#!/usr/bin/env bash
while getopts "d" opt; do
    case $opt in
        d) dryRunOpt="--dry-run";;
    esac
done

# prune local "cache" of remote branches first:
git fetch --prune origin

# delete merged to HEAD branches:
mergedBranches=$(git branch -r --merged origin/HEAD | grep -v -e "origin/master" -e "origin/develop" -e "->" | cut -d/ -f2-)
if [ -n "${mergedBranches}" ]; then
    echo -e "\033[0;32mDeleting merged branches...\033[0m"
    echo git push $dryRunOpt --delete origin ${mergedBranches}
fi

# delete branches with last (cherry picked) commit older than 5 months:
echo -e "\n\033[0;32mSearching for stale branches...\033[0m"
unameOut="$(uname -s)"
case "${unameOut}" in
    Linux*)     machine=Linux;;
    Darwin*)    machine=Mac;;
    *)          machine="UNKNOWN:${unameOut}"
esac

if [ $machine == "Mac" ]; then
    staleTimestamp=$(date -v -6m +"%s")
    maybeStaleTimestamp=$(date -v -3m +"%s")
else
    staleTimestamp=$(date -d "now - 6 months" +"%s")
    maybeStaleTimestamp=$(date -d "now - 3 months" +"%s")
fi

notMergedBranches=$(git branch -r --no-merged origin/HEAD | grep -v -e "origin/master" -e "origin/develop" -e "->")
branchesToDelete=""
branchesToReview=""

for branch in ${notMergedBranches}; do
    lastCommitInfo=$(git cherry origin/HEAD ${branch} | grep -v "^-" | cut -d" " -f2 | xargs git show --format="%H|%ct|%cr|%an" --quiet | grep -v "^$(git rev-parse HEAD)" | tail -1)
    lastCommitTimestamp=$(echo "${lastCommitInfo}" | cut -d"|" -f2)
    if [ -z "${lastCommitTimestamp}" ] || [ ${lastCommitTimestamp} -lt ${staleTimestamp} ]; then
        branchesToDelete+=" ${branch#origin/}"
    elif [ ${lastCommitTimestamp} -lt ${maybeStaleTimestamp} ]; then
        branchesToReview+="${branch#origin/}|${lastCommitInfo}"$'\n'
    fi
    echo -n .
done
echo # for new line after dots

if [ -n "${branchesToDelete}" ]; then
    echo -e "\n\033[0;32mDeleting stale branches...\033[0m"
    echo git push $dryRunOpt --delete origin ${branchesToDelete}
else
    echo -e "\n\033[0;32mNo stale branches...\033[0m"
fi

if [ -n "${branchesToReview}" ]; then
    echo -e "\n\033[1;33mBranches to review (may be stale):\033[0m"
    echo "${branchesToReview}" | sort -t"|" -k5 | awk -F"|" 'NF {print $5 " changed branch \"" $1 "\" in project \"'${PWD##*/}'\" " $4}'
fi