using System.Collections;
using System.Collections.Generic;
using System.IO;
using System;
using Convention.EasySave.Types;
using Convention.EasySave.Internal;
using System.Linq;

namespace Convention.EasySave
{

    /// <summary>Represents a cached file which can be saved to and loaded from, and commited to storage when necessary.</summary>
    public class EasySaveFile
    {
        [System.ComponentModel.EditorBrowsable(System.ComponentModel.EditorBrowsableState.Never)]
        public static Dictionary<string, EasySaveFile> cachedFiles = new Dictionary<string, EasySaveFile>();

        public EasySaveSettings settings;
        private Dictionary<string, EasySaveData> cache = new Dictionary<string, EasySaveData>();
        private bool syncWithFile = false;
        private DateTime timestamp = DateTime.UtcNow;

        /// <summary>Creates a new EasySaveFile and loads the default file into the EasySaveFile if there is data to load.</summary>
        public EasySaveFile() : this(new EasySaveSettings(), true) { }

        /// <summary>Creates a new EasySaveFile and loads the specified file into the EasySaveFile if there is data to load.</summary>
        /// <param name="filepath">The relative or absolute path of the file in storage our EasySaveFile is associated with.</param>
        public EasySaveFile(string filePath) : this(new EasySaveSettings(filePath), true) { }

        /// <summary>Creates a new EasySaveFile and loads the specified file into the EasySaveFile if there is data to load.</summary>
        /// <param name="filepath">The relative or absolute path of the file in storage our EasySaveFile is associated with.</param>
        /// <param name="settings">The settings we want to use to override the default settings.</param>
        public EasySaveFile(string filePath, EasySaveSettings settings) : this(new EasySaveSettings(filePath, settings), true) { }

        /// <summary>Creates a new EasySaveFile and loads the specified file into the EasySaveFile if there is data to load.</summary>
        /// <param name="settings">The settings we want to use to override the default settings.</param>
        public EasySaveFile(EasySaveSettings settings) : this(settings, true) { }

        /// <summary>Creates a new EasySaveFile and only loads the default file into it if syncWithFile is set to true.</summary>
        /// <param name="syncWithFile">Whether we should sync this EasySaveFile with the one in storage immediately after creating it.</param>
        public EasySaveFile(bool syncWithFile) : this(new EasySaveSettings(), syncWithFile) { }
        /// <summary>Creates a new EasySaveFile and only loads the specified file into it if syncWithFile is set to true.</summary>
        /// <param name="filepath">The relative or absolute path of the file in storage our EasySaveFile is associated with.</param>
        /// <param name="syncWithFile">Whether we should sync this EasySaveFile with the one in storage immediately after creating it.</param>
        public EasySaveFile(string filePath, bool syncWithFile) : this(new EasySaveSettings(filePath), syncWithFile) { }
        /// <summary>Creates a new EasySaveFile and only loads the specified file into it if syncWithFile is set to true.</summary>
        /// <param name="filepath">The relative or absolute path of the file in storage our EasySaveFile is associated with.</param>
        /// <param name="settings">The settings we want to use to override the default settings.</param>
        /// <param name="syncWithFile">Whether we should sync this EasySaveFile with the one in storage immediately after creating it.</param>
        public EasySaveFile(string filePath, EasySaveSettings settings, bool syncWithFile) : this(new EasySaveSettings(filePath, settings), syncWithFile) { }

        /// <summary>Creates a new EasySaveFile and loads the specified file into the EasySaveFile if there is data to load.</summary>
        /// <param name="settings">The settings we want to use to override the default settings.</param>
        /// <param name="syncWithFile">Whether we should sync this EasySaveFile with the one in storage immediately after creating it.</param>
        public EasySaveFile(EasySaveSettings settings, bool syncWithFile)
        {
            this.settings = settings;
            this.syncWithFile = syncWithFile;
            if (syncWithFile)
            {
                // Type checking must be enabled when syncing.
                var settingsWithTypeChecking = (EasySaveSettings)settings.Clone();
                settingsWithTypeChecking.typeChecking = true;

                using (var reader = EasySaveReader.Create(settingsWithTypeChecking))
                {
                    if (reader == null)
                        return;
                    foreach (KeyValuePair<string, EasySaveData> kvp in reader.RawEnumerator)
                        cache[kvp.Key] = kvp.Value;
                }

                timestamp = EasySave.GetTimestamp(settingsWithTypeChecking);
            }
        }

