#!/usr/bin/env bash
set -euo pipefail

# Stage a subset of kernel modules into a target rootfs/initramfs tree.
#
# Example:
#   ./stage-initramfs-modules.sh \
#       /out/rootfs/lib/modules/6.18.2 \
#       /out/initramfs
#
# Result:
#   /out/initramfs/lib/modules/6.18.2/...
#
# Notes:
# - This copies selected directories and modules.* metadata.
# - It does NOT run depmod for you unless you uncomment that section.
# - Best run after kernel modules have already been installed into the source tree.

if [[ $# -ne 2 ]]; then
    echo "Usage: $0 <source-lib-modules-version-dir> <dest-root>"
    echo "Example: $0 /out/rootfs/lib/modules/6.18.2 /out/initramfs"
    exit 1
fi

SRC_MODDIR="$1"   # e.g. /out/rootfs/lib/modules/6.18.2
DEST_ROOT="$2"    # e.g. /out/initramfs

if [[ ! -d "$SRC_MODDIR" ]]; then
    echo "Source module dir does not exist: $SRC_MODDIR" >&2
    exit 1
fi

KVER="$(basename "$SRC_MODDIR")"
DEST_MODDIR="$DEST_ROOT/lib/modules/$KVER"

mkdir -p "$DEST_MODDIR"

echo "==> Source: $SRC_MODDIR"
echo "==> Dest:   $DEST_MODDIR"
echo

# Relative paths under /lib/modules/<version>
PATHS=(
    # Metadata files used by modprobe/depmod.
    "modules.builtin"
    "modules.builtin.modinfo"
    "modules.order"

    "modules.dep"
    "modules.dep.bin"
    "modules.alias"
    "modules.alias.bin"
    "modules.symbols"
    "modules.symbols.bin"
    "modules.softdep"

    # Core module dirs we may need.
    "kernel/drivers/pwm"
    "kernel/drivers/hwmon"
    "kernel/drivers/thermal"

    # Optional
    # "kernel/drivers/i2c"
    # "kernel/drivers/gpio"
    # "kernel/drivers/base"
    # "kernel/drivers/power"
    # "kernel/drivers/platform"
)

copy_one() {
    local rel="$1"
    local src="$SRC_MODDIR/$rel"
    local dst="$DEST_MODDIR/$rel"

    if [[ -d "$src" ]]; then
        echo "[DIR ] $rel"
        mkdir -p "$(dirname "$dst")"
        cp -a "$src" "$dst"
    elif [[ -f "$src" ]]; then
        echo "[FILE] $rel"
        mkdir -p "$(dirname "$dst")"
        cp -a "$src" "$dst"
    else
        echo "[MISS] $rel"
    fi
}

for rel in "${PATHS[@]}"; do
    copy_one "$rel"
done

echo
echo "==> Done staging selected modules."

# Optional: show what got copied
echo
echo "==> Staged files summary:"
find "$DEST_MODDIR" -type f | sed "s#^$DEST_ROOT/##" | sort

# Optional: if depmod exists INSIDE the build environment and you want to
# regenerate metadata for the destination tree, uncomment this block.
#
# if command -v depmod >/dev/null 2>&1; then
#     echo
#     echo "==> Running depmod for destination tree..."
#     depmod -b "$DEST_ROOT" "$KVER"
# fi