using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading;
using System.Threading.Tasks;
using xCommons.Extensions;
using xExceptions.Constants;
using xModels.Dtos;
using xStringService.Interfaces;
using xStringService.Interfaces.Dtos;
using xStringService.Models.Dtos;

namespace xStringService.Providers
{
    public abstract class XBaseItemResourceProvider : IXItemResourceProvider
    {
        //
        #region Props ...
        /// <summary>
        /// Item Name for Resource Providing ... 
        /// </summary>
        private readonly string item;

        /// <summary>
        /// an Implementation of Item Resource Provider 
        /// </summary>
        /// <value></value>
        private readonly XBaseResourceProvider provider;

        /// <summary>
        /// String Provider Service ...
        /// </summary>
        private readonly IXStringServiceProvider stringProvider;
        #endregion

        //
        #region Constructor ...
        protected XBaseItemResourceProvider(
            string item,
            IXStringServiceProvider stringProvider
        )
        {
            //
            this.item = item;
            this.stringProvider = stringProvider;
            provider = new XBaseResourceProvider(
                item,
                stringProvider
            );
        }
        #endregion

        //
        #region Group Actions ...
        /// <summary>
        /// Retrieve a List of Exists Languages for Current Item ...
        /// </summary>
        /// <param name="cancellationToken"></param>
        /// <returns></returns>
        public virtual async Task<IEnumerable<string>> GetLanguages(
            CancellationToken cancellationToken = default
        )
        {
            //
            var result = (await ExtractItems(cancellationToken))
                .Select(x => x.Language)
                .Distinct();

            //
            return result;
        }

        /// <summary>
        /// Retrieve all Exists Items of type ...
        /// </summary>
        /// <param name="cancellationToken"></param>
        /// <returns></returns>
        public virtual async Task<IEnumerable<XStringDto>> GetResourceLocales(
            CancellationToken cancellationToken = default
        )
        {
            //
            var result = await ExtractItems(cancellationToken);

            //
            return result;
        }

        /// <summary>
        /// Remove all Exists Locales which Related to this Provider ...
        /// </summary>
        /// <param name="connectionId"></param>
        /// <param name="cancellationToken"></param>
        /// <returns></returns>
        public virtual async Task RemoveResourceLocales(
            string connectionId = null,
            CancellationToken cancellationToken = default
        )
        {
            //
            var isDelete = false;
            XStringDto deleted = null;
            var items = await ExtractItems(cancellationToken);
            foreach (var item in items)
            {
                //
                // Check Cancellation ...
                if (cancellationToken.IsCancellationRequested)
                {
                    break;
                }

                //
                // Remove Item ...
                deleted = await stringProvider.RemoveAsync(
                    id: item.Id,
                    softDelete: false,
                    saveChanges: true,
                    connectionId: connectionId,
                    cancellationToken: cancellationToken
                );

                //
                // Check Removation Succeed ...
                isDelete = !deleted.IsNullOrDefault();
                if (!isDelete)
                {
                    XException.ActionFailed.Throw();
                }
            }
        }
        #endregion

        //
        #region Item Actions ...
        /// <summary>
        /// Get all Exists Items for Specified identitifer ...
        /// </summary>
        /// <param name="identifier"></param>
        /// <param name="cancellationToken"></param>
        /// <returns></returns>
        public virtual async Task<IEnumerable<XStringDto>> GetResourceLocales(
            object identifier,
            CancellationToken cancellationToken = default
        )
        {
            //
            // Validate ...
            var isValid = !identifier.IsNull();
            if (!isValid)
            {
                XException.InvalidArgs.Throw();
            }

            //
            // Setting Resource Title ...
            SetResourceTitle(identifier);

            //
            // Retrieve Resource List ...
            var result = await provider
                .GetResourceLocales(cancellationToken);

            //
            return result;
        }

        /// <summary>
        /// Get all Exists Items for Specified identitifer ...
        /// </summary>
        /// <param name="identifier"></param>
        /// <param name="cancellationToken"></param>
        /// <returns></returns>
        public virtual async Task<IEnumerable<XLocaleResourceDto>> GetLocales(
            object identifier,
            CancellationToken cancellationToken = default
        )
        {
            //
            // Validate ...
            var isValid = !identifier.IsNull();
            if (!isValid)
            {
                XException.InvalidArgs.Throw();
            }

            //
            // Setting Resource Title ...
            SetResourceTitle(identifier);

