using OpenMetaverse;
using OpenSim.Framework;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace OpenSim.Modules.Appearance2Avatar.helper
{
    public class NotecardCache
    {
        protected class Notecard
        {
            public string[] text;
            public DateTime lastRef;
        }

        private static Dictionary<UUID, Notecard> m_Notecards =
            new Dictionary<UUID, Notecard>();

        public static void Cache(UUID assetID, byte[] text)
        {
            CheckCache();

            lock (m_Notecards)
            {
                if (m_Notecards.ContainsKey(assetID))
                    return;

                Notecard nc = new Notecard();
                nc.lastRef = DateTime.Now;
                nc.text = SLUtil.ParseNotecardToArray(text);
                m_Notecards[assetID] = nc;
            }
        }

        public static bool IsCached(UUID assetID)
        {
            lock (m_Notecards)
            {
                return m_Notecards.ContainsKey(assetID);
            }
        }

        public static int GetLines(UUID assetID)
        {
            if (!IsCached(assetID))
                return -1;

            lock (m_Notecards)
            {
                m_Notecards[assetID].lastRef = DateTime.Now;
                return m_Notecards[assetID].text.Length;
            }
        }

        /// <summary>
        /// Get a notecard line.
        /// </summary>
        /// <param name="assetID"></param>
        /// <param name="lineNumber">Lines start at index 0</param>
        /// <returns></returns>
        public static string GetLine(UUID assetID, int lineNumber)
        {
            if (lineNumber < 0)
                return "";

            string data;

            if (!IsCached(assetID))
                return "";

            lock (m_Notecards)
            {
                m_Notecards[assetID].lastRef = DateTime.Now;

                if (lineNumber >= m_Notecards[assetID].text.Length)
                    return "\n\n\n";

                data = m_Notecards[assetID].text[lineNumber];

                return data;
            }
        }

        /// <summary>
        /// Get a notecard line.
        /// </summary>
        /// <param name="assetID"></param>
        /// <param name="lineNumber">Lines start at index 0</param>
        /// <param name="maxLength">
        /// Maximum length of the returned line.
        /// </param>
        /// <returns>
        /// If the line length is longer than <paramref name="maxLength"/>,
        /// the return string will be truncated.
        /// </returns>
        public static string GetLine(UUID assetID, int lineNumber, int maxLength)
        {
            string line = GetLine(assetID, lineNumber);

            if (line.Length > maxLength)
                line = line.Substring(0, maxLength);

            return line;
        }

        public static void CheckCache()
        {
            lock (m_Notecards)
            {
                foreach (UUID key in new List<UUID>(m_Notecards.Keys))
                {
                    Notecard nc = m_Notecards[key];
                    if (nc.lastRef.AddSeconds(30) < DateTime.Now)
                        m_Notecards.Remove(key);
                }
            }
        }

    }
}