# frozen_string_literal: true

class Review < ApplicationRecord
  belongs_to :word

  EASE_MIN   = 1.3
  EASE_START = 2.5

  # status: new | known | learning | skipped

  scope :due,      -> { where(status: "learning").where("due_at <= ?", Time.current).order(:due_at) }
  scope :upcoming, -> { where(status: "learning").order(:due_at) }

  def mark_known!
    update!(status: "known", last_reviewed_at: Time.current, due_at: nil)
  end

  def mark_learning!
    update!(
      status: "learning",
      interval: 1,
      repetitions: 0,
      ease_factor: EASE_START,
      due_at: 1.day.from_now,
      last_reviewed_at: Time.current
    )
  end

  def mark_skipped!
    update!(status: "skipped", last_reviewed_at: Time.current)
  end

  # SM-2 algorithm: quality 0-5
  # 0-2 = forgot/hard  3-5 = remembered
  def sm2_update!(quality)
    quality = quality.to_i.clamp(0, 5)

    new_ease = [EASE_MIN, ease_factor + 0.1 - (5 - quality) * (0.08 + (5 - quality) * 0.02)].max.round(3)

    if quality < 3
      update!(
        status: "learning",
        repetitions: 0,
        interval: 1,
        ease_factor: new_ease,
        due_at: 1.day.from_now,
        last_reviewed_at: Time.current
      )
    else
      new_reps = repetitions + 1
      new_interval = case repetitions
        when 0 then 1
        when 1 then 6
        else [ (interval * new_ease).ceil, 1 ].max
      end
      update!(
        status: "learning",
        repetitions: new_reps,
        interval: new_interval,
        ease_factor: new_ease,
        due_at: new_interval.days.from_now,
        last_reviewed_at: Time.current
      )
    end
  end

  def due_label
    return "Now" unless due_at
    return "Now" if due_at <= Time.current

    days = ((due_at - Time.current) / 1.day).ceil
    case days
    when 0 then "Today"
    when 1 then "Tomorrow"
    else "#{days} days"
    end
  end
end