#!/bin/bash
set -euo pipefail

declare BINARY_NAME

E_UNSUPPORTED_ARCH=5
CHECKSUM_FILE_NAME='checksums'

DEBUG=${DEBUG:-''}
VERSION=${VERSION:-'latest'}
INSTALL_ORG_REPO=${INSTALL_ORG_REPO:-'thoughtworks/talisman'}
INSTALL_LOCATION=${INSTALL_LOCATION:-'/usr/local/bin'}

function echo_error() {
  echo -ne "$(tput setaf 1)" >&2
  echo "$1" >&2
  echo -ne "$(tput sgr0)" >&2
}

function echo_debug() {
  [[ -z "$DEBUG" ]] && return
  echo -ne "$(tput setaf 3)" >&2
  echo "$1" >&2
  echo -ne "$(tput sgr0)" >&2
}

function echo_success() {
  echo -ne "$(tput setaf 2)"
  echo "$1" >&2
  echo -ne "$(tput sgr0)"
}

function operating_system() {
  OS=$(uname -s)
  case $OS in
  "Linux")
    echo "linux"
    ;;
  "Darwin")
    echo "darwin"
    ;;
  MINGW32_NT-* | MINGW64_NT-* | MSYS_NT-*)
    echo "windows"
    ;;
  *)
    echo_error "Talisman currently only supports Windows, Linux, and MacOS (darwin) systems."
    echo_error "If this is a problem for you, please open an issue: https://github.com/$INSTALL_ORG_REPO/issues/new"
    exit $E_UNSUPPORTED_ARCH
    ;;
  esac
}

function architecture() {
  ARCH=$(uname -m)
  case $ARCH in
  "x86_64")
    echo "amd64"
    ;;
  "i686" | "i386")
    echo "386"
    ;;
  "arm64" | "aarch64")
    echo "arm64"
    ;;
  *)
    echo_error "Talisman currently only supports x86 and x86_64 and arm64 architectures."
    echo_error "If this is a problem for you, please open an issue: https://github.com/$INSTALL_ORG_REPO/issues/new"
    exit $E_UNSUPPORTED_ARCH
    ;;
  esac
}

function set_binary_name() {
  BINARY_NAME="talisman_$(operating_system)_$(architecture)"
  if [ "$(operating_system)" = "windows" ]; then
    BINARY_NAME="$BINARY_NAME.exe"
  fi
  echo_success "Selected $BINARY_NAME"
}

function download() {
  ASSETS=$(curl -Ls https://api.github.com/repos/"$INSTALL_ORG_REPO"/releases/latest |
    grep download_url | awk '{print $2}' | tr -d '"')
  BINARY_URL=$(echo "$ASSETS" | grep "$BINARY_NAME")
  CHECKSUM_URL=$(echo "$ASSETS" | grep $CHECKSUM_FILE_NAME)
  echo_debug "Downloading $BINARY_NAME and from $BINARY_URL"
  curl --location --silent "$BINARY_URL" >"$TEMP_DIR/$BINARY_NAME"
  echo_debug "Downloading $CHECKSUM_FILE_NAME and from $CHECKSUM_URL"
  curl --location --silent "$CHECKSUM_URL" >"$TEMP_DIR/$CHECKSUM_FILE_NAME"
  echo_success "Downloaded talisman binary and checksums"
}

function verify_checksum() {
  pushd "$TEMP_DIR" >/dev/null 2>&1

  if ! command -v shasum &> /dev/null; then
    sha256sum --ignore-missing -c $CHECKSUM_FILE_NAME
  else
    shasum -a 256 --ignore-missing -c $CHECKSUM_FILE_NAME
  fi

  popd >/dev/null 2>&1
  echo_success "Checksum OK"
}

function install() {
  if (touch "$INSTALL_LOCATION/$BINARY_NAME" &>/dev/null); then
    cp "$TEMP_DIR/$BINARY_NAME" "$INSTALL_LOCATION/$BINARY_NAME"
    chmod +x "$INSTALL_LOCATION/$BINARY_NAME"
    ln -s "$INSTALL_LOCATION/$BINARY_NAME" "$INSTALL_LOCATION/talisman"
  elif (which sudo &>/dev/null); then
    sudo cp "$TEMP_DIR/$BINARY_NAME" "$INSTALL_LOCATION/$BINARY_NAME"
    sudo chmod +x "$INSTALL_LOCATION/$BINARY_NAME"
    sudo ln -s "$INSTALL_LOCATION/$BINARY_NAME" "$INSTALL_LOCATION/talisman"
  else
    echo_error "Insufficient permission to install to $INSTALL_LOCATION"
    exit 126
  fi
}

function run() {
  TEMP_DIR=$(mktemp -d 2>/dev/null || mktemp -d -t 'talisman_setup')
  # shellcheck disable=SC2064
  trap "rm -r $TEMP_DIR" EXIT
  chmod 0700 "$TEMP_DIR"

  if [ ! -d "$INSTALL_LOCATION" ]; then
    echo_error "$INSTALL_LOCATION is not a directory!"
    exit 1
  fi

  set_binary_name
  download
  verify_checksum
  install
}

run