using Grand.Business.Core.Interfaces.Cms;
using Grand.Domain.Blogs;
using Grand.Infrastructure;
using Grand.Infrastructure.Caching;
using Grand.Web.Events.Cache;
using Grand.Web.Features.Models.Blogs;
using Grand.Web.Models.Blogs;
using MediatR;

namespace Grand.Web.Features.Handlers.Blogs;

public class GetBlogPostYearHandler : IRequestHandler<GetBlogPostYear, IList<BlogPostYearModel>>
{
    private readonly IBlogService _blogService;
    private readonly ICacheBase _cacheBase;
    private readonly IWorkContext _workContext;

    public GetBlogPostYearHandler(IBlogService blogService, ICacheBase cacheBase,
        IWorkContext workContext)
    {
        _blogService = blogService;
        _cacheBase = cacheBase;
        _workContext = workContext;
    }

    public async Task<IList<BlogPostYearModel>> Handle(GetBlogPostYear request, CancellationToken cancellationToken)
    {
        var cacheKey = string.Format(CacheKeyConst.BLOG_MONTHS_MODEL_KEY, _workContext.WorkingLanguage.Id,
            _workContext.CurrentStore.Id);
        var cachedModel = await _cacheBase.GetAsync(cacheKey, async () =>
        {
            var model = new List<BlogPostYearModel>();

            var blogPosts = await _blogService.GetAllBlogPosts(_workContext.CurrentStore.Id);
            if (!blogPosts.Any()) return model;
            var months = new SortedDictionary<DateTime, int>();

            var blogPost = blogPosts[^1];
            var first = blogPost.StartDateUtc ?? blogPost.CreatedOnUtc;
            while (DateTime.SpecifyKind(first, DateTimeKind.Utc) <= DateTime.UtcNow.AddMonths(1))
            {
                var list = blogPosts.GetPostsByDate(new DateTime(first.Year, first.Month, 1),
                    new DateTime(first.Year, first.Month, 1).AddMonths(1).AddSeconds(-1));
                if (list.Any())
                {
                    var date = new DateTime(first.Year, first.Month, 1);
                    months.Add(date, list.Count);
                }

                first = first.AddMonths(1);
            }


            var current = 0;
            foreach (var (date, blogPostCount) in months)
            {
                if (current == 0)
                    current = date.Year;

                if (date.Year > current || !model.Any())
                {
                    var yearModel = new BlogPostYearModel {
                        Year = date.Year
                    };
                    model.Insert(0, yearModel);
                }

                model.First().Months.Insert(0, new BlogPostMonthModel {
                    Month = date.Month,
                    BlogPostCount = blogPostCount
                });

                current = date.Year;
            }

            return model;
        });
        return cachedModel;
    }
}