/*
 *
 * (c) Copyright Ascensio System Limited 2010-2021
 * 
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * http://www.apache.org/licenses/LICENSE-2.0
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
*/


using System;
using System.Collections.Generic;
using System.Linq;
using System.Linq.Expressions;

using ASC.Common;
using ASC.Common.Caching;
using ASC.Core.Common.EF;
using ASC.Core.Common.EF.Context;
using ASC.Core.Tenants;
using ASC.Files.Core;
using ASC.Files.Core.EF;
using ASC.Web.Files.Core.Search;

namespace ASC.Files.ThumbnailBuilder
{
    [Scope]
    internal class FileDataProvider
    {
        private readonly ThumbnailSettings thumbnailSettings;
        private readonly ICache cache;
        private Lazy<Core.EF.FilesDbContext> LazyFilesDbContext { get; }
        private Core.EF.FilesDbContext filesDbContext { get => LazyFilesDbContext.Value; }
        private Lazy<TenantDbContext> LazyTenantDbContext { get; }
        private TenantDbContext TenantDbContext { get => LazyTenantDbContext.Value; }
        private Lazy<CoreDbContext> LazyCoreDbContext { get; }
        private CoreDbContext coreDbContext { get => LazyCoreDbContext.Value; }
        private readonly string cacheKey;

        public FileDataProvider(
            Common.Utils.ConfigurationExtension configurationExtension,
            ICache ascCache,
            DbContextManager<Core.EF.FilesDbContext> dbContextManager,
            DbContextManager<TenantDbContext> tenantdbContextManager,
            DbContextManager<CoreDbContext> coredbContextManager
            )
        {
            thumbnailSettings = ThumbnailSettings.GetInstance(configurationExtension);
            cache = ascCache;
            LazyFilesDbContext = new Lazy<Core.EF.FilesDbContext>(() => dbContextManager.Get(thumbnailSettings.ConnectionStringName));
            LazyTenantDbContext = new Lazy<TenantDbContext>(() => tenantdbContextManager.Get(thumbnailSettings.ConnectionStringName));
            LazyCoreDbContext = new Lazy<CoreDbContext>(() => coredbContextManager.Get(thumbnailSettings.ConnectionStringName));
            cacheKey = "PremiumTenants";
        }

        public int[] GetPremiumTenants()
        {
            var result = cache.Get<int[]>(cacheKey);

            if (result != null)
            {
                return result;
            }

            /*
            // v_premium_tenants view:
            select
                t.tenant,
                (now() < max(t.stamp)) AS premium

            from tenants_tariff t
            left join tenants_quota q ON (t.tariff = q.tenant)

            where
            (
                (
                    isnull(t.comment) or
                    (
                        (not((t.comment like '%non-profit%'))) and
                        (not((t.comment like '%test%'))) and
                        (not((t.comment like '%translate%'))) and
                        (not((t.comment like '%trial%')))
                    )
                ) and
                (not((q.features like '%free%'))) and
                (not((q.features like '%non-profit%'))) and
                (not((q.features like '%trial%')))
            )
            group by t.tenant
            */

            var search =
                coreDbContext.Tariffs
                .Join(coreDbContext.Quotas.DefaultIfEmpty(), a => a.Tariff, b => b.Tenant, (tariff, quota) => new { tariff, quota })
                .Where(r =>
                        (
                            r.tariff.Comment == null ||
                            (
                             !r.tariff.Comment.Contains("non-profit") &&
                             !r.tariff.Comment.Contains("test") &&
                             !r.tariff.Comment.Contains("translate") &&
                             !r.tariff.Comment.Contains("trial")
                            )
                        ) &&
                        (
                            !r.quota.Features.Contains("free") &&
                            !r.quota.Features.Contains("non-profit") &&
                            !r.quota.Features.Contains("trial")
                        )
                )
                .GroupBy(r => r.tariff.Tenant)
                .Select(r => new { tenant = r.Key, stamp = r.Max(b => b.tariff.Stamp) })
                .Where(r => r.stamp > DateTime.UtcNow);

            result = search.Select(r => r.tenant).ToArray();

            cache.Insert(cacheKey, result, DateTime.UtcNow.AddHours(1));

            return result;
        }

        private IEnumerable<FileData<int>> GetFileData(Expression<Func<DbFile, bool>> where)
        {
            var search = filesDbContext.Files
                .Where(r => r.CurrentVersion && r.Thumb == Thumbnail.Waiting && !r.Encrypted)
                .OrderByDescending(r => r.ModifiedOn)
                .Take(thumbnailSettings.SqlMaxResults);

            if (where != null)
            {
                search = search.Where(where);
            }

            return search
                .Join(TenantDbContext.Tenants, r => r.TenantId, r => r.Id, (f, t) => new FileTenant { DbFile = f, DbTenant = t })
                .Where(r => r.DbTenant.Status == TenantStatus.Active)
                .Select(r => new FileData<int>(r.DbFile.TenantId, r.DbFile.Id, ""))
                .ToList();
        }

        public IEnumerable<FileData<int>> GetFilesWithoutThumbnails()
        {
            IEnumerable<FileData<int>> result;

            var premiumTenants = GetPremiumTenants();

            if (premiumTenants.Any())
            {
                result = GetFileData(r => premiumTenants.Contains(r.TenantId));

                if (result.Any())
                {
                    return result;
                }
            }

            result = GetFileData(null);

            return result;
        }
    }
}