#!/usr/bin/env bash
# Usage: apply-lo-patches.sh <lo-src> — applies the missing patches.
set -euo pipefail

root=$(cd "$(dirname "$0")/.." && pwd)
src=${1:?usage: apply-lo-patches.sh <lo-src>}
patches=("$root"/patches/libreoffice/*.patch)
files=$(sed -n 's|^+++ b/||p' "${patches[@]}" | sort -u)
work=$(mktemp -d)
trap 'rm -rf "$work"' EXIT

# Whether $src is HEAD plus the first $1 patches.
holds() {
  local n=$1 base=$work/base f i
  rm -rf "$base"
  mkdir -p "$base"
  git -C "$base" init -q
  for f in $files; do
    if git -C "$src" cat-file -e "HEAD:$f" 2>/dev/null; then
      mkdir -p "$base/$(dirname "$f")"
      git -C "$src" show "HEAD:$f" >"$base/$f"
    fi
  done
  for ((i = 0; i < n; i++)); do
    git -C "$base" apply "${patches[$i]}" 2>/dev/null || return 1
  done
  for f in $files; do
    if [ -e "$base/$f" ]; then
      cmp -s "$base/$f" "$src/$f" || return 1
    elif [ -e "$src/$f" ]; then
      return 1
    fi
  done
}

n=${#patches[@]}
while [ "$n" -ge 0 ] && ! holds "$n"; do
  n=$((n - 1))
done
if [ "$n" -lt 0 ]; then
  echo "apply-lo-patches.sh: $src matches no prefix of the patch series" >&2
  exit 1
fi
echo "apply-lo-patches.sh: $n of ${#patches[@]} patches already in $src"
for ((i = n; i < ${#patches[@]}; i++)); do
  git -C "$src" apply "${patches[$i]}"
  echo "apply-lo-patches.sh: applied ${patches[$i]##*/}"
done