from datetime import datetime
from app import db


class Instruction(db.Model):
    """Model for instruction files (PDFs or images)."""
    
    __tablename__ = 'instructions'
    
    id = db.Column(db.Integer, primary_key=True)
    set_id = db.Column(db.Integer, db.ForeignKey('sets.id'), nullable=False, index=True)
    
    # File information
    file_type = db.Column(db.String(10), nullable=False)  # 'PDF' or 'IMAGE'
    file_path = db.Column(db.String(500), nullable=False)
    file_name = db.Column(db.String(200), nullable=False)
    file_size = db.Column(db.Integer)  # Size in bytes
    thumbnail_path = db.Column(db.String(500))  # Thumbnail preview (especially for PDFs)
    
    # For image sequences
    page_number = db.Column(db.Integer, default=1)
    
    # Metadata
    user_id = db.Column(db.Integer, db.ForeignKey('users.id'), nullable=False)
    uploaded_at = db.Column(db.DateTime, nullable=False, default=datetime.utcnow)
    
    def __repr__(self):
        return f'<Instruction {self.file_name} for Set {self.set_id}>'
    
    def to_dict(self):
        """Convert instruction to dictionary."""
        # Ensure forward slashes for web URLs
        clean_path = self.file_path.replace('\\', '/')
        thumbnail_clean = self.thumbnail_path.replace('\\', '/') if self.thumbnail_path else None
        
        return {
            'id': self.id,
            'set_id': self.set_id,
            'file_type': self.file_type,
            'file_name': self.file_name,
            'file_size': self.file_size,
            'page_number': self.page_number,
            'file_url': f'/static/uploads/{clean_path}',
            'thumbnail_url': f'/static/uploads/{thumbnail_clean}' if thumbnail_clean else None,
            'uploaded_at': self.uploaded_at.isoformat()
        }
    
    @property
    def file_size_mb(self):
        """Return file size in MB."""
        if self.file_size:
            return round(self.file_size / (1024 * 1024), 2)
        return 0
    
    @staticmethod
    def allowed_file(filename):
        """Check if file extension is allowed."""
        from flask import current_app
        return '.' in filename and \
               filename.rsplit('.', 1)[1].lower() in current_app.config['ALLOWED_EXTENSIONS']