#!/usr/bin/env bash

BANGER_PACKAGES_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
BANGER_APT_PACKAGES_FILE="${BANGER_APT_PACKAGES_FILE:-$BANGER_PACKAGES_DIR/packages.apt}"

banger_packages_file() {
  printf '%s' "$BANGER_APT_PACKAGES_FILE"
}

banger_packages_normalized_lines() {
  local packages_file="${1:-$BANGER_APT_PACKAGES_FILE}"

  [[ -f "$packages_file" ]] || return 1
  awk '
    {
      sub(/\r$/, "")
      sub(/[[:space:]]*#.*$/, "")
      gsub(/^[[:space:]]+|[[:space:]]+$/, "")
      if ($0 != "") print
    }
  ' "$packages_file"
}

banger_packages_read_array() {
  local -n out="$1"
  local packages_file="${2:-$BANGER_APT_PACKAGES_FILE}"

  mapfile -t out < <(banger_packages_normalized_lines "$packages_file")
  (( ${#out[@]} > 0 ))
}

banger_packages_hash_stream() {
  command -v sha256sum >/dev/null 2>&1 || return 1
  sha256sum | awk '{print $1}'
}

banger_packages_manifest_hash() {
  local packages_file="${1:-$BANGER_APT_PACKAGES_FILE}"

  [[ -f "$packages_file" ]] || return 1
  banger_packages_normalized_lines "$packages_file" | banger_packages_hash_stream
}

banger_rootfs_manifest_metadata_path() {
  local rootfs_path="$1"
  printf '%s.packages.sha256' "$rootfs_path"
}

banger_rootfs_manifest_recorded_hash() {
  local rootfs_path="$1"
  local metadata_file recorded_hash

  metadata_file="$(banger_rootfs_manifest_metadata_path "$rootfs_path")"
  [[ -f "$metadata_file" ]] || return 1

  recorded_hash="$(head -n 1 "$metadata_file" | tr -d '[:space:]')"
  [[ -n "$recorded_hash" ]] || return 1
  printf '%s' "$recorded_hash"
}

banger_write_rootfs_manifest_metadata() {
  local rootfs_path="$1"
  local manifest_hash="$2"
  local metadata_file

  metadata_file="$(banger_rootfs_manifest_metadata_path "$rootfs_path")"
  printf '%s\n' "$manifest_hash" > "$metadata_file"
}

banger_rootfs_manifest_status() {
  local rootfs_path="$1"
  local current_hash recorded_hash

  if [[ ! -f "$rootfs_path" ]]; then
    printf '%s' "missing-rootfs"
    return 0
  fi

  if ! current_hash="$(banger_packages_manifest_hash)"; then
    printf '%s' "unknown"
    return 0
  fi

  if ! recorded_hash="$(banger_rootfs_manifest_recorded_hash "$rootfs_path")"; then
    printf '%s' "missing-metadata"
    return 0
  fi

  if [[ "$recorded_hash" == "$current_hash" ]]; then
    printf '%s' "fresh"
  else
    printf '%s' "stale"
  fi
}

banger_rootfs_manifest_warning() {
  local rootfs_path="$1"
  local status

  status="$(banger_rootfs_manifest_status "$rootfs_path")"
  case "$status" in
    stale)
      printf '%s was built with an older package manifest; rebuild it explicitly to pick up package changes' "$rootfs_path"
      ;;
    missing-metadata)
      printf '%s has no package manifest metadata; rebuild it explicitly to pick up package changes' "$rootfs_path"
      ;;
    unknown)
      printf 'unable to compare %s against %s; install sha256sum and verify the package manifest manually' "$rootfs_path" "$BANGER_APT_PACKAGES_FILE"
      ;;
    *)
      return 1
      ;;
  esac
}