// (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

namespace ASC.Data.Backup;

[Scope]
public class DbHelper : IDisposable
{
    private readonly DbProviderFactory _factory;
    private readonly DbConnection _connect;
    private readonly DbCommandBuilder _builder;
    private readonly DataTable _columns;
    private readonly bool _mysql;
    private readonly ILogger<DbHelper> _logger;
    private readonly TenantDbContext _tenantDbContext;
    private readonly CoreDbContext _coreDbContext;
    private readonly IDictionary<string, string> _whereExceptions
        = new Dictionary<string, string>();

    public DbHelper(
        ILogger<DbHelper> logger,
        ConnectionStringSettings connectionString,
        IDbContextFactory<TenantDbContext> tenantDbContext,
        IDbContextFactory<CoreDbContext> coreDbContext)
    {
        _logger = logger;
        _tenantDbContext = tenantDbContext.CreateDbContext();
        _coreDbContext = coreDbContext.CreateDbContext();
        var file = connectionString.ElementInformation.Source;

        if ("web.connections.config".Equals(Path.GetFileName(file), StringComparison.InvariantCultureIgnoreCase))
        {
            file = CrossPlatform.PathCombine(Path.GetDirectoryName(file), "Web.config");
        }

        var xconfig = XDocument.Load(file);
        var provider = xconfig.XPathSelectElement("/configuration/system.data/DbProviderFactories/add[@invariant='" + connectionString.ProviderName + "']");
        _factory = (DbProviderFactory)Activator.CreateInstance(Type.GetType(provider.Attribute("type").Value, true));
        _builder = _factory.CreateCommandBuilder();
        _connect = _factory.CreateConnection();
        _connect.ConnectionString = connectionString.ConnectionString;
        _connect.Open();

        _mysql = connectionString.ProviderName.Contains("mysql", StringComparison.OrdinalIgnoreCase);
        if (_mysql)
        {
            CreateCommand("set @@session.sql_mode = concat(@@session.sql_mode, ',NO_AUTO_VALUE_ON_ZERO')").ExecuteNonQuery();
        }

        _columns = _connect.GetSchema("Columns");

        _whereExceptions["calendar_calendar_item"] = " where calendar_id in (select id from calendar_calendars where tenant = {0}) ";
        _whereExceptions["calendar_calendar_user"] = " where calendar_id in (select id from calendar_calendars where tenant = {0}) ";
        _whereExceptions["calendar_event_item"] = " inner join calendar_events on calendar_event_item.event_id = calendar_events.id where calendar_events.tenant = {0} ";
        _whereExceptions["calendar_event_user"] = " inner join calendar_events on calendar_event_user.event_id = calendar_events.id where calendar_events.tenant = {0} ";
        _whereExceptions["crm_entity_contact"] = " inner join crm_contact on crm_entity_contact.contact_id = crm_contact.id where crm_contact.tenant_id = {0} ";
        _whereExceptions["crm_entity_tag"] = " inner join crm_tag on crm_entity_tag.tag_id = crm_tag.id where crm_tag.tenant_id = {0} ";
        _whereExceptions["files_folder_tree"] = " inner join files_folder on folder_id = id where tenant_id = {0} ";
        _whereExceptions["forum_answer_variant"] = " where answer_id in (select id from forum_answer where tenantid = {0})";
        _whereExceptions["forum_topic_tag"] = " where topic_id in (select id from forum_topic where tenantid = {0})";
        _whereExceptions["forum_variant"] = " where question_id in (select id from forum_question where tenantid = {0})";
        _whereExceptions["projects_project_participant"] = " inner join projects_projects on projects_project_participant.project_id = projects_projects.id where projects_projects.tenant_id = {0} ";
        _whereExceptions["projects_following_project_participant"] = " inner join projects_projects on projects_following_project_participant.project_id = projects_projects.id where projects_projects.tenant_id = {0} ";
        _whereExceptions["projects_project_tag"] = " inner join projects_projects on projects_project_tag.project_id = projects_projects.id where projects_projects.tenant_id = {0} ";
        _whereExceptions["tenants_tenants"] = " where id = {0}";
        _whereExceptions["core_acl"] = " where tenant = {0} or tenant = -1";
        _whereExceptions["core_subscription"] = " where tenant = {0} or tenant = -1";
        _whereExceptions["core_subscriptionmethod"] = " where tenant = {0} or tenant = -1";
    }

    public List<string> GetTables()
    {
        var allowTables = new List<string>
            {
                "blogs_",
                "bookmarking_",
                "calendar_",
                "core_",
                "crm_",
                "events_",
                "files_",
                "forum_",
                "photo_",
                "projects_",
                "tenants_",
                "webstudio_",
                "wiki_",
            };

        var disallowTables = new List<string>
            {
                "core_settings",
                "webstudio_uservisit",
                "webstudio_useractivity",
                "tenants_forbiden",
            };

