<script lang="ts">
	import { goto } from '$app/navigation';
	import { getToken } from '$lib/auth';
	import { api } from '$lib/api';
	import { connectSse, disconnectSse, onSseEvent } from '$lib/sse';
	import { onMount, onDestroy } from 'svelte';
	import FeedGrid from '$lib/components/FeedGrid.svelte';
	import FeedListCard from '$lib/components/FeedListCard.svelte';
	import HashtagChips from '$lib/components/HashtagChips.svelte';
	import LightboxModal from '$lib/components/LightboxModal.svelte';
	import OnboardingGuide from '$lib/components/OnboardingGuide.svelte';
	import type { FeedUpload, FeedResponse, HashtagCount } from '$lib/types';

	let uploads = $state<FeedUpload[]>([]);
	let hashtags = $state<HashtagCount[]>([]);
	let selectedHashtag = $state<string | null>(null);
	let nextCursor = $state<string | null>(null);
	let loadingMore = $state(false);
	let selectedUpload = $state<FeedUpload | null>(null);
	let sentinel: HTMLDivElement;

	// View mode
	let viewMode = $state<'list' | 'grid'>('list');

	// Grid search / filter state
	let searchQuery = $state('');
	let showAutocomplete = $state(false);

	interface Filter { type: 'tag' | 'user'; value: string }
	let activeFilters = $state<Filter[]>([]);

	let unsubscribers: (() => void)[] = [];

	// ── Autocomplete derived from loaded uploads (no extra API calls) ────────
	let allTags = $derived.by(() => {
		const freq = new Map<string, number>();
		for (const u of uploads) {
			for (const m of (u.caption ?? '').matchAll(/#(\w+)/g)) {
				const t = m[1].toLowerCase();
				freq.set(t, (freq.get(t) ?? 0) + 1);
			}
		}
		return [...freq.entries()].sort((a, b) => b[1] - a[1]).map(([t]) => t);
	});

	let allUploaders = $derived([...new Set(uploads.map((u) => u.uploader_name))].sort());

	let suggestions = $derived.by((): Filter[] => {
		const q = searchQuery.trim();
		if (!q) {
			// Show top suggestions on focus
			if (!showAutocomplete) return [];
			return [
				...allUploaders.slice(0, 3).map((u) => ({ type: 'user' as const, value: u })),
				...allTags.slice(0, 3).map((t) => ({ type: 'tag' as const, value: t })),
			];
		}
		if (q.startsWith('#')) {
			const prefix = q.slice(1).toLowerCase();
			return allTags
				.filter((t) => t.startsWith(prefix))
				.slice(0, 8)
				.map((t) => ({ type: 'tag' as const, value: t }));
		}
		const lower = q.toLowerCase();
		return [
			...allUploaders
				.filter((u) => u.toLowerCase().includes(lower))
				.slice(0, 4)
				.map((u) => ({ type: 'user' as const, value: u })),
			...allTags
				.filter((t) => t.includes(lower))
				.slice(0, 4)
				.map((t) => ({ type: 'tag' as const, value: t })),
		];
	});

	// ── Filtered uploads for grid view ───────────────────────────────────────
	let displayUploads = $derived.by(() => {
		if (viewMode === 'list' || activeFilters.length === 0) return uploads;
		const tags = activeFilters.filter((f) => f.type === 'tag').map((f) => f.value);
		const users = activeFilters.filter((f) => f.type === 'user').map((f) => f.value);
		return uploads.filter((u) => {
			const cap = (u.caption ?? '').toLowerCase();
			const passTag = !tags.length || tags.some((t) => cap.includes('#' + t));
			const passUser = !users.length || users.includes(u.uploader_name);
			return passTag && passUser;
		});
	});

	onMount(async () => {
		if (!getToken()) {
			goto('/join');
			return;
		}

		await Promise.all([loadFeed(), loadHashtags()]);
		connectSse();

		unsubscribers.push(
			onSseEvent('new-upload', (data) => {
				try {
					const upload: FeedUpload = JSON.parse(data);
					uploads = [upload, ...uploads];
				} catch { /* ignore */ }
			}),
			onSseEvent('upload-processed', () => loadFeed(true)),
			onSseEvent('like-update', () => loadFeed(true)),
			onSseEvent('new-comment', () => loadFeed(true))
		);

		if (sentinel) {
			const observer = new IntersectionObserver(
				(entries) => {
					if (entries[0].isIntersecting && nextCursor && !loadingMore) loadMore();
				},
				{ rootMargin: '200px' }
			);
			observer.observe(sentinel);
		}
	});

	onDestroy(() => {
		disconnectSse();
		for (const unsub of unsubscribers) unsub();
	});

	async function loadFeed(refresh = false) {
		try {
			const params = new URLSearchParams();
			if (!refresh && nextCursor) params.set('cursor', nextCursor);
			if (selectedHashtag) params.set('hashtag', selectedHashtag);
			params.set('limit', '20');
			const res = await api.get<FeedResponse>(`/feed?${params}`);
			uploads = res.uploads;
			nextCursor = res.next_cursor;
		} catch { /* ignore */ }
	}