        /// <summary>Creates a new EasySaveFile and loads the bytes into the EasySaveFile. Note the bytes must represent that of a file.</summary>
        /// <param name="bytes">The bytes representing our file.</param>
        /// <param name="settings">The settings we want to use to override the default settings.</param>
        /// <param name="syncWithFile">Whether we should sync this EasySaveFile with the one in storage immediately after creating it.</param>
        public EasySaveFile(byte[] bytes, EasySaveSettings settings = null)
        {
            if (settings == null)
                this.settings = new EasySaveSettings();
            else
                this.settings = settings;

            syncWithFile = true; // This ensures that the file won't be merged, which would prevent deleted keys from being deleted.

            SaveRaw(bytes, settings);
        }

        /// <summary>Synchronises this EasySaveFile with a file in storage.</summary>
        public void Sync()
        {
            Sync(this.settings);
        }

        /// <summary>Synchronises this EasySaveFile with a file in storage.</summary>
        /// <param name="filepath">The relative or absolute path of the file in storage we want to synchronise with.</param>
        /// <param name="settings">The settings we want to use to override the default settings.</param>
        public void Sync(string filePath, EasySaveSettings settings = null)
        {
            Sync(new EasySaveSettings(filePath, settings));
        }

        /// <summary>Synchronises this EasySaveFile with a file in storage.</summary>
        /// <param name="settings">The settings we want to use to override the default settings.</param>
        public void Sync(EasySaveSettings settings = null)
        {
            if (settings == null)
                settings = new EasySaveSettings();

            if (cache.Count == 0)
            {
                EasySave.DeleteFile(settings);
                return;
            }

            using (var baseWriter = EasySaveWriter.Create(settings, true, !syncWithFile, false))
            {
                foreach (var kvp in cache)
                {
                    // If we change the name of a type, the type may be null.
                    // In this case, use System.Object as the type.
                    Type type;
                    if (kvp.Value.type == null)
                        type = typeof(System.Object);
                    else
                        type = kvp.Value.type.type;
                    baseWriter.Write(kvp.Key, type, kvp.Value.bytes);
                }
                baseWriter.Save(!syncWithFile);
            }
        }

        /// <summary>Removes the data stored in this EasySaveFile. The EasySaveFile will be empty after calling this method.</summary>
        public void Clear()
        {
            cache.Clear();
        }

        /// <summary>Returns an array of all of the key names in this EasySaveFile.</summary>
        public string[] GetKeys()
        {
            var keyCollection = cache.Keys;
            var keys = new string[keyCollection.Count];
            keyCollection.CopyTo(keys, 0);
            return keys;
        }

        #region Save Methods

        /// <summary>Saves a value to a key in this EasySaveFile.</summary>
        /// <param name="key">The key we want to use to identify our value in the file.</param>
        /// <param name="value">The value we want to save.</param>
        public void Save<T>(string key, T value)
        {
            var unencryptedSettings = (EasySaveSettings)settings.Clone();
            unencryptedSettings.encryptionType = EasySave.EncryptionType.None;
            unencryptedSettings.compressionType = EasySave.CompressionType.None;

            // If T is object, use the value to get it's type. Otherwise, use T so that it works with inheritence.
            Type type;
            if (value == null)
                type = typeof(T);
            else
                type = value.GetType();

            cache[key] = new EasySaveData(EasySaveTypeMgr.GetOrCreateEasySaveType(type), EasySave.Serialize(value, unencryptedSettings));
        }

        /// <summary>Merges the data specified by the bytes parameter into this EasySaveFile.</summary>
        /// <param name="bytes">The bytes we want to merge with this EasySaveFile.</param>
        /// <param name="settings">The settings we want to use to override the default settings.</param>
        public void SaveRaw(byte[] bytes, EasySaveSettings settings = null)
        {
            if (settings == null)
                settings = new EasySaveSettings();

            // Type checking must be enabled when syncing.
            var settingsWithTypeChecking = (EasySaveSettings)settings.Clone();
            settingsWithTypeChecking.typeChecking = true;

            using (var reader = EasySaveReader.Create(bytes, settingsWithTypeChecking))
            {
                if (reader == null)
                    return;
                foreach (KeyValuePair<string, EasySaveData> kvp in reader.RawEnumerator)
                    cache[kvp.Key] = kvp.Value;
            }
        }

