using Entity;
using Microsoft.EntityFrameworkCore;
using Shared;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace Contextlib
{
    public class DbCommentManager : ICommentService<Commentary>
    {
        private WTFContext _context;

        public DbCommentManager(WTFContext context)
        {
            _context = context ?? throw new ArgumentNullException(nameof(context), "Database context cannot be null.");
        }

        /// <summary>
        /// Adds a new comment to the database.
        /// </summary>
        /// <param name="comment">The comment to add.</param>
        /// <returns>A task representing the asynchronous operation.</returns>
        /// <exception cref="ArgumentNullException">Thrown when the comment is null.</exception>
        public async Task AddComment(Commentary comment)
        {
            if (comment == null)
            {
                throw new ArgumentNullException(nameof(comment), "Comment cannot be null.");
            }

            await _context.comments.AddAsync(comment);
            await _context.SaveChangesAsync();
        }

        /// <summary>
        /// Deletes all comments associated with a specific quote ID from the database.
        /// </summary>
        /// <param name="quoteId">The ID of the quote whose comments need to be deleted.</param>
        /// <returns>A task representing the asynchronous operation.</returns>
        /// <exception cref="KeyNotFoundException">Thrown when no comments are found for the provided quote ID.</exception>
        public async Task DeleteCommentForQuote(int quoteId)
        {
            var comments = await _context.comments.Where(x => x.IdQuote == quoteId).ToListAsync();
            if (!comments.Any())
            {
                throw new KeyNotFoundException($"No comments found for the quote ID: {quoteId}.");
            }

            _context.comments.RemoveRange(comments);
            await _context.SaveChangesAsync();
        }

        /// <summary>
        /// Deletes all comments associated with a specific user ID from the database.
        /// </summary>
        /// <param name="userId">The ID of the user whose comments need to be deleted.</param>
        /// <returns>A task representing the asynchronous operation.</returns>
        /// <exception cref="KeyNotFoundException">Thrown when no comments are found for the provided user ID.</exception>
        public async Task DeleteCommentForUser(int userId)
        {
            var comments = await _context.comments.Where(x => x.IdUser == userId).ToListAsync();
            if (!comments.Any())
            {
                throw new KeyNotFoundException($"No comments found for the user ID: {userId}.");
            }

            _context.comments.RemoveRange(comments);
            await _context.SaveChangesAsync();
        }

        public async Task<PaginationResult<Commentary>> GetAllComment()
        {
            var comments = _context.comments.ToList();
            return new PaginationResult<Commentary>(comments.Count, 0, comments.Count, comments);
        }

        public async Task<Commentary> GetCommentById(int id)
        {
            var comment = await _context.comments.Where(x => x.Id == id).FirstOrDefaultAsync();
            if(comment == null)
            {
                throw new KeyNotFoundException($"No comments found with the given ID: {id}.");
            }
            return comment;
        }

        public async Task<PaginationResult<Commentary>> GetCommentByQuote(int quoteId, int index, int pageSize)
        {
            var comments = await _context.comments.Where(x => x.IdQuote == quoteId).ToListAsync();
            if (!comments.Any())
            {
                throw new KeyNotFoundException($"No comments found for the quote ID: {quoteId}.");
            }
            if ((index * pageSize + pageSize) > comments.Count)
            {
                if (pageSize > comments.Count)
                {
                    return new PaginationResult<Commentary>(comments.Count(), index, pageSize, comments);
                }
                else
                {
                    return new PaginationResult<Commentary>(pageSize, index, pageSize, comments.Skip(index * pageSize - (((index * pageSize) + pageSize) - comments.Count)).Take(pageSize).ToList());
                }

            }
            return new PaginationResult<Commentary>(comments.Count, index, pageSize, comments.Skip(index * pageSize).Take(pageSize).ToList());
        }

        public async Task<PaginationResult<Commentary>> GetCommentByUser(int userId, int index, int pageSize)
        {
            var comments = await _context.comments.Where(x => x.IdUser == userId).ToListAsync();
            if (!comments.Any())
            {
                throw new KeyNotFoundException($"No comments found for the user ID: {userId}.");
            }
            if ((index * pageSize + pageSize) > comments.Count)
            {
                if (pageSize > comments.Count)
                {
                    return new PaginationResult<Commentary>(comments.Count(), index, pageSize, comments);
                }
                else
                {
                    return new PaginationResult<Commentary>(pageSize, index, pageSize, comments.Skip(index * pageSize - (((index * pageSize) + pageSize) - comments.Count)).Take(pageSize).ToList());
                }

            }
            return new PaginationResult<Commentary>(comments.Count, index, pageSize, comments.Skip(index * pageSize).Take(pageSize).ToList());
        }

        public async Task<int> LastCommentId()
        {
            var last = _context.comments.OrderByDescending(x => x.Id).FirstOrDefault();
            if(last == null)
            {
                return 0;
            }
            return last.Id;
        }

        public async Task RemoveComment(int id)
        {
            var comment = await _context.comments.Where(x => x.Id == id).FirstOrDefaultAsync();
            if (comment == null)
            {
                throw new KeyNotFoundException($"No comments found with the given ID: {id}.");
            }
            _context.comments.Remove(comment);
            await _context.SaveChangesAsync();
        }

        public async Task UpdateComment(int id, Commentary comment)
        {
            throw new NotImplementedException();
        }
    }
}