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

from .entry import Entry

class RepeatEntry(Entry):
    """
    Entry type for scripts that are executed on every update.

    Attributes:
        script: The script/command to execute
        timeout: Maximum time to wait for script execution
        limit: Maximum number of characters to capture from stdout/stderr
        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
    """

    default_timeout = 1
    default_limit = 1024
    
    def __init__(
            self,
            id: str,
            timestamp: datetime,
            script: str,
            timeout: Optional[float],
            limit: Optional[int],
        ):
        """
        Initialize a new repeat entry.
        
        Args:
            id: Unique identifier for this entry
            timestamp: Creation timestamp for this entry
            script: The script/command to execute
            timeout: Maximum time to wait for script execution
            limit: Maximum number of characters to capture from stdout/stderr
        """
        super().__init__(id, timestamp)
        self._script = script
        self._timeout = timeout
        self._limit = limit
        self._stdout = ""
        self._stderr = ""
        self._exit_code: Optional[int] = None
        self._timed_out = False

    @property
    def script(self) -> str:
        """Get the script/command being executed."""
        return self._script

    @property
    def stdout(self) -> str:
        """Get the captured standard output."""
        return self._stdout

    @property
    def stderr(self) -> str:
        """Get the captured standard error."""
        return self._stderr

    @property
    def exit_code(self) -> Optional[int]:
        """Get the exit code of the process (None if still running)."""
        return self._exit_code
        
    def update(self) -> None:
        """
        Execute the script and update the output.
        Captures stdout, stderr and exit code from each execution.
        """
        try:
            process = subprocess.run(
                self._script,
                timeout=(self._timeout or self.default_timeout),
                shell=True,
                capture_output=True,
                text=True
            )
            self._stdout = process.stdout
            self._stderr = process.stderr
            self._exit_code = process.returncode
        except subprocess.TimeoutExpired as e:
            self._timed_out = True


    def generate_context(self) -> ET.Element:
        """
        Generate an XML Element representing this repeat entry.
        
        Returns:
            ET.Element: XML element containing the entry's data
        """
        element = ET.Element("repeat", {
            "id": self.id,
        })
        if self._timeout:
            element.set("timeout", str(self._timeout))
        element.text = self.script
        if self._timed_out:
            element.set("timed_out", "true")
        elif self._exit_code is not None:
            element.set("exit_code", str(self._exit_code))
            if self._limit:
                element.set("limit", str(self._limit))
            if len(self._stdout) > (self._limit or self.default_limit):
                element.set("stdout_truncated", "true")
                element.set("stdout_length", str(len(self._stdout)))
            stdout_elem = ET.SubElement(element, "stdout")
            stdout_elem.text = self._stdout[:(self._limit or self.default_limit)]
            if len(self._stderr) > (self._limit or self.default_limit):
                element.set("stderr_truncated", "true")
                element.set("stderr_length", str(len(self._stderr)))
            stderr_elem = ET.SubElement(element, "stderr")
            stderr_elem.text = self._stderr[:(self._limit or self.default_limit)]
        
        return element