        /// <summary>Merges the data specified by the bytes parameter into this EasySaveFile.</summary>
        /// <param name="bytes">The bytes we want to merge with this EasySaveFile.</param>
        /// <param name="settings">The settings we want to use to override the default settings.</param>
        public void AppendRaw(byte[] bytes, EasySaveSettings settings = null)
        {
            if (settings == null)
                settings = new EasySaveSettings();
            // AppendRaw just does the same thing as SaveRaw in EasySaveFile.
            SaveRaw(bytes, settings);
        }

        #endregion

        #region Load Methods

        /* Standard load methods */

        /// <summary>Loads the value from this EasySaveFile with the given key.</summary>
        /// <param name="key">The key which identifies the value we want to load.</param>
        public object Load(string key)
        {
            return Load<object>(key);
        }

        /// <summary>Loads the value from this EasySaveFile with the given key.</summary>
        /// <param name="key">The key which identifies the value we want to load.</param>
        /// <param name="defaultValue">The value we want to return if the key does not exist in this EasySaveFile.</param>
        public object Load(string key, object defaultValue)
        {
            return Load<object>(key, defaultValue);
        }

        /// <summary>Loads the value from this EasySaveFile with the given key.</summary>
        /// <param name="key">The key which identifies the value we want to load.</param>
        public T Load<T>(string key)
        {
            EasySaveData es3Data;

            if (!cache.TryGetValue(key, out es3Data))
                throw new KeyNotFoundException("Key \"" + key + "\" was not found in this EasySaveFile. Use Load<T>(key, defaultValue) if you want to return a default value if the key does not exist.");

            var unencryptedSettings = (EasySaveSettings)this.settings.Clone();
            unencryptedSettings.encryptionType = EasySave.EncryptionType.None;
            unencryptedSettings.compressionType = EasySave.CompressionType.None;

            if (typeof(T) == typeof(object))
                return (T)EasySave.Deserialize(es3Data.type, es3Data.bytes, unencryptedSettings);
            return EasySave.Deserialize<T>(es3Data.bytes, unencryptedSettings);
        }

        /// <summary>Loads the value from this EasySaveFile with the given key.</summary>
        /// <param name="key">The key which identifies the value we want to load.</param>
        /// <param name="defaultValue">The value we want to return if the key does not exist in this EasySaveFile.</param>
        public T Load<T>(string key, T defaultValue)
        {
            EasySaveData es3Data;

            if (!cache.TryGetValue(key, out es3Data))
                return defaultValue;
            var unencryptedSettings = (EasySaveSettings)this.settings.Clone();
            unencryptedSettings.encryptionType = EasySave.EncryptionType.None;
            unencryptedSettings.compressionType = EasySave.CompressionType.None;

            if (typeof(T) == typeof(object))
                return (T)EasySave.Deserialize(es3Data.type, es3Data.bytes, unencryptedSettings);
            return EasySave.Deserialize<T>(es3Data.bytes, unencryptedSettings);
        }

        /// <summary>Loads the value from this EasySaveFile with the given key into an existing object.</summary>
        /// <param name="key">The key which identifies the value we want to load.</param>
        /// <param name="obj">The object we want to load the value into.</param>
        public void LoadInto<T>(string key, T obj) where T : class
        {
            EasySaveData es3Data;

            if (!cache.TryGetValue(key, out es3Data))
                throw new KeyNotFoundException("Key \"" + key + "\" was not found in this EasySaveFile. Use Load<T>(key, defaultValue) if you want to return a default value if the key does not exist.");

            var unencryptedSettings = (EasySaveSettings)this.settings.Clone();
            unencryptedSettings.encryptionType = EasySave.EncryptionType.None;
            unencryptedSettings.compressionType = EasySave.CompressionType.None;

            if (typeof(T) == typeof(object))
                EasySave.DeserializeInto(es3Data.type, es3Data.bytes, obj, unencryptedSettings);
            else
                EasySave.DeserializeInto(es3Data.bytes, obj, unencryptedSettings);
        }

        #endregion

        #region Load Raw Methods

        /// <summary>Loads the EasySaveFile as a raw, unencrypted, uncompressed byte array.</summary>
        public byte[] LoadRawBytes()
        {
            var newSettings = (EasySaveSettings)settings.Clone();
            if (!newSettings.postprocessRawCachedData)
            {
                newSettings.encryptionType = EasySave.EncryptionType.None;
                newSettings.compressionType = EasySave.CompressionType.None;
            }
            return GetBytes(newSettings);
        }

