom aspect ratio'
    })