defmodule GenDOM.PointerEvent do
  @moduledoc """
  Represents the state of a DOM event produced by a pointer.

  The PointerEvent interface represents the state of a DOM event produced by a pointer
  such as the geometry of the contact point, the device type that generated the event,
  the amount of pressure that was applied on the contact surface, etc.

  A pointer is a hardware agnostic representation of input devices (such as a mouse,
  pen or contact point on a touch-enable surface). The pointer can target a specific
  coordinate (or set of coordinates) on the contact surface such as a screen.

  ## Specification Compliance

  This module implements the PointerEvent interface as defined by:
  - **Pointer Events Level 3**: https://www.w3.org/TR/pointerevents3/
  - **Pointer Events Level 2**: https://www.w3.org/TR/pointerevents2/
  - **MDN PointerEvent Reference**: https://developer.mozilla.org/en-US/docs/Web/API/PointerEvent

  ## Inheritance Chain

  ```
  GenDOM.Event (Base)
  └── GenDOM.UIEvent
      └── GenDOM.MouseEvent
          └── GenDOM.PointerEvent (extends MouseEvent)
  ```

  **Inherits from:** `GenDOM.MouseEvent`

  ## Properties

  ### Pointer Identification
  - `pointer_id` - Unique identifier for the pointer causing the event
  - `pointer_type` - Device type ("mouse", "pen", "touch", etc.)
  - `is_primary` - Indicates if this is the primary pointer of this type
  - `persistent_device_id` - Unique identifier for the pointing device

  ### Geometry and Orientation
  - `width` - Width of contact area in CSS pixels
  - `height` - Height of contact area in CSS pixels
  - `tilt_x` - Angle between Y-Z plane and pointer axis (-90 to 90 degrees)
  - `tilt_y` - Angle between X-Z plane and pointer axis (-90 to 90 degrees)
  - `twist` - Clockwise rotation around major axis (0 to 359 degrees)

  ### Pressure and Angle
  - `pressure` - Normalized pressure (0.0 to 1.0)
  - `tangential_pressure` - Normalized tangential/barrel pressure (-1.0 to 1.0)
  - `altitude_angle` - Angle between pointer axis and X-Y plane
  - `azimuth_angle` - Angle between Y-Z plane and plane containing pointer axis

  ## Event Types

  PointerEvent is used for the following event types:
  - `pointerdown` - Pointer becomes active
  - `pointerup` - Pointer ceases to be active
  - `pointermove` - Pointer changes coordinates
  - `pointercancel` - Pointer unlikely to produce further events
  - `pointerover` - Pointer enters element boundaries
  - `pointerout` - Pointer leaves element boundaries
  - `pointerenter` - Pointer enters element and descendants (doesn't bubble)
  - `pointerleave` - Pointer leaves element and descendants (doesn't bubble)
  - `gotpointercapture` - Element receives pointer capture
  - `lostpointercapture` - Element loses pointer capture
  - `pointerrawupdate` - Raw pointer update (experimental)

  ## Advantages Over Mouse Events

  PointerEvent provides several advantages over traditional mouse events:
  - **Unified API** - Single event model for mouse, touch, and pen
  - **Multiple pointers** - Support for multi-touch and multiple simultaneous inputs
  - **Pressure sensitivity** - Access to pressure data from supported devices
  - **Tilt and rotation** - Orientation data for stylus devices
  - **Coalesced events** - Access to high-frequency input data
  - **Predicted events** - Reduced latency through prediction

  ## Examples

      # Creating a PointerEvent
      {:ok, event} = GenDOM.PointerEvent.new("pointerdown", %{
        pointer_id: 1,
        pointer_type: "touch",
        is_primary: true,
        client_x: 150,
        client_y: 200,
        pressure: 0.8,
        width: 20,
        height: 20
      })

      # Handling different pointer types
      case event.pointer_type do
        "mouse" -> handle_mouse_input(event)
        "pen" -> handle_pen_input(event)
        "touch" -> handle_touch_input(event)
      end

