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

ROOT=$(CDPATH='' cd -- "$(dirname -- "$0")/.." && pwd)

mapfile -d '' -t candidate_files < <(
  git -C "$ROOT" ls-files \
    --cached \
    --others \
    --exclude-standard \
    -z \
    -- android |
    LC_ALL=C sort -z
)

source_files=()
for relative_path in "${candidate_files[@]}"; do
  absolute_path="$ROOT/$relative_path"

  # `git ls-files --cached` also reports tracked paths deleted in the working
  # tree. They are not inputs to the artifact being built, so exclude them
  # from the working-tree fingerprint instead of treating a valid deletion as
  # a broken source tree.
  if [[ ! -e "$absolute_path" && ! -L "$absolute_path" ]]; then
    continue
  fi

  source_files+=("$relative_path")
done

if [[ "${#source_files[@]}" -eq 0 ]]; then
  echo "No Android source files were found." >&2
  exit 1
fi

{
  for relative_path in "${source_files[@]}"; do
    absolute_path="$ROOT/$relative_path"

    if [[ ! -f "$absolute_path" ]]; then
      echo "Android source input is not a regular file: $relative_path" >&2
      exit 1
    fi

    printf '%s\0' "$relative_path"
    sha256sum "$absolute_path" | awk '{print $1}'
  done
} | sha256sum | awk '{print $1}'