#!/bin/bash
output_type='text'
days_back='60'
branch_command=`git branch -r | grep -v HEAD`
dryrun=false
sanityCheck=false
protected=("master" "develop" "origin/master" "origin/develop")

get_backlog_date() {
  local backlog_date=""
  if [[ "$(uname)" == "Darwin" ]]; then
    backlog_date=$(date -v-${days_back}d +%s)
  else
    backlog_date=$(date -d"now-${days_back}days" +%s)
  fi
  return $backlog_date
}

containsElement () {
  local e
  for e in "${@:2}";
    do
      [[ "$e" == "$1" ]] && return 0;
    done
  return 1
}

usage() {
  echo "$(basename "$0") [-h] [-o TEXT] [-m -nm -dryrun] [-d NUMBER]

  where:
    -h|--help   show this help text
    -o TEXT     set the output (text or csv). Text is default, CSV will force dryrun.
    -m          Only search for branches that have been merged and meet the days_back
    -nm         Only search for branches that have not been merged and meet the days_back
    -d NUMBER   Number of days to go back. Defaults to 60
    --dryrun    Will only output the list of branches to be deleted
  "
}

_setArgs() {
  while [ "$1" != "" ]; do
    case $1 in
      "-h" | "--help")
        usage
        exit
        ;;
      "-o" | "--output")
        shift
        if [ $1 != "csv" ] && [ $1 != "text" ]; then
          echo "Only allowed types are csv and text."
          exit 1
        fi
        output_type=$1
        dryrun=true
        ;;
      "-m" | "--merged")
        branch_command=`git branch -r --merged | grep -v HEAD`
        ;;
      "-nm" | "--not-merged")
        branch_command=`git branch -r --no-merged | grep -v HEAD`
        ;;
      "-d" | "--days")
        shift
        days_back=$1
        ;;
      "--dryrun")
        dryrun=true
        ;;
    esac
    shift
  done
}

get_converted_date() {
  local converted_date=""
  if [[ "$(uname)" == "Darwin" ]]; then
    converted_date=$(date -j -f "%Y-%m-%d %T %z" "${last_touched}" +%s)
  else
    converted_date=$(date -d"${last_touched}" +%s)
  fi
  return $converted_date
}

main() { if [[ $output_type == "csv" ]]; then
    echo "Branch, Last Commited To"
  fi

  for branch in $branch_command;
    do
      last_touched=`git show --format="%ci" $branch | head -n 1`
      months_ago=`git show --format="%cr" $branch | head -n 1`
      coverted_date=$(get_converted_date)

      # Stringify months ago for csv output
      if [[ $output_type == "csv" ]]; then
        months_ago="\"${months_ago}\""
      fi

      # Rewrite branch name to drop origin
      branch="${branch/origin\/}"

      # Check if the last commit is greater than the backlog date
      if [ $backlog_date -ge $converted_date ]; then
        if (containsElement "${branch}" "${protected[@]}") ; then
          echo "Skipping protected branch: ${branch}"
          continue
        fi
        if [[ $output_type == "csv"  ]]; then
          echo "${branch},${months_ago}"
        else
          echo "${branch}"
        fi
      fi

      if [ ! $dryrun ]; then
        branches_to_delete+=($branch)
      fi
    done

    if [ ! $dryrun ] && [ sanityCheck ]; then
      delete_branches $branches_to_delete
    fi
}

delete_branches() {
  local branches="$1"
  for branch in "${branches[@]}";
    do
      deleteBranch $branch
    done
}

sanityCheck() {
  echo "Are you sure you want to delete all branches that have not had a commit
in the last ${days_back} days? (This will also prune local branches) (y/N)"

  read check_value
  return [[ "${check_value}" == "y" ]]
}

deleteBranch() {
  local branch=$1
  echo "Deleting ${branch}"
  git push origin :$branch
  git fetch -p
}

# Run the main function
_setArgs "$@"
backlog_date=$(get_backlog_date)
main