from datetime import datetime
import xml.etree.ElementTree as ET

from .entry import Entry
from .util import escape_text_for_xml

class ReadEntry(Entry):
    """
    Entry type for reading content from standard input.
    
    Attributes:
        content: Content read from stdin, empty until first update
        io_buffer: Buffer to use for IO operations
        _read: Whether content has been read
    """
    
    def __init__(self, io_buffer, id: str, timestamp: datetime):
        """
        Initialize a new read entry.
        
        Args:
            io_buffer: Buffer to use for IO operations
            id: Unique identifier for this entry
            timestamp: Creation timestamp for this entry
        """
        super().__init__(id, timestamp)
        self.content = ""
        self.io_buffer = io_buffer
        self._read = False
        
    def update(self) -> None:
        """
        Read from stdin if not already read.
        Uses the provided IO buffer for the actual read operation.
        """
        if not self._read:
            self.content = self.io_buffer.read()
            self._read = True

    def generate_context(self) -> ET.Element:
        """
        Generate an XML Element representing this read entry.
        
        Returns:
            ET.Element: XML element containing the entry's data
        """
        # Create root element
        element = ET.Element("read_stdin", {"id": self.id})
        
        # Add content as CDATA or escaped text if content has been read
        if self._read:
            element.text = escape_text_for_xml(self.content)
            
        return element