#!/usr/bin/bash

set -e -o pipefail

ref="$1"
old="$2"
new="$3"
protected_file="$GIT_DIR/protected"

die() {
  echo "error: $*" > /dev/stderr
  exit 1
}

if [[ -f "$protected_file" ]]; then
  while read -r line; do
    if grep -q -E "$line" - <<< "$ref" ; then
      if grep -q -E "^0+$" <<< "$new"; then
        die "protected branch $ref (rule: $line) cannot be deleted"
      fi

      if ! git merge-base --is-ancestor "$old" "$new"; then
        die "protected branch $ref (rule: $line) is not fast-forward $(expr substr "$old" 1 8) -> $(expr substr "$new" 1 8)"
      fi
    fi
  done <"$protected_file"
fi

global_hook="/git/private/git/hooks/update"
local_hook="$GIT_DIR/hooks/update"

if [[ -x "$global_hook" ]]; then
  "$global_hook" "$ref" "$old" "$new"
fi

if [[ -x "$local_hook" ]]; then
  "$local_hook" "$ref" "$old" "$new"
fi