namespace Minint.Core.Models;

/// <summary>
/// A single document (frame) within a container.
/// Has its own palette shared by all layers, plus a list of layers.
/// </summary>
public sealed class MinintDocument
{
    public string Name { get; set; }

    /// <summary>
    /// Delay before showing the next frame during animation playback (ms).
    /// </summary>
    public uint FrameDelayMs { get; set; }

    /// <summary>
    /// Document palette. Index 0 is always <see cref="RgbaColor.Transparent"/>.
    /// All layers reference colors by index into this list.
    /// </summary>
    public List<RgbaColor> Palette { get; }

    public List<MinintLayer> Layers { get; }

    public MinintDocument(string name)
    {
        Name = name;
        FrameDelayMs = 100;
        Palette = [RgbaColor.Transparent];
        Layers = [];
    }

    /// <summary>
    /// Constructor for deserialization — accepts pre-built palette and layers.
    /// </summary>
    public MinintDocument(string name, uint frameDelayMs, List<RgbaColor> palette, List<MinintLayer> layers)
    {
        Name = name;
        FrameDelayMs = frameDelayMs;
        Palette = palette;
        Layers = layers;
    }

    /// <summary>
    /// Returns the number of bytes needed to store a single palette index on disk.
    /// </summary>
    public int IndexByteWidth => Palette.Count switch
    {
        <= 255 => 1,
        <= 65_535 => 2,
        <= 16_777_215 => 3,
        _ => 4
    };
}