Recurable

require 'recurable/recurrence'

# Build a recurrence from attributes
recurrence = Recurrence.new(frequency: 'DAILY', interval: 1)
recurrence.to_rrule   # => "FREQ=DAILY;INTERVAL=1"

# Parse an existing RRULE string
recurrence = Recurrence.from_rrule('FREQ=WEEKLY;INTERVAL=2;BYDAY=MO,WE,FR')
recurrence.frequency  # => "WEEKLY"
recurrence.interval   # => 2
recurrence.by_day     # => ["MO", "WE", "FR"]

# Frequency predicates
recurrence.weekly?    # => true
recurrence.daily?     # => false

# Frequency comparison (YEARLY < MONTHLY < ... < MINUTELY)
yearly  = Recurrence.new(frequency: 'YEARLY')
monthly = Recurrence.new(frequency: 'MONTHLY')
yearly < monthly      # => true

class Plan < ApplicationRecord
  include Recurable
end

plan = Plan.new
plan.frequency = 'MONTHLY'
plan.interval = 3
plan.by_month_day = [15]
plan.rrule                    # => #<Recurrence> with to_rrule "FREQ=MONTHLY;INTERVAL=3;BYMONTHDAY=15"
plan.valid?                   # validates both the model and the recurrence
plan.monthly?                 # => true
plan.humanize_recurrence      # => "every 3 months on the 15th"

# Time projection
plan.recurrence_times(
  project_from: Time.zone.local(2026, 1, 1),
  project_to:   Time.zone.local(2026, 7, 1)
)

# Boundary queries
plan.last_recurrence_time_before(Time.zone.now, dt_start_at: plan.created_at)
plan.next_recurrence_time_after(Time.zone.now, dt_start_at: plan.created_at)

gem 'recurable'

# Then in your code:
require 'recurable/recurrence'

gem 'recurable'

# Then in your code:
require 'recurable'

recurrence = Recurrence.new
recurrence.by_day = 'MO'       # => stored as ["MO"]
recurrence.by_day = %w[MO FR]  # => stored as ["MO", "FR"]
recurrence.by_day = []          # => stored as nil

# By date: "the 15th of every month"
Recurrence.new(frequency: 'MONTHLY', interval: 1, by_month_day: [15])
  .monthly_option         # => "DATE"

# By nth weekday: "the last Friday of every month"
Recurrence.new(frequency: 'MONTHLY', interval: 1, by_day: ['FR'], by_set_pos: [-1])
  .monthly_option         # => "NTH_DAY"

# Generate: attributes → RRULE string
recurrence = Recurrence.new(frequency: 'MONTHLY', interval: 1, by_day: ['FR'], by_set_pos: [-1])
recurrence.to_rrule  # => "FREQ=MONTHLY;INTERVAL=1;BYDAY=FR;BYSETPOS=-1"

# Parse: RRULE string → Recurrence
parsed = Recurrence.from_rrule('FREQ=MONTHLY;INTERVAL=1;BYDAY=FR;BYSETPOS=-1')
parsed.by_day        # => ["FR"]
parsed.by_set_pos    # => [-1]

# Round-trip
parsed.to_rrule == recurrence.to_rrule  # => true

# Limit by count
Recurrence.new(frequency: 'DAILY', interval: 1, count: 10)
  .to_rrule  # => "FREQ=DAILY;INTERVAL=1;COUNT=10"

# Limit by end date (stored as UTC)
Recurrence.new(frequency: 'DAILY', interval: 1, repeat_until: Time.utc(2026, 12, 31, 23, 59, 59))
  .to_rrule  # => "FREQ=DAILY;INTERVAL=1;UNTIL=20261231T235959Z"

# Project occurrences in a date range
model.recurrence_times(
  project_from: Time.zone.local(2026, 1, 1),
  project_to:   Time.zone.local(2026, 2, 1),
  dt_start_at:  model.created_at          # optional; defaults to project_from
)

# Find the last occurrence before a boundary
model.last_recurrence_time_before(Time.zone.now, dt_start_at: model.created_at)

# Find the next occurrence after a boundary
model.next_recurrence_time_after(Time.zone.now, dt_start_at: model.created_at)

# Human-readable description
model.humanize_recurrence  # => "every 3 months on the 15th"

Time.use_zone('America/New_York') do
  spring_forward = Time.zone.local(2023, 3, 12)

  # Daily at 1 PM: fires every day regardless of DST
  daily = Recurrence.new(frequency: 'DAILY', interval: 1)
  model = Struct.new(:recurrence).new(daily).extend(RruleUtils)
  model.recurrence_times(
    project_from: Time.zone.local(2023, 3, 11, 13),
    project_to:   Time.zone.local(2023, 3, 13, 13),
    dt_start_at:  Time.zone.local(2023, 3, 11, 13)
  ).map { |t| t.strftime('%b %d %l:%M %p %Z') }
  # => ["Mar 11  1:00 PM EST", "Mar 12  1:00 PM EDT", "Mar 13  1:00 PM EDT"]

  # Hourly on spring-forward day: 23 unique hours, 2 AM is skipped
  hourly = Recurrence.new(frequency: 'HOURLY', interval: 1)
  model  = Struct.new(:recurrence).new(hourly).extend(RruleUtils)
  hours  = model.recurrence_times(
    project_from: spring_forward.beginning_of_day,
    project_to:   spring_forward.end_of_day,
    dt_start_at:  spring_forward
  )
  hours.size # => 23

  # Hourly on fall-back day: 24 unique hours, duplicate 1 AM removed
  fall_back = Time.zone.local(2023, 11, 5)
  model = Struct.new(:recurrence).new(hourly).extend(RruleUtils)
  hours = model.recurrence_times(
    project_from: fall_back.beginning_of_day,
    project_to:   fall_back.end_of_day,
    dt_start_at:  Time.zone.local(2023, 11, 1)
  )
  hours.size # => 24
end

class Plan < ApplicationRecord
  include Recurable
end

Recurrence::DAILY          # => "DAILY"
Recurrence::MONDAY         # => "MO"
Recurrence::SUNDAY         # => "SU"
Recurrence::MONTHLY_DATE   # => "DATE"
Recurrence::MONTHLY_NTH_DAY # => "NTH_DAY"
Recurrence::FREQUENCIES    # => {"YEARLY"=>365, "MONTHLY"=>31, ...}
Recurrence::DAYS_OF_WEEK   # => ["SU", "MO", "TU", "WE", "TH", "FR", "SA"]
Recurrence::NTH_DAY_OF_MONTH # => {first: 1, second: 2, ..., last: -1}