#!/usr/bin/env bash

set -euo pipefail

RELEASE_REPO="${INSPECTOR_RELEASE_REPO:-inspectorai/inspector-releases}"
INSTALL_ROOT="${INSPECTOR_INSTALL_ROOT:-${HOME}/.local/share/inspector}"
BIN_DIR="${INSPECTOR_BIN_DIR:-${HOME}/.local/bin}"

need_cmd() {
  if ! command -v "$1" >/dev/null 2>&1; then
    echo "Missing required command: $1" >&2
    exit 1
  fi
}

normalize_repo() {
  local value="${1:-}"
  value="${value#https://github.com/}"
  value="${value#http://github.com/}"
  value="${value#github.com/}"
  value="${value%/}"
  printf '%s' "${value}"
}

detect_target() {
  local os arch
  os="$(uname -s)"
  arch="$(uname -m)"

  case "${os}:${arch}" in
    Linux:x86_64)
      printf 'x86_64-unknown-linux-gnu'
      ;;
    *)
      echo "Inspector installer currently supports Linux x86_64 only." >&2
      exit 1
      ;;
  esac
}

extract_json_string() {
  local key="${1:?missing key}"
  local value
  value="$(
    sed -nE "s/^[[:space:]]*\"${key}\":[[:space:]]*\"([^\"]+)\".*/\1/p" \
      | head -n1
  )"
  if [[ -z "${value}" ]]; then
    echo "Failed to parse '${key}' from release manifest" >&2
    exit 1
  fi
  printf '%s' "${value}"
}

checksum_for_asset() {
  local asset_name="${1:?missing asset name}"
  awk -v asset_name="${asset_name}" '
    $2 == asset_name || $2 == "*" asset_name { print $1; exit }
  '
}

verify_checksum() {
  local asset_path="${1:?missing asset path}"
  local expected="${2:?missing checksum}"
  local actual
  actual="$(sha256sum "${asset_path}" | awk '{print $1}')"
  if [[ "${actual}" != "${expected}" ]]; then
    echo "Checksum mismatch for ${asset_path}" >&2
    echo "Expected: ${expected}" >&2
    echo "Actual:   ${actual}" >&2
    exit 1
  fi
}

ensure_path_hint() {
  case ":${PATH}:" in
    *":${BIN_DIR}:"*) ;;
    *)
      echo
      echo "Add ${BIN_DIR} to your PATH to run 'inspector' directly." >&2
      ;;
  esac
}

main() {
  local repo target manifest_url manifest version tag asset_name download_url
  local checksums_url expected_sha temp_dir archive_path extract_root bundle_root
  local releases_dir release_dir current_link

  need_cmd curl
  need_cmd tar
  need_cmd sha256sum
  need_cmd mktemp

  repo="$(normalize_repo "${RELEASE_REPO}")"
  target="$(detect_target)"
  manifest_url="https://github.com/${repo}/releases/latest/download/release-manifest.json"

  echo "Fetching latest Inspector release metadata..."
  manifest="$(curl -fsSL "${manifest_url}")"
  version="$(printf '%s\n' "${manifest}" | extract_json_string version)"
  tag="$(printf '%s\n' "${manifest}" | extract_json_string tag)"

  asset_name="inspector-bundle-${version}-${target}.tar.gz"
  download_url="https://github.com/${repo}/releases/download/${tag}/${asset_name}"
  checksums_url="https://github.com/${repo}/releases/download/${tag}/SHA256SUMS.txt"

  echo "Resolving checksum for ${asset_name}..."
  expected_sha="$(
    curl -fsSL "${checksums_url}" | checksum_for_asset "${asset_name}"
  )"
  if [[ -z "${expected_sha}" ]]; then
    echo "Failed to find ${asset_name} in ${checksums_url}" >&2
    exit 1
  fi

  temp_dir="$(mktemp -d)"
  trap 'rm -rf "${temp_dir}"' EXIT
  archive_path="${temp_dir}/${asset_name}"
  extract_root="${temp_dir}/extract"

  echo "Downloading ${asset_name}..."
  curl -fL "${download_url}" -o "${archive_path}"
  verify_checksum "${archive_path}" "${expected_sha}"

  mkdir -p "${extract_root}" "${BIN_DIR}"
  tar -xzf "${archive_path}" -C "${extract_root}"

  bundle_root="${extract_root}/inspector-bundle-${version}-${target}"
  if [[ ! -f "${bundle_root}/bundle.json" ]]; then
    echo "Downloaded archive does not contain a valid Inspector bundle" >&2
    exit 1
  fi

  releases_dir="${INSTALL_ROOT}/releases"
  release_dir="${releases_dir}/${version}"
  current_link="${INSTALL_ROOT}/current"

  mkdir -p "${releases_dir}"
  rm -rf "${release_dir}"
  mv "${bundle_root}" "${release_dir}"

  ln -sfn "${release_dir}" "${current_link}"
  ln -sfn "${current_link}/bin/inspector" "${BIN_DIR}/inspector"

  echo
  echo "Inspector ${version} installed successfully."
  echo "Binary: ${BIN_DIR}/inspector"
  echo "Bundle: ${release_dir}"
  ensure_path_hint
}

main "$@"