using Cryville.Common;
using Cryville.Common.Pdt;
using Cryville.Crtr.Skin.Components;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Runtime.Serialization;
using UnityEngine;
using CAnchor = Cryville.Crtr.Anchor;

namespace Cryville.Crtr.Skin {
	public class SkinSelectors {
		readonly SkinSelector[] selectors;
		public readonly HashSet<string> annotations;

		public SkinSelectors(IEnumerable<SkinSelector> s, IEnumerable<string> a) {
			selectors = s.ToArray();
			annotations = a.ToHashSet();
		}
		public override string ToString() {
			if (selectors.Length == 0) return "";
			bool flag = false;
			string r = "";
			foreach (var a in annotations) {
				if (flag) r += " @" + a;
				else { r += "@" + a; flag = true; }
			}
			foreach (var s in selectors) {
				if (flag) r += " " + s.ToString();
				else { r += s.ToString(); flag = true; }
			}
			return r;
		}
		public void Optimize(PdtEvaluatorBase etor) {
			for (int i = 0; i < selectors.Length; i++) {
				selectors[i].Optimize(etor);
			}
		}
		public IEnumerable<SkinContext> MatchStatic(ISkinnableGroup g, SkinContext ctx) {
			IEnumerable<SkinContext> result = new SkinContext[] { ctx };
			foreach (var s in selectors) {
				result = result.SelectMany(l => s.MatchStatic(g, l));
			}
			return result;
		}
		public bool IsUpdatable(ISkinnableGroup g, int dl) {
			foreach (var s in selectors)
				if (!s.IsUpdatable(g, dl)) return false;
			return true;
		}
		public SkinContext MatchDynamic(ISkinnableGroup g, SkinContext ctx) {
			foreach (var s in selectors) {
				ctx = s.MatchDynamic(g, ctx);
				if (ctx == null) return null;
			}
			return ctx;
		}
	}

	public abstract class SkinSelector {
		protected SkinSelector() { }
		public abstract override string ToString();

		public virtual void Optimize(PdtEvaluatorBase etor) { }
		public virtual IEnumerable<SkinContext> MatchStatic(ISkinnableGroup g, SkinContext c) { throw new SelectorNotAvailableException(); }
		public virtual SkinContext MatchDynamic(ISkinnableGroup g, SkinContext c) { throw new SelectorNotAvailableException(); }
		public virtual bool IsUpdatable(ISkinnableGroup g, int dl) {
			return true;
		}
		public class CreateObject : SkinSelector {
			public CreateObject() { }
			public override string ToString() { return "$"; }

			public override IEnumerable<SkinContext> MatchStatic(ISkinnableGroup g, SkinContext c) {
				var obj = new GameObject("__obj__");
				obj.transform.SetParent(c.Transform, false);
				obj.AddComponent<TransformInterface>();
				return new SkinContext[] { new(obj.transform) };
			}
		}
		public class Anchor : SkinSelector {
			public int Name { get; private set; }
			public Anchor(string name) {
				Name = IdentifierManager.Shared.Request(name);
			}
			public override string ToString() { return string.Format(".{0}", IdentifierManager.Shared.Retrieve(Name)); }

			public override IEnumerable<SkinContext> MatchStatic(ISkinnableGroup g, SkinContext c) {
				if (g.TryGetAnchorsByName(Name, out IReadOnlyCollection<CAnchor> anchors)) {
					return anchors.Select(a => a.SkinContext);
				}
				else return Enumerable.Empty<SkinContext>();
			}
		}
		public class AtAnchor : SkinSelector {
			public int Name { get; private set; }
			public AtAnchor(string name) {
				Name = IdentifierManager.Shared.Request(name);
			}
			public override string ToString() { return string.Format("..{0}", IdentifierManager.Shared.Retrieve(Name)); }

			public override SkinContext MatchDynamic(ISkinnableGroup g, SkinContext c) {
				return g.OpenedAnchorName == Name ? c : null;
			}
			public override bool IsUpdatable(ISkinnableGroup g, int dl) {
				return dl >= g.AtAnchorDynamicLevel;
			}
		}
		public class Property : SkinSelector {
			readonly PdtExpression _exp;
			readonly PdtOperator _op;
			bool _flag;
			public Property(PdtExpression exp) {
				_exp = exp;
				_op = new PropOp.Boolean(v => _flag = v);
			}
			public override string ToString() { return string.Format("> {{{0}}}", _exp); }

			public override void Optimize(PdtEvaluatorBase etor) {
				etor.Optimize(_exp);
			}
			public override IEnumerable<SkinContext> MatchStatic(ISkinnableGroup g, SkinContext c) {
				var result = Match(c);
				if (result != null) return new SkinContext[] { result };
				else return Enumerable.Empty<SkinContext>();
			}
			public override SkinContext MatchDynamic(ISkinnableGroup g, SkinContext c) {
				return Match(c);
			}
			public SkinContext Match(SkinContext a) {
				PdtEvaluator.Instance.ContextTransform = a.Transform;
				try {
					if (!PdtEvaluator.Instance.Evaluate(_op, _exp))
						throw new EvaluationFailureException();
					return _flag ? a : null;
				}
				catch (Exception ex) {
					throw new SelectorNotAvailableException("The expression is not evaluatable under the current context", ex);
				}
				finally {
					PdtEvaluator.Instance.ContextTransform = null;
				}
			}
		}
		public class ElementType : SkinSelector {
			readonly string _type;
			public ElementType(string type) { _type = type; }
			public override string ToString() { return _type; }

			public override IEnumerable<SkinContext> MatchStatic(ISkinnableGroup g, SkinContext c) {
				return g.TypeName == _type ? new SkinContext[] { c } : Enumerable.Empty<SkinContext>();
			}
		}
	}
	public class SelectorNotAvailableException : Exception {
		public SelectorNotAvailableException() : base("The selector is not available under the current context") { }
		public SelectorNotAvailableException(string message) : base(message) { }
		public SelectorNotAvailableException(string message, Exception innerException) : base(message, innerException) { }
		protected SelectorNotAvailableException(SerializationInfo info, StreamingContext context) : base(info, context) { }
	}
}