using MySql.Data.MySqlClient;
using Mysql_example.Database.Schema;
using Mysql_example.Util;
using System;
using System.Collections.Generic;
using System.Data;
using System.Data.Common;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace Mysql_example.Database
{
    class DBConnectSpecific : DBConnectGeneral
    {
        public DBConnectSpecific(){ }

        public struct usersAndAddressesStruct
        {
            public Dictionary<UInt64, User> users { get; set; }
            public Dictionary<UInt64, Address> addresses { get; set; }
        }
        public usersAndAddressesStruct ReadUsersAndAddresses()
        {
            string querry = @$"
                SELECT users.*,
                addresses.id As `addr.id`,
                addresses.user_id AS `addr.user_id`,
                addresses.first_name As `addr.first_name`, 
                addresses.last_name AS `addr.last_name`, 
                addresses.street AS `addr.street`, 
                addresses.house_number AS `addr.house_number`, 
                addresses.city AS `addr.city`, 
                addresses.postal_code AS `addr.postal_code`, 
                addresses.country AS `addr.country`,
                addresses.last_updated AS `addr.last_updated` 
                FROM `users` LEFT JOIN `addresses` ON users.id = addresses.user_id;
            ";

            if (!this.OpenConnection()) throw new Exception("No Database Connection");

            usersAndAddressesStruct result = new usersAndAddressesStruct();
            Dictionary<UInt64, User> users = new Dictionary<UInt64, User>();
            Dictionary<UInt64, Address> addresses = new Dictionary<UInt64, Address>();

            MySqlCommand selectCmd = new MySqlCommand(querry, connection);
            MySqlDataReader dataReader = selectCmd.ExecuteReader();
            while (dataReader.Read())
            {
                UInt64 userId = dataReader.GetUInt64("id");
                if (users.ContainsKey(userId))
                {
                    User user = users[userId];
                    Address address = ReadAddress(dataReader);
                    user.Addresses[address.Id] = address;
                    addresses[address.Id] = address;

                    if (!dataReader.IsDBNull("billing_address_id") && dataReader.GetUInt64("billing_address_id") == address.Id) user.BillingAdress = address;
                    if (!dataReader.IsDBNull("shipping_address_id") && dataReader.GetUInt64("shipping_address_id") == address.Id) user.ShippingAddress = address;
                    continue;
                }

                User readedUser = ReadUser(dataReader);

                if (!dataReader.IsDBNull("addr.id"))
                {
                    Address address = ReadAddress(dataReader);
                    readedUser.Addresses[address.Id] = address;
                    addresses[address.Id] = address;

                    if (!dataReader.IsDBNull("billing_address_id") && dataReader.GetUInt64("billing_address_id") == address.Id) readedUser.BillingAdress = address;
                    if (!dataReader.IsDBNull("shipping_address_id") && dataReader.GetUInt64("shipping_address_id") == address.Id) readedUser.ShippingAddress = address;
                }
                users.Add(readedUser.Id, readedUser);
            }
            CloseConnection();
            result.users = users;
            result.addresses = addresses;
            return result;
        }
    
        private static User ReadUser(MySqlDataReader reader)
        {
            User user = new User();
            user.Id = reader.GetUInt64("id");
            user.Email = reader.GetString("email");
            user.FirstName = reader.GetString("first_name");
            user.LastName = reader.GetString("last_name");
            user.Birthday = reader.GetDateTime("birthday");
            user.LastUpdated = reader.GetDateTime("last_updated");
            user.Addresses = new Dictionary<UInt64, Address>();

            return user;
        }
        private static Address ReadAddress(MySqlDataReader reader)
        {
            Address address = new Address();
            address.Id = reader.GetUInt64("addr.id");
            address.UserID = reader.GetUInt64("addr.user_id");
            address.FirstName = reader.GetString("addr.first_name");
            address.LastName = reader.GetString("addr.last_name");
            address.Street = reader.GetString("addr.street");
            address.HouseNumber = reader.GetString("addr.house_number");
            address.City = reader.GetString("addr.city");
            address.PostalCode = reader.GetString("addr.postal_code");
            address.Region = reader.GetString("addr.country");
            address.LastUpdated = reader.GetDateTime("addr.last_updated");
            return address;
        }
        public void UpdateUser(ref User user, Dictionary<UInt64, User> oldUsers)
        {
            List<String> fields = new List<String>();
            List<Object> values = new List<Object>();
            if (!oldUsers.ContainsKey(user.Id))
            {
                fields.Add("email");
                values.Add(user.Email);
                fields.Add("first_name");
                values.Add(user.FirstName);
                fields.Add("last_name");
                values.Add(user.LastName);
                fields.Add("birthday");
                values.Add(Utility.dateTimeToDatabaseBirthday(user.Birthday));

                DateTime createTime = DateTime.Now;
                user.LastUpdated = createTime;
                fields.Add("last_updated");
                values.Add(Utility.dateTimeToDatabaseTimestamp(createTime));

                UInt64 newUserID = Insert("users", fields, values);

                user.Id = newUserID;
            }
            User olduser = oldUsers[user.Id];

            if (olduser.Email != user.Email)
            {
                fields.Add("email");
                values.Add(user.Email);
            }
            if (olduser.FirstName != user.FirstName)
            {
                fields.Add("first_name");
                values.Add(user.FirstName);
            }
            if (olduser.LastName != user.LastName)
            {
                fields.Add("last_name");
                values.Add(user.LastName);
            }
            if (olduser.Birthday != user.Birthday)
            {
                fields.Add("birthday");
                values.Add(Utility.dateTimeToDatabaseBirthday(user.Birthday));
            }
            if (olduser.BillingAdress != user.BillingAdress)
            {
                fields.Add("billing_address_id");
                values.Add(user.BillingAdress != null ? user.BillingAdress.Id : null);
            }
            if (olduser.ShippingAddress != user.ShippingAddress)
            {
                fields.Add("shipping_address_id");
                values.Add(user.ShippingAddress != null ? user.ShippingAddress.Id : null);
            }

