require 'uri'
require 'cgi'
require 'time'
require 'json'
require 'hashdiff' # gem install hashdiff
require 'kennel' # gem install kennel

class Logs
  class << self
    # does not flatten arrays, but we don't need this here
    def flatten_hash(hash)
      hash.each_with_object({}) do |(k, v), h|
        if v.is_a? Hash
          flatten_hash(v).map do |h_k, h_v|
            h["#{k}.#{h_k}".to_sym] = h_v
          end
        else
          h[k] = v
        end
      end
    end

    def clean_for_diff(object, ignore_status:)
      # datadog turns labels like metadata.labels.foo.bar into a nested foo: bar hash
      object.replace flatten_hash object

      # general
      object.delete :"metadata.annotations.deployment.kubernetes.io/revision"
      object.delete :"metadata.annotations.kubectl.kubernetes.io/last-applied-configuration"
      object.delete :"metadata.generation"
      object.delete :"metadata.managedFields"
      object.delete :"metadata.resourceVersion"
      object.delete :"spec.template.metadata.creationTimestamp"

      # status
      if ignore_status
        object.delete_if { |k, _| k.start_with? "status" }
      else
        object.delete :"status.observedGeneration"
      end
    end
  end
end

namespace :logs do
  desc "show change history for a given resource by parsing the audit log CLUSTER= RESOURCE= [NAMESPACE=] NAME= [DAYS=7] [STATUS=ignore|include]"
    cluster = ENV.fetch("CLUSTER")
    resource = ENV.fetch("RESOURCE")
    name = ENV.fetch("NAME")
    namespace = ENV["NAMESPACE"]
    ignore_status = ((ENV["STATUS"] || "ignore") == "ignore")
    days = Integer(ENV["DAYS"] || "7")

    # get current version to be able to diff the latest update
    result = `kubectl --context #{cluster} get #{resource} #{name} #{"-n #{namespace}" if namespace} -o json --ignore-not-found`
    raise unless $?.success?
    if result == ""
      warn "Resource not found, assuming it was deleted"
      current = nil
    else
      current = Logs.clean_for_diff(JSON.parse(result, symbolize_names: true), ignore_status:)
    end

    # build log url
    url = <whatever your log system is>

    # say what we are looking at
    warn "Inspecting #{days} days of logs #{ignore_status ? "ignoring" : "including"} status changes."
    warn url

    # produce diff from logs
    verb_colors = { "update" => :yellow, "delete" => :red, "patch" => :cyan, "create" => :green }
    printer = Kennel::AttributeDiffer.new
    list_logs(url) do |line| # build this method for whatever your log system is
      status = line.dig(:attributes, :http, :status_code)
      next if status >= 300

      # print what happened
      verb = line.dig(:attributes, :verb)
      time = line.dig(:attributes, :requestReceivedTimestamp).sub(/\..*/, "")
      user = line.dig(:attributes, :user, :username)
      puts(Kennel::Console.color(verb_colors.fetch(verb), "#{time} #{verb} by #{user}"))
      next if verb == "delete"

      # print diff
      previous = Logs.clean_for_diff(line.dig(:attributes, :responseObject), ignore_status:)
      unless current # support looking at deleted resources
        current = previous
        next
      end
      diff = Hashdiff.diff(previous, current, use_lcs: false, strict: false, similarity: 1)
      diff.each { |l| puts printer.format(*l) }
      current = previous
    end