using System;
using System.Collections.Generic;
using System.Linq;
using System.Linq.Expressions;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Http;
using Microsoft.AspNetCore.Mvc;
using MongoDB.Driver.Core.Connections;
using xCommons.Extensions;
using xExceptions.Constants;
using xFileService.Interfaces;
using xFileService.Models.Dtos;
using xFileService.Models.Entities;
using xIdentityModels.Models;
using xModels.Dtos;
using XFileDto = xFileService.Models.Dtos.XFileDto;

namespace xFileService.Providers
{
    public abstract class XBaseFileProvider<TKey> : IXBaseFileProvider<TKey>
    {
        //
        #region Props ...
        /// <summary>
        /// Specified Provider ...
        /// </summary>
        public string ProvidedFor { get; }

        /// <summary>
        /// Specified Provider Repositroy ...
        /// </summary>
        public IXFileProvider Provider { get; }
        #endregion

        //
        #region Constructor ...
        public XBaseFileProvider(
            string providedFor,
            IXFileProvider provider
        )
        {
            //
            Provider = provider;
            ProvidedFor = providedFor;
        }
        #endregion

        //
        #region Helper ...
        /// <summary>
        /// Get Specified Identifier ...
        /// </summary>
        /// <param name="forProvidedId"></param>
        /// <returns></returns>
        public string GetIdentifier(TKey forProvidedId)
        {
            //
            return Provider.GetIdentifier(
                providedFor: ProvidedFor,
                forProvidedId: forProvidedId
            );
        }
        #endregion

        //
        #region Tools ...
        /// <summary>
        /// Stream Specified File ...
        /// </summary>
        /// <param name="id"></param>
        /// <returns></returns>
        public async Task<FileStreamResult> Stream(Guid id)
        {
            //
            // Check Validation and Owning ...
            var isValid = await IsOwned(id);
            if (!isValid)
            {
                XException.NotAllowed.Throw();
            }

            //
            var result = await Provider.Stream(id);
            return result;
        }

        /// <summary>
        /// Stream Specified File ...
        /// </summary>
        /// <param name="fileName"></param>
        /// <returns></returns>
        public async Task<FileStreamResult> Stream(string fileName)
        {
            //
            // Validate ...
            var isValid = !fileName.IsNullOrEmpty();
            if (!isValid)
            {
                XException.InvalidArgs.Throw();
            }

            //
            // Retrieve Dto and also Checking Owned ...
            var dto = await GetDto(fileName);
            isValid = !dto.IsNullOrDefault();
            if (!isValid)
            {
                XException.NotAllowed.Throw();
            }

            //
            var result = await Provider.Stream(fileName);
            return result;
        }

        /// <summary>
        /// Download Specified File ...
        /// </summary>
        /// <param name="id"></param>
        /// <returns></returns>
        public async Task<PhysicalFileResult> Download(Guid id)
        {
            //
            // Validate ...
            var isValid = await IsOwned(id);
            if (!isValid)
            {
                XException.NotAllowed.Throw();
            }

            //
            var result = await Provider.Download(id);
            return result;
        }

        /// <summary>
        /// Download Specified File ...
        /// </summary>
        /// <param name="fileName"></param>
        /// <returns></returns>
        public async Task<PhysicalFileResult> Download(string fileName)
        {
            //
            // Validate ...
            var isValid = !fileName.IsNullOrEmpty();
            if (!isValid)
            {
                XException.InvalidArgs.Throw();
            }

            //
            // Retrieve Dto and also Checking Owned ...
            var dto = await GetDto(fileName);
            isValid = !dto.IsNullOrDefault();
            if (!isValid)
            {
                XException.NotAllowed.Throw();
            }

            //
            var result = await Provider.Download(fileName);
            return result;
        }

        /// <summary>
        /// Upload Files ...
        /// </summary>
        /// <param name="forProvidedId"></param>
        /// <param name="files"></param>
        /// <param name="userInfo"></param>
        /// <param name="connectionId"></param>
        /// <returns></returns>
        public async Task<IEnumerable<XFileDto>> Upload(
            TKey forProvidedId,
            IFormFileCollection files,
            XUserClaimsInfoDto userInfo = null,
            string connectionId = null
        )
        {
            //
            // Validate ...
            var isValid = !forProvidedId.IsNull();
            if (!isValid)
            {
                XException.InvalidArgs.Throw();
            }

            //
            // Here we are Following Custom Senario ...
            var dtos = await Provider.Upload(
                files: files,
                userInfo: userInfo,
                connectionId: connectionId
            );

            //
            // Validate Dtos ...
            isValid = !dtos.IsNull() && dtos.HasChild();
            if (isValid)
            {
                //
                foreach (var dto in dtos)
                {
                    //
                    await AddReference(
                        id: dto.Id,
                        userInfo: userInfo,
                        forProvidedId: forProvidedId
                    );
                }
            }

