# frozen_string_literal: true

module Gitlab
  module Ci
    class Trace
      include ::Gitlab::ExclusiveLeaseHelpers
      include ::Gitlab::Utils::StrongMemoize
      include Checksummable

      LOCK_TTL = 10.minutes
      LOCK_RETRIES = 2
      LOCK_SLEEP = 0.001.seconds
      WATCH_FLAG_TTL = 10.seconds

      UPDATE_FREQUENCY_DEFAULT = 60.seconds
      UPDATE_FREQUENCY_WHEN_BEING_WATCHED = 3.seconds

      LOAD_BALANCING_STICKING_NAMESPACE = 'ci/build/trace'

      ArchiveError = Class.new(StandardError)
      AlreadyArchivedError = Class.new(StandardError)
      LockedError = Class.new(StandardError)

      attr_reader :job

      delegate :can_attempt_archival_now?, :increment_archival_attempts!,
        :archival_attempts_message, :archival_attempts_available?, to: :trace_metadata

      def initialize(job)
        @job = job
      end

      def html(last_lines: nil)
        read do |stream|
          stream.html(last_lines: last_lines)
        end
      end

      def raw(last_lines: nil)
        read do |stream|
          stream.raw(last_lines: last_lines)
        end
      end

      def extract_coverage(regex)
        read do |stream|
          stream.extract_coverage(regex)
        end
      end

      def extract_sections
        read do |stream|
          stream.extract_sections
        end
      end

      def set(data)
        write('w+b') do |stream|
          data = job.hide_secrets(data)
          stream.set(data)
        end
      end

      def append(data, offset)
        write('a+b') do |stream|
          current_length = stream.size
          break current_length unless current_length == offset

          data = job.hide_secrets(data)
          stream.append(data, offset)
          stream.size
        end
      end

      def exist?
        archived? || live?
      end

      def archived?
        trace_artifact&.stored?
      end

      def live?
        job.trace_chunks.any? || current_path.present?
      end

      def read(&block)
        read_stream(&block)
      rescue Errno::ENOENT, ChunkedIO::FailedToGetChunkError
        job.reset
        read_stream(&block)
      end

      def write(mode, &blk)
        in_write_lock do
          unsafe_write!(mode, &blk)
        end
      end

      def erase_trace_chunks!
        job.trace_chunks.fast_destroy_all # Destroy chunks of a live trace
      end

      def erase!
        ##
        # Erase the archived trace
        trace_artifact&.destroy!

        ##
        # Erase the live trace
        erase_trace_chunks!
        FileUtils.rm_f(current_path) if current_path # Remove a trace file of a live trace
      ensure
        @current_path = nil
      end

      def archive!
        in_write_lock do
          unsafe_archive!
        end
      end

      def attempt_archive_cleanup!
        destroy_any_orphan_trace_data!
      end

      def update_interval
        if being_watched?
          UPDATE_FREQUENCY_WHEN_BEING_WATCHED
        else
          UPDATE_FREQUENCY_DEFAULT
        end
      end

      def being_watched!
        Gitlab::Redis::SharedState.with do |redis|
          redis.set(being_watched_cache_key, true, ex: WATCH_FLAG_TTL)
        end
      end

      def being_watched?
        Gitlab::Redis::SharedState.with do |redis|
          redis.exists(being_watched_cache_key)
        end
      end

      def lock(&block)
        in_write_lock(&block)
      rescue FailedToObtainLockError
        raise LockedError, "build trace `#{job.id}` is locked"
      end

      private

      def read_stream
        stream = Gitlab::Ci::Trace::Stream.new do
          if archived?
            trace_artifact.open
          elsif job.trace_chunks.any?
            Gitlab::Ci::Trace::ChunkedIO.new(job)
          elsif current_path
            File.open(current_path, "rb")
          end
        end

        yield stream
      ensure
        stream&.close
      end

      def unsafe_write!(mode, &blk)
        stream = Gitlab::Ci::Trace::Stream.new do
          if archived?
            raise AlreadyArchivedError, 'Could not write to the archived trace'
          elsif current_path
            File.open(current_path, mode)
          elsif Feature.enabled?(:ci_enable_live_trace, job.project)
            Gitlab::Ci::Trace::ChunkedIO.new(job)
          else
            File.open(ensure_path, mode)
          end
        end

        yield(stream).tap do
          job.touch if job.needs_touch?
        end
      ensure
        stream&.close
      end

      def unsafe_archive!
        raise ArchiveError, 'Job is not finished yet' unless job.complete?

        archived?.tap do |archived|
          destroy_any_orphan_trace_data!
          raise AlreadyArchivedError, 'Could not archive again' if archived
        end

        if job.trace_chunks.any?
          Gitlab::Ci::Trace::ChunkedIO.new(job) do |stream|
            archive_stream!(stream)
            destroy_stream(job) { stream.destroy! }
          end
        elsif current_path
          File.open(current_path) do |stream|
            archive_stream!(stream)
            FileUtils.rm(current_path)
          end
        end
      end

      def destroy_any_orphan_trace_data!
        return unless trace_artifact

        if archived?
          # An archive file exists, so remove the trace chunks
          erase_trace_chunks!
        else
          # A trace artifact record exists with no archive file
          # but an archive was attempted, so cleanup the associated record
          trace_artifact.destroy!
        end
      end

      def in_write_lock(&blk)
        lock_key = "trace:write:lock:#{job.id}"
        in_lock(lock_key, ttl: LOCK_TTL, retries: LOCK_RETRIES, sleep_sec: LOCK_SLEEP, &blk)
      end

      def archive_stream!(stream)
        ::Gitlab::Ci::Trace::Archive.new(job, trace_metadata).execute!(stream)
      end

      def trace_metadata
        strong_memoize(:trace_metadata) do
          job.ensure_trace_metadata!
        end
      end

      def ensure_path
        return current_path if current_path

        ensure_directory
        default_path
      end

      def ensure_directory
        unless Dir.exist?(default_directory)
          FileUtils.mkdir_p(default_directory)
        end
      end

      def current_path
        @current_path ||= paths.find do |trace_path|
          File.exist?(trace_path)
        end
      end

      def paths
        [default_path]
      end

      def default_directory
        File.join(
          Settings.gitlab_ci.builds_path,
          job.created_at.utc.strftime("%Y_%m"),
          job.project_id.to_s
        )
      end

      def default_path
        File.join(default_directory, "#{job.id}.log")
      end

      def trace_artifact
        read_trace_artifact(job) { job.job_artifacts_trace }
      end

      def destroy_stream(build)
        if consistent_archived_trace?(build)
          ::Ci::Build
            .sticking
            .stick(LOAD_BALANCING_STICKING_NAMESPACE, build.id)
        end

        yield
      end

      def read_trace_artifact(build)
        if consistent_archived_trace?(build)
          ::Ci::Build
            .sticking
            .unstick_or_continue_sticking(LOAD_BALANCING_STICKING_NAMESPACE, build.id)
        end

        yield
      end

      def consistent_archived_trace?(build)
        ::Feature.enabled?(:gitlab_ci_archived_trace_consistent_reads, build.project)
      end

      def being_watched_cache_key
        "gitlab:ci:trace:#{job.id}:watched"
      end
    end
  end
end