using System;
using System.Collections.Generic;
using System.Linq;
using System.Reflection;
using System.Text;
using ChaosBot.Database;
using NLog;

namespace ChaosBot.Attribute
{
    public static class AssemblyController
    {
        private static Logger _logger = Program._logger;
        public static void Register()
        {
            Assembly dbEntityAssembly = Assembly.GetAssembly(typeof(DBEntity));
            if (dbEntityAssembly != null)
            {
                foreach (Type type in dbEntityAssembly.GetTypes())
                {
                    try
                    {
                        if (type.GetCustomAttributes(typeof(DBEntity), true).Length > 0)
                        {
                            // Get a reference to the attribute
                            DBEntity dbEntity = type.GetCustomAttributes(typeof(DBEntity)).Cast<DBEntity>().First();
                            
                            // Generate columns
                            // name, type, constraintName, constraints, 
                            List<Tuple<string, string, string, string>> columnList = new List<Tuple<string, string, string, string>>();
                                
                            // Get the table as an easy variable
                            string table = dbEntity.Table;

                            // Loop through all fields
                            foreach (PropertyInfo prop in type.GetProperties())
                            {
                                string columnName = prop.Name;
                                string columnType = DBEntity.DataTypes.GetValueOrDefault(prop.PropertyType).ToString();
                                StringBuilder constraintNameBuilder = new StringBuilder($"{table}_{columnName}");
                                List<string> constraintsList = new List<string>();

                                // Go through every attribute
                                foreach (object fieldAttribute in prop.GetCustomAttributes(true))
                                {
                                    if (fieldAttribute is DBFieldAttribute dBFieldAttribute)
                                    {
                                        string constraintSuffix =
                                            DBEntity.ConstrainNames.GetValueOrDefault(dBFieldAttribute.GetType(), null);
                                        if (constraintSuffix != null)
                                        {
                                            constraintNameBuilder.Append($"_{constraintSuffix}");
                                            constraintsList.Add($"{dBFieldAttribute.GetSQLiteQuery()}");
                                        }
                                    }
                                }

                                string constraintName = constraintNameBuilder.ToString();
                                if (constraintsList.Count > 0)
                                {
                                    constraintsList.Insert(0, "CONSTRAINT");
                                    constraintsList.Insert(1, constraintName);
                                }
                                string constraints = String.Join(" ", constraintsList);
                                columnList.Add(new Tuple<string, string, string, string>(columnName, columnType, constraintName, constraints));
                            }
                            
                            // Check table exists
                            bool tableExists =
                                Controller.RawQuery($"SELECT name FROM sqlite_master WHERE type='table' AND name='{table}'")
                                    .Rows.Count > 0;

                            if (!tableExists)
                            {
                                string columnDefs = String.Join(", ", columnList.Select(c => $"{c.Item1} {c.Item2} {c.Item4}"));
                                string query = $"CREATE TABLE {table} ({columnDefs})";
                                Controller.RawQuery(query, readOutput: false);
                            }
                            else
                            {
                                foreach (Tuple<string,string,string,string> column in columnList)
                                {
                                    try
                                    {
                                        string query =
                                            $"ALTER TABLE {table} ADD COLUMN {column.Item1} {column.Item2} {column.Item4}";
                                        Controller.RawQuery(query, readOutput: false, throwError: true);
                                    }
                                    catch
                                    {
                                        // ignored
                                    }
                                }
                            }
                        }
                    }
                    catch (Exception ex)
                    {
                        _logger.Error($"AssemblyController.Register: Exception [{ex}] thrown, <[{ex.Message}]>.");
                    }
                }
            }
        }
    }
}