using System;
using System.Collections.Generic;
using System.IO;
using UnityEngine;

/// <summary>
/// Keep track of all users
/// </summary>
[CreateAssetMenu(menuName = "Create new Scriptable/UserList")]
public class UserList : ScriptableObject
{
    /// <summary>
    /// Helper class to enable serialization of the UserList class
    /// (<c>ScriptableObject</c>s cannot be serialized)
    /// </summary>
    [Serializable]
    public class StoredUserList
    {
        /// <summary>
        /// The index of the current/last logged in user in the <c>storedUsers</c> list
        /// </summary>
        public int currentUserIndex = -1;

        /// <summary>
        /// A list containing all users (which can be serialized)
        /// </summary>
        public List<User> storedUsers = new List<User>();
    }

    /// <summary>
    /// Reference to the serializable version of <c>UserList</c>
    /// </summary>
    [SerializeField]
    private StoredUserList storedUserList = new StoredUserList();

    /// <summary>
    /// Path of the <c>.json</c>-file to store all serialized data
    /// </summary>
    public static string PATH = null;

    /// <summary>
    /// OnEnable will make sure the <c>PATH</c>-variable is correctly initialized
    /// </summary>
    void OnEnable()
    {
        // The PATH variable can be set by the testing framework,
        // so we don't overwrite the actual userlist with test data
        if (PATH == null)
        {
            PATH = $"{Application.persistentDataPath}/users.json";
            Load();
        }
    }

    /// <summary>
    /// Create a new user
    /// </summary>
    /// <param name="name">The username of the new user</param>
    /// <param name="avatar">Reference to the user avatar</param>
    /// <returns>A newly created user</returns>
    public User CreateNewUser(string name, Sprite avatar)
    {
        User user = new User();
        user.username = name;
        user.avatar = avatar;
        return user;
    }

    /// <summary>
    /// Create a new user and save (add to list)
    /// </summary>
    /// <param name="name">The username of the new user</param>
    /// <param name="avatar">Reference to the user avatar</param>
    /// <returns>A newly created user</returns>
    public User CreateAndAddNewUser(string name, Sprite avatar)
    {
        User user = CreateNewUser(name, avatar);
        storedUserList.storedUsers.Add(user);
        if (storedUserList.storedUsers.Count == 1)
        {
            storedUserList.currentUserIndex = 0;
        }
        Save();
        return user;
    }

    /// <summary>
    /// Get a user by username
    /// </summary>
    /// <param name="username">The username of the user</param>
    /// <returns><c>User</c>-object if a user with such username was found, <c>null</c> otherwise</returns>
    public User GetUserByUsername(string username)
    {
        foreach (User user in storedUserList.storedUsers)
            if (user.username == username) return user;

        return null;
    }

    /// <summary>
    /// Get a list of all users currently stored
    /// </summary>
    /// <returns>A list of all users</returns>
    public List<User> GetUsers()
    {
        return storedUserList.storedUsers;
    }

    /// <summary>
    /// Get the current logged in user
    /// </summary>
    /// <returns>The current logged in user</returns>
    public User GetCurrentUser()
    {
        if (storedUserList.storedUsers.Count == 0)
        {
            return null;
        }
        return storedUserList.storedUsers[storedUserList.currentUserIndex];
    }

    /// <summary>
    /// Get the index in the userlist of the current playing user
    /// </summary>
    /// <returns></returns>
    public int GetCurrentUserIndex()
    {
        return storedUserList.currentUserIndex;
    }

    /// <summary>
    /// Change the current user
    /// </summary>
    /// <param name="index">Index of the user in the userlist</param>
    /// <exception cref="IndexOutOfRangeException"></exception>
    public void ChangeCurrentUser(int index)
    {
        if (0 <= index && index < storedUserList.storedUsers.Count)
        {
            storedUserList.currentUserIndex = index;
        }
        else
        {
            throw new IndexOutOfRangeException();
        }
    }

    /// <summary>
    /// Change the current user
    /// </summary>
    /// <param name="user">Reference to the user in the userlist</param>
    /// <exception cref="KeyNotFoundException"></exception>
    public void ChangeCurrentUser(User user)
    {
        int idx = storedUserList.storedUsers.IndexOf(user);
        if (idx < 0)
        {
            throw new KeyNotFoundException();
        }
        storedUserList.currentUserIndex = idx;
    }

    /// <summary>
    /// Remove the user
    /// </summary>
    /// <param name="index">The index of the user in the userlist</param>
    /// <returns>true if user was successful removed, false otherwise</returns
    public bool DeleteUser(int index)
    {
        if (0 <= index && index < storedUserList.storedUsers.Count)
        {
            return DeleteUser(storedUserList.storedUsers[index]);
        }
        return false;
    }

    /// <summary>
    /// I am inevitable, *snap*
    /// </summary>
    /// <param name="user">Reference to the user to be removed</param>
    /// <returns>true if the user was successful removed, false otherwise</returns>
    public bool DeleteUser(User user)
    {
        if (1 < storedUserList.storedUsers.Count)
        {
            if (storedUserList.currentUserIndex == storedUserList.storedUsers.Count - 1)
            {
                storedUserList.currentUserIndex--;
            }

            return storedUserList.storedUsers.Remove(user);
        }
        return false;
    }

    /// <summary>
    /// Save the users
    /// </summary>
    public void Save()
    {
        string json = JsonUtility.ToJson(storedUserList);
        File.CreateText(PATH).Close();
        File.WriteAllText(PATH, json);
    }

    /// <summary>
    /// Override the current content of the userlist by what is stored on disk
    /// </summary>
    public void Load()
    {
        storedUserList.storedUsers.Clear();
        storedUserList.currentUserIndex = -1;

        if (!File.Exists(PATH))
        {
            Save();
        }
        string text = File.ReadAllText(PATH);
        storedUserList = JsonUtility.FromJson<StoredUserList>(text);
    }
}