        /// <summary>Loads the EasySaveFile as a raw, unencrypted, uncompressed string, using the encoding defined in the EasySaveFile's settings variable.</summary>
        public string LoadRawString()
        {
            if (cache.Count == 0)
                return "";
            return settings.encoding.GetString(LoadRawBytes());
        }

        /*
         * Same as LoadRawString, except it will return an encrypted/compressed file if these are enabled.
         */
        internal byte[] GetBytes(EasySaveSettings settings = null)
        {
            if (cache.Count == 0)
                return new byte[0];

            if (settings == null)
                settings = this.settings;

            using (var ms = new System.IO.MemoryStream())
            {
                var memorySettings = (EasySaveSettings)settings.Clone();
                memorySettings.location = EasySave.Location.InternalMS;
                // Ensure we return unencrypted bytes.
                if (!memorySettings.postprocessRawCachedData)
                {
                    memorySettings.encryptionType = EasySave.EncryptionType.None;
                    memorySettings.compressionType = EasySave.CompressionType.None;
                }

                using (var baseWriter = EasySaveWriter.Create(EasySaveStream.CreateStream(ms, memorySettings, EasySaveFileMode.Write), memorySettings, true, false))
                {
                    foreach (var kvp in cache)
                        baseWriter.Write(kvp.Key, kvp.Value.type.type, kvp.Value.bytes);
                    baseWriter.Save(false);
                }

                return ms.ToArray();
            }
        }

        #endregion

        #region Other EasySave Methods

        /// <summary>Deletes a key from this EasySaveFile.</summary>
        /// <param name="key">The key we want to delete.</param>
        public void DeleteKey(string key)
        {
            cache.Remove(key);
        }

        /// <summary>Checks whether a key exists in this EasySaveFile.</summary>
        /// <param name="key">The key we want to check the existence of.</param>
        /// <returns>True if the key exists, otherwise False.</returns>
        public bool KeyExists(string key)
        {
            return cache.ContainsKey(key);
        }

        /// <summary>Gets the size of the cached data in bytes.</summary>
        public int Size()
        {
            int size = 0;
            foreach (var kvp in cache)
                size += kvp.Value.bytes.Length;
            return size;
        }

        public Type GetKeyType(string key)
        {
            EasySaveData es3data;
            if (!cache.TryGetValue(key, out es3data))
                throw new KeyNotFoundException("Key \"" + key + "\" was not found in this EasySaveFile. Use Load<T>(key, defaultValue) if you want to return a default value if the key does not exist.");

            return es3data.type.type;
        }

        #endregion

        [System.ComponentModel.EditorBrowsable(System.ComponentModel.EditorBrowsableState.Never)]
        internal static EasySaveFile GetOrCreateCachedFile(EasySaveSettings settings)
        {
            EasySaveFile cachedFile;
            if (!cachedFiles.TryGetValue(settings.path, out cachedFile))
            {
                cachedFile = new EasySaveFile(settings, false);
                cachedFiles.Add(settings.path, cachedFile);
                cachedFile.syncWithFile = true; // This ensures that the file won't be merged, which would prevent deleted keys from being deleted.
            }
            // Settings might refer to the same file, but might have changed.
            // To account for this, we update the settings of the EasySaveFile each time we access it.
            cachedFile.settings = settings;
            return cachedFile;
        }

        internal static void CacheFile(EasySaveSettings settings)
        {
            // If we're still using cached settings, set it to the default location.
            if (settings.location == EasySave.Location.Cache)
            {
                settings = (EasySaveSettings)settings.Clone();
                // If the default settings are also set to cache, assume EasySave.Location.File. Otherwise, set it to the default location.
                settings.location = EasySaveSettings.defaultSettings.location == EasySave.Location.Cache ? EasySave.Location.File : EasySaveSettings.defaultSettings.location;
            }

            if (!EasySave.FileExists(settings))
                return;

            // Disable compression and encryption when loading the raw bytes, and the EasySaveFile constructor will expect encrypted/compressed bytes.
            var loadSettings = (EasySaveSettings)settings.Clone();
            loadSettings.compressionType = EasySave.CompressionType.None;
            loadSettings.encryptionType = EasySave.EncryptionType.None;

            cachedFiles[settings.path] = new EasySaveFile(EasySave.LoadRawBytes(loadSettings), settings);
        }

