@inherits LocalizableComponentBase

@* A picker of emoji: the server's custom emoji its picker offers (EmojiService, by category) and common unicode ones
   (Helpers/UnicodeEmojis.cs, by group), searched by shortcode, category or word. It is a DDropdown, a sheet on a phone,
   whose trigger is the caller's ChildContent (data-emoji-picker-open); what it holds is rendered only while it is open
   (data-emoji-picker), so a feed whose every card has one costs nothing until one opens, and the server's emoji are read
   on the first opening. A choice (data-emoji-choice: the shortcode, or the character itself) is handed to OnPick as
   `:shortcode:` for a custom emoji and as the character for a unicode one, and closes the picker. The composer writes it
   into the words; a card and the announcements banner react with it, their quick reactions (Quick) first. *@
<DDropdown @attributes="AdditionalAttributes" IsOpen="isOpen" IsOpenChanged="Opened" Placement="Placement" Align="Align" SheetOnNarrow="true"
		   TriggerClass="@(isOpen ? ActiveTriggerClass : TriggerClass)" ContentClass="@ContentClass" TriggerAttributes="TriggerHooks" title="@TriggerLabel">
	<Trigger>@ChildContent</Trigger>
	<ChildContent>
		@if (isOpen)
		{
			<div class="flex flex-col gap-2 w-full md:w-80" data-emoji-picker>
				@* its form attribute names no form, so Enter in the search submits no form around the picker (the composer's) *@
				<DInput TValue="string" Size="DSize.Sm" class="w-full" Value="query" ValueChanged="Search" ValueExpression="() => query" Immediate="true"
						autocomplete="off" form="emoji-picker-search" placeholder="@Localizer["Search emoji"]" aria-label="@Localizer["Search emoji"]"
						@onkeydown="PickFirst" data-emoji-picker-search>
					<Prefix><i class="ion-md-search" aria-hidden="true"></i></Prefix>
				</DInput>
				<div class="flex flex-col gap-2 max-h-72 max-md:max-h-[50dvh] overflow-y-auto overscroll-contain pr-1">
					@if (IsLoading)
					{
						<p class="flex items-center gap-2 text-xs opacity-70">
							<DLoading Size="DSize.Xs" LabelText="@Localizer["loading"]" />@Localizer["loading"]
						</p>
					}
					@if (QuickShown.Count > 0)
					{
						<section class="flex flex-col gap-1" data-emoji-section="quick">
							<h4 class="sticky top-0 z-[1] bg-base-100 py-1 text-xs font-semibold opacity-70">@Localizer["Often used"]</h4>
							<div class="grid grid-cols-8 pointer-coarse:grid-cols-6 justify-items-center gap-1 pointer-coarse:gap-2">
								@foreach (var emoji in QuickShown)
								{
									<DButton Size="DSize.Sm" Variant="DButtonVariant.Ghost" Shape="DButtonShape.Square" Disabled="IsDefaultDisabled || ChoicesDisabled"
											 OnClick="() => Pick(emoji)" data-emoji-choice="@emoji">
										<span class="text-xl leading-none">@emoji</span>
									</DButton>
								}
							</div>
						</section>
					}
					@foreach (var group in CustomShown)
					{
						<section class="flex flex-col gap-1" data-emoji-section="@("custom:" + group.Key)">
							<h4 class="sticky top-0 z-[1] bg-base-100 py-1 text-xs font-semibold opacity-70 truncate">@(group.Key is { Length: > 0 } category ? category : Localizer["This server's emoji"])</h4>
							<div class="grid grid-cols-8 pointer-coarse:grid-cols-6 justify-items-center gap-1 pointer-coarse:gap-2">
								@foreach (var emoji in group)
								{
									<DButton Size="DSize.Sm" Variant="DButtonVariant.Ghost" Shape="DButtonShape.Square" Disabled="IsDefaultDisabled || ChoicesDisabled"
											 OnClick="@(() => Pick($":{emoji.Shortcode}:"))" title="@($":{emoji.Shortcode}:")" aria-label="@($":{emoji.Shortcode}:")"
											 data-emoji-choice="@emoji.Shortcode">
										@* alt="": the button is named by the shortcode. *@
										<img alt="" loading="lazy" draggable="false" class="h-6 w-6 object-contain" src="@PictureOf(emoji)" />
									</DButton>
								}
							</div>
						</section>
					}
					@foreach (var group in UnicodeShown)
					{
						<section class="flex flex-col gap-1" data-emoji-section="@group.Key">
							<h4 class="sticky top-0 z-[1] bg-base-100 py-1 text-xs font-semibold opacity-70">@Localizer[group.Name]</h4>
							<div class="grid grid-cols-8 pointer-coarse:grid-cols-6 justify-items-center gap-1 pointer-coarse:gap-2">
								@foreach (var emoji in group.Emojis)
								{
									<DButton Size="DSize.Sm" Variant="DButtonVariant.Ghost" Shape="DButtonShape.Square" Disabled="IsDefaultDisabled || ChoicesDisabled"
											 OnClick="() => Pick(emoji.Character)" title="@($":{emoji.Shortcode}:")" data-emoji-choice="@emoji.Character">
										<span class="text-xl leading-none">@emoji.Character</span>
									</DButton>
								}
							</div>
						</section>
					}
					@if (!IsLoading && QuickShown.Count == 0 && CustomShown.Count == 0 && UnicodeShown.Count == 0)
					{
						<p class="text-sm opacity-70" data-emoji-picker-empty>@Localizer["No emoji matches."]</p>
					}
				</div>
			</div>
		}
	</ChildContent>
</DDropdown>

