#!/usr/bin/env ruby
# Copyright (C) The Arvados Authors. All rights reserved.
#
# SPDX-License-Identifier: AGPL-3.0

require 'rubygems'
require 'pp'
require 'arvados'
require 'etc'
require 'fileutils'
require 'yaml'
require 'optparse'
require 'open3'

req_envs = %w(ARVADOS_API_HOST ARVADOS_API_TOKEN ARVADOS_VIRTUAL_MACHINE_UUID)
req_envs.each do |k|
  unless ENV[k]
    abort "Fatal: These environment vars must be set: #{req_envs}"
  end
end

options = {}
OptionParser.new do |parser|
  parser.on('--exclusive', 'Manage SSH keys file exclusively.')
  parser.on('--rotate-tokens', 'Force a rotation of all user tokens.')
  parser.on('--skip-missing-users', "Don't try to create any local accounts.")
  parser.on('--token-lifetime SECONDS', 'Create user tokens that expire after SECONDS.', Integer)
  parser.on('--debug', 'Enable debug output')
end.parse!(into: options)

exclusive_banner = "#######################################################################################
#  THIS FILE IS MANAGED BY #{$0} -- CHANGES WILL BE OVERWRITTEN  #
#######################################################################################\n\n"
start_banner = "### BEGIN Arvados-managed keys -- changes between markers will be overwritten\n"
end_banner = "### END Arvados-managed keys -- changes between markers will be overwritten\n"

keys = ''

begin
  debug = false
  if options[:"debug"]
    debug = true
  end
  arv = Arvados.new({ :suppress_ssl_warnings => false })
  logincluster_host = ENV['ARVADOS_API_HOST']
  logincluster_name = arv.cluster_config['Login']['LoginCluster'] or ''

  if logincluster_name != '' and logincluster_name != arv.cluster_config['ClusterID']
    logincluster_host = arv.cluster_config['RemoteClusters'][logincluster_name]['Host']
  end
  logincluster_arv = Arvados.new({ :api_host => logincluster_host,
                                   :suppress_ssl_warnings => false })

  vm_uuid = ENV['ARVADOS_VIRTUAL_MACHINE_UUID']

  logins = arv.virtual_machine.logins(:uuid => vm_uuid)[:items]
  logins = [] if logins.nil?
  logins = logins.reject { |l| l[:username].nil? or l[:hostname].nil? or l[:virtual_machine_uuid] != vm_uuid }

  # No system users
  uid_min = 1000
  open("/etc/login.defs", encoding: "utf-8") do |login_defs|
    login_defs.each_line do |line|
      next unless match = /^UID_MIN\s+(\S+)$/.match(line)
      if match[1].start_with?("0x")
        base = 16
      elsif match[1].start_with?("0")
        base = 8
      else
        base = 10
      end
      new_uid_min = match[1].to_i(base)
      uid_min = new_uid_min if (new_uid_min > 0)
    end
  end

  pwnam = Hash.new()
  logins.reject! do |l|
    if not pwnam[l[:username]]
      begin
        pwnam[l[:username]] = Etc.getpwnam(l[:username])
      rescue
        if options[:"skip-missing-users"]
          STDERR.puts "Account #{l[:username]} not found. Skipping"
          true
        end
      else
        if pwnam[l[:username]].uid < uid_min
          STDERR.puts "Account #{l[:username]} uid #{pwnam[l[:username]].uid} < uid_min #{uid_min}. Skipping" if debug
          true
        end
      end
    end
  end
  keys = Hash.new()

  # Collect all keys
  logins.each do |l|
    STDERR.puts("Considering #{l[:username]} ...") if debug
    keys[l[:username]] = Array.new() if not keys.has_key?(l[:username])
    key = l[:public_key]
    if !key.nil?
      # Handle putty-style ssh public keys
      key.sub!(/^(Comment: "r[^\n]*\n)(.*)$/m,'ssh-rsa \2 \1')
      key.sub!(/^(Comment: "d[^\n]*\n)(.*)$/m,'ssh-dss \2 \1')
      key.gsub!(/\n/,'')
      key.strip

      keys[l[:username]].push(key) if not keys[l[:username]].include?(key)
    end
  end

  seen = Hash.new()

  current_user_groups = Hash.new
  while (ent = Etc.getgrent()) do
    ent.mem.each do |member|
      current_user_groups[member] ||= Array.new
      current_user_groups[member].push ent.name
    end
  end
  Etc.endgrent()

  logins.each do |l|
    next if seen[l[:username]]
    seen[l[:username]] = true

    username = l[:username]

    unless pwnam[l[:username]]
      STDERR.puts "Creating account #{l[:username]}"
      # Create new user
      out, st = Open3.capture2e("useradd", "-m",
                "-c", username,
                "-s", "/bin/bash",
                username)
      if st.exitstatus != 0
        STDERR.puts "Account creation failed for #{l[:username]}:\n#{out}"
        next
      end
      begin
        pwnam[username] = Etc.getpwnam(username)
      rescue => e
        STDERR.puts "Created account but then getpwnam() failed for #{l[:username]}: #{e}"
        raise
      end
    end

