#!/usr/bin/env bash
# shellcheck disable=SC2164,SC2181
#
# Upgrade gitea binary
# - run this under sudo as it replaces and restarts gitea
# - "gitea" is a symlink to the numbered github download binary
# - allows for quick rollback if needed
# - e.g.: 'ln -s gitea-1.16.3-linux-amd64 gitea'
#
# Exit codes
#  0 = Success (already newest or upgrade worked)
#  1 = curl failed to download new version
#  2 = sha256sum check failed on download
#  3 = "gitea" wasn't a symlink
#  4 = upgrade version check failed, gitea not restarted
#  5 = could not change directory to run sha256sum
#  6 = cannot determine Gitea version info
#  20 = not running under sudo (see TEA_SUDO)
#  21 = gitea upgraded but not restarted (see TEA_HUP)
#  22 = gitea upgrade downloaded only (see TEA_LINK)
#
# Requires: curl, awk, grep, sha256sum
# Debug: bash -x /path/to/script.sh
#
# SPDX-License-Identifier: MIT

_VERSION="0.0.1"

# symlink name used to run gitea (e.g. "gitea")
TEA_SYM="gitea"
# where the binary is located (e.g. "/usr/local/bin")
TEA_DIR="/var/xyzzy/bin"
# 0 = verbose status, 1 = silent and rely on exit codes
TEA_QUIET=0

# require running this script under sudo, 0 to disable
TEA_SUDO=1
# restart gitea using TEA_CMD, 0 to disable
TEA_HUP=0
# replace symlink, 0 to disable (download only, implies TEA_HUP=0)
TEA_LINK=1
# command to restart gitea (e.g. "systemctl restart gitea")
TEA_CMD="systemctl restart gitea"

# github API endpoint to get latest version
TEA_API="https://api.github.com/repos/go-gitea/gitea/releases/latest"
# github download base URL to prepend with version info
TEA_DLB="https://github.com/go-gitea/gitea/releases/download"
# architecture being used, matches download name
TEA_ARCH="linux-amd64"

function noise() {
  if [[ ${TEA_QUIET} -eq 0 ]]; then
    echo "$*"
  fi
}

if [[ ${TEA_SUDO} -eq 1 ]]; then
  if [[ $(id -u) -ne 0 ]]; then
    noise "Run this script as root (sudo)"
    exit 20
  fi
fi

# disable curl download progress if in quiet mode
_COPT=""
if [[ ${TEA_QUIET} -eq 1 ]]; then
  _COPT="-s"
fi

noise "Checking gitea..."

# get installed version
_LOCAL=$("${TEA_DIR}/${TEA_SYM}" -version | awk '{print $3}')
# get latest version, strip leading "v" (v1.55.1 -> 1.55.1)
_REMOTE=$(curl -s "${TEA_API}" | grep -Po '"tag_name": "\K.*?(?=")')
_REMOTE=${_REMOTE#v}

# API failed, can't run local binary, etc. - something went wrong
if [[ -z "${_LOCAL}" || -z "${_REMOTE}" ]]; then
  noise "Cannot determine Gitea version information"
  exit 6
fi

# bash doesn't see versions as numbers, but as strings
if [[ "${_LOCAL}" != "${_REMOTE}" ]]; then
  _TEA_NAME="gitea-${_REMOTE}-${TEA_ARCH}"
  noise "Upgrading gitea - installed ${_LOCAL}, latest ${_REMOTE}"
  # curl will handle a failure being able to write to output dir, etc.
  curl ${_COPT} -L --output-dir "${TEA_DIR}" --remote-name-all \
    "${TEA_DLB}/v${_REMOTE}/${_TEA_NAME}" \
    "${TEA_DLB}/v${_REMOTE}/${_TEA_NAME}.sha256"
  if [[ $? -eq 0 ]]; then
    # downloads were successful and written to disk
    pushd "$(pwd)" >/dev/null
    cd "${TEA_DIR}" || (noise "Cannot cd to ${TEA_DIR}"; exit 5)
    noise "Checking sha256sum..."
    sha256sum --status -c "${_TEA_NAME}.sha256"
    if [[ $? -eq 0 ]]; then
      # sha256sum check passed
      chmod +x "${_TEA_NAME}"
      if [[ ${TEA_LINK} -eq 1 ]]; then
        # user requested replacing symlink
        if [[ -h "${TEA_SYM}" ]]; then
          noise "Replacing symlink..."
          rm -f "${TEA_SYM}"
          ln -s "${_TEA_NAME}" "${TEA_SYM}"
          # trust, but verify
          _TEA_NEW=$("${TEA_DIR}/${TEA_SYM}" -version | awk '{print $3}')
          if [[ "${_TEA_NEW}" == "${_REMOTE}" ]]; then
            noise "Gitea binary/symlink upgraded to ${_TEA_NEW}"
            if [[ ${TEA_HUP} -eq 1 ]]; then
              # user requested restart
              noise "Restarting gitea..."
              ${TEA_CMD}
            else
              noise "Gitea needs restarted"
              exit 21
            fi
          else
            noise "Upgrade failed, not restarting gitea"
            exit 4
          fi
        else
          noise "${TEA_SYM} is not a symlink, not overwriting"
          exit 3
        fi
      else
        noise "Gitea ${_TEA_NAME} downloaded, ready to upgrade"
        exit 22
      fi
    else
      noise "Download of ${_TEA_NAME} failed sha256sum, not upgrading"
      exit 2
    fi
    popd >/dev/null
  else
    noise "Download of ${_TEA_NAME} and sha256 failed, not upgrading"
    exit 1
  fi
else
  noise "Installed gitea is the latest - ${_LOCAL}"
fi