#!/usr/bin/env bash
#
# Assemble the rpmbuild sources for kernel-surface.spec:
#
#   * kernel-surface-patches-<upstream_ver>-<patchset_ver>.tar.gz, built from the
#     directories listed in patch-order.txt: bare names come from the overlay
#     submodule's sys-kernel/vanilla-kernel/files, "local:" ones from this
#     repository's patches/
#   * the upstream kernel tarball
#   * the base kernel config and the fragments from config/
#
# The versions default to the spec file's, so a plain checkout needs no
# arguments. UPSTREAM_VER and PATCHSET_VER override them, which is how the
# release pipeline hands over the versions it read out of the git tag; they have
# to be passed to rpmbuild as --define too, or the two disagree about what the
# Source1 tarball is called.
#
# Usage: ./make-sources.sh [-o OUTPUT_DIR] [-n]
#
#   -o  where to write the sources (default: rpm's %_sourcedir, else ./SOURCES)
#   -n  build the patch tarball only, skip the downloads
#
# Environment:
#
#   UPSTREAM_VER  kernel version to assemble for, overriding the spec's
#   PATCHSET_VER  patchset version to assemble for, overriding the spec's
#   OVERLAY_DIR   the Gentoo overlay checkout (default: ./overlay)

set -euo pipefail

script_dir=$(cd -- "$(dirname -- "${BASH_SOURCE[0]}")" && pwd)
spec="${script_dir}/kernel-surface.spec"
order_file="${script_dir}/patch-order.txt"
overlay_dir=${OVERLAY_DIR:-${script_dir}/overlay}
patch_root="${overlay_dir}/sys-kernel/vanilla-kernel/files"
local_patch_root="${script_dir}/patches"

output_dir=""
skip_download=false

while getopts ':o:nh' opt; do
	case "${opt}" in
		o) output_dir=${OPTARG} ;;
		n) skip_download=true ;;
		h) sed -n '2,20p' "${BASH_SOURCE[0]}"; exit 0 ;;
		*) echo "unknown option -${OPTARG}" >&2; exit 2 ;;
	esac
done

if [[ -z ${output_dir} ]]; then
	if command -v rpm >/dev/null 2>&1; then
		output_dir=$(rpm --eval '%{_sourcedir}')
	else
		output_dir="${script_dir}/SOURCES"
	fi
fi

spec_global() {
	# %global <name> <value>  ->  <value>
	awk -v key="$1" '$1 == "%global" && $2 == key { print $3; exit }' "${spec}"
}

upstream_ver=${UPSTREAM_VER:-$(spec_global upstream_ver)}
patchset_ver=${PATCHSET_VER:-$(spec_global patchset_ver)}

for var in upstream_ver patchset_ver; do
	[[ -n ${!var} ]] || {
		echo "${var} is neither set in the environment nor readable as a" >&2
		echo "%global from ${spec}" >&2
		exit 1
	}
done

echo "Assembling sources for kernel ${upstream_ver}, patchset ${patchset_ver}"

if [[ ! -d ${patch_root} ]]; then
	echo "${patch_root} not found." >&2
	echo "Run: git submodule update --init overlay" >&2
	exit 1
fi

mkdir -p "${output_dir}"

#--------------------------------------
# Patch tarball
#--------------------------------------
# The directory names inside the tarball carry a numeric prefix so that the
# spec's `for patchdir in patches/*/` loop reproduces patch-order.txt without
# having to read it.
staging=$(mktemp -d)
trap 'rm -rf "${staging}"' EXIT

index=0
total=0
while read -r dir; do
	dir=${dir%%#*}
	dir=${dir//[[:space:]]/}
	[[ -n ${dir} ]] || continue

	# "local:foo" is patches/foo in this repository, "foo" is the overlay's
	# files/foo. The staging name keeps the prefix so the tarball, and the
	# spec's "Applying ..." log, say where each patch came from.
	if [[ ${dir} == local:* ]]; then
		name=${dir#local:}
		src="${local_patch_root}/${name}"
		label="local-${name}"
	else
		name=${dir}
		src="${patch_root}/${name}"
		label=${name}
	fi

	if [[ ! -d ${src} ]]; then
		echo "ERROR: ${src} does not exist (listed in patch-order.txt)" >&2
		exit 1
	fi

	count=$(find "${src}" -maxdepth 1 -name '*.patch' | wc -l | tr -d ' ')
	if [[ ${count} -eq 0 ]]; then
		echo "ERROR: no patches in ${src}" >&2
		exit 1
	fi

	dest=$(printf '%s/patches/%02d-%s' "${staging}" "${index}" "${label}")
	mkdir -p "${dest}"
	cp "${src}"/*.patch "${dest}/"

	printf '  %02d %-18s %2d patches\n' "${index}" "${label}" "${count}"
	index=$((index + 1))
	total=$((total + count))
done < "${order_file}"

tarball="${output_dir}/kernel-surface-patches-${upstream_ver}-${patchset_ver}.tar.gz"
# COPYFILE_DISABLE stops macOS tar from adding ._ AppleDouble members, which
# would show up as bogus patch files in the spec's glob.
COPYFILE_DISABLE=1 tar -czf "${tarball}" -C "${staging}" patches
echo "${tarball} (${index} directories, ${total} patches)"

#--------------------------------------
# Base config and fragments
#--------------------------------------
for cfg in base-aarch64 surface live-image no-debug-info; do
	cp "${script_dir}/config/${cfg}.config" "${output_dir}/${cfg}.config"
done
echo "${output_dir}/{base-aarch64,surface,live-image,no-debug-info}.config"

if [[ ${skip_download} == true ]]; then
	exit 0
fi

#--------------------------------------
# Upstream tarball
#--------------------------------------
fetch() {
	local url=$1 dest=$2
	if [[ -s ${dest} ]]; then
		echo "${dest} (already present)"
		return
	fi
	echo "Fetching ${url}"
	curl -fL --retry 3 --progress-bar -o "${dest}.part" "${url}"
	mv "${dest}.part" "${dest}"
	echo "${dest}"
}

if [[ ${upstream_ver} == *-rc* ]]; then
	# Release candidates only exist as a git snapshot, not on cdn.kernel.org.
	kernel_url="https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/snapshot/linux-${upstream_ver}.tar.gz"
else
	kernel_url="https://cdn.kernel.org/pub/linux/kernel/v${upstream_ver%%.*}.x/linux-${upstream_ver}.tar.gz"
fi
fetch "${kernel_url}" "${output_dir}/linux-${upstream_ver}.tar.gz"