using System;
using System.Collections.Generic;
using System.Diagnostics;
using Umbraco.Core;
using Umbraco.Core.Models;
using Umbraco.Core.Models.PublishedContent;

namespace Umbraco.Web.Models
{
    /// <summary>
    /// Provide an abstract base class for <c>IPublishedContent</c> implementations.
	/// </summary>
	/// <remarks>This base class does which (a) consitently resolves and caches the Url, (b) provides an implementation
    /// for this[alias], and (c) provides basic content set management.</remarks>
    [DebuggerDisplay("Content Id: {Id}, Name: {Name}")]
    public abstract class PublishedContentBase : IPublishedContent
    {
        #region Content

        private string _url;

	    /// <summary>
		/// Gets the url of the content.
		/// </summary>
		/// <remarks>
		/// If this content is Content, the url that is returned is the one computed by the NiceUrlProvider, otherwise if 
		/// this content is Media, the url returned is the value found in the 'umbracoFile' property.
		/// </remarks>
		public virtual string Url
		{
	        get
	        {
	            // should be thread-safe although it won't prevent url from being resolved more than once
	            if (_url != null)
	                return _url;

	            switch (ItemType)
	            {
	                case PublishedItemType.Content:
	                    if (UmbracoContext.Current == null)
	                        throw new InvalidOperationException(
	                            "Cannot resolve a Url for a content item when UmbracoContext.Current is null.");
	                    if (UmbracoContext.Current.UrlProvider == null)
	                        throw new InvalidOperationException(
	                            "Cannot resolve a Url for a content item when UmbracoContext.Current.UrlProvider is null.");
	                    _url = UmbracoContext.Current.UrlProvider.GetUrl(Id);
	                    break;
	                case PublishedItemType.Media:
	                    var prop = GetProperty(Constants.Conventions.Media.File);
	                    if (prop == null || prop.Value == null)
	                    {
	                        _url = string.Empty;
	                        return _url;
	                    }

	                    var propType = ContentType.GetPropertyType(Constants.Conventions.Media.File);

	                    //This is a hack - since we now have 2 properties that support a URL: upload and cropper, we need to detect this since we always
	                    // want to return the normal URL and the cropper stores data as json
	                    switch (propType.PropertyEditorAlias)
	                    {
	                        case Constants.PropertyEditors.UploadFieldAlias:
	                            _url = prop.Value.ToString();
	                            break;
	                        case Constants.PropertyEditors.ImageCropperAlias:
	                            //get the url from the json format
	                            var val = prop.Value.ToString();
	                            var crops = val.SerializeToCropDataSet();
	                            _url = crops != null ? crops.Src : string.Empty;
	                            break;
	                    }
	                    break;
	                default:
	                    throw new NotSupportedException();
	            }

	            return _url;
	        }
		}

		public abstract PublishedItemType ItemType { get; }
		public abstract int Id { get; }
		public abstract int TemplateId { get; }
		public abstract int SortOrder { get; }
		public abstract string Name { get; }
		public abstract string UrlName { get; }
		public abstract string DocumentTypeAlias { get; }
		public abstract int DocumentTypeId { get; }
		public abstract string WriterName { get; }
		public abstract string CreatorName { get; }
		public abstract int WriterId { get; }
		public abstract int CreatorId { get; }
		public abstract string Path { get; }
		public abstract DateTime CreateDate { get; }
		public abstract DateTime UpdateDate { get; }
		public abstract Guid Version { get; }
		public abstract int Level { get; }

        public abstract bool IsDraft { get; }
        
        public int GetIndex()
        {
            var index = this.Siblings().FindIndex(x => x.Id == Id);
            if (index < 0)
                throw new IndexOutOfRangeException("Could not find content in the content set.");
            return index;
        }

        #endregion

        #region Tree

        /// <summary>
        /// Gets the parent of the content.
        /// </summary>
        public abstract IPublishedContent Parent { get; }

        /// <summary>
        /// Gets the children of the content.
        /// </summary>
        /// <remarks>Children are sorted by their sortOrder.</remarks>
        public abstract IEnumerable<IPublishedContent> Children { get; }

        #endregion

        #region ContentSet

        public virtual IEnumerable<IPublishedContent> ContentSet
        {
            // the default content set of a content is its siblings
            get { return this.Siblings(); }
        }

        #endregion

        #region ContentType

        public abstract PublishedContentType ContentType { get; }

        #endregion

        #region Properties

        /// <summary>
        /// Gets the properties of the content.
        /// </summary>
        public abstract ICollection<IPublishedProperty> Properties { get; }

        /// <summary>
        /// Gets the value of a property identified by its alias.
        /// </summary>
        /// <param name="alias">The property alias.</param>
        /// <returns>The value of the property identified by the alias.</returns>
        /// <remarks>
        /// <para>If <c>GetProperty(alias)</c> is <c>null</c> then returns <c>null</c> else return <c>GetProperty(alias).Value</c>.</para>
        /// <para>So if the property has no value, returns the default value for that property type.</para>
        /// <para>This one is defined here really because we cannot define index extension methods, but all it should do is:
        /// <code>var p = GetProperty(alias); return p == null ? null : p.Value;</code> and nothing else.</para>
        /// <para>The recursive syntax (eg "_title") is _not_ supported here.</para>
        /// <para>The alias is case-insensitive.</para>
        /// </remarks>
        public virtual object this[string alias]
		{
			get
			{
                // no cache here: GetProperty should be fast, and .Value cache should be managed by the property.              
                var property = GetProperty(alias);
			    return property == null ? null : property.Value;
			}
		}

        /// <summary>
        /// Gets a property identified by its alias.
        /// </summary>
        /// <param name="alias">The property alias.</param>
        /// <returns>The property identified by the alias.</returns>
        /// <remarks>
        /// <para>If no property with the specified alias exists, returns <c>null</c>.</para>
        /// <para>The returned property may have no value (ie <c>HasValue</c> is <c>false</c>).</para>
        /// <para>The alias is case-insensitive.</para>
        /// </remarks>
        public abstract IPublishedProperty GetProperty(string alias);

        /// <summary>
        /// Gets a property identified by its alias.
        /// </summary>
        /// <param name="alias">The property alias.</param>
        /// <param name="recurse">A value indicating whether to navigate the tree upwards until a property with a value is found.</param>
        /// <returns>The property identified by the alias.</returns>
        /// <remarks>
        /// <para>Navigate the tree upwards and look for a property with that alias and with a value (ie <c>HasValue</c> is <c>true</c>).
        /// If found, return the property. If no property with that alias is found, having a value or not, return <c>null</c>. Otherwise
        /// return the first property that was found with the alias but had no value (ie <c>HasValue</c> is <c>false</c>).</para>
        /// <para>The alias is case-insensitive.</para>
        /// </remarks>
        public virtual IPublishedProperty GetProperty(string alias, bool recurse)
        {
            var property = GetProperty(alias);
            if (recurse == false) return property;

            IPublishedContent content = this;
            var firstNonNullProperty = property;
            while (content != null && (property == null || property.HasValue == false))
            {
                content = content.Parent;
                property = content == null ? null : content.GetProperty(alias);
                if (firstNonNullProperty == null && property != null) firstNonNullProperty = property;
            }

            // if we find a content with the property with a value, return that property
            // if we find no content with the property, return null
            // if we find a content with the property without a value, return that property
            //   have to save that first property while we look further up, hence firstNonNullProperty

            return property != null && property.HasValue ? property : firstNonNullProperty;
        }

        #endregion
    }
}