@spec conflicting_events(DateTime.t(), DateTime.t(), [PhoenixLiveCalendar.Event.t()]) ::
  [
    PhoenixLiveCalendar.Event.t()
  ]

Returns all events that conflict with a proposed time range.

@spec has_overlap?(
  DateTime.t(),
  DateTime.t(),
  PhoenixLiveCalendar.BookingConfig.t(),
  [
    PhoenixLiveCalendar.Event.t()
  ]
) :: boolean()

Checks if a proposed time range overlaps with any existing events.

Accounts for buffer times defined in the config.

@spec overlap_count(DateTime.t(), DateTime.t(), [PhoenixLiveCalendar.Event.t()]) ::
  non_neg_integer()

Counts how many bookings overlap with a given time range.

Used for capacity/seat checking.

@spec snap_datetime_to_slot(DateTime.t(), pos_integer()) :: DateTime.t()

Snaps a DateTime to the nearest slot boundary.

@spec snap_to_slot(Time.t(), pos_integer()) :: Time.t()

Snaps a time to the nearest slot boundary based on the slot interval.

Examples

iex> Constraints.snap_to_slot(~T[10:17:00], 15)
~T[10:15:00]

iex> Constraints.snap_to_slot(~T[10:23:00], 15)
~T[10:15:00]

iex> Constraints.snap_to_slot(~T[10:38:00], 15)
~T[10:30:00]

@spec validate_booking(
  DateTime.t(),
  DateTime.t(),
  PhoenixLiveCalendar.BookingConfig.t(),
  [PhoenixLiveCalendar.Event.t()],
  keyword()
) :: validation_result()

Validates a proposed booking against all constraints.

Returns :ok if the booking is valid, or {:error, reason, message} if not.

Parameters

• start_dt — Proposed start DateTime
• end_dt — Proposed end DateTime
• config — BookingConfig with constraints
• existing_events — List of existing events to check for overlaps
• opts — Additional options:
  • now — Current DateTime (default: DateTime.utc_now())
  • resource_id — Resource to check availability against
  • availabilities — List of Availability windows

Examples

iex> Constraints.validate_booking(
...>   ~U[2026-04-01 10:00:00Z],
...>   ~U[2026-04-01 10:30:00Z],
...>   %BookingConfig{duration: 30, min_notice: 60},
...>   existing_events
...> )
:ok

iex> Constraints.validate_booking(
...>   ~U[2026-04-01 10:00:00Z],
...>   ~U[2026-04-01 10:15:00Z],
...>   %BookingConfig{duration: 30, min_duration: 30},
...>   []
...> )
{:error, :too_short, "Booking must be at least 30 minutes"}