@code {
	[Inject] EmojiService EmojiService { get; set; }

	/// <summary>The trigger's content: an icon, as a rule.</summary>
	[Parameter] public RenderFragment ChildContent { get; set; }
	/// <summary>`:shortcode:` for one of the server's custom emoji, the character itself for a unicode one.</summary>
	[Parameter] public EventCallback<string> OnPick { get; set; }
	/// <summary>Emoji shown first while nothing is searched (a card's quick reactions).</summary>
	[Parameter] public IReadOnlyList<string> Quick { get; set; } = [];
	/// <summary>The trigger's name, its title and aria-label.</summary>
	[Parameter] public string TriggerLabel { get; set; }
	[Parameter] public string TriggerClass { get; set; } = "btn btn-sm";
	[Parameter] public string ActiveTriggerClass { get; set; } = "btn btn-sm btn-active";
	[Parameter] public string ContentClass { get; set; } = "mt-2 p-2 rounded-box";
	[Parameter] public DDropdownPlacement Placement { get; set; }
	[Parameter] public DDropdownAlign Align { get; set; }
	/// <summary>The choices can't be made now (the caller is busy with the last one).</summary>
	[Parameter] public bool ChoicesDisabled { get; set; }
	/// <summary>Passed to the dropdown: its class, a data- hook.</summary>
	[Parameter(CaptureUnmatchedValues = true)] public IReadOnlyDictionary<string, object> AdditionalAttributes { get; set; }

	bool isOpen;
	string query;
	List<CustomEmoji> custom = [];

	IReadOnlyDictionary<string, object> TriggerHooks => new Dictionary<string, object>
	{
		["data-emoji-picker-open"] = true,
		["aria-label"] = TriggerLabel
	};

	// what is searched: a shortcode may be typed with its colons
	string Searched => query?.Trim().Trim(':') is { Length: > 0 } searched ? searched : null;

	List<string> QuickShown => Searched is null ? [.. Quick] : [];

	// the server's emoji by category, those with none first
	List<IGrouping<string, CustomEmoji>> CustomShown =>
	[
		.. custom.Where(e => Searched is not { } searched || e.Shortcode.Contains(searched, StringComparison.OrdinalIgnoreCase)
				|| e.Category?.Contains(searched, StringComparison.OrdinalIgnoreCase) == true)
			.GroupBy(e => e.Category ?? string.Empty)
			.OrderBy(g => g.Key.Length == 0 ? 0 : 1)
			.ThenBy(g => g.Key, StringComparer.CurrentCultureIgnoreCase)
	];

	List<UnicodeEmojis.Group> UnicodeShown => Searched is not { } searched
		? [.. UnicodeEmojis.Groups]
		:
		[
			.. UnicodeEmojis.Groups
				.Select(g => g with
				{
					Emojis = [.. g.Emojis.Where(e => e.Character == searched || e.Shortcode.Contains(searched, StringComparison.OrdinalIgnoreCase)
						|| e.Words?.Contains(searched, StringComparison.OrdinalIgnoreCase) == true)]
				})
				.Where(g => g.Emojis.Count > 0)
		];

	// the still picture when the reader asked for less motion (an animated GIF moves)
	string PictureOf(CustomEmoji emoji) => CascadingState.Status.PrefersReducedMotion() && emoji.StaticUrl is { Length: > 0 } still ? still : emoji.Url;

	async Task Opened(bool open)
	{
		isOpen = open;
		if (!open)
		{
			query = null;
			return;
		}

		custom = await EmojiService.Custom();
		IsLoading = false;
	}

	void Search(string searched) => query = searched;

	// Enter takes the first emoji found
	async Task PickFirst(KeyboardEventArgs e)
	{
		if (e.Key != "Enter" || Searched is null || IsDefaultDisabled || ChoicesDisabled)
			return;

		if (CustomShown.SelectMany(g => g).FirstOrDefault() is { } first)
		{
			await Pick($":{first.Shortcode}:");
			return;
		}
		if (UnicodeShown.SelectMany(g => g.Emojis).FirstOrDefault() is { } unicode)
			await Pick(unicode.Character);
	}

	// closed first: what the choice opens (the notice that reactions are public) is not under it
	async Task Pick(string emoji)
	{
		isOpen = false;
		query = null;
		await OnPick.InvokeAsync(emoji);
	}
}