#! /usr/bin/env bash

set -euo pipefail

#### Detect Toolkit Project Root ####
# if realpath is not available, create a semi-equivalent function
command -v realpath >/dev/null 2>&1 || realpath() {
  [[ $1 = /* ]] && echo "$1" || echo "$PWD/${1#./}"
}
SCRIPT_PATH="$(realpath "${BASH_SOURCE[0]}")"
SCRIPT_DIR="$(dirname "$SCRIPT_PATH")"
TOOLKIT_ROOT="$(realpath "$SCRIPT_DIR/..")"
if [[ ! -d "$TOOLKIT_ROOT/bin" ]] || [[ ! -d "$TOOLKIT_ROOT/config" ]]; then
  echo "ERROR: could not find root of overleaf-toolkit project (inferred project root as '$TOOLKIT_ROOT')"
  exit 1
fi

function usage() {
  echo "Usage: bin/upgrade"
  echo ""
  echo "This script will check for updates to the toolkit code (via git),"
  echo "and offer to pull the new changes. It will then check the latest"
  echo "available version of the docker image, and offer to update the"
  echo "locally configured image (in config/image) if applicable"
  echo ""
  echo "This script will prompt the user for confirmation at"
  echo "each step along the way."
}

function services_up() {
  local top_output="$("$TOOLKIT_ROOT/bin/docker-compose" top)"
  if [[ -z "$top_output" ]]; then
    return 1
  else
    return 0
  fi
}

function git_pull_available() {
  local branch="$1"
  local fetch_output="$(git -C "$TOOLKIT_ROOT" fetch --dry-run origin "$branch" 2>&1)"
  local filtered_fetch_output="$(echo "$fetch_output" | grep '\-> origin/'"$branch")"
  if [[ -z "$filtered_fetch_output" ]]; then
    return 1
  else
    return 0
  fi
}

function handle_image_upgrade() {
  local user_image_version="$(head -n 1 "$TOOLKIT_ROOT/config/version")"
  local seed_image_version="$(head -n 1 "$TOOLKIT_ROOT/lib/config-seed/version")"

  if [[ ! "$seed_image_version" > "$user_image_version" ]]; then
    echo "No change to docker image version"
    return 0
  fi

  echo "New docker image version available ($seed_image_version)"
  echo "Current image version is '$user_image_version' (from config/version)"

  local should_upgrade="n"
  read -r -p "Upgrade image? [y/n] " should_upgrade

  if [[ ! "$should_upgrade" =~ [Yy] ]]; then
    echo "Keeping image version '$user_image_version'"
    return 0
  fi

  echo "Upgrading config/version from $user_image_version to $seed_image_version"

  ## Offer to stop docker services
  local services_stopped="false"
  if services_up; then
    echo "docker services are up, stop them first?"
    local should_stop="n"
    read -r -p "Stop docker services? [y/n] " should_stop
    if [[ ! "$should_stop" =~ [Yy] ]]; then
      echo "exiting without stopping services"
      exit 1
    fi
    services_stopped="true"
    echo "Stopping docker services"
    "$TOOLKIT_ROOT/bin/docker-compose" stop
  fi

  ## Advise the user to take a backup
  ## (NOTE: we can't do this automatically because it will likely require
  ##  sudo privileges. We leave it to the user to sort out for now)
  echo "At this point, we recommend backing up your data before proceeding"
  echo "!! WARNING: Only do this while the docker services are stopped!!"
  local should_proceed="n"
  read -r -p "Proceed? [y/n] " should_proceed
  if [[ ! "$should_proceed" =~ [Yy] ]]; then
    echo "Not proceeding with upgrade"
    return 1
  fi

  ## Set the new image version
  echo "Backing up old version file to config/__old-version"
  cp "$TOOLKIT_ROOT/config/version" "$TOOLKIT_ROOT/config/__old-version"
  echo "Over-writing config/version with $seed_image_version"
  cp "$TOOLKIT_ROOT/lib/config-seed/version" "$TOOLKIT_ROOT/config/version"

  ## Maybe offer to start services again
  if [[ "${services_stopped:-null}" == "true" ]]; then
    local should_start="n"
    read -r -p "Start docker services again? [y/n] " should_start
    if [[ "$should_start" =~ [Yy] ]]; then
      echo "Starting docker services"
      "$TOOLKIT_ROOT/bin/docker-compose" up -d
    fi
  fi
}

function handle_git_update() {
  local current_branch
  current_branch="$(git -C "$TOOLKIT_ROOT" rev-parse --abbrev-ref HEAD)"
  local current_commit
  current_commit="$(git -C "$TOOLKIT_ROOT" rev-parse --short HEAD)"

  if [[ ! "$current_branch" == "master" ]]; then
    echo "Warning: current branch is not master, '$current_branch' instead"
  fi

  echo "Checking for code update..."

  if ! git_pull_available "$current_branch"; then
    echo "No code update available"
  else
    echo "Code update available! (current commit is $current_commit)"

    local should_pull="n"
    read -r -p "Proceed to pull update? [y/n] " should_pull

    if [[ ! "$should_pull" =~ [Yy] ]]; then
      echo "Continuing without pulling update"
    else
      echo "Pulling new code..."
      git -C "$TOOLKIT_ROOT" pull origin "$current_branch"
    fi
  fi
}

function __main__() {
  if [[ "${1:-null}" == "help" ]] \
    || [[ "${1:-null}" == "--help" ]] ; then
    usage && exit
  fi
  handle_git_update
  handle_image_upgrade
  echo "Done"
  exit 0
}

__main__ "$@"