#!/usr/bin/env bash
set -euo pipefail

# Changed files come from git: uncommitted work, plus everything committed on this
# branch since it left the default branch. Without git, or when git reports nothing, run the
# full refresh.
if ! git rev-parse --is-inside-work-tree >/dev/null 2>&1; then
  echo "No git repository here, so no changed files to read. Running full refresh."
  exec "$(dirname "$0")/refresh-registry.sh"
fi

# The default branch: what origin/HEAD points at, else main, else master.
DEFAULT_BRANCH="$(git symbolic-ref --quiet --short refs/remotes/origin/HEAD 2>/dev/null || true)"
DEFAULT_BRANCH="${DEFAULT_BRANCH#origin/}"
BASE=""
for candidate in "$DEFAULT_BRANCH" main master; do
  [ -n "$candidate" ] || continue
  for ref in "$candidate" "origin/$candidate"; do
    BASE="$(git merge-base HEAD "$ref" 2>/dev/null || true)"
    [ -n "$BASE" ] && break 2
  done
done

# NUL-separated git output, so paths with spaces or quotes come through as they are.
list_changed() {
  local entry status
  git status --porcelain -z --untracked-files=all | while IFS= read -r -d '' entry; do
    status="${entry:0:2}"
    printf '%s\n' "${entry:3}"
    # A rename or copy is followed by its original path, which is not a changed file here.
    case "$status" in
      R* | C*) IFS= read -r -d '' _ || true ;;
    esac
  done
  if [ -n "$BASE" ]; then
    git diff --name-only -z "$BASE"..HEAD | while IFS= read -r -d '' entry; do
      printf '%s\n' "$entry"
    done
  fi
}

CHANGED="$(list_changed | sed '/^$/d' | sort -u)"

if [ -z "$CHANGED" ]; then
  echo "Git reports no changed files. Running full refresh."
  exec "$(dirname "$0")/refresh-registry.sh"
fi

echo "Diff refresh for {{projectName}} ($(printf '%s\n' "$CHANGED" | wc -l | tr -d ' ') changed files)"
printf '%s\n' "$CHANGED"