#!/usr/bin/env bash

set -euo pipefail

# git rev-parse emits an error if not in a git repo so only need to bail out
gitdir="$(git rev-parse --git-dir)" || exit

discover_op() {
  local op
  for op in cherry_pick merge rebase revert ; do
      if [ -f "${gitdir}/${op^^}_HEAD" ]; then
          echo "${op/_/-}"
      fi
  done
}

validate_op() {
  local op="$1"
  if [ -z "$op" ]; then
    echo "No active operation found" >&2
    exit 1
  fi
  if [[ "$(echo "$op" | wc -l)" -gt 1 ]]; then
    echo "Multiple active operations found:" >&2
    for o in $op; do
      echo "  - $o: HEAD: $(cat "${gitdir}/${o}_HEAD")" >&2
    done
    exit 1
  fi
}

discover_action() {
    local action=${1/git-/}
    if [ "$action" != "abort" ] && [ "$action" != "continue" ]; then
        echo "Invalid action: $1" >&2
        exit 1
    fi
    echo "$action"
}

action=$(discover_action "$(basename "$0")")
op=$(discover_op)
validate_op "$op"

git "$op" "--$action"