using System;
using System.Collections.Generic;
using UAF;
using UAF.Interfaces.Logging;

namespace DataFileAnalyzer
{
    /// <summary>
    /// Manages the keys of the data file.
    /// Knows all the keys and all the files. Can create new keys.
    /// </summary>
    public class FileKeyManager
    {
        private ILog m_logger = new ConsoleLog();
        private Dictionary<string, DataFileKey> m_pathToKey = new Dictionary<string, DataFileKey>();
        private Dictionary<DataFileKey, string> m_keyToPath = new Dictionary<DataFileKey, string>();

        /// <summary>
        /// Constructor
        /// </summary>
        public FileKeyManager()
        {
        }

        /// <summary>
        /// Delete all the keys
        /// </summary>
        public void Clear()
        {
            m_pathToKey.Clear();
            m_keyToPath.Clear();
        }

        /// <summary>
        /// The logger. Cannot be set to a null value.
        /// </summary>
        public ILog Logger
        {
            get { return m_logger; }
            set { if (value != null) m_logger = value; }
        }

        /// <summary>
        /// Get the path of a file from its key
        /// </summary>
        public bool GetFilePath(DataFileKey _key, out string _path)
        {
            return m_keyToPath.TryGetValue(_key, out _path);
        }

        /// <summary>
        /// Get the key of a file from its path
        /// </summary>
        public bool GetFileKey(string _path, out DataFileKey _key)
        {
            return m_pathToKey.TryGetValue(_path, out _key);
        }

        /// <summary>
        /// Create a new key.
        /// </summary>
        public bool AddFile(string _path, out DataFileKey _newKey)
        {
            if (GetUnusedKey(_path, out _newKey))
            {
                m_pathToKey[_path] = _newKey;
                m_keyToPath[_newKey] = _path;
                return true;
            }
            return false;
        }

        /// <summary>
        /// Get a key that has not yet been created.
        /// <returns> false if this key already exists.
        /// </summary>
        public bool GetUnusedKey(string _newPath, out DataFileKey _newKey)
        {
            // Try with a hash code
            UInt64 hashCode = HashCode.GetUInt64HashCode(_newPath);
            DataFileKey newKey = new DataFileKey(hashCode);
            string path;
            if (m_keyToPath.TryGetValue(newKey, out path))
            {
                // This hash code already exists. Look for an unused key by iterating
                // from 0 to the maximum possible value
                newKey.KeyValue = 0;
                while (m_keyToPath.TryGetValue(newKey, out path) && newKey != DataFileKey.Invalid)
                {
                    ++newKey.KeyValue;
                }
            }
            _newKey = newKey;
            return newKey != DataFileKey.Invalid;
        }

        /// <summary>
        /// Register an existing key.
        /// <returns> false if this key already exists.
        /// </summary>
        public bool RegisterFile(DataFileKey _newKey, string _path)
        {
            string path;
            if (m_keyToPath.TryGetValue(_newKey, out path))
                return false;

            m_keyToPath.Add(_newKey, _path);
            m_pathToKey.Add(_path, _newKey);

            return true;
        }

        /// <summary>
        /// Remove a key.
        /// </summary>
        public void RemoveKey(DataFileKey _key)
        {
            string path;
            if (m_keyToPath.TryGetValue(_key, out path))
            {
                m_keyToPath.Remove(_key);
                m_pathToKey.Remove(path);
            }
        }
    }
}