// Copyright (c) 2004, 2020 Oracle and/or its affiliates.
//
// This program is free software; you can redistribute it and/or modify
// it under the terms of the GNU General Public License, version 2.0, as
// published by the Free Software Foundation.
//
// This program is also distributed with certain software (including
// but not limited to OpenSSL) that is licensed under separate terms,
// as designated in a particular file or component or in included license
// documentation.  The authors of MySQL hereby grant you an
// additional permission to link the program and your derivative works
// with the separately licensed software that they have included with
// MySQL.
//
// Without limiting anything contained in the foregoing, this file,
// which is part of MySQL Connector/NET, is also subject to the
// Universal FOSS Exception, version 1.0, a copy of which can be found at
// http://oss.oracle.com/licenses/universal-foss-exception.
//
// This program is distributed in the hope that it will be useful, but
// WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
// See the GNU General Public License, version 2.0, for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program; if not, write to the Free Software Foundation, Inc.,
// 51 Franklin St, Fifth Floor, Boston, MA 02110-1301  USA

using System;
using System.Collections.Generic;
using System.Globalization;
using System.Text;
using Sog.Properties;

namespace MySql.Data.MySqlClient
{
    internal class ProcedureCacheEntry
    {
        public MySqlSchemaCollection procedure;
        public MySqlSchemaCollection parameters;
    }

    internal class ProcedureCache
    {
        private readonly Dictionary<int, ProcedureCacheEntry> _procHash;
        private readonly Queue<int> _hashQueue;
        private readonly int _maxSize;

        public ProcedureCache(int size)
        {
            this._maxSize = size;
            this._hashQueue = new Queue<int>(this._maxSize);
            this._procHash = new Dictionary<int, ProcedureCacheEntry>(this._maxSize);
        }

        public ProcedureCacheEntry GetProcedure(MySqlConnection conn, string spName, string cacheKey)
        {
            ProcedureCacheEntry proc = null;

            if (cacheKey != null)
            {
                int hash = cacheKey.GetHashCode();

                lock (this._procHash)
                {
                    this._procHash.TryGetValue(hash, out proc);
                }
            }

            if (proc == null)
            {
                proc = this.AddNew(conn, spName);
                conn.PerfMonitor.AddHardProcedureQuery();
                if (conn.Settings.Logging)
                {
                    MySqlTrace.LogInformation(
                        conn.ServerThread,
            String.Format(Resources.HardProcQuery, spName));
                }
            }
            else
            {
                conn.PerfMonitor.AddSoftProcedureQuery();
                if (conn.Settings.Logging)
                {
                    MySqlTrace.LogInformation(
                        conn.ServerThread,
            String.Format(Resources.SoftProcQuery, spName));
                }
            }

            return proc;
        }

        internal string GetCacheKey(string spName, ProcedureCacheEntry proc)
        {
            string retValue = String.Empty;
            StringBuilder key = new StringBuilder(spName);
            key.Append("(");
            string delimiter = "";
            if (proc.parameters != null)
            {
                foreach (MySqlSchemaRow row in proc.parameters.Rows)
                {
                    if (row["ORDINAL_POSITION"].Equals(0))
                    {
                        retValue = "?=";
                    }
                    else
                    {
                        key.AppendFormat(CultureInfo.InvariantCulture, "{0}?", delimiter);
                        delimiter = ",";
                    }
                }
            }

            key.Append(")");
            return retValue + key.ToString();
        }

        private ProcedureCacheEntry AddNew(MySqlConnection connection, string spName)
        {
            ProcedureCacheEntry procData = GetProcData(connection, spName);

            if (this._maxSize <= 0)
            {
                return procData;
            }

            string cacheKey = this.GetCacheKey(spName, procData);
            int hash = cacheKey.GetHashCode();
            lock (this._procHash)
            {
                if (this._procHash.Keys.Count >= this._maxSize)
                {
                    this.TrimHash();
                }

                if (!this._procHash.ContainsKey(hash))
                {
                    this._procHash[hash] = procData;
                    this._hashQueue.Enqueue(hash);
                }
            }

            return procData;
        }

        private void TrimHash()
        {
            int oldestHash = this._hashQueue.Dequeue();
            this._procHash.Remove(oldestHash);
        }

        private static ProcedureCacheEntry GetProcData(MySqlConnection connection, string spName)
        {
            string schema = string.Empty;
            string name = spName;

            int dotIndex = spName.IndexOf("`.`");
            if (dotIndex != -1)
            {
                schema = spName.Substring(1, dotIndex - 1);
                name = spName.Substring(dotIndex + 3, spName.Length - dotIndex - 4);
            }

            string[] restrictions = new string[4];
            restrictions[1] = schema.Length > 0 ? schema : connection.CurrentDatabase();
            restrictions[2] = name;
            MySqlSchemaCollection proc = connection.GetSchemaCollection("procedures", restrictions);
            if (proc.Rows.Count > 1)
            {
                throw new MySqlException(Resources.ProcAndFuncSameName);
            }

            if (proc.Rows.Count == 0)
            {
                string msg = string.Format(Resources.InvalidProcName, name, schema) + " " +
                string.Format(Resources.ExecuteProcedureUnauthorized, connection.Settings.UserID, connection.Settings.Server);
                throw new MySqlException(msg);
            }

            ProcedureCacheEntry entry = new ProcedureCacheEntry();
            entry.procedure = proc;

            // we don't use GetSchema here because that would cause another
            // query of procedures and we don't need that since we already
            // know the procedure we care about.
            ISSchemaProvider isp = new ISSchemaProvider(connection);
            string[] rest = isp.CleanRestrictions(restrictions);
            MySqlSchemaCollection parameters = isp.GetProcedureParameters(rest, proc);
            entry.parameters = parameters;

            return entry;
        }
    }
}