"""Chroot environment preparation."""

import shutil
from pathlib import Path

from .utils import info, success, warn, run, is_mounted


def prepare_chroot(mount_root: Path | None = None) -> None:
    """Prepare chroot environment with bind mounts."""
    if mount_root is None:
        mount_root = Path("/mnt/gentoo")

    info("=== Preparing Chroot Environment ===")

    # Check if already prepared (idempotency)
    if is_mounted(mount_root / "proc"):
        info("Chroot already prepared (skipping)")
        return

    # Copy DNS configuration
    info("Copying DNS configuration...")
    resolv_src = Path("/etc/resolv.conf")
    resolv_dst = mount_root / "etc/resolv.conf"

    if resolv_src.exists():
        # Use --dereference to copy the actual file if it's a symlink
        shutil.copy2(resolv_src.resolve(), resolv_dst)
        success("Copied resolv.conf")

    # Bind mount pseudo-filesystems
    mounts = [
        ("proc", "/proc", ["--rbind"]),
        ("sys", "/sys", ["--rbind"]),
        ("dev", "/dev", ["--rbind"]),
        ("run", "/run", ["--rbind"]),
    ]

    for name, source, flags in mounts:
        target = mount_root / name.lstrip("/")
        target.mkdir(parents=True, exist_ok=True)

        run("mount", *flags, source, str(target))
        run("mount", "--make-rslave", str(target))
        success(f"Mounted {source}")

    print()
    success("=== Chroot environment ready ===")
    print()
    info("To enter chroot:")
    print(f"  chroot {mount_root} /bin/bash")
    print("  source /etc/profile")
    print("  export PS1=\"(chroot) $PS1\"")


def enter_chroot(mount_root: Path | None = None) -> None:
    """Enter the chroot environment."""
    if mount_root is None:
        mount_root = Path("/mnt/gentoo")

    import os
    os.execvp("chroot", ["chroot", str(mount_root), "/bin/bash", "--login"])


def cleanup_chroot(mount_root: Path | None = None) -> None:
    """Unmount chroot bind mounts."""
    if mount_root is None:
        mount_root = Path("/mnt/gentoo")

    info("Cleaning up chroot mounts...")

    # Unmount in reverse order
    for name in ["run", "dev", "sys", "proc"]:
        target = mount_root / name
        result = run("umount", "-R", str(target), check=False)
        if not result.ok:
            # Try lazy unmount as fallback
            warn(f"Normal unmount failed for {target}, trying lazy unmount...")
            run("umount", "-Rl", str(target), check=False)

    success("Chroot mounts cleaned up.")