from datetime import datetime
import subprocess
import xml.etree.ElementTree as ET
from typing import Optional

from .entry import Entry
from .util import escape_text_for_xml

class SingleShotEntry(Entry):
    """
    Entry type for one-time script executions.
    
    Attributes:
        script: The script/command to execute
        stdout: Captured standard output from script execution
        stderr: Captured standard error from script execution 
        exit_code: Process exit code after completion
        _executed: Whether the script has been executed
    """
    
    def __init__(self, script: str, id: str, timestamp: datetime):
        """
        Initialize a new single shot entry.
        
        Args:
            script: The script/command to execute
            id: Unique identifier for this entry
            timestamp: Creation timestamp for this entry
        """
        super().__init__(id, timestamp)
        self.script = script
        self.stdout = ""
        self.stderr = ""
        self.exit_code: Optional[int] = None
        self._executed = False
        
    def update(self) -> None:
        """
        Execute the script if not already executed.
        Captures stdout, stderr and exit code.
        """
        if self._executed:
            return
            
        try:
            # Run script and capture output
            process = subprocess.run(
                self.script,
                shell=True,
                capture_output=True,
                text=True
            )
            
            # Store results
            self.stdout = process.stdout
            self.stderr = process.stderr
            self.exit_code = process.returncode
            
        except subprocess.SubprocessError as e:
            # Handle subprocess errors by capturing the error message
            self.stdout = ""
            self.stderr = str(e)
            self.exit_code = -1
            
        except Exception as e:
            # Handle any other errors
            self.stdout = ""
            self.stderr = f"Error executing script: {str(e)}"
            self.exit_code = -1
            
        self._executed = True

    def generate_context(self) -> ET.Element:
        """
        Generate an XML Element representing this single shot entry.
        
        Returns:
            ET.Element: XML element containing the entry's data
        """
        # Create root element
        element = ET.Element("single_shot", {
            "id": self.id,
        })
        
        # Add script as CDATA or escaped text
        element.text = escape_text_for_xml(self.script)
        
        # Only add output elements if script has executed
        if self._executed:
            # Add stdout element if there is output
            stdout_elem = ET.SubElement(element, "stdout")
            stdout_elem.text = escape_text_for_xml(self.stdout)
            
            # Add stderr element if there are errors
            stderr_elem = ET.SubElement(element, "stderr")
            stderr_elem.text = escape_text_for_xml(self.stderr)
            
            # Add exit code attribute after execution
            element.set("exit_code", str(self.exit_code))
            
        return element