ServerDatabase/Database/CommandHandler.cs

using Npgsql;
using ServerDatabase.Utils;

namespace ServerDatabase;

public class CommandHandler
{
    private IBetterTable _betterTable;
    
    internal CommandHandler(IBetterTable betterTable)
    {
        this._betterTable = betterTable;
    }

    private List<Parameter> Parameters = new();
    private List<Parameter> Values = new();

    private Order? Order = null;

    public CommandHandler WithFilter(Parameter p)
    {
        Parameters.Add(p);
        return this;
    }
    public CommandHandler WithValue(Parameter p)
    {
        Values.Add(p);
        return this;
    }
    
    public CommandHandler WithFilter<T>(TableColumn<T> column, T value, string sign = "=") where T : notnull
    {
        return WithFilter(column.CreateParameter(value, sign));
    }
    
    public CommandHandler WithValue<T>(TableColumn<T> column, T value) where T : notnull
    {
        return WithValue(column.CreateParameter(value));
    }

    public CommandHandler AscendBy<T>(TableColumn<T> column) where T : notnull
    {
        Order = column.GetAssendingOrder();
        return this;
    }
    
    public CommandHandler DescendBy<T>(TableColumn<T> column) where T : notnull
    {
        Order = column.GetDecendingOrder();
        return this;
    }
    
    
    public T Read<T>(TableColumn<T> column) where T : notnull
    {
        return _betterTable.DatabaseHandler.Read<T>($"SELECT {column.Name} FROM {_betterTable.Name} WHERE", Order, Parameters.ToArray());
    }

    public void Insert()
    {
        _betterTable.Insert(Values.ToArray());
    }
    
    public void Update()
    {
        if (string.IsNullOrEmpty(_betterTable.DatabaseHandler.DB) || string.IsNullOrEmpty(_betterTable.DatabaseHandler.IP) || string.IsNullOrEmpty(_betterTable.DatabaseHandler.Uname) || string.IsNullOrEmpty(_betterTable.DatabaseHandler.PW)) throw new Exception("Database connection not fully defined");
        using NpgsqlConnection con = new(_betterTable.DatabaseHandler.ConectionString);
        con.Open();
        using NpgsqlCommand cmd = new();
        cmd.Connection = con;
        string values = "";
        foreach (Parameter param in Values)
        {
            values += $"{param.PGParameter.ParameterName} {param.Sign} @{param.PGParameter.ParameterName}, ";
            cmd.Parameters.Add(param.PGParameter);
        }
        values = values.Remove(values.Length - 2, 2);
        
        string fils = "";
        foreach (Parameter param in Parameters)
        {
            fils += $"{param.PGParameter.ParameterName} {param.Sign} @{param.PGParameter.ParameterName} AND";
            cmd.Parameters.Add(param.PGParameter);
        }
        fils = fils.Remove(fils.Length - 4, 4);
        cmd.CommandText = $"UPDATE {_betterTable.Name} SET {values} WHERE {fils};";
        cmd.Prepare();
        cmd.ExecuteNonQuery();
        con.Close();
    }
}