using System.Collections.Generic;
using TMPro;
using UnityEngine;
using UnityEngine.SceneManagement;
using UnityEngine.UI;

public class ChangeUserScreen : MonoBehaviour
{
    /// <summary>
    /// Prefab of the user selection
    /// </summary>
    public GameObject userPrefab;

    /// <summary>
    /// Reference to the container to list all users
    /// </summary>
    public Transform usersContainer;

    /// <summary>
    /// Reference to the user list
    /// </summary>
    public UserList userList;

    /// <summary>
    /// Index of the current selected user in the UserList
    /// </summary>
    private int currentUserIndex;

    /// <summary>
    /// List of references to avatar background sprites (so we can color them nicely)
    /// </summary>
    private List<Image> userBackgrounds = new List<Image>();

    /// <summary>
    /// Start is called before the first frame update
    /// </summary>
    void Start()
    {
        List<User> users = userList.GetUsers();
        currentUserIndex = userList.GetCurrentUserIndex();
        for (int i = 0; i < users.Count; i++)
        {
            User user = users[i];

            // Create instance of prefab
            GameObject instance = GameObject.Instantiate(userPrefab, usersContainer);

            // Store value of i so we can use it the callback (else it would get the value of sprites.Count)
            int x = i;
            // Add onClick callback
            instance.GetComponent<Button>().onClick.AddListener(() => UpdateSelection(x));
            // Set username
            instance.GetComponentInChildren<TMP_Text>().text = user.username;

            // Store reference to image for fancy coloring
            Image background = instance.GetComponent<Image>();
            userBackgrounds.Add(background);
            // Set background color
            background.color = i == currentUserIndex ? Color.blue : Color.gray;
            // Find correct component for setting the sprite
            foreach (Image img in background.GetComponentsInChildren<Image>())
                if (img != background)
                {
                    img.sprite = user.avatar;
                    break;
                }
        }
    }

    /// <summary>
    /// Update the current selected user
    /// </summary>
    /// <param name="index">Index to the user in the <c>this.userBackgrounds</c> list</param>
    private void UpdateSelection(int index)
    {
        userBackgrounds[currentUserIndex].color = Color.gray;
        currentUserIndex = index;
        userBackgrounds[currentUserIndex].color = Color.blue;
    }

    /// <summary>
    /// Select the current selected user and return to the StartScreenScene
    /// </summary>
    public void IChooseYou()
    {
        userList.ChangeCurrentUser(currentUserIndex);
        userList.Save();
        SceneManager.LoadScene("Common/Scenes/StartScreen");
    }
}