#!/bin/bash

set -e

WORK_DIRECTORY="work-directory"
GENERATED_PATCHSET_FOLDER="results"
POSTMARKETOS_KERNEL_DIRECTORY_NAME="postmarketos-kernel"
POSTMARKETOS_KERNEL_FORK_GIT_CLONE_URL="https://gitlab.com/exynos5-mainline/linux.git"
UNPATCHED_LINUX_KERNEL_DIRECTORY_NAME="regular-linux-kernel"

if [ -d "$WORK_DIRECTORY" ]; then
    rm -rf "$WORK_DIRECTORY"
fi

if [ -d "$GENERATED_PATCHSET_FOLDER" ]; then
    rm -rf "$GENERATED_PATCHSET_FOLDER"
fi

mkdir "$WORK_DIRECTORY"

cd "$WORK_DIRECTORY"

git clone "$POSTMARKETOS_KERNEL_FORK_GIT_CLONE_URL" "$POSTMARKETOS_KERNEL_DIRECTORY_NAME"

cd "$POSTMARKETOS_KERNEL_DIRECTORY_NAME"

if [[ -f "localversion-next" ]]; then
    LOCALVERSION=$(<"localversion-next")
    LINUX_RELEASE="${LOCALVERSION/-/}"
    GIT_CLONE_URL="https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git"
else
    VERSION=$(grep '^VERSION =' Makefile | sed 's/^VERSION = //')
    PATCHLEVEL=$(grep '^PATCHLEVEL =' Makefile | sed 's/^PATCHLEVEL = //')
    SUBLEVEL=$(grep '^SUBLEVEL =' Makefile | sed 's/^SUBLEVEL = //')
    EXTRAVERSION=$(grep '^EXTRAVERSION =' Makefile | sed 's/^EXTRAVERSION = //')

    LINUX_RELEASE="${VERSION}.${PATCHLEVEL}"

    if [[ "$EXTRAVERSION" == *rc* ]]; then
        LINUX_RELEASE+="${EXTRAVERSION}"
    else
        if [[ $SUBLEVEL -ne 0 ]]; then
            LINUX_RELEASE+=".$SUBLEVEL${EXTRAVERSION}"
        else
            LINUX_RELEASE+="${EXTRAVERSION}"
        fi
    fi
    LINUX_RELEASE="v${LINUX_RELEASE}"
    GIT_CLONE_URL="https://github.com/torvalds/linux.git"
fi

echo

echo "The postmarketOS Exynos 5 kernel fork is based on Linux $LINUX_RELEASE"

echo

PATCHSET_GENERATION_UTILITY_LOG="$(date +%F) | Linux Kernel Base: $LINUX_RELEASE"

git clone --depth 1 "$GIT_CLONE_URL" -b "$LINUX_RELEASE" ../"$UNPATCHED_LINUX_KERNEL_DIRECTORY_NAME"

cd ../"$UNPATCHED_LINUX_KERNEL_DIRECTORY_NAME"

git remote add "$POSTMARKETOS_KERNEL_DIRECTORY_NAME" ../"$POSTMARKETOS_KERNEL_DIRECTORY_NAME"

git remote update

mkdir ../../"$GENERATED_PATCHSET_FOLDER"

git diff "$POSTMARKETOS_KERNEL_DIRECTORY_NAME"/master -R > ../../"$GENERATED_PATCHSET_FOLDER"/"mainline-patchset-$(date +%F).patch"

echo "$PATCHSET_GENERATION_UTILITY_LOG" | tee ../../"$GENERATED_PATCHSET_FOLDER"/"mainline-patchset-$(date +%F).log"

cd ../..

rm -rf "$WORK_DIRECTORY"