using System;
using System.Collections.Generic;
using System.Linq;
using Umbraco.Core;
using Umbraco.Core.Exceptions;
using Umbraco.Core.Models;
using Umbraco.Core.Models.PublishedContent;
using Umbraco.Core.Services;
using Umbraco.Core.Strings;
using Umbraco.ModelsBuilder.Embedded.Building;

namespace Umbraco.ModelsBuilder.Embedded
{

    public sealed class UmbracoServices
    {
        private readonly IContentTypeService _contentTypeService;
        private readonly IMediaTypeService _mediaTypeService;
        private readonly IMemberTypeService _memberTypeService;
        private readonly IPublishedContentTypeFactory _publishedContentTypeFactory;
        private readonly IShortStringHelper _shortStringHelper;

        /// <summary>
        /// Initializes a new instance of the <see cref="UmbracoServices"/> class.
        /// </summary>
        public UmbracoServices(
            IContentTypeService contentTypeService,
            IMediaTypeService mediaTypeService,
            IMemberTypeService memberTypeService,
            IPublishedContentTypeFactory publishedContentTypeFactory,
            IShortStringHelper shortStringHelper)
        {
            _contentTypeService = contentTypeService;
            _mediaTypeService = mediaTypeService;
            _memberTypeService = memberTypeService;
            _publishedContentTypeFactory = publishedContentTypeFactory;
            _shortStringHelper = shortStringHelper;
        }

        #region Services

        public IList<TypeModel> GetAllTypes()
        {
            var types = new List<TypeModel>();

            // TODO: this will require 3 rather large SQL queries on startup in PureLive. I know that these will be cached after lookup but it will slow
            // down startup time ... BUT these queries are also used in NuCache on startup so we can't really avoid them. Maybe one day we can
            // load all of these in in one query and still have them cached per service, and/or somehow improve the perf of these since they are used on startup
            // in more than one place.
            types.AddRange(GetTypes(PublishedItemType.Content, _contentTypeService.GetAll().Cast<IContentTypeComposition>().ToArray()));
            types.AddRange(GetTypes(PublishedItemType.Media, _mediaTypeService.GetAll().Cast<IContentTypeComposition>().ToArray()));
            types.AddRange(GetTypes(PublishedItemType.Member, _memberTypeService.GetAll().Cast<IContentTypeComposition>().ToArray()));

            return EnsureDistinctAliases(types);
        }

        public IList<TypeModel> GetContentTypes()
        {
            var contentTypes = _contentTypeService.GetAll().Cast<IContentTypeComposition>().ToArray();
            return GetTypes(PublishedItemType.Content, contentTypes); // aliases have to be unique here
        }

        public IList<TypeModel> GetMediaTypes()
        {
            var contentTypes = _mediaTypeService.GetAll().Cast<IContentTypeComposition>().ToArray();
            return GetTypes(PublishedItemType.Media, contentTypes); // aliases have to be unique here
        }

        public IList<TypeModel> GetMemberTypes()
        {
            var memberTypes = _memberTypeService.GetAll().Cast<IContentTypeComposition>().ToArray();
            return GetTypes(PublishedItemType.Member, memberTypes); // aliases have to be unique here
        }

        public static string GetClrName(IShortStringHelper shortStringHelper, string name, string alias)
        {
            // ModelsBuilder's legacy - but not ideal
            return alias.ToCleanString(shortStringHelper, CleanStringType.ConvertCase | CleanStringType.PascalCase);
        }

        private IList<TypeModel> GetTypes(PublishedItemType itemType, IContentTypeComposition[] contentTypes)
        {
            var typeModels = new List<TypeModel>();
            var uniqueTypes = new HashSet<string>();

            // get the types and the properties
            foreach (var contentType in contentTypes)
            {
                var typeModel = new TypeModel
                {
                    Id = contentType.Id,
                    Alias = contentType.Alias,
                    ClrName = GetClrName(_shortStringHelper, contentType.Name, contentType.Alias),
                    ParentId = contentType.ParentId,

                    Name = contentType.Name,
                    Description = contentType.Description
                };

