@page "/urls"
@using Microsoft.AspNetCore.Authorization
@using Microsoft.Extensions.Caching.Distributed
@using System.ComponentModel.DataAnnotations
@using System.Text.RegularExpressions
@using System.Web
@using Humanizer
@using Microsoft.AspNetCore.WebUtilities
@attribute [Authorize]

@inject IDistributedCache Db
@inject IConfiguration Configuration
@inject NavigationManager Navigation

<PageTitle>Urls - Just Short It</PageTitle>

<div class="grid place-items-center h-full text-primary-content">
    <section class="w-full md:max-w-lg">
        <h1 class="text-3xl lg:text-5xl text-primary-content text-center mb-6">
            Urls Administration
        </h1>
        <MessageComponent Message="@Message" Type="MessageType" LinkToCopy="@Link" />

        <EditForm class="mb-6" method="post" id="inspect-form" 
                  FormName="inspect" Model="Inspect" OnValidSubmit="Submit_Inspect">
            <DataAnnotationsValidator />
            <h2 class="text-xl lg:text-2xl mb-3">Inspect URL</h2>

            <div class="join w-full">
                <label class="join-item btn btn-outline no-animation text-primary-content border-white">
                    ID
                </label>
                <div class="join-item flex-1">
                    <InputText id="inspect_id" class="input input-bordered w-full border-white" 
                               min="2" max="16" autocomplete="off"
                               @bind-Value="Inspect.Id" required />
                </div>
                <div class="join-item">
                    <button class="btn btn-primary border-1" type="submit">Inspect</button>
                </div>
            </div>
            
            <ValidationSummary class="text-error pt-2" />
        </EditForm>
        
        <EditForm method="post" id="new-form"
                  FormName="new" Model="New" OnValidSubmit="Submit_New">
            <DataAnnotationsValidator />
            <h2 class="text-xl lg:text-2xl mb-3">New URL</h2>

            <div class="form-control w-full">
                <span class="label">
                    <label class="label-text text-primary-content">ID</label>
                </span>
                <InputText id="new_id" class="input input-bordered w-full" 
                           min="2" max="16" autocomplete="off"
                           @bind-Value="New.Id" required />
                <span class="label">
                    <ValidationMessage class="label-text-alt text-error" For="() => New.Id" />
                </span>
            </div>

            <div class="form-control w-full">
                <div class="label">
                    <label class="label-text text-primary-content">Target</label>
                </div>
                <InputText id="new_url" class="input input-bordered w-full" type="url" @bind-Value="New.Url" 
                       autocomplete="off" required />
                <span class="label">
                    <ValidationMessage class="label-text-alt text-error" For="() => New.Url" />
                </span>
            </div>
            
            <div class="form-control w-full">
                <div class="label">
                    <label class="label-text text-primary-content">Expiration</label>
                </div>
                <InputSelect id="new_expiration" class="select select-bordered w-full" 
                             @bind-Value="New.RedirectExpiration" DisplayName="Expiration" required>
                    <option value="null" disabled selected>Select Expiration</option>
                    @foreach (var expiration in Enum.GetValues<Expiration>()) {
                        <option value="@expiration">@expiration.Humanize()</option>
                    }
                </InputSelect>
                <span class="label">
                    <ValidationMessage class="label-text-alt text-error" For="() => New.RedirectExpiration" />
                </span>
            </div>

            <button class="btn btn-primary w-full" type="submit">Create</button>    
        </EditForm>
    </section>
</div>

