using Ophelias.Models;
using System.Data.SQLite;

namespace Ophelias.Managers
{
    internal class Database : IDisposable
    {
        /*
         * This class provides some basic functions that
         * mirror SQLite. The reason for this class is to include
         * some functions on it that typically would be separate.
         * In another world, these functions could be of another
         * static class as they don't really serve a purpose other
         * than a one-time use if the database needs initialization.
         */
        internal SQLiteConnection con = new("DataSource=database.sqlite3;Version=3;");

        internal Database()
        {
            Connect();
        }
        internal void Connect()
        {
            con.Open();
        }
        internal void Close()
        {
            con.Close();
            con.Dispose();
        }
        internal void InitializeTables()
        {
            /*
             * This string is used to create the tables used by the models
             * and the database functions. For more details, see the formatting
             * string below as it has been organized in such a way there it is readable.
             */
            string tableCommands =
                @"CREATE TABLE IF NOT EXISTS [transactions] (
                  [ID] INTEGER NOT NULL PRIMARY KEY AUTOINCREMENT,
                  [Rate] INTEGER NOT NULL,
                  [Owed] INTEGER NOT NULL,
                  [Penalty] INTEGER NOT NULL,
                  [Multiplier] INTEGER NOT NULL,
                  [RefundAmount] INTEGER NOT NULL,
                  [AmountPaid] INTEGER NOT NULL,
                  [PayBy] TEXT NOT NULL,
                  [LastPaid] TEXT NULL,
                  [PaidOn] TEXT NULL);

                CREATE TABLE IF NOT EXISTS [reservations] (
                  [ID] INTEGER NOT NULL PRIMARY KEY AUTOINCREMENT,
                  [RoomNum] INTEGER NULL,
                  [GuestID] INTEGER NOT NULL,
                  [TransactionID] INTEGER NOT NULL UNIQUE,
                  [IsNoShow] BOOLEAN NOT NULL CHECK ([IsNoShow] IN (0,1)),
                  [Type] INTEGER NOT NULL CHECK ([Type] IN (0,1,2,3)),
                  [Status] INTEGER NOT NULL CHECK ([Status] IN (0,1,2,3)),
                  [CreationDate] TEXT NOT NULL,
                  [StartDate] TEXT NOT NULL,
                  [EndDate] TEXT NOT NULL,
                  [CheckIn] TEXT NULL,
                  [CheckOut] TEXT NULL,
                  [DateChanged] TEXT NULL,
                  FOREIGN KEY ([RoomNum]) REFERENCES rooms(ID),
                  FOREIGN KEY ([GuestID]) REFERENCES guests(ID),
                  FOREIGN KEY ([TransactionID]) REFERENCES transactions(ID));

                CREATE TABLE IF NOT EXISTS [guests] (
                  [ID] INTEGER NOT NULL PRIMARY KEY AUTOINCREMENT,
                  [Fname] TEXT NOT NULL,
                  [Lname] TEXT NOT NULL,
                  [Email] TEXT NOT NULL UNIQUE,
                  [CreditCard] TEXT NULL UNIQUE,
                  [Expiration] TEXT NULL,
                  [CCV] TEXT NULL);
  
                CREATE TABLE IF NOT EXISTS [rooms] (
                  [ID] INTEGER NOT NULL PRIMARY KEY AUTOINCREMENT,
                  [Occupied] BOOLEAN NOT NULL CHECK ([Occupied] IN (0,1)));

                CREATE TABLE IF NOT EXISTS [rates] (
                  [ID] INTEGER NOT NULL PRIMARY KEY AUTOINCREMENT,
                  [Rate] INTEGER NOT NULL,
                  [DateSet] TEXT NOT NULL UNIQUE,
                  [DefaultRate] INTEGER NULL UNIQUE CHECK ([DefaultRate] IN (1)));";

            using SQLiteCommand cmd = con.CreateCommand();
            cmd.CommandText = tableCommands;
            cmd.ExecuteNonQuery();
        }

        internal void InitializeRoomsTable()
        {
            /*
             * This is a one off initialization function to intialize
             * a list of 45 rooms. The design specification called
             * for a static 45 rooms that were not configurable hence
             * it being hardcoded here for now. Ideally this is moved
             * out to config file.
             */
            using SQLiteCommand cmd = con.CreateCommand();
            for (int i = 0; i < 45; i++)
            {
                cmd.CommandText = $"INSERT INTO ROOMS (Occupied) VALUES (0);";
                cmd.ExecuteNonQuery();
            }
        }
        public void Dispose() // Needed to support "using"
        {
            Close();
        }
    }

