#!/bin/bash

set +e
#set -x

BRANCHMAINLINE=mainline
BRANCH318=stable/linux-3.18.y
BRANCH44=stable/linux-4.4.y
BRANCH49=stable/linux-4.9.y
BRANCH53=stable/linux-5.3.y

WORKTREERELPATH=..  # Worktree location with respect to current repo

declare -a CANDIDATES
BRANCHES=""

usage()
{
    echo "Usage: $0 [[-if <find-backports-output.txt>] | [-o|-ib <backport-patches-output.txt>]]"
}

while [ $# -gt 0 ]; do
    case $1 in
        -if|--find-backports-file|--found)
            FBINFILE=$2
	    shift
            ;;
        -ib|--backport-patches-file|--read)
            BPINFILE=$2
	    shift
            ;;
	-o|--output|--out)
	    OUTFILE=$2
	    shift
	    ;;
        *)
            echo "Unrecognised parameter $1"
            usage
	    exit 1
            ;;
    esac
    shift
done

print_red()
{
    echo -e "\e[01;31m$@\e[0m"
}

print_green()
{
    echo -e "\e[01;32m$@\e[0m"
}

print_blue()
{
    echo -e "\e[01;34m$@\e[0m"
}

was_backported_to_stable()
{
    branch=$1; shift
    subject=${@}

    if git log --no-merges --oneline --grep "${subject}" ${branch} 2>&1 | grep -q "${subject}"; then
	return 0
    fi

    return 1
}

find_candidates()
{
    while read add del sha subject; do
	declare -a branches_present; unset branches_present
	declare -a branches_missing; unset branches_missing
	local candidate; candidate=""

	if [ "${add}" == "$" ] || [ "${add}" == "#" ]; then
	    continue
	fi

	# Patch should be in Mainline
	mainline=$(git branch --contains ${sha} | sed 's/+/ /' | sed 's/*/ /')
	if ! echo $mainline | grep -q ${BRANCHMAINLINE}; then
	    print_red "${sha} ${subject}\n  Does not appear to be a Mainline commit?"
	    continue
	fi

	# Quick search: Was patch commited *before* the base release i.e. does it have the same SHA as Mainline
	readarray branches_present < <(git branch --contains ${sha} | sed 's/+/ /' | sed 's/*/ /')
	if echo ${branches_present[*]} | \
		grep ${BRANCH318} | grep ${BRANCH44} | grep ${BRANCH49} | grep -q ${BRANCH53}; then
	    print_green "\u2714 OC: ${sha} ${subject}";	# Commit is in all Stable branches
	    continue
	fi

	# Fast then slow search
	for b in ${BRANCH318} ${BRANCH44} ${BRANCH49} ${BRANCH53}; do
	    # Fast: Did we inherit this patch?
	    if ! echo ${branches_present[*]} | grep -q ${b}; then
		# Slow: Was this patch backported?
		if ! was_backported_to_stable ${b} ${subject}; then
		    # Commit is missing from this branch - lets backport it
		    branches_missing+=(${b})
		fi
	    fi
	done

	if ! echo ${branches_missing[*]} | \
		grep -q "${BRANCH318}\|${BRANCH44}\|${BRANCH49}\|${BRANCH53}"; then
	    print_green "\u2714 BP: ${sha} ${subject}";	# Commit is in all Stable branches
	    continue
	elif ! echo ${branches_present[*]} | \
		grep -q "${BRANCH318}\|${BRANCH44}\|${BRANCH49}\|${BRANCH53}"; then
	    print_red "\u2718 NO: ${sha} ${subject}"	# Commit is not in any Stable branch
	    candidate=true
	else
	    print_blue "${sha} ${subject}"		# Commit is in at least one, but not all Stable branches

	    for b in ${BRANCH318} ${BRANCH44} ${BRANCH49} ${BRANCH53}; do
		if echo ${branches_missing[*]} | grep -q ${b}; then
		    print_red "  \u2718 NO: ${b}"
		    candidate=true
		else
		    if echo ${branches_present[*]} | grep -q ${b}; then
			print_green "  \u2714 OC: ${b}"
		    else
			print_green "  \u2714 BP: ${b}"
		    fi
		fi
	    done
	fi

	if [ "${candidate}" == "true" ]; then
	    CANDIDATES+=("${sha} ${branches_missing[*]}")
	fi

    done < <(cat ${FBINFILE})
}


save_candidates()
{
    if [ "${OUTFILE}" == "" ]; then
	return
    fi

    rm ${OUTFILE} 2>&1 > /dev/null || true
    touch ${OUTFILE}

    for c in "${CANDIDATES[@]}"; do
	echo ${c} >> ${OUTFILE}
    done
}

read_candidates()
{
    while read -r line; do
	CANDIDATES+=("${line}")
    done < ${BPINFILE}
}

review_candidates()
{
    for c in "${CANDIDATES[@]}"; do
	sha=$(echo ${c} | cut -d' ' -f1)
	branches_missing=$(echo ${c} | cut -d' ' -f2-)
	subject=$(git log --pretty=%s -n1 ${sha})

	git --no-pager show ${sha}
	print_red "\nDoes this patch look like Stable material (y/N)?"
	read choice

	if [ "${choice}" != "y" ] && [ "${choice}" != "Y" ]; then
	    continue
	fi

	for b in ${BRANCH318} ${BRANCH44} ${BRANCH49} ${BRANCH53}; do
	    if echo ${branches_missing} | grep -q ${b}; then
		worktree=${WORKTREERELPATH}/${b}
		print_blue "Attempting to apply '${subject}' to ${b}"
		print_blue "Moving to $worktree"
		pushd $worktree
		git cherry-pick -s ${sha} || \
		    { print_red "Failed, try to apply it manually and press return OR Ctrl+c"; read; }
		popd
	    fi
	done
    done
}

if [ ! -d drivers ] || [ ! -f MAINTAINERS ]; then
    print_red "Not in the Kernel Git repository"
    exit 1
fi

if [ "${FBINFILE}" != "" ] && [ ! -f "${FBINFILE}" ]; then
    echo "${FBINFILE} does not exist"
    usage
    exit 1
fi

if [ "${BPINFILE}" != "" ] && [ ! -f "${BPINFILE}" ]; then
    echo "${BPINFILE} does not exist"
    usage
    exit 1
fi

# All Mainline and Stable branches need to exist locally
git branch | grep -q "${BRANCHMAINLINE}" || { print_red "$BRANCHMAINLINE not found locally"; exit 1; }
git branch | grep -q      "${BRANCH318}" || { print_red      "$BRANCH318 not found locally"; exit 1; }
git branch | grep -q       "${BRANCH44}" || { print_red       "$BRANCH44 not found locally"; exit 1; }
git branch | grep -q       "${BRANCH49}" || { print_red       "$BRANCH49 not found locally"; exit 1; }
git branch | grep -q       "${BRANCH53}" || { print_red       "$BRANCH53 not found locally"; exit 1; }

if [ "${FBINFILE}" != "" ]; then
    find_candidates
    save_candidates
elif [ "${BPINFILE}" != "" ]; then
    read_candidates
else
    usage
    exit 1
fi

review_candidates