            //
            var result = new List<XFileDto>();

            //
            isValid = !dtos.IsNull() && dtos.HasChild();
            if (isValid)
            {
                //
                foreach (var dto in dtos)
                {
                    //
                    var idto = await Provider.Get(dto.Id);
                    isValid = !idto.IsNullOrDefault() &&
                        await IsOwned(idto.Id);
                    if (isValid)
                    {
                        result.Add(idto);
                    }
                }
            }

            //
            return result;
        }

        /// <summary>
        /// Remove Specified Files ...
        /// </summary>
        /// <param name="forProvidedId"></param>
        /// <param name="ids"></param>
        /// <param name="userInfo"></param>
        /// <param name="connectionId"></param>
        /// <returns></returns>
        public async Task<IEnumerable<Guid>> Remove(
            TKey forProvidedId,
            string ids = null,
            XUserClaimsInfoDto userInfo = null,
            string connectionId = null
        )
        {
            //
            // Validate ...
            var isValid = userInfo.IsNullOrDefault();
            if (!isValid)
            {
                XException.InvalidArgs.Throw();
            }

            //
            // if ids Provided, Find all id's Specified Dtos ...
            // if not, gell all models which Owned and has Reference to forProvidedId ...
            var dtos = await GetAll();
            if (!forProvidedId.IsNull())
            {
                //
                var identifier = GetIdentifier(forProvidedId);
                dtos = dtos
                    .Where(e => e.References.Any(er => er.ToNormalString() == identifier.ToNormalString()));
            }

            //
            // Filter Provided IDS ...
            if (!ids.IsNullOrEmpty())
            {
                //
                var idsList = ids.ParseListGuid();
                dtos = dtos.Where(d => !idsList.Contains(d.Id));
            }

            //
            var result = new List<Guid>();
            isValid = !dtos.IsNullOrDefault() && dtos.HasChild();
            if (isValid)
            {
                //
                foreach (var dto in dtos)
                {
                    //
                    var dtoIds = new List<string> { dto.Id.ToString() }.ToListString();
                    var removeIds = await Provider.Remove(dtoIds, userInfo, connectionId);
                    isValid = !removeIds.IsNull() && removeIds.HasChild() && removeIds.Contains(dto.Id);
                    if (isValid)
                    {
                        result.Add(dto.Id);
                    }
                }
            }

            //
            return result;
        }

        /// <summary>
        /// Retrieve Specified File Streaming Info ...
        /// </summary>
        /// <param name="id"></param>
        /// <returns></returns>
        public async Task<XFileStreamDescriptorDto> GetFileDescriptor(Guid id)
        {
            //
            // Validate ...
            var isValid = !id.IsNull() && !id.IsDefaultGuid();
            if (!isValid)
            {
                XException.InvalidArgs.Throw();
            }

            //
            // Check Owned ...
            isValid = await IsOwned(id);
            if (!isValid)
            {
                XException.NotAllowed.Throw();
            }

            //
            var result = await Provider.GetFileDescriptor(id);
            return result;
        }

        /// <summary>
        /// Retrieve Specified File Streaming Info ...
        /// </summary>
        /// <param name="fileName"></param>
        /// <returns></returns>
        public async Task<XFileStreamDescriptorDto> GetFileDescriptor(string fileName)
        {
            //
            // Validate ...
            var isValid = !fileName.IsNullOrEmpty();
            if (!isValid)
            {
                XException.InvalidArgs.Throw();
            }

            //
            // Check Owned ...
            var dto = GetDto(fileName);
            isValid = !dto.IsNullOrDefault();
            if (!isValid)
            {
                XException.NotAllowed.Throw();
            }

            //
            var result = await Provider.GetFileDescriptor(fileName);
            return result;
        }
        #endregion

        //
        #region Data Model ...
        /// <summary>
        /// Get Specified File Model ...
        /// </summary>
        /// <param name="id"></param>
        /// <returns></returns>
        public async Task<XFileDto> Get(
            Guid id
        )
        {
            //
            // Validate ...
            var isValid = !id.IsNull() && !id.IsDefaultGuid();
            if (!isValid)
            {
                XException.InvalidArgs.Throw();
            }

            //
            // Check Owned ...
            isValid = await IsOwned(id);
            if (!isValid)
            {
                XException.NotAllowed.Throw();
            }

            //
            var result = await Provider.Get(id);
            return result;
        }

        /// <summary>
        /// Get All Exists File Models ...
        /// </summary>
        /// <returns></returns>
        public async Task<IEnumerable<XFileDto>> GetAll()
        {
            //
            var result = await Provider
                .FindMany(e => e.References.ToNormalString().Contains(ProvidedFor.ToNormalString()));
            return result;
        }

