using AngleSharp.Css; using AngleSharp.Extensions; using System; using System.Collections; using System.Collections.Generic; namespace AngleSharp.Dom.Css { internal sealed class CssMedium : IEnumerable<MediaFeature>, IEnumerable { private static readonly string[] Types = new string[4] { Keywords.Screen, Keywords.Speech, Keywords.Print, Keywords.All }; private readonly List<MediaFeature> _features; public string Type { get; set; } public bool IsExclusive { get; set; } public bool IsInverse { get; set; } public string Constraints { get { string[] array = new string[_features.Count]; for (int i = 0; i < _features.Count; i++) { array[i] = _features[i].CssText; } return string.Join(" and ", array); } } public string CssText { get { string constraints = Constraints; string str = IsExclusive ? "only " : (IsInverse ? "not " : string.Empty); if (string.IsNullOrEmpty(constraints)) return str + (Type ?? string.Empty); if (string.IsNullOrEmpty(Type)) return str + constraints; return str + Type + " and " + constraints; } } internal CssMedium() { _features = new List<MediaFeature>(); } public bool Validate(RenderDevice device) { if (!string.IsNullOrEmpty(Type) && Types.Contains(Type, StringComparison.Ordinal) == IsInverse) return false; if (IsInvalid(device, Keywords.Screen, RenderDevice.Kind.Screen) || IsInvalid(device, Keywords.Speech, RenderDevice.Kind.Speech) || IsInvalid(device, Keywords.Print, RenderDevice.Kind.Printer)) return false; foreach (MediaFeature feature in _features) { if (feature.Validate(device) == IsInverse) return false; } return true; } public IEnumerator<MediaFeature> GetEnumerator() { return _features.GetEnumerator(); } IEnumerator IEnumerable.GetEnumerator() { return GetEnumerator(); } internal bool AddConstraint(string name, ICssValue value = null) { MediaFeature mediaFeature = Factory.MediaFeatures.Create(name); if (mediaFeature == null || !mediaFeature.TrySetValue(value)) return false; _features.Add(mediaFeature); return true; } private bool IsInvalid(RenderDevice device, string keyword, RenderDevice.Kind kind) { if (Type == keyword) return device.DeviceType == kind == IsInverse; return false; } } }