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

/// <summary>
/// Class to handle course list progress display
/// </summary>
public class PanelCourseProgress : MonoBehaviour
{
    /// <summary>
    /// Reference to the current user
    /// </summary>
    private User user;

    /// <summary>
    /// Reference to the courses list
    /// </summary>
    public CourseList courseList;

    /// <summary>
    /// Prefab of a course card
    /// </summary>
    public GameObject courseCardPrefab;

    /// <summary>
    /// UI reference to the container holding all course cards
    /// </summary>
    public Transform coursesContainer;

    /// <summary>
    /// UI reference to the course info panel
    /// </summary>
    public GameObject courseInfo;

    /// <summary>
    /// UI reference to the message that displays when no course progress is present
    /// </summary>
    public GameObject emptyCourses;

    /// <summary>
    /// Reference to the title on the info panel
    /// </summary>
    public TMP_Text courseTitle;

    /// <summary>
    /// Reference to the learnable card prefab
    /// </summary>
    public GameObject learnableCardPrefab;

    /// <summary>
    /// Reference to the container for holding the learnable cards
    /// </summary>
    public Transform learnablesContainer;

    /// <summary>
    /// Reference to the course progress bar on the info panel
    /// </summary>
    public SlicedSlider progressBar;

    /// <summary>
    /// Current selected course
    /// </summary>
    private int selectedCourse = 0;

    /// <summary>
    /// List of course backgrounds and indices
    /// </summary>
    private List<Tuple<Image, CourseIndex>> courseCards = new List<Tuple<Image, CourseIndex>>();

    /// <summary>
    /// Start is called before the first frame update
    /// </summary>
    void Start()
    {
        PersistentDataController.GetInstance().Load();
        user = UserList.GetCurrentUser();

        var courses = user.GetCourses();
        courseInfo.SetActive(0 < courses.Count);
        emptyCourses.SetActive(courses.Count <= 0);
        int i = 0;
        foreach (var courseProgress in courses)
        {
            // Create instance of prefab
            GameObject instance = GameObject.Instantiate(courseCardPrefab, coursesContainer);
            int j = i++;

            // Initialize card
            CourseProgressCard cpc = instance.GetComponent<CourseProgressCard>();
            cpc.courseProgress = courseProgress;
            cpc.selectActivity = () => UpdateSelection(j);

            // Store reference to background so we can apply fancy coloring
            Image background = instance.GetComponent<Image>();
            background.color = Color.gray;
            this.courseCards.Add(Tuple.Create(background, courseProgress.courseIndex));
        }
        if (0 < courses.Count)
            UpdateSelection(0);
    }

    /// <summary>
    /// Update the current selected course
    /// </summary>
    /// <param name="newCourse">Index to the new course</param>
    private void UpdateSelection(int newCourse)
    {
        courseCards[selectedCourse].Item1.color = Color.gray;
        selectedCourse = newCourse;
        courseCards[selectedCourse].Item1.color = Color.blue;

        var progress = user.GetCourseProgress(courseCards[selectedCourse].Item2);
        var course = courseList.GetCourseByIndex(progress.courseIndex);
        courseTitle.text = course.title;
        progressBar.fillAmount = progress.progress;

        foreach (Transform child in learnablesContainer)
            Destroy(child.gameObject);

        for (int i = 0; i < course.theme.learnables.Count; i++)
        {
            GameObject instance = GameObject.Instantiate(learnableCardPrefab, learnablesContainer);
            var script = instance.GetComponent<LearnableProgressCard>();
            script.learnable = course.theme.learnables[i];
            script.progress = progress.learnables[i];
        }
    }
}