        [System.ComponentModel.EditorBrowsable(System.ComponentModel.EditorBrowsableState.Never)]
        internal static void Store(EasySaveSettings settings = null)
        {
            if (settings == null)
                settings = new EasySaveSettings(EasySave.Location.File);
            // If we're still using cached settings, set it to the default location.
            else if (settings.location == EasySave.Location.Cache)
            {
                settings = (EasySaveSettings)settings.Clone();
                // If the default settings are also set to cache, assume EasySave.Location.File. Otherwise, set it to the default location.
                settings.location = EasySaveSettings.defaultSettings.location == EasySave.Location.Cache ? EasySave.Location.File : EasySaveSettings.defaultSettings.location;
            }

            EasySaveFile cachedFile;
            if (!cachedFiles.TryGetValue(settings.path, out cachedFile))
                throw new FileNotFoundException("The file '" + settings.path + "' could not be stored because it could not be found in the cache.");
            cachedFile.Sync(settings);
        }

        [System.ComponentModel.EditorBrowsable(System.ComponentModel.EditorBrowsableState.Never)]
        internal static void RemoveCachedFile(EasySaveSettings settings)
        {
            cachedFiles.Remove(settings.path);
        }

        [System.ComponentModel.EditorBrowsable(System.ComponentModel.EditorBrowsableState.Never)]
        internal static void CopyCachedFile(EasySaveSettings oldSettings, EasySaveSettings newSettings)
        {
            EasySaveFile cachedFile;
            if (!cachedFiles.TryGetValue(oldSettings.path, out cachedFile))
                throw new FileNotFoundException("The file '" + oldSettings.path + "' could not be copied because it could not be found in the cache.");
            if (cachedFiles.ContainsKey(newSettings.path))
                throw new InvalidOperationException("Cannot copy file '" + oldSettings.path + "' to '" + newSettings.path + "' because '" + newSettings.path + "' already exists");

            cachedFiles.Add(newSettings.path, (EasySaveFile)cachedFile.MemberwiseClone());
        }

        [System.ComponentModel.EditorBrowsable(System.ComponentModel.EditorBrowsableState.Never)]
        internal static void DeleteKey(string key, EasySaveSettings settings)
        {
            EasySaveFile cachedFile;
            if (cachedFiles.TryGetValue(settings.path, out cachedFile))
                cachedFile.DeleteKey(key);
        }

        [System.ComponentModel.EditorBrowsable(System.ComponentModel.EditorBrowsableState.Never)]
        internal static bool KeyExists(string key, EasySaveSettings settings)
        {
            EasySaveFile cachedFile;
            if (cachedFiles.TryGetValue(settings.path, out cachedFile))
                return cachedFile.KeyExists(key);
            return false;
        }

        [System.ComponentModel.EditorBrowsable(System.ComponentModel.EditorBrowsableState.Never)]
        internal static bool FileExists(EasySaveSettings settings)
        {
            return cachedFiles.ContainsKey(settings.path);
        }

        [System.ComponentModel.EditorBrowsable(System.ComponentModel.EditorBrowsableState.Never)]
        internal static string[] GetKeys(EasySaveSettings settings)
        {
            EasySaveFile cachedFile;
            if (!cachedFiles.TryGetValue(settings.path, out cachedFile))
                throw new FileNotFoundException("Could not get keys from the file '" + settings.path + "' because it could not be found in the cache.");
            return cachedFile.cache.Keys.ToArray();
        }

        [System.ComponentModel.EditorBrowsable(System.ComponentModel.EditorBrowsableState.Never)]
        internal static string[] GetFiles()
        {
            return cachedFiles.Keys.ToArray();
        }

        internal static DateTime GetTimestamp(EasySaveSettings settings)
        {
            EasySaveFile cachedFile;
            if (!cachedFiles.TryGetValue(settings.path, out cachedFile))
                return new DateTime(1970, 1, 1, 0, 0, 0, 0, System.DateTimeKind.Utc);
            return cachedFile.timestamp;
        }
    }

    namespace Internal
    {
        public struct EasySaveData
        {
            public EasySaveType type;
            public byte[] bytes;

            public EasySaveData(Type type, byte[] bytes)
            {
                this.type = type == null ? null : EasySaveTypeMgr.GetOrCreateEasySaveType(type);
                this.bytes = bytes;
            }

            public EasySaveData(EasySaveType type, byte[] bytes)
            {
                this.type = type;
                this.bytes = bytes;
            }
        }
    }
}