    existing_groups = current_user_groups[username] || []
    groups = l[:groups] || []
    # Adding users to the FUSE group has long been hardcoded behavior.
    groups << "fuse"
    groups << username
    groups.select! { |g| Etc.getgrnam(g) rescue false }

    groups.each do |addgroup|
      if existing_groups.index(addgroup).nil?
        # User should be in group, but isn't, so add them.
        STDERR.puts "Add user #{username} to #{addgroup} group"
        out, st = Open3.capture2e("usermod", "-aG", addgroup, username)
        if st.exitstatus != 0
          STDERR.puts "Failed to add #{username} to #{addgroup} group:\n#{out}"
        end
      end
    end

    existing_groups.each do |removegroup|
      if groups.index(removegroup).nil?
        # User is in a group, but shouldn't be, so remove them.
        STDERR.puts "Remove user #{username} from #{removegroup} group"
        out, st = Open3.capture2e("gpasswd", "-d", username, removegroup)
        if st.exitstatus != 0
          STDERR.puts "Failed to remove user #{username} from #{removegroup} group:\n#{out}"
        end
      end
    end

    homedir = pwnam[l[:username]].dir
    userdotssh = File.join(homedir, ".ssh")
    Dir.mkdir(userdotssh) if !File.exist?(userdotssh)

    newkeys = "###\n###\n" + keys[l[:username]].join("\n") + "\n###\n###\n"

    keysfile = File.join(userdotssh, "authorized_keys")

    if File.exist?(keysfile)
      oldkeys = IO::read(keysfile)
    else
      oldkeys = ""
    end

    if options[:exclusive]
      newkeys = exclusive_banner + newkeys
    elsif oldkeys.start_with?(exclusive_banner)
      newkeys = start_banner + newkeys + end_banner
    elsif (m = /^(.*?\n|)#{start_banner}(.*?\n|)#{end_banner}(.*)/m.match(oldkeys))
      newkeys = m[1] + start_banner + newkeys + end_banner + m[3]
    else
      newkeys = start_banner + newkeys + end_banner + oldkeys
    end

    if oldkeys != newkeys then
      f = File.new(keysfile, 'w')
      f.write(newkeys)
      f.close()
    end

    userdotconfig = File.join(homedir, ".config")
    if !File.exist?(userdotconfig)
      Dir.mkdir(userdotconfig)
    end

    configarvados = File.join(userdotconfig, "arvados")
    Dir.mkdir(configarvados) if !File.exist?(configarvados)

    tokenfile = File.join(configarvados, "settings.conf")

    begin
      STDERR.puts "Processing #{tokenfile} ..." if debug
      newToken = false
      if File.exist?(tokenfile)
        # check if the token is still valid
        myToken = ENV["ARVADOS_API_TOKEN"]
        userEnv = IO::read(tokenfile)
        if (m = /^ARVADOS_API_TOKEN=(.*?\n)/m.match(userEnv))
          begin
            tmp_arv = Arvados.new({ :api_host => logincluster_host,
                                    :api_token => (m[1]),
                                    :suppress_ssl_warnings => false })
            tmp_arv.user.current
          rescue Arvados::TransactionFailedError => e
            if e.to_s =~ /401 Unauthorized/
              STDERR.puts "Account #{l[:username]} token not valid, creating new token."
              newToken = true
            else
              raise
            end
          end
        end
      elsif !File.exist?(tokenfile) || options[:"rotate-tokens"]
        STDERR.puts "Account #{l[:username]} token file not found, creating new token."
        newToken = true
      end
      if newToken
        aca_params = {owner_uuid: l[:user_uuid], api_client_id: 0}
        if options[:"token-lifetime"] && options[:"token-lifetime"] > 0
          aca_params.merge!(expires_at: (Time.now + options[:"token-lifetime"]))
        end
        user_token = logincluster_arv.api_client_authorization.create(api_client_authorization: aca_params)
        f = File.new(tokenfile, 'w')
        f.write("ARVADOS_API_HOST=#{ENV['ARVADOS_API_HOST']}\n")
        f.write("ARVADOS_API_TOKEN=v2/#{user_token[:uuid]}/#{user_token[:api_token]}\n")
        f.close()
      end
    rescue => e
      STDERR.puts "Error setting token for #{l[:username]}: #{e}"
    end

    FileUtils.chown_R(l[:username], nil, userdotssh)
    FileUtils.chown_R(l[:username], nil, userdotconfig)
    File.chmod(0700, userdotssh)
    File.chmod(0700, userdotconfig)
    File.chmod(0700, configarvados)
    File.chmod(0750, homedir)
    File.chmod(0600, keysfile)
    if File.exist?(tokenfile)
      File.chmod(0600, tokenfile)
    end
  end

rescue Exception => bang
  puts "Error: " + bang.to_s
  puts bang.backtrace.join("\n")
  exit 1
end