        /// <summary>
        /// Get All Exists File Models ...
        /// </summary>
        /// <param name="forProvidedId"></param>
        /// <returns></returns>
        public async Task<IEnumerable<XFileDto>> GetAllFor(TKey forProvidedId)
        {
            //
            // Validate ...
            if (forProvidedId.IsNull())
            {
                XException.InvalidArgs.Throw();
            }

            //
            var identifier = GetIdentifier(forProvidedId);
            var result = await Provider
                .FindMany(e => e.References.ToNormalString().Contains(identifier.ToNormalString()));
            return result;
        }

        /// <summary>
        /// find an Entity by providing a Conditional Expression ...
        /// </summary>
        /// <param name="whereClause"></param>
        public async Task<XFileDto> FindOne(Expression<Func<XFile, bool>> whereClause)
        {
            //
            // Validate ...
            if (whereClause.IsNull())
            {
                XException.InvalidArgs.Throw();
            }

            //
            var whereFunc = whereClause.Compile();
            var result = await Provider
                .FindOne(e => whereFunc(e) && e.References.ToNormalString().Contains(ProvidedFor.ToNormalString()));
            return result;
        }

        /// <summary>
        /// find a collection of Entities by proving a Conditional Expression ...
        /// </summary>
        /// <param name="whereClause"></param>
        /// <returns></returns>
        public async Task<IEnumerable<XFileDto>> FindMany(
            Expression<Func<XFile, bool>> whereClause
        )
        {
            //
            // Validate ...
            if (whereClause.IsNull())
            {
                XException.InvalidArgs.Throw();
            }

            //
            var whereFunc = whereClause.Compile();
            var result = await Provider
                .FindMany(e => whereFunc(e) && e.References.ToNormalString().Contains(ProvidedFor.ToNormalString()));
            return result;
        }

        /// <summary>
        /// retrieve Entities based on XQuery Pagination structure ...
        /// </summary>
        /// <param name="query"></param>
        /// <returns></returns>
        public async Task<XQueryResult<XFileDto>> Query(
            XQuery query
        )
        {
            //
            // Define Owning Conditions ...
            Expression<Func<XFile, bool>> whereClause = e => e.References
                .ToNormalString()
                .Contains(ProvidedFor.ToNormalString());

            //
            var result = await Provider.ConditionalQuery(
                query: query,
                whereClause: whereClause
            );
            return result;
        }

        /// <summary>
        /// retrieve Entities based on XQuery Pagination structure by providing a Conditional Expression ...
        /// </summary>
        /// <param name="whereClause"></param>
        /// <param name="query"></param>
        /// <returns></returns>
        public async Task<XQueryResult<XFileDto>> ConditionalQuery(
            Expression<Func<XFile, bool>> whereClause,
            XQuery query
        )
        {
            //
            // Validate ...
            if (whereClause.IsNull())
            {
                XException.InvalidArgs.Throw();
            }

            //
            // Prepare a Combination Where Condition ...
            var whereFunc = whereClause.Compile();
            Expression<Func<XFile, bool>> condition = e => whereFunc(e) &&
                e.References.ToNormalString().Contains(ProvidedFor.ToNormalString());

            //
            var result = await Provider.ConditionalQuery(
                query: query,
                whereClause: condition
            );
            return result;
        }

        /// <summary>
        /// Update an Entity values ...
        /// </summary>
        /// <param name="id"></param>
        /// <param name="item"></param>
        /// <param name="userInfo"></param>
        /// <returns></returns>
        public async Task<XFileDto> Update(
            Guid id,
            XFileDto item,
            XUserClaimsInfoDto userInfo = null
        )
        {
            //
            // Validate ...
            var isValid =
                !id.IsNull() &&
                !id.IsDefaultGuid() &&
                !item.IsNullOrDefault() &&
                !userInfo.IsNullOrDefault();
            if (!isValid)
            {
                XException.InvalidArgs.Throw();
            }

            //
            // Validate Own ...
            isValid = await IsOwned(item.Id);
            if (!isValid)
            {
                XException.NotAllowed.Throw();
            }

            //
            var result = await Provider.Update(item.Id, item, userInfo);
            return result;
        }

        /// <summary>
        /// remove an Entity ...
        /// </summary>
        /// <param name="item"></param>
        /// <param name="userInfo"></param>
        /// <returns></returns>
        public async Task<XFileDto> Remove(
            Guid id,
            XUserClaimsInfoDto userInfo = null
        )
        {
            //
            // Validate ...
            var isValid = !id.IsNull() &&
                !id.IsDefaultGuid() &&
                !userInfo.IsNullOrDefault();
            if (!isValid)
            {
                XException.InvalidArgs.Throw();
            }

            //
            // Validate Owned ...
            isValid = await IsOwned(id);
            if (!isValid)
            {
                XException.NotAllowed.Throw();
            }

