/*
 *
 * (c) Copyright Ascensio System Limited 2010-2018
 *
 * This program is freeware. You can redistribute it and/or modify it under the terms of the GNU 
 * General Public License (GPL) version 3 as published by the Free Software Foundation (https://www.gnu.org/copyleft/gpl.html). 
 * In accordance with Section 7(a) of the GNU GPL its Section 15 shall be amended to the effect that 
 * Ascensio System SIA expressly excludes the warranty of non-infringement of any third-party rights.
 *
 * THIS PROGRAM IS DISTRIBUTED WITHOUT ANY WARRANTY; WITHOUT EVEN THE IMPLIED WARRANTY OF MERCHANTABILITY OR
 * FITNESS FOR A PARTICULAR PURPOSE. For more details, see GNU GPL at https://www.gnu.org/copyleft/gpl.html
 *
 * You can contact Ascensio System SIA by email at sales@onlyoffice.com
 *
 * The interactive user interfaces in modified source and object code versions of ONLYOFFICE must display 
 * Appropriate Legal Notices, as required under Section 5 of the GNU GPL version 3.
 *
 * Pursuant to Section 7 § 3(b) of the GNU GPL you must retain the original ONLYOFFICE logo which contains 
 * relevant author attributions when distributing the software. If the display of the logo in its graphic 
 * form is not reasonably feasible for technical reasons, you must include the words "Powered by ONLYOFFICE" 
 * in every copy of the program you distribute. 
 * Pursuant to Section 7 § 3(e) we decline to grant you any rights under trademark law for use of our trademarks.
 *
*/


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

using ASC.Common;
using ASC.Common.Caching;
using ASC.Core.Common.EF;
using ASC.Core.Data;
using ASC.Core.Tenants;

using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.Options;

namespace ASC.Core.Caching
{
    class QuotaServiceCache
    {
        internal const string KEY_QUOTA = "quota";
        internal const string KEY_QUOTA_ROWS = "quotarows";

        internal TrustInterval Interval { get; set; }
        internal ICache Cache { get; }
        internal ICacheNotify<QuotaCacheItem> CacheNotify { get; }

        internal bool QuotaCacheEnabled { get; }

        public QuotaServiceCache(IConfiguration Configuration, ICacheNotify<QuotaCacheItem> cacheNotify)
        {
            if (Configuration["core:enable-quota-cache"] == null)
            {
                QuotaCacheEnabled = true;
            }
            else
            {
                QuotaCacheEnabled = !bool.TryParse(Configuration["core:enable-quota-cache"], out var enabled) || enabled;
            }

            CacheNotify = cacheNotify;
            Cache = AscCache.Memory;
            Interval = new TrustInterval();

            cacheNotify.Subscribe((i) =>
            {
                if (i.Key == KEY_QUOTA_ROWS)
                {
                    Interval.Expire();
                }
                else if (i.Key == KEY_QUOTA)
                {
                    Cache.Remove(KEY_QUOTA);
                }
            }, CacheNotifyAction.Any);
        }
    }

    class ConfigureCachedQuotaService : IConfigureNamedOptions<CachedQuotaService>
    {
        public IOptionsSnapshot<DbQuotaService> Service { get; }
        public QuotaServiceCache QuotaServiceCache { get; }

        public ConfigureCachedQuotaService(
            IOptionsSnapshot<DbQuotaService> service,
            QuotaServiceCache quotaServiceCache)
        {
            Service = service;
            QuotaServiceCache = quotaServiceCache;
        }

        public void Configure(string name, CachedQuotaService options)
        {
            Configure(options);
            options.Service = Service.Get(name);
        }

        public void Configure(CachedQuotaService options)
        {
            options.Service = Service.Value;
            options.QuotaServiceCache = QuotaServiceCache;
            options.Cache = QuotaServiceCache.Cache;
            options.CacheNotify = QuotaServiceCache.CacheNotify;
        }
    }

    class CachedQuotaService : IQuotaService
    {
        internal IQuotaService Service { get; set; }
        internal ICache Cache { get; set; }
        internal ICacheNotify<QuotaCacheItem> CacheNotify { get; set; }
        internal TrustInterval Interval { get; set; }

        internal TimeSpan CacheExpiration { get; set; }
        internal QuotaServiceCache QuotaServiceCache { get; set; }

        public CachedQuotaService()
        {
            Interval = new TrustInterval();
            CacheExpiration = TimeSpan.FromMinutes(10);
        }