@code {
    [SupplyParameterFromForm(FormName = "inspect")]
    public InspectModel Inspect { get; set; } = default!;
    [SupplyParameterFromForm(FormName = "new")]
    public NewModel New { get; set; } = default!;

    private string BaseUrl { get; set; } = null!;
    private string? Message { get; set; }
    private string? Link { get; set; }
    private MessageComponent.AlertType MessageType { get; set; }

    protected override void OnInitialized() {
        // ReSharper disable NullCoalescingConditionIsAlwaysNotNullAccordingToAPIContract
        Inspect ??= new InspectModel();
        New ??= new NewModel();
        // ReSharper restore NullCoalescingConditionIsAlwaysNotNullAccordingToAPIContract
        New.Id ??= GenerateNewId();

        string url = Configuration.GetValue<string>("BaseUrl") ?? throw new ApplicationException("BaseUrl not set");
        BaseUrl = new Uri(url, UriKind.Absolute).ToString();
    }

    private async Task Submit_Inspect(EditContext context) {
        if (string.IsNullOrWhiteSpace(Inspect.Id)) return;

        if (await Db.GetAsync(Inspect.Id) is null) {
            Message = "ID does not exist";
            MessageType = MessageComponent.AlertType.Error;
            return;
        }

        Navigation.NavigateTo(QueryHelpers.AddQueryString("/inspect", "Id", Inspect.Id));
    }

    private async Task Submit_New() {
        if (string.IsNullOrWhiteSpace(New.Id)) return;

        string id = HttpUtility.UrlEncode(New.Id);

        if (await Db.GetAsync(id) is not null) {
            Message = "This ID is already taken, sorry!";
            MessageType = MessageComponent.AlertType.Error;
            return;
        }

        if (Uri.TryCreate($"{BaseUrl}{id}", UriKind.Absolute, out var link) is false) {
            Message = "This ID cannot be used in a URL, sorry!";
            MessageType = MessageComponent.AlertType.Error;
            return;
        }
        
        await Db.SetStringAsync(id, New.Url!, new DistributedCacheEntryOptions {
            AbsoluteExpiration = DateTime.FromBinary(ToUnixTime(New.RedirectExpiration!.Value))
        });

        Message = $"URL Generated! {link}";
        Link = link.ToString();
        MessageType = MessageComponent.AlertType.Success;
    }
    
    private static string GenerateNewId() {
        string base64Guid = Regex.Replace(
            Convert.ToBase64String(Guid.NewGuid().ToByteArray()), 
            "[/+=]", "");
        return base64Guid[..6];
    }

    #region Models

    public sealed class InspectModel {
        [Required(AllowEmptyStrings = false, ErrorMessage = "Id is required.")]
        [MinLength(2, ErrorMessage = "Id needs to be at least 2 characters long.")]
        [MaxLength(16, ErrorMessage = "Id needs to be at maximum 16 characters long.")]
        public string? Id { get; set; }
    }
    public sealed class NewModel {
        [Required(AllowEmptyStrings = false, ErrorMessage = "Id is required.")]
        [MinLength(2, ErrorMessage = "Id needs to be at least 2 characters long.")]
        [MaxLength(16, ErrorMessage = "Id needs to be at maximum 16 characters long.")]
        public string? Id { get; set; } 
        [Required(AllowEmptyStrings = false, ErrorMessage = "Target is required.")]
        [Url(ErrorMessage = "Target needs to be a valid URL.")]
        public string? Url { get; set; }
        [Required(ErrorMessage = "Expiration is required.")]
        public Expiration? RedirectExpiration { get; set; }
    }

    public enum Expiration {
        OneDay, OneWeek, FourWeeks, OneMonth, OneYear, Never
    }

    private static long ToUnixTime(Expiration expiration) => expiration switch{
        Expiration.OneDay => DateTime.UtcNow.AddDays(1).ToBinary(),
        Expiration.OneWeek => DateTime.UtcNow.AddDays(7).ToBinary(),
        Expiration.FourWeeks => DateTime.UtcNow.AddDays(4*7).ToBinary(),
        Expiration.OneYear => DateTime.UtcNow.AddYears(1).ToBinary(),
        Expiration.Never => DateTime.UtcNow.AddYears(1000).ToBinary(),
        _ => throw new ArgumentOutOfRangeException(nameof(expiration), expiration, null)};

    #endregion
}