using System.CodeDom;
using System.Text;
using ProjectCruiser.DrawningSamples;

namespace ProjectCruiser.CollectionGenericObj;

public class StorageCollection<T>
    where T : DrawningBase // class
{
    private readonly string _separatorForKeyValue = "|";
    private readonly string _separatorItems = ";";
    private readonly string _collectionKey = "CollectionsStorage";

    // Словарь (хранилище) с коллекциями < CollectionInfo, type (class) >
    readonly Dictionary<CollectionInfo, ICollectionGenObj<T>> _storages;

    // Возвращение списка коллекций
    public List<CollectionInfo> Keys => _storages.Keys.ToList();

    public StorageCollection()
    {
        _storages = new Dictionary<CollectionInfo, ICollectionGenObj<T>>();
    }

    // Добавление коллекции в хранилище
    public void AddCollection(string name, CollectionType collType)
    {
        // descroption [ ? ] >>>
        CollectionInfo coll = new CollectionInfo(name, collType, string.Empty);

        if (name == null || _storages.ContainsKey(coll)
            || collType == CollectionType.None)
        {
            throw new NullReferenceException("> Not enough information to save");
        }

        _storages.Add(coll, CreateCollection(collType));
    }

    // Удаление коллекции ( по ключу-строке - её имени )
    public void DelCollection(string name)
    {
        // descroption [ ? ] >>>
        CollectionInfo coll = new CollectionInfo(name,
            CollectionType.None, string.Empty);

        if (_storages.ContainsKey(coll)) _storages.Remove(coll);
        else throw new NullReferenceException("> No such key in the list");
    }

    // Доступ к коллекции , индексатор [!!!]
    public ICollectionGenObj<T>? this[string name]
    {
        get => _storages.ContainsKey(new CollectionInfo(name, CollectionType.None, string.Empty))
            ? _storages[new CollectionInfo(name, CollectionType.None, string.Empty)] : null;
    }

    /// Сохранение информации по автомобилям в хранилище в файл
    /// <param name="filename">Путь и имя файла</param>
    /// <returns>true - сохранение прошло успешно,
    /// false - ошибка при сохранении данных</returns>
    public void SaveData(string filename)
    {
        if (_storages.Count == 0)
            throw new NullReferenceException("> No existing collections to save");

        if (File.Exists(filename)) { File.Delete(filename); }

        StringBuilder sb = new();

        sb.Append(_collectionKey); // const

        foreach (KeyValuePair<CollectionInfo, ICollectionGenObj<T>> pair in _storages)
        {
            sb.Append(Environment.NewLine); // не сохраняем пустые коллекции
            if (pair.Value.Count == 0) { continue; }

            sb.Append(pair.Key);
            sb.Append(_separatorForKeyValue);
            // <...>
            sb.Append(pair.Value.MaxCount);
            sb.Append(_separatorForKeyValue);

            foreach (T? item in pair.Value.GetItems())
            {
                string data = item?.GetDataForSave() ?? string.Empty;
                if (string.IsNullOrEmpty(data))
                {
                    continue;
                }

                sb.Append(data);
                sb.Append(_separatorItems);
            }
        }

        using FileStream fs = new(filename, FileMode.Create);
        byte[] info = new UTF8Encoding(true).GetBytes(sb.ToString());
        fs.Write(info, 0, info.Length);
    }

    // Создание коллекции по типу
    private static ICollectionGenObj<T>? CreateCollection(CollectionType collectionType)
    {
        return collectionType switch
        {
            CollectionType.Array => new ArrayGenObj<T>(),
            CollectionType.List => new ListGenObj<T>(),
            _ => null,
        };
    }

    // Загрузка информации по кораблям в хранилище из файла
    public void LoadData(string filename)
    {
        if (!File.Exists(filename)) throw new FileNotFoundException("> No such file");

        string bufferTextFromFile = "";

        using (FileStream fs = new(filename, FileMode.Open))
        {
            byte[] b = new byte[fs.Length];
            UTF8Encoding temp = new(true);
            while (fs.Read(b, 0, b.Length) > 0)
            {
                bufferTextFromFile += temp.GetString(b);
            }
        }

        string[] strs = bufferTextFromFile.Split(
            new char[] { '\n', '\r' }, StringSplitOptions.RemoveEmptyEntries);

        if (strs == null || strs.Length == 0)
            throw new NullReferenceException("> No data to decode");
        if (!strs[0].Equals(_collectionKey))
            throw new InvalidDataException("> Incorrect data");

        string[] companies = new string[strs.Length - 1];
        for (int k = 1; k < strs.Length; k++)
        {
            companies[k - 1] = strs[k];
        }

        _storages.Clear();
        foreach (string data in companies)
        {
            string[] record = data.Split(_separatorForKeyValue, StringSplitOptions.RemoveEmptyEntries);
            if (record.Length != 3) // >
                // [key + collType] | maxcount | all next inf > 4
            { continue; }

            CollectionInfo? collInfo = CollectionInfo.GetCollectionInfo(record[0]) ??
                throw new Exception("[!] Failed to decode information : " + record[0]);

            ICollectionGenObj<T>? collection = StorageCollection<T>.CreateCollection(
                collInfo.CollectionType) ??
                throw new Exception("[!] Failed to create a collection");

            collection.MaxCount = Convert.ToInt32(record[1]);
            string[] set = record[2].Split(_separatorItems,
            StringSplitOptions.RemoveEmptyEntries);

            foreach (string elem in set)
            {
                if (elem?.CreateDrawningCar() is T ship)
                {
                    try
                    {
                        collection.Insert(ship);
                    }
                    catch (Exception e)
                    {
                        throw new Exception(e.Message);
                    }
                }
            }
            _storages.Add(collInfo, collection);
        }
    }
}