#! /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

source "$TOOLKIT_ROOT/lib/shared-functions.sh"

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

function git_diff() {
  git -C "$TOOLKIT_ROOT" diff "$@"
}

function is_up_to_date_with_remote() {
  local branch="$1"
  git_diff --quiet HEAD "origin/$branch"
}

function show_changes() {
  local branch="$1"

  if git_diff --quiet HEAD "origin/$branch" -- CHANGELOG.md; then
    echo "No changelog available"
    return 0
  fi

  # show CHANGELOG.md changes
  # git diff --unified=0  hide diff context
  # tail -n+6             hide the patch header

  # Example output
  #
  # Changelog:
  # ----------
  # +## 2020-11-19
  # +### Added
  # +- Updated ...
  # ----------

  echo "Changelog:"
  echo "----------"
  git_diff --color --unified=0 HEAD "origin/$branch" -- CHANGELOG.md \
  | tail -n+6
  echo "----------"
}

function read_seed_image_version() {
  SEED_IMAGE_VERSION="$(head -n 1 "$TOOLKIT_ROOT/lib/config-seed/version")"
  if [[ ! "$SEED_IMAGE_VERSION" =~ ^([0-9]+)\.([0-9]+)\.[0-9]+(-RC[0-9]*)?(-with-texlive-full)?$ ]]; then
    echo "ERROR: invalid config-seed/version '${SEED_IMAGE_VERSION}'"
    exit 1
  fi
  SEED_IMAGE_VERSION_MAJOR=${BASH_REMATCH[1]}
  SEED_IMAGE_VERSION_MINOR=${BASH_REMATCH[2]}
}

function handle_image_upgrade() {
  if [[ ! "$SEED_IMAGE_VERSION" > "$IMAGE_VERSION" ]]; then
    echo "No change to docker image version"
    return 0
  fi

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

  local user_image_major_version="$(echo "$IMAGE_VERSION" | awk -F. '{print $1}')"
  local seed_image_major_version="$(echo "$SEED_IMAGE_VERSION" | awk -F. '{print $1}')"
  if [[ "$seed_image_major_version" > "$user_image_major_version" ]]; then
    echo "WARNING: this is a major version update, please check the Release Notes for breaking changes before proceeding:"
    echo "* https://github.com/overleaf/overleaf/wiki#release-notes"
  fi

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

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

  echo "Upgrading config/version from $IMAGE_VERSION to $SEED_IMAGE_VERSION"

  local docker_compose_override_path="$TOOLKIT_ROOT/config/docker-compose.override.yml"
  if [ -f "$docker_compose_override_path" ]; then
     if grep -q -E '^\s*image: sharelatex/sharelatex.*' "$docker_compose_override_path"; then
        echo "WARNING: you are using a customized docker image, the server may not run on the latest version post upgrade."
        echo "* If you have followed the guide 'Upgrading TexLive', please remove and recreate the modified image."
        echo "* Remove the image: 'docker rm sharelatex/sharelatex:with-texlive-full'"
        echo "* Remove the override file: 'rm config/docker-compose.override.yml'"
        echo "* Recreate the image by following: https://github.com/overleaf/toolkit/blob/master/doc/ce-upgrading-texlive.md"
     fi
  fi


  ## 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 with the upgrade? [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"

  if [[ "$IMAGE_VERSION_MAJOR" -le 4 && "$SEED_IMAGE_VERSION_MAJOR" -ge 5 ]]; then
    rebrand_sharelatex_env_variables 'variables.env'
  fi

  ## 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 "$current_branch"; then
    echo "No code update available for download"
  else
    echo "Code update available for download!"
    git -C "$TOOLKIT_ROOT" fetch origin "$current_branch"
  fi

  if ! is_up_to_date_with_remote "$current_branch"; then
    show_changes "$current_branch"

    local should_pull="n"
    read -r -p "Perform code update? [y/n] " should_pull

    if [[ ! "$should_pull" =~ [Yy] ]]; then
      echo "Continuing without updating code"
    else
      echo "Current commit is $current_commit"
      echo "Updating code..."
      git -C "$TOOLKIT_ROOT" pull origin "$current_branch"
      echo "Relaunching bin/upgrade after code update"
      exec $0 --skip-git-update
    fi
  fi
}

function handle_rc_rebranding() {
  ## Rename variables in overleaf.rc SHARELATEX_ -> OVERLEAF_
  rebrand_sharelatex_env_variables 'overleaf.rc' silent_if_no_match
}

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

  if [[ "${1:-null}" == "--skip-git-update" ]]; then
    echo "Skipping git update"
  else
    handle_git_update
  fi

  read_seed_image_version
  read_image_version
  handle_rc_rebranding
  handle_image_upgrade

  echo "Done"
  exit 0
}

__main__ "$@"