    internal static class QueryBuilder
    {
        /*
         * This class is for building update query strings. To prevent SQL injection
         * on dynamically built strings, the inputs are now used as null check values,
         * rather than as null check values that get set if they exist. Parameters are
         * now used in their place which prevent SQL injection.
         */
        internal static string? UpdateTransaction(int Id,
            double? Rate = null, double? Owed = null, double? Penalty = null,
            double? Multiplier = null, double? Refund = null,
            DateTime? PayBy = null, DateTime? LastPaid = null, DateTime? PaidOn = null, double? AmountPaid = null)
        {
            /*
             * Builds an update query string for the transaction model 
             */
            List<string> queryComponents = new();
            string query = "UPDATE transactions SET";

            if (Rate.HasValue)
            {
                queryComponents.Add($"Rate = @Rate");
            }

            if (Owed.HasValue)
            {
                queryComponents.Add($"Owed = @Owed");
            }

            if (Penalty.HasValue)
            {
                queryComponents.Add($"Penalty = @Penalty");
            }

            if (Multiplier.HasValue)
            {
                queryComponents.Add($"Multiplier = @Multiplier");
            }

            if (Refund.HasValue)
            {
                queryComponents.Add($"RefundAmount = @RefundAmount");
            }

            if (AmountPaid.HasValue)
            {
                queryComponents.Add($"AmountPaid = @AmountPaid");
            }

            if (PayBy.HasValue)
            {
                queryComponents.Add($"PayBy = @PayBy");
            }

            if (LastPaid.HasValue)
            {
                queryComponents.Add($"LastPaid = @LastPaid");
            }

            if (PaidOn.HasValue)
            {
                queryComponents.Add($"PaidOn = @PaidOn");
            }

            if (queryComponents.Count >= 0)
            {
                query += " " + string.Join(", ", queryComponents) + " " + $"WHERE ID = @ID;";
            }
            else
            {
                return null;
            }

            return query;
        }

        internal static string? UpdateReservation(int Id,
            int? RoomID = null, int? GuestID = null, int? TransactionID = null, bool? IsNoShow = null, ReservationType? Type = null,
            ReservationStatus? Status = null, DateTime? CreationDate = null, DateTime? StartDate = null, DateTime? EndDate = null,
            DateTime? CheckIn = null, DateTime? CheckOut = null, DateTime? DateChanged = null)
        {
            /*
             * Builds an update query string for the reservation model 
             */
            List<string> QueryParts = new();
            string query = "UPDATE reservations SET";

            if (RoomID.HasValue)
            {
                QueryParts.Add($"RoomID = @RID");
            }

            if (GuestID.HasValue)
            {
                QueryParts.Add($"GuestID = @GID");
            }

            if (TransactionID.HasValue)
            {
                QueryParts.Add($"TransactionID = @TID");
            }

            if (IsNoShow.HasValue)
            {
                QueryParts.Add($"IsNoShow = @IsNoShow");
            }

            if (Type.HasValue)
            {
                QueryParts.Add($"Type = @Type");
            }

            if (Status.HasValue)
            {
                QueryParts.Add($"Status = @Status");
            }

            if (CreationDate.HasValue)
            {
                QueryParts.Add($"CreationDate = @CreationDate");
            }

            if (StartDate.HasValue)
            {
                QueryParts.Add($"StartDate = @StartDate");
            }

            if (EndDate.HasValue)
            {
                QueryParts.Add($"EndDate = @EndDate");
            }

            if (CheckIn.HasValue)
            {
                QueryParts.Add($"CheckIn = @CheckIn");
            }

            if (CheckOut.HasValue)
            {
                QueryParts.Add($"CheckOut = @CheckOut");
            }

            if (DateChanged.HasValue)
            {
                QueryParts.Add($"DateChanged = @DateChanged");
            }

            if (QueryParts.Count >= 0)
            {
                query += " " + string.Join(", ", QueryParts) + " " + $"WHERE ID = @ID;";
            }
            else
            {
                return null;
            }

            return query;
        }

        internal static string? UpdateGuest(int Id, string? FirstName = null, string? LastName = null, string? Email = null, string? CreditCard = null, string? Expiration = null, string? CCV = null)
        {
            /*
             * Builds an update query string for the guest model 
             */
            List<string> QueryParts = new();
            string query = "UPDATE guests SET";

            if (!string.IsNullOrEmpty(FirstName))
            {
                QueryParts.Add($"Fname = @Fname");
            }

            if (!string.IsNullOrEmpty(LastName))
            {
                QueryParts.Add($"Lname = @Lname");
            }

            if (!string.IsNullOrEmpty(LastName))
            {
                QueryParts.Add($"Email = @Email");
            }

            if (!string.IsNullOrEmpty(CreditCard))
            {
                QueryParts.Add($"CreditCard = @CreditCard");
            }

            if (!string.IsNullOrEmpty(Expiration))
            {
                QueryParts.Add($"Expiration = @Expiry");
            }

            if (!string.IsNullOrEmpty(CCV))
            {
                QueryParts.Add($"CCV = @CCV");
            }

            if (QueryParts.Count >= 0)
            {
                query += " " + string.Join(", ", QueryParts) + " " + $"WHERE ID = @ID;";
            }
            else
            {
                return null;
            }

            return query;
        }
    }
}