@page "/Learn"
@using System.Text;
@using LearningChineseSimplified.ExtensionMethods;

@inject NavigationManager navigator
@inject Blazored.LocalStorage.ILocalStorageService localStorage
@inject HttpClient httpClient
@inject ISnackbar Snackbar


<style>
    .LargeCharecter{
        width: 0;
        height: 0;
        display: flex;
        justify-content: center;
        align-items: center;
        font-size: 125px;
    }

    .PinyinButtons{
        width: 125px;
        font-size: 20px;
    }
</style>

<MudContainer Class="justify-center d-flex ma-0" Style="height: 100%;">
    <MudStack Class="d-flex">
        <MudStack Row=true Class="pt-2 d-flex justify-center">
            <MudButton Color="Color.Default" OnClick="RemoveCCharFromSelection" Variant="Variant.Outlined">Avoid</MudButton>
            <MudButton Color="Color.Default" Variant="Variant.Outlined" OnClick="ShowMeaning">Meaning</MudButton>
            <MudButton Color="Color.Default" Variant="Variant.Outlined" OnClick="ShowPinyin">Pinyin</MudButton>
        </MudStack>
        <MudContainer>
            <MudPaper Class="pa-16 ma-2 rounded-xl mud-dark" Elevation="1">
                <MudContainer Style="width: 100px; height: 100px" Class="pa-8 ma-4 d-flex justify-center align-center">
                    @if (!Answers.Any(x => x == null))
                    {
                        <p class="LargeCharecter">@GetDisplayChar()</p>
                    }
                </MudContainer>
            </MudPaper>
        </MudContainer>
        <MudContainer Class="pa-8 pt-10 justify-center align-center d-flex"
        Style="max-width:300px">
            <MudGrid Spacing="10" Class="align-center justify-center d-flex">
                @if (!Answers.Any(x=>x == null))
                {
                    @for (int i = 0; i < Answers.Length; i++)
                    {
                        int buttonIndex = i;
                        <MudButton Class="PinyinButtons ma-3"
                           Variant="Variant.Outlined"
                           @onclick="() => SelectButton(buttonIndex)"
                           Color="@(Answers[buttonIndex].isSelected ? Color.Primary : Color.Default)">
                           <MudText>
                                @Answers[buttonIndex].cchar.pinyin.ToTitleCase()
                           </MudText>
                       </MudButton>
                    }
                }
            </MudGrid>
        </MudContainer>
        <MudSpacer/>
        <MudContainer Class="pb-8 justify-center align-center d-flex">
            @if (!Answers.Any(x => x == null))
            {
                <MudButton Disabled="@(!(Answers.Any(x=>x.isSelected)))" OnClick="Submit" Class="px-8 py-3" Variant="Variant.Filled" Size="Size.Large" Color="Color.Success" Style="font-size: 20px;"> Submit</MudButton>
            }
        </MudContainer>
    </MudStack>
</MudContainer>

<MudOverlay @bind-Visible="ShowOverlay" DarkBackground="true" AutoClose="true" />

@code {
    public bool ShowOverlay = false;

    bool isSavedLocally = false;

    public Answer[] Answers = new Answer[4];
    public void SelectButton(int selectedIndex)
    {
        for (int i = 0; i < Answers.Length; i++)
        {
            Answers[i].isSelected = (i == selectedIndex);
        }
    }

    private CChar[]? _charecters;
    public CChar[]? Charecters
    {
        get
        {
            if (_charecters == null) throw new Exception("Loaded dataset empty?");

            return _charecters;
        }
        set { _charecters = value; }
    }

    public List<CChar>? DontSkipTheseCChar;

    private async Task<string> GetFileContentsAsync(string filePath)
    {
        var fileResponse = await httpClient.GetByteArrayAsync(filePath);
        return Encoding.UTF8.GetString(fileResponse);
    }

    protected override async Task OnInitializedAsync()
    {
        Program.UpdateUiEvent += OnUiUpdate;

        isSavedLocally = await localStorage.ContainKeyAsync("Normalized_chunk_001.json");

        int selectedChunk = await localStorage.GetItemAsync<int>("SelectedChunk");

        if (!isSavedLocally)
            Charecters = await httpClient.GetFromJsonAsync<CChar[]>($"Data/Normalized_chunk_{selectedChunk.ToString("000")}.json");
        else
        {
            string json = await localStorage.GetItemAsync<string>($"Normalized_chunk_{selectedChunk.ToString("000")}.json");
            Charecters = JsonConvert.DeserializeObject<CChar[]>(json);
        }

