defmodule Mv.MembershipFees.CalendarCyclesTest do
  @moduledoc """
  Tests for CalendarCycles module.
  """
  use ExUnit.Case, async: true

  alias Mv.MembershipFees.CalendarCycles

  doctest Mv.MembershipFees.CalendarCycles

  describe "calculate_cycle_start/3" do
    test "uses reference_date when provided" do
      date = ~D[2024-03-15]
      reference = ~D[2024-05-20]

      assert CalendarCycles.calculate_cycle_start(date, :monthly, reference) == ~D[2024-05-01]
      assert CalendarCycles.calculate_cycle_start(date, :quarterly, reference) == ~D[2024-04-01]
    end
  end

  describe "current_cycle?/3" do
    # Basic examples are covered by doctests

    test "works for all interval types" do
      today = ~D[2024-03-15]

      for interval <- [:monthly, :quarterly, :half_yearly, :yearly] do
        cycle_start = CalendarCycles.calculate_cycle_start(today, interval)
        result = CalendarCycles.current_cycle?(cycle_start, interval, today)

        assert result == true, "Expected current cycle for #{interval} with start #{cycle_start}"
      end
    end
  end

  describe "current_cycle?/2 wrapper" do
    test "calls current_cycle?/3 with Date.utc_today()" do
      today = Date.utc_today()
      cycle_start = CalendarCycles.calculate_cycle_start(today, :monthly)

      # This test verifies the wrapper works, but uses actual today
      # The real testing happens in current_cycle?/3 tests above
      result = CalendarCycles.current_cycle?(cycle_start, :monthly)

      assert result == true
    end
  end

  describe "last_completed_cycle?/3" do
    # Basic examples are covered by doctests

    test "returns false when next cycle has also ended" do
      # Two cycles ago: cycle ended, but next cycle also ended
      today = ~D[2024-05-15]
      cycle_start = ~D[2024-03-01]
      # Cycle ended 2024-03-31, next cycle ended 2024-04-30, today is 2024-05-15

      assert CalendarCycles.last_completed_cycle?(cycle_start, :monthly, today) == false
    end

    test "works correctly for quarterly intervals" do
      # Q1 2024 ended on 2024-03-31
      # Q2 2024 ends on 2024-06-30
      # Today is 2024-04-15 (after Q1 ended, before Q2 ended)
      today = ~D[2024-04-15]
      past_quarter_start = ~D[2024-01-01]

      assert CalendarCycles.last_completed_cycle?(past_quarter_start, :quarterly, today) == true
    end

    test "returns false when cycle ended on the given date" do
      # Cycle ends on today, so it's still current, not completed
      today = ~D[2024-03-31]
      cycle_start = ~D[2024-03-01]

      assert CalendarCycles.last_completed_cycle?(cycle_start, :monthly, today) == false
    end
  end

  describe "last_completed_cycle?/2 wrapper" do
    test "calls last_completed_cycle?/3 with Date.utc_today()" do
      today = Date.utc_today()
      cycle_start = CalendarCycles.calculate_cycle_start(today, :monthly)

      # This test verifies the wrapper works, but uses actual today
      # The real testing happens in last_completed_cycle?/3 tests above
      result = CalendarCycles.last_completed_cycle?(cycle_start, :monthly)

      # Result depends on actual today, so we just verify it's a boolean
      assert is_boolean(result)
    end
  end

  describe "edge cases" do
    test "leap year: February has 29 days" do
      # 2024 is a leap year
      assert CalendarCycles.calculate_cycle_end(~D[2024-02-01], :monthly) == ~D[2024-02-29]

      # 2023 is not a leap year
      assert CalendarCycles.calculate_cycle_end(~D[2023-02-01], :monthly) == ~D[2023-02-28]
    end

    test "year boundary: December 31 to January 1" do
      # Yearly cycle
      assert CalendarCycles.next_cycle_start(~D[2024-01-01], :yearly) == ~D[2025-01-01]

      # Monthly cycle across year boundary
      assert CalendarCycles.next_cycle_start(~D[2024-12-01], :monthly) == ~D[2025-01-01]

      # Half-yearly cycle across year boundary
      assert CalendarCycles.next_cycle_start(~D[2024-07-01], :half_yearly) == ~D[2025-01-01]

