"""
Null/headless display backend.
"""

import time


class NullDisplay:
    """Headless/null display - discards all output.

    This display does nothing - useful for headless benchmarking
    or when no display output is needed.
    """

    width: int = 80
    height: int = 24

    def init(self, width: int, height: int, reuse: bool = False) -> None:
        """Initialize display with dimensions.

        Args:
            width: Terminal width in characters
            height: Terminal height in rows
            reuse: Ignored for NullDisplay (no resources to reuse)
        """
        self.width = width
        self.height = height

    def show(self, buffer: list[str]) -> None:
        from engine.display import get_monitor

        monitor = get_monitor()
        if monitor:
            t0 = time.perf_counter()
            chars_in = sum(len(line) for line in buffer)
            elapsed_ms = (time.perf_counter() - t0) * 1000
            monitor.record_effect("null_display", elapsed_ms, chars_in, chars_in)

    def clear(self) -> None:
        pass

    def cleanup(self) -> None:
        pass