#!/bin/bash
# Update all local branches from remote
# src: https://stackoverflow.com/a/9076361

main() {
  REMOTES="$@";
  if [ -z "$REMOTES" ]; then
    REMOTES=$(git remote);
  fi
  REMOTES=$(echo "$REMOTES" | xargs -n1 echo)
  CLB=$(git rev-parse --abbrev-ref HEAD);
  echo "$REMOTES" | while read REMOTE; do
    git remote update $REMOTE
    git remote show $REMOTE -n \
    | awk '/merges with remote/{print $5" "$1}' \
    | while read RB LB; do
      ARB="refs/remotes/$REMOTE/$RB";
      ALB="refs/heads/$LB";
      NBEHIND=$(( $(git rev-list --count $ALB..$ARB 2>/dev/null) +0));
      NAHEAD=$(( $(git rev-list --count $ARB..$ALB 2>/dev/null) +0));
      if [ "$NBEHIND" -gt 0 ]; then
        if [ "$NAHEAD" -gt 0 ]; then
          echo " branch $LB is $NBEHIND commit(s) behind and $NAHEAD commit(s) ahead of $REMOTE/$RB. could not be fast-forwarded";
        elif [ "$LB" = "$CLB" ]; then
          echo " branch $LB was $NBEHIND commit(s) behind of $REMOTE/$RB. fast-forward merge";
          git merge -q $ARB;
        else
          echo " branch $LB was $NBEHIND commit(s) behind of $REMOTE/$RB. resetting local branch to remote";
          git branch -f $LB -t $ARB >/dev/null;
        fi
      fi
    done
  done
}

main $@