        public CachedQuotaService(DbQuotaService service, QuotaServiceCache quotaServiceCache) : this()
        {
            Service = service ?? throw new ArgumentNullException("service");
            QuotaServiceCache = quotaServiceCache;
            Cache = quotaServiceCache.Cache;
            CacheNotify = quotaServiceCache.CacheNotify;
        }

        public IEnumerable<TenantQuota> GetTenantQuotas()
        {
            var quotas = Cache.Get<IEnumerable<TenantQuota>>(QuotaServiceCache.KEY_QUOTA);
            if (quotas == null)
            {
                quotas = Service.GetTenantQuotas();
                if (QuotaServiceCache.QuotaCacheEnabled)
                {
                    Cache.Insert(QuotaServiceCache.KEY_QUOTA, quotas, DateTime.UtcNow.Add(CacheExpiration));
                }
            }
            return quotas;
        }

        public TenantQuota GetTenantQuota(int tenant)
        {
            return GetTenantQuotas().SingleOrDefault(q => q.Id == tenant);
        }

        public TenantQuota SaveTenantQuota(TenantQuota quota)
        {
            var q = Service.SaveTenantQuota(quota);
            CacheNotify.Publish(new QuotaCacheItem { Key = QuotaServiceCache.KEY_QUOTA }, CacheNotifyAction.Any);
            return q;
        }

        public void RemoveTenantQuota(int tenant)
        {
            throw new NotImplementedException();
        }


        public void SetTenantQuotaRow(TenantQuotaRow row, bool exchange)
        {
            Service.SetTenantQuotaRow(row, exchange);
            CacheNotify.Publish(new QuotaCacheItem { Key = QuotaServiceCache.KEY_QUOTA_ROWS }, CacheNotifyAction.Any);
        }

        public IEnumerable<TenantQuotaRow> FindTenantQuotaRows(TenantQuotaRowQuery query)
        {
            if (query == null) throw new ArgumentNullException("query");

            var rows = Cache.Get<Dictionary<string, List<TenantQuotaRow>>>(QuotaServiceCache.KEY_QUOTA_ROWS);
            if (rows == null || Interval.Expired)
            {
                var date = rows != null ? Interval.StartTime : DateTime.MinValue;
                Interval.Start(CacheExpiration);

                var changes = Service.FindTenantQuotaRows(new TenantQuotaRowQuery(Tenant.DEFAULT_TENANT).WithLastModified(date))
                    .GroupBy(r => r.Tenant.ToString())
                    .ToDictionary(g => g.Key, g => g.ToList());

                // merge changes from db to cache
                if (rows == null)
                {
                    rows = changes;
                }
                else
                {
                    lock (rows)
                    {
                        foreach (var p in changes)
                        {
                            if (rows.ContainsKey(p.Key))
                            {
                                var cachedRows = rows[p.Key];
                                foreach (var r in p.Value)
                                {
                                    cachedRows.RemoveAll(c => c.Path == r.Path);
                                    cachedRows.Add(r);
                                }
                            }
                            else
                            {
                                rows[p.Key] = p.Value;
                            }
                        }
                    }
                }

                if (QuotaServiceCache.QuotaCacheEnabled)
                {
                    Cache.Insert(QuotaServiceCache.KEY_QUOTA_ROWS, rows, DateTime.UtcNow.Add(CacheExpiration));
                }
            }

            var quotaRows = Cache.Get<Dictionary<string, List<TenantQuotaRow>>>(QuotaServiceCache.KEY_QUOTA_ROWS);
            if (quotaRows == null)
            {
                return Enumerable.Empty<TenantQuotaRow>();
            }

            lock (quotaRows)
            {
                var list = quotaRows.ContainsKey(query.Tenant.ToString()) ?
                    quotaRows[query.Tenant.ToString()] :
                    new List<TenantQuotaRow>();

                if (query != null && !string.IsNullOrEmpty(query.Path))
                {
                    return list.Where(r => query.Path == r.Path);
                }
                return list.ToList();
            }
        }
    }

    public static class QuotaConfigExtension
    {
        public static DIHelper AddQuotaService(this DIHelper services)
        {
            if (services.TryAddScoped<DbQuotaService>())
            {
                services.TryAddScoped<IQuotaService, CachedQuotaService>();

                services.TryAddScoped<IConfigureOptions<DbQuotaService>, ConfigureDbQuotaService>();
                services.TryAddScoped<IConfigureOptions<CachedQuotaService>, ConfigureCachedQuotaService>();

                services.AddCoreDbContextService();

                services.TryAddSingleton(typeof(ICacheNotify<>), typeof(KafkaCache<>));
                services.TryAddSingleton<QuotaServiceCache>();
            }

            return services;
        }
    }
}