      # Quarterly cycle across year boundary
      assert CalendarCycles.next_cycle_start(~D[2024-10-01], :quarterly) == ~D[2025-01-01]
    end

    test "month boundary: different month lengths" do
      # 31-day months
      assert CalendarCycles.calculate_cycle_end(~D[2024-01-01], :monthly) == ~D[2024-01-31]
      assert CalendarCycles.calculate_cycle_end(~D[2024-03-01], :monthly) == ~D[2024-03-31]
      assert CalendarCycles.calculate_cycle_end(~D[2024-05-01], :monthly) == ~D[2024-05-31]

      # 30-day months
      assert CalendarCycles.calculate_cycle_end(~D[2024-04-01], :monthly) == ~D[2024-04-30]
      assert CalendarCycles.calculate_cycle_end(~D[2024-06-01], :monthly) == ~D[2024-06-30]
      assert CalendarCycles.calculate_cycle_end(~D[2024-09-01], :monthly) == ~D[2024-09-30]
      assert CalendarCycles.calculate_cycle_end(~D[2024-11-01], :monthly) == ~D[2024-11-30]
    end

    test "date in middle of cycle: all functions work correctly" do
      middle_date = ~D[2024-03-15]

      # calculate_cycle_start
      assert CalendarCycles.calculate_cycle_start(middle_date, :monthly) == ~D[2024-03-01]
      assert CalendarCycles.calculate_cycle_start(middle_date, :quarterly) == ~D[2024-01-01]
      assert CalendarCycles.calculate_cycle_start(middle_date, :half_yearly) == ~D[2024-01-01]
      assert CalendarCycles.calculate_cycle_start(middle_date, :yearly) == ~D[2024-01-01]

      # calculate_cycle_end
      monthly_start = CalendarCycles.calculate_cycle_start(middle_date, :monthly)
      assert CalendarCycles.calculate_cycle_end(monthly_start, :monthly) == ~D[2024-03-31]

      # next_cycle_start
      assert CalendarCycles.next_cycle_start(monthly_start, :monthly) == ~D[2024-04-01]
    end

    test "quarterly: all quarter boundaries correct" do
      # Q1 boundaries
      assert CalendarCycles.calculate_cycle_start(~D[2024-01-15], :quarterly) == ~D[2024-01-01]
      assert CalendarCycles.calculate_cycle_end(~D[2024-01-01], :quarterly) == ~D[2024-03-31]

      # Q2 boundaries
      assert CalendarCycles.calculate_cycle_start(~D[2024-05-15], :quarterly) == ~D[2024-04-01]
      assert CalendarCycles.calculate_cycle_end(~D[2024-04-01], :quarterly) == ~D[2024-06-30]

      # Q3 boundaries
      assert CalendarCycles.calculate_cycle_start(~D[2024-08-15], :quarterly) == ~D[2024-07-01]
      assert CalendarCycles.calculate_cycle_end(~D[2024-07-01], :quarterly) == ~D[2024-09-30]

      # Q4 boundaries
      assert CalendarCycles.calculate_cycle_start(~D[2024-11-15], :quarterly) == ~D[2024-10-01]
      assert CalendarCycles.calculate_cycle_end(~D[2024-10-01], :quarterly) == ~D[2024-12-31]
    end

    test "half_yearly: both half boundaries correct" do
      # First half boundaries
      assert CalendarCycles.calculate_cycle_start(~D[2024-03-15], :half_yearly) == ~D[2024-01-01]
      assert CalendarCycles.calculate_cycle_end(~D[2024-01-01], :half_yearly) == ~D[2024-06-30]

      # Second half boundaries
      assert CalendarCycles.calculate_cycle_start(~D[2024-09-15], :half_yearly) == ~D[2024-07-01]
      assert CalendarCycles.calculate_cycle_end(~D[2024-07-01], :half_yearly) == ~D[2024-12-31]
    end

    test "yearly: full year boundaries" do
      assert CalendarCycles.calculate_cycle_start(~D[2024-06-15], :yearly) == ~D[2024-01-01]
      assert CalendarCycles.calculate_cycle_end(~D[2024-01-01], :yearly) == ~D[2024-12-31]
      assert CalendarCycles.next_cycle_start(~D[2024-01-01], :yearly) == ~D[2025-01-01]
    end
  end
end