            //If no Changes, Do no Databse Call
            if (fields.Count() == 0) return;

            //Add Last Updated Field
            DateTime updateTime = DateTime.Now;
            fields.Add("last_updated");
            values.Add(Utility.dateTimeToDatabaseTimestamp(updateTime));

            Update("users", fields, values, $"`id`={user.Id} and `last_updated`='{Utility.dateTimeToDatabaseTimestamp(user.LastUpdated)}'");
            return;
        }

        public void UpdateAddressesOnUser(ref User user, Dictionary<UInt64, User> oldUsers)
        {
            if (!oldUsers.ContainsKey(user.Id))
            {
                AddAddressesOfNewUser(user);
            }

            //Get Diffrences for each Adress and make a Database Call
            User olduser = oldUsers[user.Id];
            foreach (Address newAddress in user.Addresses.Values)
            {
                List<String> fields = new List<String>();
                List<Object> values = new List<Object>();

                if (!olduser.Addresses.ContainsKey(newAddress.Id))
                {
                    AddNewAddressOfUser(newAddress, user);
                    continue;
                }
                Address oldAdress = olduser.Addresses[newAddress.Id];

                if (oldAdress.FirstName != newAddress.FirstName)    fields.Add("first_name");   values.Add(newAddress.FirstName);
                if (oldAdress.LastName != newAddress.LastName)      fields.Add("last_name");    values.Add(newAddress.LastName);
                if (oldAdress.Street != newAddress.Street)          fields.Add("street");       values.Add(newAddress.Street);
                if (oldAdress.HouseNumber != newAddress.HouseNumber)fields.Add("house_number"); values.Add(newAddress.HouseNumber);
                if (oldAdress.City != newAddress.City)              fields.Add("city");         values.Add(newAddress.City);
                if (oldAdress.PostalCode != newAddress.PostalCode)  fields.Add("postal_code");  values.Add(newAddress.PostalCode);
                if (oldAdress.Region != newAddress.Region)          fields.Add("country");      values.Add(newAddress.Region);

                //If no Changes, Do no Databse Call
                if (fields.Count() == 0) continue;

                //Add Last Updated Field
                DateTime updateTime = DateTime.Now;
                fields.Add("last_updated");
                values.Add(Utility.dateTimeToDatabaseTimestamp(updateTime));

                Update("addresses", fields, values, $"`id`={newAddress.Id} and `last_updated`='{Utility.dateTimeToDatabaseTimestamp(newAddress.LastUpdated)}'");
            }
            foreach (Address deletedAddress in user.deletedAddreses)
            {
                Delete("addresses", $"`id`='{deletedAddress.Id}'");
            }
        }
        private UInt64 AddNewAddressOfUser(Address address, User user)
        {
            List<String> fields = new List<String>();
            List<Object> values = new List<Object>();

            fields.Add("user_id");
            values.Add(user.Id);
            fields.Add("first_name");
            values.Add(address.FirstName);
            fields.Add("last_name");
            values.Add(address.LastName);
            fields.Add("street");
            values.Add(address.Street);
            fields.Add("house_number");
            values.Add(address.HouseNumber);
            fields.Add("city");
            values.Add(address.City);
            fields.Add("postal_code");
            values.Add(address.PostalCode);
            fields.Add("country");
            values.Add(address.Region);

            DateTime createTime = DateTime.Now;
            fields.Add("last_updated");
            values.Add(Utility.dateTimeToDatabaseTimestamp(createTime));

            return Insert("addresses", fields, values);
        }
        private void AddAddressesOfNewUser(User user)
        {
            List<String> fields = new List<String>();
            List<Object> values = new List<Object>();
            foreach (Address address in user.Addresses.Values)
            {
                if (
                   address.FirstName == null ||
                   address.LastName == null ||
                   address.Street == null ||
                   address.City == null ||
                   address.PostalCode == null ||
                   address.Region == null
                ) continue;

                UInt64 addressId = AddNewAddressOfUser(address, user);
                if (user.BillingAdress == null && user.ShippingAddress == null) continue;

                fields = new List<String>();
                values = new List<Object>();

                if (user.BillingAdress != null)
                {
                    fields.Add("billing_address_id");
                    values.Add(addressId);
                }
                if (user.ShippingAddress != null)
                {
                    fields.Add("shipping_address_id");
                    values.Add(addressId);
                }

                //Add Last Updated Field
                DateTime updateTime = DateTime.Now;
                fields.Add("last_updated");
                values.Add(Utility.dateTimeToDatabaseTimestamp(updateTime));

                Update("users", fields, values, $"`id`={user.Id} and `last_updated`='{Utility.dateTimeToDatabaseTimestamp(user.LastUpdated)}'");
                continue;
            }
            return;
        }

        public void DeleteUser(User user)
        {
            foreach (Address address in user.Addresses.Values)
            {
                Delete("addresses", $"`id`='{address.Id}'");
            }
            Delete("users", $"`id`='{user.Id}'");
        }
    }
}