            //
            // Retrieve Resource List ...
            var result = await provider
                .GetLocales(cancellationToken);

            //
            return result;
        }

        /// <summary>
        /// Get all Exists Locales Representaion based on Specified Identitifer
        /// as XResourceDto ...
        /// </summary>
        /// <param name="identifier"></param>
        /// <param name="cancellationToken"></param>
        /// <returns></returns>
        public virtual async Task<XResourceDto> GetResource(
            object identifier,
            CancellationToken cancellationToken = default
        )
        {
            //
            // Validate ...
            var isValid = !identifier.IsNull();
            if (!isValid)
            {
                XException.InvalidArgs.Throw();
            }

            //
            // Setting Resource Title ...
            SetResourceTitle(identifier);

            //
            // Retrieve Resource List ...
            var result = await provider
                .GetResource(cancellationToken);

            //
            return result;
        }

        /// <summary>
        /// Add Or Update Locale for Specified Identitifer ...
        /// </summary>
        /// <param name="identifier"></param>
        /// <param name="locale"></param>
        /// <param name="connectionId"></param>
        /// <param name="cancellationToken"></param>
        /// <returns></returns>
        public virtual async Task<XResourceDto> AddOrUpdateLocale(
            object identifier,
            XLocaleResourceDto locale,
            string connectionId = null,
            CancellationToken cancellationToken = default
        )
        {
            //
            // Validate ...
            var isValid =
                !identifier.IsNull() &&
                !locale.IsNullOrDefault() &&
                !locale.Value.IsNullOrEmpty() &&
                !locale.Language.IsNullOrEmpty();
            if (!isValid)
            {
                XException.InvalidArgs.Throw();
            }

            //
            // Setting Resource Title ...
            SetResourceTitle(identifier);

            //
            // Retrieve Resource List ...
            var result = await provider
                .AddOrUpdateLocale(
                    locale: locale,
                    connectionId: connectionId,
                    cancellationToken: cancellationToken
                );

            //
            return result;
        }

        /// <summary>
        /// Update a Resource State ...
        /// </summary>
        /// <param name="identifier"></param>
        /// <param name="resource"></param>
        /// <param name="connectionId"></param>
        /// <param name="cancellationToken"></param>
        /// <returns></returns>
        public virtual async Task<XResourceDto> AddOrUpdateResource(
            object identifier,
            XResourceDto resource,
            string connectionId = null,
            CancellationToken cancellationToken = default
        )
        {
            //
            // Validate ...
            var isValid =
                !identifier.IsNull();
            if (!isValid)
            {
                XException.InvalidArgs.Throw();
            }

            //
            // Retrieve Identified Resource Title ...
            var identifiedResource = GetResourceTitle(identifier);
            isValid =
                !resource.IsNullOrDefault() &&
                (resource.Resource.IsNullOrEmpty() ||
                    resource.Resource == identifiedResource);
            if (!isValid)
            {
                XException.InvalidArgs.Throw();
            }
            if (resource.Resource.IsNullOrEmpty())
            {
                resource.Resource = identifiedResource;
            }

            //
            // Setting Resource Title ...
            SetResourceTitle(identifier);

            //
            // Retrieve Resource List ...
            var result = await provider
                .AddOrUpdateResource(
                    resource: resource,
                    connectionId: connectionId,
                    cancellationToken: cancellationToken
                );

            //
            return result;
        }

        /// <summary>
        /// Remove Specified Language Locale of Specified Identifier ...
        /// </summary>
        /// <param name="identifier"></param>
        /// <param name="language"></param>
        /// <param name="connectionId"></param>
        /// <param name="cancellationToken"></param>
        /// <returns></returns>
        public virtual async Task<XResourceDto> RemoveLocale(
            object identifier,
            string language,
            string connectionId = null,
            CancellationToken cancellationToken = default
        )
        {
            //
            // Validate ...
            var isValid =
                !identifier.IsNull() &&
                !language.IsNullOrEmpty();
            if (!isValid)
            {
                XException.InvalidArgs.Throw();
            }

            // 
            // Check Locale Exists ...
            isValid = await HasLocale(
                language: language,
                identifier: identifier,
                cancellationToken: cancellationToken
            );
            if (!isValid)
            {
                XException.NotFound.Throw();
            }

