# Copyright(c) 2015-2018 ACCESS CO., LTD. All rights reserved.

use Croma

defmodule Antikythera.AsyncJob.Id do
  use Croma.SubtypeOfString, pattern: ~r/^[0-9A-Za-z_-]{1,32}$/

  defun generate() :: t do
    Enum.map(1..20, fn _ -> gen_base64url_char() end) |> List.to_string()
  end

  defunp gen_base64url_char() :: char do
    case :rand.uniform(64) do
      i when i <= 10 -> i + 47 # 0-9
      i when i <= 36 -> i + 54 # A-Z
      i when i <= 62 -> i + 60 # a-z
      63             -> 45     # -
      64             -> 95     # _
    end
  end
end

defmodule Antikythera.AsyncJob.Schedule do
  alias Antikythera.{Time, Cron}

  @type t :: {:once, Time.t} | {:cron, Cron.t}

  defun valid?(t :: term) :: boolean do
    {:once, t} -> Time.valid?(t)
    {:cron, c} -> Cron.valid?(c)
    _otherwise -> false
  end
end

defmodule Antikythera.AsyncJob.Attempts do
  use Croma.SubtypeOfInt, min: 1, max: 10, default: 3
end

defmodule Antikythera.AsyncJob.MaxDuration do
  use Croma.SubtypeOfInt, min: 1, max: 30 * 60_000, default: 5 * 60_000
end

defmodule Antikythera.AsyncJob.RetryInterval do
  defmodule Factor do
    use Croma.SubtypeOfInt, min: 0, max: 5 * 60_000, default: 5_000
  end

  defmodule Base do
    use Croma.SubtypeOfFloat, min: 1.0, max: 5.0, default: 2.0
  end

  use Croma.SubtypeOfTuple, elem_modules: [Factor, Base], default: {Factor.default(), Base.default()}

  defun interval(t :: v[t], n_retries_done_so_far :: v[non_neg_integer]) :: non_neg_integer do
    {factor, base} = t
    factor * round(:math.pow(base, n_retries_done_so_far))
  end
end

defmodule Antikythera.AsyncJob.Metadata do
  alias Antikythera.Time
  alias Antikythera.AsyncJob.{Id, Attempts, MaxDuration, RetryInterval}

  use Croma.Struct, recursive_new?: true, fields: [
    id:                 Id,
    run_at:             Time,
    max_duration:       MaxDuration,
    attempts:           Attempts,
    remaining_attempts: Attempts,
    retry_interval:     RetryInterval,
  ]
end

defmodule Antikythera.AsyncJob.StateLabel do
  use Croma.SubtypeOfAtom, values: [:waiting, :runnable, :running]
end

defmodule Antikythera.AsyncJob.Status do
  alias Antikythera.{Time, GearName}
  alias Antikythera.AsyncJob.{Id, Schedule, Attempts, MaxDuration, RetryInterval, StateLabel}

  use Croma.Struct, recursive_new?: true, fields: [
    id:                 Id,
    gear_name:          GearName,
    module:             Croma.Atom,
    payload:            Croma.Map,
    schedule:           Schedule,
    start_time:         Time,
    state:              StateLabel,
    max_duration:       MaxDuration,
    attempts:           Attempts,
    remaining_attempts: Attempts,
    retry_interval:     RetryInterval,
  ]
end