require "bundler/setup"
require "sinatra"
require "sinatra/json"
require "sinatra/cookies"
require "time"
require "fileutils"
require "json"

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

require "jwt"

SESSION_SECRET_HEX_LENGTH = 64

set :session_secret, ENV.fetch("SESSION_SECRET") { SecureRandom.hex(SESSION_SECRET_HEX_LENGTH) }

CLK_TCK = 100
PID_FILE_PATH = "/run/app/pid".freeze
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

JWT_SECRET = SecureRandom.bytes(64).freeze

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 = master_pid
    @procfs_f = format "/proc/%s/stat", @pid
    puts @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 = "./healthy"
  end

  def healthy?
    enabled?
  end
end

class Ready
  include Singleton
  include State
  include UpDown

  def initialize
    @file = "./ready"
  end

  def ready?
    enabled?
  end
end

class Sleep
  include Singleton
  include State

  def initialize
    @file = "./sleep"
  end

  def asleep?
    enabled?
  end

  def wake
    disable
  end

  def sleep
    enable
  end
end

def master_pid
  pid_s = File.read PID_FILE_PATH
  Integer pid_s.strip
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

enable :sessions

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"
end

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

get "/env", provides: "json" do
  content_type :json

  return JSON.pretty_generate ENV.sort.to_h if params.key? "pretty"

  JSON.generate ENV.sort.to_h
end

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

  JSON.generate h
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 "/livez/uptime" do
  tt = TickTock.new
  x = {started_at: tt.started_at, seconds: tt.uptime.to_i, human: human_time(tt.uptime.to_i)}
  json x
end

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

post "/livez/sleep" do
  Sleep.instance.toggle
  "ok\n"
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", master_pid)
  nil
end

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

get "/pid" do
  JSON.generate({puma: master_pid, pid: Process.pid})
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}
  json x
end

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

post "/session" do
  session.merge! params
  json session.to_hash
end

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

get "/cookies" do
  json response.headers
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