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

repository_root=$(cd "$(dirname "$0")/.." && pwd)
install_directory="${THT_INSTALL_DIRECTORY:-/usr/local/bin}"
staging_root=$(mktemp -d)
trap 'rm -rf "$staging_root"' EXIT HUP INT TERM

fail() {
  echo "install-tht.sh: $*" >&2
  exit 1
}

sha256() {
  if command -v sha256sum >/dev/null 2>&1; then
    sha256sum "$1" | awk '{print $1}'
  elif command -v shasum >/dev/null 2>&1; then
    shasum -a 256 "$1" | awk '{print $1}'
  else
    fail "SHA-256 verification requires sha256sum or shasum"
  fi
}

platform_artifact_name() {
  local system architecture
  system=$(uname -s)
  architecture=$(uname -m)
  case "$system" in
    Darwin) system=darwin ;;
    Linux) system=linux ;;
    *) fail "unsupported operating system: $system (supported: macOS and Linux)" ;;
  esac
  case "$architecture" in
    x86_64|amd64) architecture=amd64 ;;
    arm64|aarch64) architecture=arm64 ;;
    *) fail "unsupported processor architecture: $architecture (supported: amd64 and arm64)" ;;
  esac
  printf 'tht-%s-%s\n' "$system" "$architecture"
}

validate_packaged_artifact() {
  local artifact=$1 expected actual
  expected=${THT_BUILD_ARTIFACT_SHA256:-}
  [[ "$expected" =~ ^[[:xdigit:]]{64}$ ]] || fail "THT_BUILD_ARTIFACT_SHA256 must be a 64-character SHA-256 digest"
  actual=$(sha256 "$artifact")
  actual=$(printf '%s' "$actual" | tr '[:upper:]' '[:lower:]')
  expected=$(printf '%s' "$expected" | tr '[:upper:]' '[:lower:]')
  [[ "$actual" == "$expected" ]] || fail "packaged tht artifact checksum does not match"
}

build_artifact() {
  local build_output="$staging_root/build"
  mkdir -p "$build_output"
  THT_THT_OUTPUT_DIRECTORY="$build_output" bash "$repository_root/scripts/build-tht.sh" --all >&2
  printf '%s/%s\n' "$build_output" "$(platform_artifact_name)"
}

install_atomically() {
  local destination_directory=$1 source_file=$2
  local temporary_destination
  if mkdir -p "$destination_directory" 2>/dev/null && [[ -w "$destination_directory" ]]; then
    temporary_destination=$(mktemp "$destination_directory/.tht.XXXXXX")
    cp "$source_file" "$temporary_destination"
    chmod 0755 "$temporary_destination"
    mv -f "$temporary_destination" "$destination_directory/tht"
    return
  fi

  command -v sudo >/dev/null 2>&1 || fail "cannot write to $destination_directory and sudo is unavailable"
  sudo sh -c '
    set -eu
    destination_directory=$1
    source_file=$2
    mkdir -p "$destination_directory"
    temporary_destination=$(mktemp "$destination_directory/.tht.XXXXXX")
    trap "rm -f \"$temporary_destination\"" EXIT HUP INT TERM
    cp "$source_file" "$temporary_destination"
    chmod 0755 "$temporary_destination"
    mv -f "$temporary_destination" "$destination_directory/tht"
  ' sh "$destination_directory" "$source_file"
}

[[ "$install_directory" == /* ]] || fail "THT_INSTALL_DIRECTORY must be an absolute path"
artifact_name=$(platform_artifact_name)
if [[ -n "${THT_BUILD_ARTIFACT:-}" ]]; then
  source_artifact=$THT_BUILD_ARTIFACT
  [[ -f "$source_artifact" ]] || fail "THT_BUILD_ARTIFACT is not a regular file"
  validate_packaged_artifact "$source_artifact"
else
  source_artifact=$(build_artifact)
fi

[[ -s "$source_artifact" ]] || fail "native artifact is missing: $artifact_name"
staged_binary="$staging_root/tht"
cp "$source_artifact" "$staged_binary"
chmod 0755 "$staged_binary"
"$staged_binary" --help >/dev/null || fail "native artifact did not pass its help check"

install_atomically "$install_directory" "$staged_binary"
resolved_command=$(command -v tht || true)
[[ "$resolved_command" == "$install_directory/tht" ]] || fail "installed tht is not resolvable at $install_directory/tht; add $install_directory to PATH and open a new terminal"
"$install_directory/tht" --help >/dev/null || fail "installed tht did not pass its help check"
printf 'Installed tht at %s/tht\n' "$install_directory"