            //
            var locale = (await GetLocales(
                identifier: identifier,
                cancellationToken: cancellationToken
            ))
            .FirstOrDefault(x =>
                x.Language.Equals(language, StringComparison.InvariantCultureIgnoreCase));
            isValid = !locale.IsNullOrDefault();
            if (!isValid)
            {
                XException.NotFound.Throw();
            }

            //
            // Setting Resource Title ...
            SetResourceTitle(identifier);

            //
            var result = await provider.RemoveLocale(
                locale: locale,
                connectionId: connectionId,
                cancellationToken: cancellationToken
            );

            //
            return result;
        }

        /// <summary>
        /// Remove all Exists Locales for Specified Identifier ...
        /// </summary>
        /// <param name="identifier"></param>
        /// <param name="connectionId"></param>
        /// <param name="cancellationToken"></param>
        /// <returns></returns>
        public virtual async Task RemoveLocales(
            object identifier,
            string connectionId = null,
            CancellationToken cancellationToken = default
        )
        {
            //
            // Validate ...
            var isValid =
                !identifier.IsNull();
            if (!isValid)
            {
                XException.InvalidArgs.Throw();
            }

            //
            var resource = await GetResource(
                identifier: identifier,
                cancellationToken: cancellationToken
            );
            isValid = !resource.IsNullOrDefault();
            if (!isValid)
            {
                XException.NotFound.Throw();
            }

            //
            // Setting Resource Title ...
            SetResourceTitle(identifier);

            //
            await provider.RemoveResource(
                resource: resource,
                connectionId: connectionId,
                cancellationToken: cancellationToken
            );
        }

        /// <summary>
        /// Check Specified ocale Exists for Specified Identifier ...
        /// </summary>
        /// <param name="identifier"></param>
        /// <param name="language"></param>
        /// <param name="cancellationToken"></param>
        /// <returns></returns>
        public virtual async Task<bool> HasLocale(
            object identifier,
            string language,
            CancellationToken cancellationToken = default
        )
        {
            //
            // Validate ...
            var isValid =
                !identifier.IsNull() &&
                !language.IsNullOrEmpty();
            if (!isValid)
            {
                XException.InvalidArgs.Throw();
            }

            //
            // Setting Resource Title ...
            SetResourceTitle(identifier);

            //
            var result = await provider.HasLocale(
                language: language,
                cancellationToken: cancellationToken
            );

            //
            return result;
        }

        /// <summary>
        /// Get all Exists Languages for Specified Identifier ...
        /// </summary>
        /// <param name="identifier"></param>
        /// <param name="cancellationToken"></param>
        /// <returns></returns>
        public virtual async Task<IEnumerable<string>> GetLanguages(
            object identifier,
            CancellationToken cancellationToken = default
        )
        {
            //
            // Validate ...
            var isValid = !identifier.IsNull();
            if (!isValid)
            {
                XException.InvalidArgs.Throw();
            }

            //
            // Setting Resource Title ...
            SetResourceTitle(identifier);

            //
            var result = await provider
                .GetLanguages(cancellationToken);

            //
            return result;
        }
        #endregion

        //
        #region Resource Title Action ...
        /// <summary>
        /// Retrieve Resource Title ...
        /// </summary>
        /// <param name="identifier"></param>
        /// <returns></returns>
        public string GetResourceTitle(object identifier = null)
        {
            //
            var result = item;

            //
            if (!identifier.IsNull())
            {
                result = $"{item}_{identifier}";
            }

            //
            return result;
        }
        #endregion

        //
        #region Private ...
        /// <summary>
        /// Set Resource Title ...
        /// </summary>
        /// <param name="identifier"></param>
        private void SetResourceTitle(object identifier = null)
        {
            //
            var itemIdentifier = GetResourceTitle(identifier);
            provider.SetField(
                field: "resource",
                value: $"{itemIdentifier}"
            );
        }

        /// <summary>
        /// xtract all Items which Belongs to Provider ...
        /// </summary>
        /// <param name="cancellationToken"></param>
        /// <returns></returns>
        private async Task<IEnumerable<XStringDto>> ExtractItems(
            CancellationToken cancellationToken = default
        )
        {
            //
            var result = await stringProvider
                .FindManyAsync(
                    includeBuilder: null,
                    cancellationToken: cancellationToken,
                    orderBuilder: x => x.OrderBy(y => y.Id),
                    predicate: x =>
                        x.ResourceTitle.StartsWith(
                            item,
                            StringComparison.InvariantCultureIgnoreCase)
                );
            return result;
        }
        #endregion
    }
}