#!/bin/bash
# Create a minimal initramfs for the stock H700 kernel.
# The stock kernel has most drivers built-in, so we just need
# a minimal init that mounts rootfs and exec's /sbin/init.
set -e

outdir="${1:-./artifacts}"
mkdir -p "$outdir"
tmp="$(mktemp -d)"
trap 'rm -rf "$tmp"' 0

mkdir -p "$tmp"/{bin,dev,proc,sys,newroot}

# Use busybox from host or build a static one
# For now, create a minimal shell init script
cat > "$tmp/init" << 'INITEOF'
#!/bin/busybox sh
/bin/busybox mount -t proc none /proc
/bin/busybox mount -t sysfs none /sys
/bin/busybox mount -t devtmpfs none /dev

# Find the root partition (partition 5 = rootfs)
root=""
for dev in /dev/mmcblk0p5 /dev/mmcblk0p4; do
    if [ -b "$dev" ]; then
        root="$dev"
        break
    fi
done

if [ -z "$root" ]; then
    echo "Cannot find root partition!"
    /bin/busybox sh
fi

/bin/busybox mount -t ext4 "$root" /newroot
exec /bin/busybox switch_root /newroot /sbin/init
INITEOF
chmod +x "$tmp/init"

# Get a static busybox for aarch64
if [ ! -f "$outdir/busybox" ]; then
    podman run --arch=aarch64 --security-opt=label=disable \
        -v "$(realpath "$outdir"):/out" \
        --rm "docker.io/library/alpine:latest" \
        sh -c "apk add busybox-static && cp /bin/busybox.static /out/busybox"
fi
cp "$outdir/busybox" "$tmp/bin/busybox"
chmod +x "$tmp/bin/busybox"

# Create initramfs
(cd "$tmp" && find . | cpio -o -H newc 2>/dev/null | gzip > "$outdir/initramfs")