      # Getting coalesced events for smooth drawing
      coalesced = GenDOM.PointerEvent.get_coalesced_events(event)
      Enum.each(coalesced, &draw_point/1)
  """

  use GenDOM.MouseEvent, [
    # Angle properties - stylus orientation in 3D space
    altitude_angle: 0.0,           # Angle in radians between transducer axis and X-Y plane (0 to π/2)
    azimuth_angle: 0.0,            # Angle in radians between Y-Z plane and plane containing transducer axis (0 to 2π)
    
    # Device identification - unique identifiers for tracking
    persistent_device_id: nil,     # Persistent unique identifier for the physical pointing device
    pointer_id: 0,                 # Unique identifier for this pointer in the active pointer set
    
    # Contact geometry - size of the contact area
    width: 0.0,                    # Width in CSS pixels of contact area (default: 1 for mouse)
    height: 0.0,                   # Height in CSS pixels of contact area (default: 1 for mouse)
    
    # Pressure properties - force applied by the pointer
    pressure: 0.0,                 # Normalized pressure (0.0 = no pressure, 0.5 = default, 1.0 = maximum)
    tangential_pressure: 0.0,      # Normalized tangential/barrel button pressure (-1.0 to 1.0, 0 = neutral)
    
    # Tilt properties - stylus/pen orientation relative to surface
    tilt_x: 0.0,                   # Angle in degrees (-90 to 90) between Y-Z plane and pointer axis
    tilt_y: 0.0,                   # Angle in degrees (-90 to 90) between X-Z plane and pointer axis
    twist: 0.0,                    # Clockwise rotation in degrees (0 to 359) around pointer's major axis
    
    # Device type and primary status - identifies input device characteristics
    pointer_type: "",              # Device type: "mouse", "pen", "touch", or empty string if unknown
    is_primary: false              # True if this is the primary pointer of this pointer type
  ]

  @doc """
  Returns a sequence of all PointerEvent instances that were coalesced into the dispatched pointermove event.

  This method implements the PointerEvent `getCoalescedEvents()` specification. When a user agent
  is dispatching a pointermove event, it may coalesce multiple native pointer events into a single
  pointermove event. This method returns all the events that were coalesced.

  Coalesced events are useful for drawing applications that want to render smoother curves by
  using all the intermediate pointer positions that occurred between animation frames.

  ## Parameters
  - `event` - The PointerEvent struct

  ## Returns
  A list of PointerEvent instances that were coalesced into this event. Returns an empty
  list for non-pointermove events or when no coalescing occurred.

  ## Examples
      coalesced_events = GenDOM.PointerEvent.get_coalesced_events(event)
      Enum.each(coalesced_events, fn event ->
        # Process each intermediate pointer position
        IO.puts("Pointer at: \#{event.client_x}, \#{event.client_y}")
      end)

  ## Security Context
  This feature is available only in secure contexts (HTTPS).

  ## MDN Reference
  https://developer.mozilla.org/en-US/docs/Web/API/PointerEvent/getCoalescedEvents
  """
  def get_coalesced_events(_event) do
    :not_implemented
  end

  @doc """
  Returns a sequence of PointerEvent instances that the browser predicts will follow the dispatched pointermove event's coalesced events.

  This method implements the PointerEvent `getPredictedEvents()` specification. It provides
  predicted future pointer positions based on the pointer's current trajectory. These predictions
  can be used to reduce perceived latency in drawing applications by anticipating where the
  pointer will move next.

  The predicted events are based on the browser's analysis of the pointer's velocity and
  acceleration, and may not always be accurate. Applications should be prepared to handle
  cases where predictions don't match actual future events.

  ## Parameters
  - `event` - The PointerEvent struct

  ## Returns
  A list of predicted PointerEvent instances that may follow this event. Returns an empty
  list for non-pointermove events or when prediction is not available.

  ## Examples
      predicted_events = GenDOM.PointerEvent.get_predicted_events(event)
      
      # Use predictions for speculative rendering
      Enum.each(predicted_events, fn predicted_event ->
        # Render with lower opacity or different style
        render_predicted_point(predicted_event.client_x, predicted_event.client_y)
      end)

  ## Browser Support
  This is a relatively new API and may not be supported in all browsers. Always check
  for feature availability before using.

  ## MDN Reference
  https://developer.mozilla.org/en-US/docs/Web/API/PointerEvent/getPredictedEvents
  """
  def get_predicted_events(_event) do
    :not_implemented
  end
end
