require "bundler/setup"
require "sinatra"
require "sinatra/cookies"
require "sinatra/multi_route"
require "sinatra/quiet_logger"
require "time"
require "fileutils"
require "json"
require "singleton"

require "securerandom"
require "random/formatter"
require "ulid"
require "anyflake"

require "jwt"

require "httparty"

$LOAD_PATH.unshift File.dirname(__FILE__) + "/lib"

require "config"

VERSION = "0.1.3"

CHUNK_SIZE = 1024**2
SESSION_SECRET_HEX_LENGTH = 64
JWT_SECRET_HEX_LENGTH = 64
DEFAULT_FLAKEY = 50

NAME = "kubernaut".freeze
ENV_PREFIX = NAME.upcase

CLK_TCK = 100
PROC_UPTIME_PATH = "/proc/uptime".freeze

SECONDS_PER_YEAR = 31_556_952
SECONDS_PER_MINUTE = 60
SECONDS_PER_HOUR = 3_600
SECONDS_PER_DAY = 86_400
SECONDS_PER_WEEK = 604_800
SECONDS_PER_MONTH = SECONDS_PER_YEAR / 12

DURATION_PARTS = [
  [SECONDS_PER_YEAR, "year", "y"],
  [SECONDS_PER_MONTH, "month", "m"],
  [SECONDS_PER_WEEK, "week", "w"],
  [SECONDS_PER_DAY, "day", "d"],
  [SECONDS_PER_HOUR, "hour", "h"],
  [SECONDS_PER_MINUTE, "minute", "m"],
  [1, "second", "s"]
].freeze

config = Config.new

set :quiet_logger_prefixes, %w[livez readyz]
set :session_secret, config.session_secret.unwrap
set :public_folder, __dir__ + "/static"

register Sinatra::QuietLogger

module Sinatra
  module RequestHeadersHelper
    def req_headers
      hash = request.env.select { |k, _| k.start_with? "HTTP_" }
        .collect { |k, v| [k.gsub(/^HTTP_/, "").tr("_", "-").downcase, v] }
        .sort
      h = Rack::Headers.new
      h.merge hash
    end
  end

  helpers RequestHeadersHelper
end

module State
  def enable
    FileUtils.touch(@file)
  end

  def disable
    File.delete @file if File.file? @file
  end

  def enabled?
    File.file? @file
  end

  def toggle
    return enable unless enabled?

    disable
  end
end

module UpDown
  def up
    enable
  end

  def down
    disable
  end

  def to_s
    enabled? ? "up" : "down"
  end

  def to_json(*_args)
    return unless enabled?

    JSON.generate({"status" => "ok"})
  end
end

class TickTock
  def initialize
    @pid = ppid
    @procfs_f = format "/proc/%s/stat", @pid
  end

  def uptime
    x = ""
    File.open @procfs_f do |f|
      f.each_line do |l|
        x = l.strip.split
      end
    end
    system_uptime - (Integer(x[21]) / CLK_TCK)
  end

  def started_at
    Time.now - uptime
  end
end

class Health
  include Singleton
  include State
  include UpDown

  def initialize
    @file = "/dev/shm/healthy"
  end

  def healthy?
    enabled?
  end
end

class Ready
  include Singleton
  include State
  include UpDown

  def initialize
    @file = "/dev/shm/ready"
  end

  def ready?
    enabled?
  end
end

class Sleep
  include Singleton
  include State

  def initialize
    @file = "/dev/shm/sleepy"
  end

  def asleep?
    enabled?
  end

  def wake
    disable
  end

  def sleep
    enable
  end
end

def ppid
  pid = ENV.fetch "PUMA_PID", Process.pid
  begin
    Integer pid
  rescue ArgumentError
    -1
  end
end

def system_uptime
  uptime_s = File.read PROC_UPTIME_PATH
  Float uptime_s.strip.split[0]
end

