import subprocess
import logging
import os
from contextlib import contextmanager

logger = logging.getLogger(__name__)

def run_command(cmd, check=True):
    logger.info(f"Running command: {' '.join(cmd)}")
    try:
        result = subprocess.run(cmd, check=check, capture_output=True, text=True)
        return result
    except subprocess.CalledProcessError as e:
        logger.error(f"Command failed: {e.stderr}")
        raise

@contextmanager
def mount_pseudo_fs(mount_root):
    """
    Context manager to bind mount /dev, /proc, and /sys into mount_root.
    """
    logger.info(f"Mounting pseudo-filesystems to {mount_root}...")
    mounts = ["dev", "proc", "sys"]
    mounted_paths = []
    
    try:
        for fs in mounts:
            target = os.path.join(mount_root, fs)
            os.makedirs(target, exist_ok=True)
            run_command(["mount", "--bind", f"/{fs}", target])
            mounted_paths.append(target)
        yield
    finally:
        logger.info(f"Unmounting pseudo-filesystems from {mount_root}...")
        for path in reversed(mounted_paths):
            try:
                run_command(["umount", "-l", path])
            except Exception as e:
                logger.warning(f"Failed to unmount {path}: {e}")

def install_minimal_os(mount_root, releasever="41"):
    """
    Installs minimal Fedora packages to mount_root.
    """
    logger.info(f"Installing minimal Fedora {releasever} to {mount_root}...")
    
    packages = [
        "basesystem",
        "bash",
        "coreutils",
        "kernel",
        "systemd",
        "dnf",
        "grub2-efi-x64",
        "shim-x64",
        "efibootmgr",
        "passwd",
        "rootfiles",
        "vim-minimal"
    ]
    
    cmd = [
        "dnf", "install", "-y",
        f"--installroot={mount_root}",
        f"--releasever={releasever}",
        "--use-host-config",
        "--setopt=install_weak_deps=False",
        "--nodocs"
    ] + packages
    
    with mount_pseudo_fs(mount_root):
        run_command(cmd)
    
    logger.info("Base system installation complete.")

def configure_system(mount_root, partition_info):
    """
    Basic configuration: fstab and grub.
    """
    logger.info("Configuring system...")
    
    # 1. Generate fstab
    def get_uuid(dev):
        res = run_command(["blkid", "-s", "UUID", "-o", "value", dev])
        return res.stdout.strip()

    root_uuid = get_uuid(partition_info["root"])
    efi_uuid = get_uuid(partition_info["efi"])
    swap_uuid = get_uuid(partition_info["swap"])

    fstab_content = f"""
UUID={root_uuid} / ext4 defaults 1 1
UUID={efi_uuid} /boot/efi vfat defaults 0 2
UUID={swap_uuid} none swap defaults 0 0
"""
    os.makedirs(os.path.join(mount_root, "etc"), exist_ok=True)
    with open(os.path.join(mount_root, "etc/fstab"), "w") as f:
        f.write(fstab_content)
    
    # 2. Configure GRUB
    with mount_pseudo_fs(mount_root):
        # grub2-mkconfig -o /boot/grub2/grub.cfg
        chroot_cmd = ["chroot", mount_root, "grub2-mkconfig", "-o", "/boot/grub2/grub.cfg"]
        run_command(chroot_cmd)

    logger.info("System configuration complete.")