                // of course this should never happen, but when it happens, better detect it
                // else we end up with weird nullrefs everywhere
                if (uniqueTypes.Contains(typeModel.ClrName))
                    throw new PanicException($"Panic: duplicate type ClrName \"{typeModel.ClrName}\".");
                uniqueTypes.Add(typeModel.ClrName);

                var publishedContentType = _publishedContentTypeFactory.CreateContentType(contentType);
                switch (itemType)
                {
                    case PublishedItemType.Content:
                        typeModel.ItemType = publishedContentType.ItemType == PublishedItemType.Element
                            ? TypeModel.ItemTypes.Element
                            : TypeModel.ItemTypes.Content;
                        break;
                    case PublishedItemType.Media:
                        typeModel.ItemType = publishedContentType.ItemType == PublishedItemType.Element
                            ? TypeModel.ItemTypes.Element
                            : TypeModel.ItemTypes.Media;
                        break;
                    case PublishedItemType.Member:
                        typeModel.ItemType = publishedContentType.ItemType == PublishedItemType.Element
                            ? TypeModel.ItemTypes.Element
                            : TypeModel.ItemTypes.Member;
                        break;
                    default:
                        throw new InvalidOperationException(string.Format("Unsupported PublishedItemType \"{0}\".", itemType));
                }

                typeModels.Add(typeModel);

                foreach (var propertyType in contentType.PropertyTypes)
                {
                    var propertyModel = new PropertyModel
                    {
                        Alias = propertyType.Alias,
                        ClrName = GetClrName(_shortStringHelper, propertyType.Name, propertyType.Alias),

                        Name = propertyType.Name,
                        Description = propertyType.Description
                    };

                    var publishedPropertyType = publishedContentType.GetPropertyType(propertyType.Alias);
                    if (publishedPropertyType == null)
                        throw new PanicException($"Panic: could not get published property type {contentType.Alias}.{propertyType.Alias}.");

                    propertyModel.ModelClrType = publishedPropertyType.ModelClrType;

                    typeModel.Properties.Add(propertyModel);
                }
            }

            // wire the base types
            foreach (var typeModel in typeModels.Where(x => x.ParentId > 0))
            {
                typeModel.BaseType = typeModels.SingleOrDefault(x => x.Id == typeModel.ParentId);
                // Umbraco 7.4 introduces content types containers, so even though ParentId > 0, the parent might
                // not be a content type - here we assume that BaseType being null while ParentId > 0 means that
                // the parent is a container (and we don't check).
                typeModel.IsParent = typeModel.BaseType != null;
            }

            // discover mixins
            foreach (var contentType in contentTypes)
            {
                var typeModel = typeModels.SingleOrDefault(x => x.Id == contentType.Id);
                if (typeModel == null) throw new PanicException("Panic: no type model matching content type.");

                IEnumerable<IContentTypeComposition> compositionTypes;
                var contentTypeAsMedia = contentType as IMediaType;
                var contentTypeAsContent = contentType as IContentType;
                var contentTypeAsMember = contentType as IMemberType;
                if (contentTypeAsMedia != null) compositionTypes = contentTypeAsMedia.ContentTypeComposition;
                else if (contentTypeAsContent != null) compositionTypes = contentTypeAsContent.ContentTypeComposition;
                else if (contentTypeAsMember != null) compositionTypes = contentTypeAsMember.ContentTypeComposition;
                else throw new PanicException(string.Format("Panic: unsupported type \"{0}\".", contentType.GetType().FullName));

                foreach (var compositionType in compositionTypes)
                {
                    var compositionModel = typeModels.SingleOrDefault(x => x.Id == compositionType.Id);
                    if (compositionModel == null) throw new PanicException("Panic: composition type does not exist.");

                    if (compositionType.Id == contentType.ParentId) continue;

                    // add to mixins
                    typeModel.MixinTypes.Add(compositionModel);

                    // mark as mixin - as well as parents
                    compositionModel.IsMixin = true;
                    while ((compositionModel = compositionModel.BaseType) != null)
                        compositionModel.IsMixin = true;
                }
            }

            return typeModels;
        }

        internal static IList<TypeModel> EnsureDistinctAliases(IList<TypeModel> typeModels)
        {
            var groups = typeModels.GroupBy(x => x.Alias.ToLowerInvariant());
            foreach (var group in groups.Where(x => x.Count() > 1))
                throw new NotSupportedException($"Alias \"{group.Key}\" is used by types"
                    + $" {string.Join(", ", group.Select(x => x.ItemType + ":\"" + x.Alias + "\""))}. Aliases have to be unique."
                    + " One of the aliases must be modified in order to use the ModelsBuilder.");
            return typeModels;
        }

        #endregion
    }
}