#!/usr/bin/env ruby
# Copyright (C) 2012-2021 Zammad Foundation, http://zammad-foundation.org/

require 'yaml'
require 'resolv'

#
# Configures the CI system
#   - either (randomly) mysql or postgresql, if it is available
#   - (randomly) Redis or File as web socket session back end, if Redis is available
#
# Database config happens directly in config/database.yml, other settings are written to
#   .gitlab/environment.env which must be sourced in the CI configuration.
#

class ConfigureEnvironment

  @env_file_content = <<~ENV_FILE_CONTENT
    #!/bin/bash
    FRESHENVFILE=fresh.env && test -f $FRESHENVFILE && source $FRESHENVFILE
    true
  ENV_FILE_CONTENT

  def self.configure_redis
    if ENV['REDIS_URL'].nil? || ENV['REDIS_URL'].empty? # rubocop:disable Rails/Blank
      puts 'Redis is not available, using File as web socket session store.'
      return
    end
    if [true, false].sample
      puts 'Using Redis as web socket session store.'
      return
    end
    puts 'Using File as web socket session store.'
    @env_file_content += "unset REDIS_URL\n"
  end

  def self.configure_memcached
    if ENV['MEMCACHE_SERVERS'].nil? || ENV['MEMCACHE_SERVERS'].empty? # rubocop:disable Rails/Blank
      puts 'Memcached is not available, using File as Rails cache store.'
      return
    end
    if [true, false].sample
      puts 'Using memcached as Rails cache store.'
      return
    end
    puts "Using Zammad's file store as Rails cache store."
    @env_file_content += "unset MEMCACHE_SERVERS\n"
  end

  def self.configure_database # rubocop:disable Metrics/AbcSize, Metrics/CyclomaticComplexity, Metrics/PerceivedComplexity

    if File.exist? File.join(__dir__, '../config/database.yml')
      puts "'config/database.yml' already exists and will not be changed."
      return
    end

    cnf = YAML.load_file(File.join(__dir__, '../config/database/database.yml'))
    cnf.delete('default')

    database = ENV['ENFORCE_DB_SERVICE']

    # Lookup in /etc/hosts first: gitlab uses that if FF_NETWORK_PER_BUILD is not set.
    if !database
      hostsfile = '/etc/hosts'
      database  = %w[postgresql mysql].shuffle.find do |possible_database|
        File.foreach(hostsfile).any? { |l| l[possible_database] }
      end
    end

    # Lookup via DNS if needed: gitlab uses that if FF_NETWORK_PER_BUILD is enabled.
    if !database
      dns = Resolv::DNS.new
      dns.timeouts = 3
      database = %w[postgresql mysql].shuffle.find do |possible_database|
        # Perform a lookup of the database host to check if it is configured as a service.
        if dns.getaddress possible_database
          next possible_database
        end
      rescue Resolv::ResolvError
        # Ignore DNS lookup errors
      end
    end

    raise "Can't find any supported database." if database.nil?

    puts "Using #{database} as database service."

    db_settings_map = {
      'postgresql' => {
        'adapter'  => 'postgresql',
        'username' => 'zammad',
        'password' => 'zammad',
        'host'     => 'postgresql', # db alias from gitlab-ci.yml
      },
      'mysql'      => {
        'adapter'  => 'mysql2',
        'username' => 'root',
        'password' => 'zammad',
        'host'     => 'mysql', # db alias from gitlab-ci.yml
      }
    }

    # fetch DB settings from settings map and fallback to postgresql
    db_settings = db_settings_map.fetch(database) { db_settings_map['postgresql'] }

    %w[development test production].each do |environment|
      cnf[environment].merge!(db_settings)
    end

    File.write(File.join(__dir__, '../config/database.yml'), Psych.dump(cnf))
  end

  def self.write_env_file
    File.write(File.join(__dir__, 'environment.env'), @env_file_content)
  end

  def self.run
    configure_redis
    configure_memcached
    configure_database
    write_env_file
  end
end

ConfigureEnvironment.run