# frozen_string_literal: true

require 'yaml'

module Backup
  class Database
    include Backup::Helper
    attr_reader :progress
    attr_reader :config, :db_file_name

    IGNORED_ERRORS = [
      # Ignore the DROP errors; recent database dumps will use --if-exists with pg_dump
      /does not exist$/,
      # User may not have permissions to drop extensions or schemas
      /must be owner of/
    ].freeze
    IGNORED_ERRORS_REGEXP = Regexp.union(IGNORED_ERRORS).freeze

    def initialize(progress, filename: nil)
      @progress = progress
      @config = YAML.load_file(File.join(Rails.root, 'config', 'database.yml'))[Rails.env]
      @db_file_name = filename || File.join(Gitlab.config.backup.path, 'db', 'database.sql.gz')
    end

    def dump
      FileUtils.mkdir_p(File.dirname(db_file_name))
      FileUtils.rm_f(db_file_name)
      compress_rd, compress_wr = IO.pipe
      compress_pid = spawn(gzip_cmd, in: compress_rd, out: [db_file_name, 'w', 0600])
      compress_rd.close

      dump_pid =
        case config["adapter"]
        when "postgresql" then
          progress.print "Dumping PostgreSQL database #{config['database']} ... "
          pg_env
          pgsql_args = ["--clean"] # Pass '--clean' to include 'DROP TABLE' statements in the DB dump.
          pgsql_args << '--if-exists'

          if Gitlab.config.backup.pg_schema
            pgsql_args << '-n'
            pgsql_args << Gitlab.config.backup.pg_schema

            Gitlab::Database::EXTRA_SCHEMAS.each do |schema|
              pgsql_args << '-n'
              pgsql_args << schema.to_s
            end
          end

          Process.spawn('pg_dump', *pgsql_args, config['database'], out: compress_wr)
        end
      compress_wr.close

      success = [compress_pid, dump_pid].all? do |pid|
        Process.waitpid(pid)
        $?.success?
      end

      report_success(success)
      progress.flush

      raise Backup::Error, 'Backup failed' unless success
    end

    def restore
      decompress_rd, decompress_wr = IO.pipe
      decompress_pid = spawn(*%w(gzip -cd), out: decompress_wr, in: db_file_name)
      decompress_wr.close

      status, errors =
        case config["adapter"]
        when "postgresql" then
          progress.print "Restoring PostgreSQL database #{config['database']} ... "
          pg_env
          execute_and_track_errors(pg_restore_cmd, decompress_rd)
        end
      decompress_rd.close

      Process.waitpid(decompress_pid)
      success = $?.success? && status.success?

      if errors.present?
        progress.print "------ BEGIN ERRORS -----\n".color(:yellow)
        progress.print errors.join.color(:yellow)
        progress.print "------ END ERRORS -------\n".color(:yellow)
      end

      report_success(success)
      raise Backup::Error, 'Restore failed' unless success

      errors
    end

    protected

    def ignore_error?(line)
      IGNORED_ERRORS_REGEXP.match?(line)
    end

    def execute_and_track_errors(cmd, decompress_rd)
      errors = []

      Open3.popen3(ENV, *cmd) do |stdin, stdout, stderr, thread|
        stdin.binmode

        out_reader = Thread.new do
          data = stdout.read
          $stdout.write(data)
        end

        err_reader = Thread.new do
          until (raw_line = stderr.gets).nil?
            warn(raw_line)
            errors << raw_line unless ignore_error?(raw_line)
          end
        end

        begin
          IO.copy_stream(decompress_rd, stdin)
        rescue Errno::EPIPE
        end

        stdin.close
        [thread, out_reader, err_reader].each(&:join)
        [thread.value, errors]
      end
    end

    def pg_env
      args = {
        'username'  => 'PGUSER',
        'host'      => 'PGHOST',
        'port'      => 'PGPORT',
        'password'  => 'PGPASSWORD',
        # SSL
        'sslmode'         => 'PGSSLMODE',
        'sslkey'          => 'PGSSLKEY',
        'sslcert'         => 'PGSSLCERT',
        'sslrootcert'     => 'PGSSLROOTCERT',
        'sslcrl'          => 'PGSSLCRL',
        'sslcompression'  => 'PGSSLCOMPRESSION'
      }
      args.each do |opt, arg|
        # This enables the use of different PostgreSQL settings in
        # case PgBouncer is used. PgBouncer clears the search path,
        # which wreaks havoc on Rails if connections are reused.
        override = "GITLAB_BACKUP_#{arg}"
        val = ENV[override].presence || config[opt].to_s.presence
        ENV[arg] = val if val
      end
    end

    def report_success(success)
      if success
        progress.puts '[DONE]'.color(:green)
      else
        progress.puts '[FAILED]'.color(:red)
      end
    end

    private

    def pg_restore_cmd
      ['psql', config['database']]
    end
  end
end