##
# Convert to human friendly time interval
#
# @param [Integer] time in seconds
def human_time(seconds, delim = " ")
  s = []
  DURATION_PARTS.each do |divisor, unit, abbrev|
    q = seconds / divisor
    r = seconds % divisor
    s.push "#{q}#{abbrev}" if q.positive?
    seconds = r
  end

  s.join delim
end

Health.instance.up
Ready.instance.up
Sleep.instance.wake

def flaky(pct = DEFAULT_FLAKEY)
  r = Random.rand(0..100)
  unless r < (100 - pct)
    halt 500, "so unreliable"
  end
end

enable :sessions

puts "#{NAME} #{VERSION} staring, per aspera ad astra"

configure do
  mime_type :json, "application/json"
end

before do
  # content_type 'text/plain'
  sleep(1) while Sleep.instance.asleep? && request.path_info != "/livez/sleep"
  content_type :text if request.path_info.start_with? "/_cat"
  request.session_options[:skip] = !request.path_info.start_with?("/session")

  if params.has_key? :flaky
    begin
      pct = Integer(params[:flaky])
      pct = pct.clamp(0, 100)
    rescue => e
      logger.warn "#{e.message}: falling back to default flaky percentage of #{DEFAULT_FLAKEY}"
      pct = DEFAULT_FLAKEY
    end
    flaky(pct)
  end
end

helpers do
  def jsonify(obj, opts: nil, pretty: false)
    buf = if pretty
      JSON.pretty_generate obj, opts:
    else
      JSON.generate(obj, opts:)
    end
    "#{buf}\n"
  end

  def protected! hidden = false
    return if authorized?

    if hidden
      halt 404, "Not Found"
    else
      headers["WWW-Authenticate"] = 'Basic realm="Restricted Area"'
      halt 401, "Unauthorized"
    end
  end

  def authorized?
    @auth ||= Rack::Auth::Basic::Request.new(request.env)
    @auth.provided? and
      @auth.basic? and
      @auth.credentials and
      @auth.credentials == ["qwer", "asdf"]
  end

  def hostname
    ENV["HOSTNAME"]
  end
end

get "/" do
  "hello there!\n"
end

get "/env", provides: "json" do
  pretty = params.key? :pretty

  jsonify ENV.sort.to_h, pretty:
end

get "/headers", provides: "json" do
  pretty = params.key? :pretty
  h = req_headers

  jsonify h, pretty:
end

get "/uptime", provides: "json" do
  tt = TickTock.new
  x = {started_at: tt.started_at, seconds: tt.uptime.to_i, human: human_time(tt.uptime.to_i)}

  jsonify x
end

post "/api/livez/toggle" do
  Health.instance.toggle
  "ok\n"
end

post "/api/livez/sleep" do
  Sleep.instance.toggle
  "ok\n"
end

get "/livez" do
  error 503 unless Health.instance.healthy?

  return Health.instance.to_json if request.env["HTTP_ACCEPT"] == "application/json"

  Health.instance.to_s
end

get "/readyz" do
  error 503 unless Ready.instance.ready?

  return Ready.instance.to_json if request.env["HTTP_ACCEPT"] == "application/json"

  Ready.instance.to_s
end

get "/uuid" do
  n = params.fetch(:n, 1).to_i
  stream do |out|
    n.times do |_|
      out << format("%s\n", SecureRandom.uuid)
    end
  end
end

get "/ulid" do
  n = params.fetch(:n, 1).to_i
  stream do |out|
    n.times do |_|
      out << format("%s\n", ULID.generate)
    end
  end
end

get "/snowflake" do
  n = params.fetch(:n, 1).to_i
  epoch = Time.new(2016, 7, 1, 0, 0, 0).strftime("%s%L").to_i
  node_id = 1
  af = AnyFlake.new(epoch, node_id)
  stream do |out|
    n.times do |_|
      out << format("%s\n", af.next_id)
    end
  end
end

post "/quit" do
  Process.kill("TERM", ppid)
  nil
end

post "/halt" do
  Process.kill("QUIT", ppid)
  nil
end

get "/pid" do
  pretty = params.key? :pretty

  jsonify({ppid: ppid, pid: Process.pid}, pretty:)
end

get "/token" do
  exp = Time.now.to_i + SECONDS_PER_MINUTE * 2
  payload = {name: "anonymous", exp: exp, jti: Random.uuid}
  expires_at = Time.at(exp).to_datetime
  token = JWT.encode payload, JWT_SECRET, "HS256"
  x = {token: token, expires_at: expires_at}

  jsonify x
end

get "/token/validate" do
  token = req_headers["authorization"].split[1]
  payload = JWT.decode token, JWT_SECRET, true, algorithm: "HS256"

  jsonify payload
end

post "/session" do
  session.merge! params

  jsonify session.to_hash
end

get "/session" do
  j = session.to_hash
  j[:hostname] = ENV["HOSTNAME"]

