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

repo_root="$(cd "$(dirname "${BASH_SOURCE[0]}")/../.." && pwd)"
# shellcheck source=scripts/apk/package-lib.sh
. "${repo_root}/scripts/apk/package-lib.sh"

repo_name="${ALPINE_REPO_NAME:-local}"
arches="${ALPINE_ARCHES:-x86_64 aarch64}"
cache_root="${ALPINE_APK_REPO_CACHE:-/cache/public-alpine-packages/${ALPINE_REGISTRY_BRANCH:-local}/apk-repo}"
repo_dest="${repo_root}/packages/${repo_name}"
command_name="${1:-prepare}"

all_packages() {
  while IFS= read -r package_dir; do
    apk_package_name "${package_dir}"
  done < <(apk_package_dirs "${repo_root}")
}

mark_all_packages() {
  local reason="$1"

  printf 'Rebuilding all packages: %s\n' "${reason}" >&2
  all_packages
}

diff_base() {
  local before="${GITHUB_EVENT_BEFORE:-${CI_COMMIT_BEFORE_SHA:-}}"
  local base_ref="${GITHUB_BASE_REF:-}"

  if [[ -n "${base_ref}" ]] && git rev-parse --verify "origin/${base_ref}" >/dev/null 2>&1; then
    printf '%s...HEAD\n' "origin/${base_ref}"
    return
  fi

  if [[ -n "${before}" && ! "${before}" =~ ^0+$ ]] && git rev-parse --verify "${before}^{commit}" >/dev/null 2>&1; then
    printf '%s..HEAD\n' "${before}"
    return
  fi

  if git rev-parse --verify "HEAD^" >/dev/null 2>&1; then
    printf 'HEAD^..HEAD\n'
    return
  fi

  return 1
}

changed_packages() {
  local base
  local changed_paths
  local changed_path
  local package
  declare -A selected=()

  if ! base="$(diff_base)"; then
    mark_all_packages "no usable git diff base"
    return
  fi

  if ! changed_paths="$(git diff --name-only "${base}")"; then
    mark_all_packages "git diff failed for ${base}"
    return
  fi

  while IFS= read -r changed_path; do
    [[ -n "${changed_path}" ]] || continue
    case "${changed_path}" in
      scripts/apk/*|.gitea/workflows/build.yml|mise.toml)
        mark_all_packages "shared build logic changed"
        return
        ;;
      packaging/alpine/local/*/APKBUILD)
        package="${changed_path#packaging/alpine/local/}"
        package="${package%%/*}"
        selected["${package}"]=1
        ;;
    esac
  done <<< "${changed_paths}"

  for package in "${!selected[@]}"; do
    printf '%s\n' "${package}"
  done | sort
}

restore_cache() {
  if [[ -d "${cache_root}" ]]; then
    mkdir -p "${repo_dest}"
    cp -a "${cache_root}/." "${repo_dest}/"
    printf 'Restored Alpine package repository cache from %s\n' "${cache_root}"
  else
    printf 'No Alpine package repository cache found at %s\n' "${cache_root}"
  fi
}

package_apk_names() {
  local package_dir="$1"
  local arch="$2"

  (
    set +u
    local pkgname
    local pkgver
    local pkgrel
    local subpackages
    export CARCH="${arch}"
    cd "${package_dir}"
    # shellcheck source=/dev/null
    . ./APKBUILD

    printf '%s-%s-r%s.apk\n' "${pkgname}" "${pkgver}" "${pkgrel}"
    for subpackage in ${subpackages:-}; do
      subpackage="${subpackage%%:*}"
      printf '%s-%s-r%s.apk\n' "${subpackage}" "${pkgver}" "${pkgrel}"
    done
  )
}

package_cache_complete() {
  local package_dir="$1"
  local package_name
  local arch
  local apk_name

  package_name="$(apk_package_name "${package_dir}")"

  for arch in ${arches}; do
    case "${arch}" in
      x86_64|aarch64) ;;
      *) printf 'unsupported Alpine architecture: %s\n' "${arch}" >&2; exit 2 ;;
    esac

    if ! apk_package_supports_arch "${package_dir}" "${arch}"; then
      continue
    fi

    while IFS= read -r apk_name; do
      if [[ ! -f "${repo_dest}/${arch}/${apk_name}" ]]; then
        printf 'Cache miss for %s: missing %s/%s\n' "${package_name}" "${arch}" "${apk_name}" >&2
        return 1
      fi
    done < <(package_apk_names "${package_dir}" "${arch}")
  done

  return 0
}

select_missing_packages() {
  local package_dir
  local package_name

  while IFS= read -r package_dir; do
    apk_validate_package_dir "${package_dir}"
    package_name="$(apk_package_name "${package_dir}")"
    if ! package_cache_complete "${package_dir}"; then
      printf '%s\n' "${package_name}"
    fi
  done < <(apk_package_dirs "${repo_root}")
}

prepare() {
  local selected_packages
  local selected
  declare -A selected_map=()

  restore_cache

  while IFS= read -r selected; do
    [[ -n "${selected}" ]] || continue
    selected_map["${selected}"]=1
  done < <(changed_packages)

  while IFS= read -r selected; do
    [[ -n "${selected}" ]] || continue
    selected_map["${selected}"]=1
  done < <(select_missing_packages)

  selected_packages="$(
    for selected in "${!selected_map[@]}"; do
      printf '%s\n' "${selected}"
    done | sort | xargs
  )"

  if [[ -n "${selected_packages}" ]]; then
    printf 'Selected packages for rebuild: %s\n' "${selected_packages}"
    export ALPINE_PACKAGES="${selected_packages}"
    export ALPINE_SKIP_BUILD=0
  else
    printf 'No packages selected for rebuild\n'
    export ALPINE_PACKAGES=""
    export ALPINE_SKIP_BUILD=1
  fi

  if [[ -n "${GITHUB_ENV:-}" ]]; then
    {
      printf 'ALPINE_PACKAGES=%s\n' "${ALPINE_PACKAGES}"
      printf 'ALPINE_SKIP_BUILD=%s\n' "${ALPINE_SKIP_BUILD}"
    } >> "${GITHUB_ENV}"
  fi
}

sync_cache() {
  if [[ ! -d "${repo_dest}" ]]; then
    printf 'missing package repository: %s\n' "${repo_dest}" >&2
    exit 1
  fi

  mkdir -p "${cache_root}"
  find "${cache_root}" -mindepth 1 -maxdepth 1 -exec rm -rf {} +
  cp -a "${repo_dest}/." "${cache_root}/"
  printf 'Updated Alpine package repository cache at %s\n' "${cache_root}"
}

case "${command_name}" in
  prepare)
    prepare
    ;;
  sync)
    sync_cache
    ;;
  *)
    printf 'usage: %s [prepare|sync]\n' "$0" >&2
    exit 2
    ;;
esac