        DontSkipTheseCChar = Charecters.ToList();
        Program.CCharsLeft = DontSkipTheseCChar.Count;
        Program.InvokeUiUpdate();

        GenerateQuestion();
    }

    void OnUiUpdate() => StateHasChanged();

    void GenerateQuestion()
    {
        if (DontSkipTheseCChar.Count < 5) 
        {
            FinishAndKickBackToLearn();
            return;
        }

        int correctIndex = Random.Shared.Next(0, Answers.Length);

        for (int i = 0; i < Answers.Length; i++)
        {
            bool isCorrect = i == correctIndex;
            CChar randomCChar;

        repickRandomCChar:
            randomCChar = DontSkipTheseCChar[Random.Shared.Next(0, DontSkipTheseCChar.Count)];
            if (Answers.Any(x =>x != null && x.cchar == randomCChar)) goto repickRandomCChar;

            Answers[i] = new Answer(randomCChar, isCorrect);
        }
    }

    void FinishAndKickBackToLearn()
    {
        Snackbar.Add("Congrats, you have compleated this chunk!", Severity.Success, config => 
        { 
            config.RequireInteraction = true;
            config.CloseAfterNavigation = false;
        });
        Program.UpdateUiEvent -= OnUiUpdate;
        Program.CCharsLeft = 0;

        navigator.NavigateTo("");
    }

    async void Submit()
    {
        bool isCorrect = Answers.Any(x => x.isCorrect && x.isSelected);
        CChar correctCChar = GetCorrectCChar();

        if (isCorrect)
        {
            Snackbar.Add($"<b>Definition:</b> {correctCChar.definition}", Severity.Success, config => { config.VisibleStateDuration = 1000; });
        }
        else
        {
            Snackbar.Add(   
                @<div>
                    <h3>Incorrect!</h3>
                    <ul>
                        <li>CChar: @correctCChar.charcter</li>
                        <li>Correct answer: @correctCChar.pinyin.ToTitleCase()</li>
                        <li>Meaning: @correctCChar.definition</li>
                    </ul>
                </div>
                         , Severity.Error);
        }

        GenerateQuestion();
    }

    public class Answer
    {
        public Answer()
        {
        }

        public Answer(CChar cchar, bool isCorrect)
        {
            this.cchar = cchar;
            this.isCorrect = isCorrect;
        }

        public CChar cchar { get; set; }
        public bool isCorrect { get; set; } = false;
        public bool isSelected { get; set; } = false;
    }

    public char GetDisplayChar()
    {
        char? cc = GetCorrectCChar().charcter;
        if (cc == null) return ' ';
        else return (char)cc;
    }

    public CChar GetCorrectCChar()
    {
        CChar cchar = Answers.FirstOrDefault(x => x.isCorrect)?.cchar;
        return cchar;
    }

    public void RemoveCCharFromSelection()
    {
        CChar correctChar = GetCorrectCChar();
        DontSkipTheseCChar.Remove(correctChar);
        Console.WriteLine("Remaining CChars: " + DontSkipTheseCChar);
        Program.CCharsLeft = DontSkipTheseCChar.Count;
        Program.InvokeUiUpdate();
        GenerateQuestion();
    }

    public void ShowMeaning()
    {
        Snackbar.Add($"<b>Definition:</b> {GetCorrectCChar().definition}", Severity.Info);
    }

    public void ShowPinyin()
    {
        Snackbar.Add($"<b>Pinyin:</b> {GetCorrectCChar().pinyin.ToTitleCase()}", Severity.Info);
    }
}