  jsonify j
end

get "/cookies" do
  jsonify response.headers
end

get "/config", provides: "json" do
  pretty = params.key? :pretty

  jsonify config.as_json, pretty:
end

get "/_cat" do
  stream do |out|
    out << "=^.^=\n"
    x = Sinatra::Application.routes.map do |method, route|
      route.map do |route|
        route.first.to_s
      end
    end
    x.flatten.sort.uniq.each do |route|
      out << "#{route}\n" if route.start_with? "/_cat"
    end
  end
end

get "/_cat/headers" do
  stream do |out|
    req_headers.each do |k, v|
      out << "#{k}: #{v.inspect}\n"
    end
  end
end

get "/_cat/env" do
  stream do |out|
    ENV.sort.each do |k, v|
      out << "#{k}=#{v}\n"
    end
  end
end

get "/_cat/cookies" do
  stream do |out|
    cookies.each do |k, v|
      out << "#{k}=#{v}\n"
    end
  end
end

get "/_cat/config" do
  stream do |out|
    config.instance_variables.each do |k|
      k = k.to_s.delete_prefix "@"
      begin
        v = config.send(k)
      rescue NoMethodError
        next
      end

      out << "#{k}(#{v.to_s.length})=#{v}\n"
    end
  end
end

get "/_cat/pid" do
  stream do |out|
    {ppid: ppid, pid: Process.pid}.sort.each do |k, v|
      out << "#{k}=#{v}\n"
    end
  end
end

route :delete, :get, :patch, :post, :put, "/status/:code" do
  # hello
  code = Integer(params[:code])
  status code if code.between? 100, 599
end

get "/chunked/:delay" do
  content_type "application/x-ndjson"

  delay = Float(params[:delay])
  stream do |out|
    30.times do |i|
      out << jsonify({id: i, message: (i % 2).zero? ? "tick" : "tock"})
      sleep delay
    end
  end
end

route :delete, :get, :patch, :post, :put, "/auth/basic", provides: "json" do
  pretty = params.key? :pretty

  if params.key? :hidden
    protected! hidden: true
  else
    protected!
  end

  jsonify({authenticated: true, user: @auth.username}, pretty:)
end

def human_size_to_bytes(size)
  units = %i[b kb mb gb tb pb eb zb yb rb qb]

  number, unit = size.split(/(?<=\d)(?=[A-Za-z])/)

  raise ArgumentError, "the unit is not recognized" if unit.nil?

  number = Float(number)
  unit = unit.downcase.to_sym

  exponent = units.find_index(unit)

  number *= (1024**exponent)
  Integer(number.ceil)
end

MAX_DOWNLOAD_SIZE = "1GB"

get "/bytes/:size" do
  size = params[:size]
  n = [human_size_to_bytes(size), human_size_to_bytes(MAX_DOWNLOAD_SIZE)].min

  headers["content-type"] = "application/octet-stream"
  headers["content-length"] = n

  headers["content-disposition"] = "attachment; filename=\"#{params[:f]}\"" if params.key? :f

  def generate_bytes(number, byte = "\x00", block_size = 4096)
    raise ArgumentError, "'byte' must be 1 byte" unless byte.b.length == 1

    bytes_written = 0
    block = byte * block_size
    Enumerator.new do |g|
      while bytes_written < number
        remaining_bytes = number - bytes_written
        bytes_to_write = [block_size, remaining_bytes].min
        g.yield block[0, bytes_to_write]
        bytes_written += bytes_to_write
      end
    end
  end

  generate_bytes(Integer(n))
end

get "/api/caas" do
  send_file Dir[__dir__ + "/static/cat*.jpg"].sample
end

get "/meow" do
  caas_host = ENV.fetch "CAAS_SERVICE_HOST", nil
  caas_port = ENV.fetch "CAAS_SERVICE_PORT", nil
  url = "http://#{caas_host}:#{caas_port}/"
  unless caas_host && caas_port
    url = url("/api/caas")
  end
  tmp_file = Tempfile.open binmode: true do |f|
    # f.chmod 0o644
    response = HTTParty.get(url, stream_body: true) do |fragment|
      if [301, 302].include? fragment.code
        print "skip writing for redirect"
      elsif fragment.code == 200
        f.write fragment
      else
        raise StandardError, "non-success status code while streaming #{fragment.code}"
      end
    end

    content_type response.headers["content-type"]
    f
  end

  tmp_file.open do |f|
    stream do |out|
      out << f.read
      until f.eof?
        out << f.read(CHUNK_SIZE)
      end
    end
  ensure
    f.close
    f.unlink
  end
end