            //
            var result = await Provider.Remove(id, userInfo);
            return result;
        }

        /// <summary>
        /// count all exists Entities ...
        /// </summary>
        /// <returns></returns>
        public async Task<int> Count()
        {
            //
            var result = (await GetAll()).Count();
            return result;
        }

        /// <summary>
        /// Check an Entity exists or not ...
        /// </summary>
        /// <param name="id"></param>
        /// <returns></returns>
        public async Task<bool> IsExists(
            Guid id
        )
        {
            //
            var result = await IsOwned(id);
            return result;
        }
        #endregion

        //
        #region Private ...
        /// <summary>
        /// Check Specified Dto is Has Reference to Provider ...
        /// </summary>
        /// <param name="id"></param>
        /// <returns></returns>
        private async Task<bool> IsOwned(Guid id)
        {
            //
            // Validate ...
            var result = !id.IsNull() && !id.IsDefaultGuid();
            if (!result)
            {
                XException.InvalidArgs.Throw();
            }

            //
            // Check Exists ...
            result = await Provider.IsExists(id);
            if (!result)
            {
                XException.NotFound.Throw();
            }

            //
            // Retrieve Dto ...
            var dto = await Provider.Get(id);
            result = !dto.IsNullOrDefault();
            if (!result)
            {
                XException.ActionFailed.Throw();
            }

            //
            result = !dto.References.IsNull() &&
                dto.References.HasChild() &&
                dto.References.Any(r => r.ToNormalString().Contains(ProvidedFor.ToNormalString()));

            //
            return result;
        }

        /// <summary>
        /// Get Specified Owned Dto by File Name ...
        /// </summary>
        /// <param name="fileName"></param>
        /// <returns></returns>
        private async Task<XFileDto> GetDto(string fileName)
        {
            //
            XFileDto result = null;

            //
            if (!fileName.IsNullOrEmpty())
            {
                //
                try
                {
                    //
                    result = await Provider.FindOne(d =>
                        d.Name == fileName ||
                        d.Thumb == fileName ||
                        d.FileName == fileName ||
                        d.Path.Contains(fileName) ||
                        d.ThumbPath.Contains(fileName)
                    );
                    if (!result.IsNullOrDefault())
                    {
                        //
                        // Check Owning ...
                        var isOwned = await IsOwned(result.Id);
                        if (!isOwned)
                        {
                            result = null;
                        }
                    }
                }
                catch { }
            }

            //
            return result;
        }

        /// <summary>
        /// Get Specified Provided ID's Related Files ...
        /// </summary>
        /// <param name="forProvidedId"></param>
        /// <returns></returns>
        private async Task<IEnumerable<XFileDto>> GetDtos(TKey forProvidedId)
        {
            //
            var result = new List<XFileDto>();

            //
            var identifier = GetIdentifier(forProvidedId);
            if (!forProvidedId.IsNull())
            {
                //
                result = (await Provider
                    .FindMany(e => e.References.ToNormalString().Contains(identifier.ToNormalString())))
                    .ToList();
            }

            //
            return result;
        }

        /// <summary>
        /// Check Specified File has Refernce to Provider ...
        /// </summary>
        /// <param name="forProvidedId"></param>
        /// <param name="id"></param>
        /// <returns></returns>
        private async Task<bool> IsProvidedFor(
            TKey forProvidedId,
            Guid id
        )
        {
            //
            var result = await Provider.IsProvidedFor(
                id: id,
                providedFor: ProvidedFor,
                forProvidedId: forProvidedId
            );

            //
            return result;
        }

        /// <summary>
        /// Add Specified Reference to Specified File ...
        /// </summary>
        /// <param name="forProvidedId"></param>
        /// <param name="id"></param>
        /// <param name="userInfo"></param>
        /// <param name="connectionId"></param>
        /// <returns></returns>
        private async Task AddReference(
            TKey forProvidedId,
            Guid id,
            XUserClaimsInfoDto userInfo = null,
            string connectionId = null
        )
        {
            //
            await Provider.AddReference(
                id: id,
                userInfo: userInfo,
                providedFor: ProvidedFor,
                connectionId: connectionId,
                forProvidedId: forProvidedId
            );
        }

        /// <summary>
        /// Remove Specified Reference from Specified File ...
        /// </summary>
        /// <param name="forProvidedId"></param>
        /// <param name="id"></param>
        /// <param name="userInfo"></param>
        /// <returns></returns>
        private async Task RemoveReference(
            TKey forProvidedId,
            Guid id,
            XUserClaimsInfoDto userInfo = null,
            string connectionId = null
        )
        {
            //
            await Provider.RemoveReference(
                id: id,
                userInfo: userInfo,
                providedFor: ProvidedFor,
                connectionId: connectionId,
                forProvidedId: forProvidedId
            );
        }
        #endregion
    }
}