        IEnumerable<string> tables;

        if (_mysql)
        {
            tables = ExecuteList(CreateCommand("show tables"));
        }
        else
        {
            tables = _connect
                .GetSchema("Tables")
                .Select(@"TABLE_TYPE <> 'SYSTEM_TABLE'")
                    .Select(row => (string)row["TABLE_NAME"]);
        }

        return tables
            .Where(t => allowTables.Any(a => t.StartsWith(a)) && !disallowTables.Any(d => t.StartsWith(d)))
            .ToList();
    }

    public DataTable GetTable(string table, int tenant)
    {
        try
        {
            var dataTable = new DataTable(table);
            var adapter = _factory.CreateDataAdapter();
            adapter.SelectCommand = CreateCommand("select " + Quote(table) + ".* from " + Quote(table) + GetWhere(table, tenant));

            _logger.Debug(adapter.SelectCommand.CommandText);

            adapter.Fill(dataTable);

            return dataTable;
        }
        catch (Exception error)
        {
            _logger.ErrorTableString(table, error);
            throw;
        }
    }


    public void SetTable(DataTable table)
    {
        using var tx = _connect.BeginTransaction();
        try
        {
            if ("tenants_tenants".Equals(table.TableName, StringComparison.InvariantCultureIgnoreCase))
            {
                // remove last tenant
                var tenant = _tenantDbContext.Tenants.LastOrDefault();
                if (tenant != null)
                {
                    _tenantDbContext.Tenants.Remove(tenant);
                    _tenantDbContext.SaveChanges();
                }
                /*  var tenantid = CreateCommand("select id from tenants_tenants order by id desc limit 1").ExecuteScalar();
                     CreateCommand("delete from tenants_tenants where id = " + tenantid).ExecuteNonQuery();*/
                if (table.Columns.Contains("mappeddomain"))
                {
                    foreach (var r in table.Rows.Cast<DataRow>())
                    {
                        r[table.Columns["mappeddomain"]] = null;
                        if (table.Columns.Contains("id"))
                        {
                            var tariff = _coreDbContext.Tariffs.FirstOrDefault(t => t.Tenant == tenant.Id);
                            tariff.Tenant = (int)r[table.Columns["id"]];
                            tariff.CreateOn = DateTime.Now;
                            //  CreateCommand("update tenants_tariff set tenant = " + r[table.Columns["id"]] + " where tenant = " + tenantid).ExecuteNonQuery();
                            _coreDbContext.Entry(tariff).State = EntityState.Modified;
                            _coreDbContext.SaveChanges();
                        }
                    }
                }
            }

            var sql = new StringBuilder("replace into " + Quote(table.TableName) + "(");

            var tableColumns = GetColumnsFrom(table.TableName)
                .Intersect(table.Columns.Cast<DataColumn>().Select(c => c.ColumnName), StringComparer.InvariantCultureIgnoreCase)
                .ToList();

            tableColumns.ForEach(column => sql.Append($"{Quote(column)}, "));
            sql.Replace(", ", ") values (", sql.Length - 2, 2);

            var insert = _connect.CreateCommand();
            tableColumns.ForEach(column =>
            {
                sql.Append($"@{column}, ");
                var p = insert.CreateParameter();
                p.ParameterName = "@" + column;
                insert.Parameters.Add(p);
            });
            sql.Replace(", ", ")", sql.Length - 2, 2);
            insert.CommandText = sql.ToString();

            foreach (var r in table.Rows.Cast<DataRow>())
            {
                foreach (var c in tableColumns)
                {
                    ((IDbDataParameter)insert.Parameters["@" + c]).Value = r[c];
                }

                insert.ExecuteNonQuery();
            }

            tx.Commit();
        }
        catch (Exception e)
        {
            _logger.ErrorTable(table, e);
        }
    }

    public void Dispose()
    {
        _builder.Dispose();
        _connect.Dispose();
    }

    public DbCommand CreateCommand(string sql)
    {
        var command = _connect.CreateCommand();
        command.CommandText = sql;

        return command;
    }

    public List<string> ExecuteList(DbCommand command)
    {
        var list = new List<string>();
        using (var result = command.ExecuteReader())
        {
            while (result.Read())
            {
                list.Add(result.GetString(0));
            }
        }

        return list;
    }

    private string Quote(string identifier)
    {
        return identifier;
    }

    private IEnumerable<string> GetColumnsFrom(string table)
    {
        if (_mysql)
        {
            return ExecuteList(CreateCommand("show columns from " + Quote(table)));
        }
        else
        {
            return _columns.Select($"TABLE_NAME = '{table}'")
                .Select(r => r["COLUMN_NAME"].ToString());
        }
    }

    private string GetWhere(string tableName, int tenant)
    {
        if (tenant == -1)
        {
            return string.Empty;
        }

        if (_whereExceptions.TryGetValue(tableName.ToLower(), out var exc))
        {
            return string.Format(exc, tenant);
        }
        var tenantColumn = GetColumnsFrom(tableName).FirstOrDefault(c => c.StartsWith("tenant", StringComparison.OrdinalIgnoreCase));

        return tenantColumn != null ?
            " where " + Quote(tenantColumn) + " = " + tenant :
            " where 1 = 0";
    }
}