// (c) Copyright Ascensio System SIA 2010-2022
//
// This program is a free software product.
// You can redistribute it and/or modify it under the terms
// of the GNU Affero General Public License (AGPL) version 3 as published by the Free Software
// Foundation. In accordance with Section 7(a) of the GNU AGPL 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 details, see
// the GNU AGPL at: http://www.gnu.org/licenses/agpl-3.0.html
//
// You can contact Ascensio System SIA at Lubanas st. 125a-25, Riga, Latvia, EU, LV-1021.
//
// The  interactive user interfaces in modified source and object code versions of the Program must
// display Appropriate Legal Notices, as required under Section 5 of the GNU AGPL version 3.
//
// Pursuant to Section 7(b) of the License you must retain the original Product logo when
// distributing the program. Pursuant to Section 7(e) we decline to grant you any rights under
// trademark law for use of our trademarks.
//
// All the Product's GUI elements, including illustrations and icon sets, as well as technical writing
// content are licensed under the terms of the Creative Commons Attribution-ShareAlike 4.0
// International. See the License terms at http://creativecommons.org/licenses/by-sa/4.0/legalcode

using DbContext = Microsoft.EntityFrameworkCore.DbContext;

namespace ASC.Core.Common.EF;

public enum Provider
{
    PostgreSql,
    MySql
}

public class BaseDbContext : DbContext
{
    public ConnectionStringSettings ConnectionStringSettings { get; set; }
    internal string MigrateAssembly { get; set; }
    internal ILoggerFactory LoggerFactory { get; set; }
    public static readonly ServerVersion ServerVersion = ServerVersion.Parse("8.0.25");

    protected virtual Dictionary<Provider, Func<BaseDbContext>> ProviderContext => null;
    protected Provider _provider;

    public BaseDbContext() { }
    public BaseDbContext(DbContextOptions options) : base(options) { }

    public void Migrate()
    {
        if (ProviderContext != null)
        {
            var provider = GetProviderByConnectionString();

            using var sqlProvider = ProviderContext[provider]();
            sqlProvider.ConnectionStringSettings = ConnectionStringSettings;
            sqlProvider.LoggerFactory = LoggerFactory;
            sqlProvider.MigrateAssembly = MigrateAssembly;

            sqlProvider.Database.Migrate();
        }
        else
        {
            Database.Migrate();
        }
    }

    protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
    {
        optionsBuilder.UseLoggerFactory(LoggerFactory);
        optionsBuilder.EnableSensitiveDataLogging();
        _provider = GetProviderByConnectionString();
        switch (_provider)
        {
            case Provider.MySql:
                optionsBuilder.ReplaceService<IMigrationsSqlGenerator, CustomMySqlMigrationsSqlGenerator>();
                optionsBuilder.UseMySql(ConnectionStringSettings.ConnectionString, ServerVersion, providerOptions =>
                {
                    if (!string.IsNullOrEmpty(MigrateAssembly))
                    {
                        providerOptions.MigrationsAssembly(MigrateAssembly);
                    }

                    //Configuring Connection Resiliency: https://docs.microsoft.com/en-us/ef/core/miscellaneous/connection-resiliency 
                    providerOptions.EnableRetryOnFailure(maxRetryCount: 15, maxRetryDelay: TimeSpan.FromSeconds(30), errorNumbersToAdd: null);
                });
                break;
            case Provider.PostgreSql:
                optionsBuilder.UseNpgsql(ConnectionStringSettings.ConnectionString);
                break;
        }
    }

    public Provider GetProviderByConnectionString()
    {
        switch (ConnectionStringSettings.ProviderName)
        {
            case "MySql.Data.MySqlClient":
                return Provider.MySql;
            case "Npgsql":
                return Provider.PostgreSql;
            default:
                break;
        }

        return Provider.MySql;
    }
}

public static class BaseDbContextExtension
{
    public static T AddOrUpdate<T, TContext>(this TContext b, Expression<Func<TContext, DbSet<T>>> expressionDbSet, T entity) where T : BaseEntity where TContext : BaseDbContext
    {
        var dbSet = expressionDbSet.Compile().Invoke(b);
        var existingBlog = dbSet.Find(entity.GetKeys());
        if (existingBlog == null)
        {
            return dbSet.Add(entity).Entity;
        }
        else
        {
            b.Entry(existingBlog).CurrentValues.SetValues(entity);

            return entity;
        }
    }

    public static async Task<T> AddOrUpdateAsync<T, TContext>(this TContext b, Expression<Func<TContext, DbSet<T>>> expressionDbSet, T entity) where T : BaseEntity where TContext : BaseDbContext
    {
        var dbSet = expressionDbSet.Compile().Invoke(b);
        var existingBlog = await dbSet.FindAsync(entity.GetKeys());
        if (existingBlog == null)
        {
            var entityEntry = await dbSet.AddAsync(entity);

            return entityEntry.Entity;
        }
        else
        {
            b.Entry(existingBlog).CurrentValues.SetValues(entity);

            return entity;
        }
    }
}

public abstract class BaseEntity
{
    public abstract object[] GetKeys();
}

public class MultiRegionalDbContext<T> : IDisposable, IAsyncDisposable where T : BaseDbContext, new()
{
    public MultiRegionalDbContext() { }

    internal List<T> Context { get; set; }

    public void Dispose()
    {
        if (Context == null)
        {
            return;
        }

        foreach (var c in Context)
        {
            if (c != null)
            {
                c.Dispose();
            }
        }
    }

    public ValueTask DisposeAsync()
    {
        return Context == null ? ValueTask.CompletedTask : InternalDisposeAsync();
    }

    private async ValueTask InternalDisposeAsync()
    {
        foreach (var c in Context)
        {
            if (c != null)
            {
                await c.DisposeAsync();
            }
        }
    }
}