using System;
using System.Xml;
using System.Xml.Serialization;
using Umbraco.Core.Models.PublishedContent;
using Umbraco.Core.PropertyEditors;
using Umbraco.Core.Xml;

namespace Umbraco.Web.PublishedCache.XmlPublishedCache
{

    /// <summary>
    /// Represents an IDocumentProperty which is created based on an Xml structure.
    /// </summary>
    [Serializable]
    [XmlType(Namespace = "http://umbraco.org/webservices/")]
    internal class XmlPublishedProperty : PublishedPropertyBase
    {
        private readonly string _sourceValue; // the raw, xml node value

        // Xml cache not using XPath value... and as for the rest...
        // we're single threaded here, keep it simple
        private object _objectValue;
        private bool _objectValueComputed;
        private readonly bool _isPreviewing;
        private readonly IPublishedContent _content;

        /// <summary>
        /// Gets the raw value of the property.
        /// </summary>
        public override object GetSourceValue(string culture = null, string segment = null) => _sourceValue;

        // in the Xml cache, everything is a string, and to have a value
        // you want to have a non-null, non-empty string.
        public override bool HasValue(string culture = null, string segment = null) => _sourceValue.Trim().Length > 0;

        public override object GetValue(string culture = null, string segment = null)
        {
            // NOT caching the source (intermediate) value since we'll never need it
            // everything in Xml cache is per-request anyways
            // also, properties should not be shared between requests and therefore
            // are single threaded, so the following code should be safe & fast

            if (_objectValueComputed) return _objectValue;
            var inter = PropertyType.ConvertSourceToInter(_content, _sourceValue, _isPreviewing);
            // initial reference cache level always is .Content
            _objectValue = PropertyType.ConvertInterToObject(_content, PropertyCacheLevel.Element, inter, _isPreviewing);
            _objectValueComputed = true;
            return _objectValue;
        }

        public override object GetXPathValue(string culture = null, string segment = null) { throw new NotImplementedException(); }

        public XmlPublishedProperty(PublishedPropertyType propertyType, IPublishedContent content, bool isPreviewing, XmlNode propertyXmlData)
            : this(propertyType, content, isPreviewing)
        {
            if (propertyXmlData == null)
                throw new ArgumentNullException(nameof(propertyXmlData), "Property xml source is null");
            _sourceValue = XmlHelper.GetNodeValue(propertyXmlData);
        }

        public XmlPublishedProperty(PublishedPropertyType propertyType, IPublishedContent content, bool isPreviewing, string propertyData)
            : this(propertyType, content, isPreviewing)
        {
            if (propertyData == null)
                throw new ArgumentNullException(nameof(propertyData));
            _sourceValue = propertyData;
        }

        public XmlPublishedProperty(PublishedPropertyType propertyType, IPublishedContent content, bool isPreviewing)
            : base(propertyType, PropertyCacheLevel.Unknown) // cache level is ignored
        {
            _sourceValue = string.Empty;
            _content = content;
            _isPreviewing = isPreviewing;
        }
    }
}