	async function loadMore() {
		if (!nextCursor || loadingMore) return;
		loadingMore = true;
		try {
			const params = new URLSearchParams();
			params.set('cursor', nextCursor);
			if (selectedHashtag) params.set('hashtag', selectedHashtag);
			params.set('limit', '20');
			const res = await api.get<FeedResponse>(`/feed?${params}`);
			uploads = [...uploads, ...res.uploads];
			nextCursor = res.next_cursor;
		} catch { /* ignore */ } finally {
			loadingMore = false;
		}
	}

	async function loadHashtags() {
		try {
			hashtags = await api.get<HashtagCount[]>('/hashtags');
		} catch { /* ignore */ }
	}

	function selectHashtag(tag: string | null) {
		selectedHashtag = tag;
		nextCursor = null;
		loadFeed();
	}

	async function handleLike(id: string) {
		try {
			await api.post(`/upload/${id}/like`);
			uploads = uploads.map((u) =>
				u.id === id
					? { ...u, liked_by_me: !u.liked_by_me, like_count: u.liked_by_me ? u.like_count - 1 : u.like_count + 1 }
					: u
			);
			if (selectedUpload?.id === id) {
				selectedUpload = {
					...selectedUpload,
					liked_by_me: !selectedUpload.liked_by_me,
					like_count: selectedUpload.liked_by_me ? selectedUpload.like_count - 1 : selectedUpload.like_count + 1,
				};
			}
		} catch { /* ignore */ }
	}

	function openComments(id: string) {
		const u = uploads.find((u) => u.id === id);
		if (u) selectedUpload = u;
	}

	function selectSuggestion(item: Filter) {
		if (!activeFilters.some((f) => f.type === item.type && f.value === item.value)) {
			activeFilters = [...activeFilters, item];
		}
		searchQuery = '';
		showAutocomplete = false;
	}

	function removeFilter(item: Filter) {
		activeFilters = activeFilters.filter((f) => !(f.type === item.type && f.value === item.value));
	}

	function clearFilters() {
		activeFilters = [];
		searchQuery = '';
	}

	function switchView(mode: 'list' | 'grid') {
		viewMode = mode;
		if (mode === 'list') {
			searchQuery = '';
			showAutocomplete = false;
		}
	}
</script>

<div class="min-h-screen bg-gray-50 pb-24">
	<!-- Sticky header -->
	<div class="sticky top-0 z-30 border-b border-gray-200 bg-white/95 backdrop-blur">
		<div class="mx-auto flex max-w-2xl items-center justify-between px-4 py-3">
			<h1 class="text-lg font-bold text-gray-900">Galerie</h1>

			<!-- List / Grid toggle -->
			<div class="flex items-center gap-1 rounded-lg bg-gray-100 p-1">
				<button
					onclick={() => switchView('list')}
					class="rounded-md p-1.5 transition-colors {viewMode === 'list' ? 'bg-white text-gray-900 shadow-sm' : 'text-gray-400 hover:text-gray-600'}"
					aria-label="Listenansicht"
				>
					<!-- bars-3 -->
					<svg class="h-5 w-5" fill="none" viewBox="0 0 24 24" stroke="currentColor" stroke-width="1.5">
						<path stroke-linecap="round" stroke-linejoin="round" d="M3.75 6.75h16.5M3.75 12h16.5m-16.5 5.25h16.5" />
					</svg>
				</button>
				<button
					onclick={() => switchView('grid')}
					class="rounded-md p-1.5 transition-colors {viewMode === 'grid' ? 'bg-white text-gray-900 shadow-sm' : 'text-gray-400 hover:text-gray-600'}"
					aria-label="Rasteransicht"
				>
					<!-- squares-2x2 -->
					<svg class="h-5 w-5" fill="none" viewBox="0 0 24 24" stroke="currentColor" stroke-width="1.5">
						<path stroke-linecap="round" stroke-linejoin="round" d="M3.75 6A2.25 2.25 0 0 1 6 3.75h2.25A2.25 2.25 0 0 1 10.5 6v2.25a2.25 2.25 0 0 1-2.25 2.25H6a2.25 2.25 0 0 1-2.25-2.25V6ZM3.75 15.75A2.25 2.25 0 0 1 6 13.5h2.25a2.25 2.25 0 0 1 2.25 2.25V18a2.25 2.25 0 0 1-2.25 2.25H6A2.25 2.25 0 0 1 3.75 18v-2.25ZM13.5 6a2.25 2.25 0 0 1 2.25-2.25H18A2.25 2.25 0 0 1 20.25 6v2.25A2.25 2.25 0 0 1 18 10.5h-2.25a2.25 2.25 0 0 1-2.25-2.25V6ZM13.5 15.75a2.25 2.25 0 0 1 2.25-2.25H18a2.25 2.25 0 0 1 2.25 2.25V18A2.25 2.25 0 0 1 18 20.25h-2.25A2.25 2.25 0 0 1 13.5 18v-2.25Z" />
					</svg>
				</button>
			</div>
		</div>

		<!-- List view: hashtag chips -->
		{#if viewMode === 'list'}
			<div class="mx-auto max-w-2xl px-4 pb-2">
				<HashtagChips {hashtags} selected={selectedHashtag} onselect={selectHashtag} />
			</div>
		{/if}

		<!-- Grid view: search bar + autocomplete -->
		{#if viewMode === 'grid'}
			<div class="mx-auto max-w-2xl px-4 pb-3">
				<div class="relative">
					<div class="flex items-center gap-2 rounded-xl border border-gray-200 bg-gray-50 px-3 py-2 focus-within:border-blue-400 focus-within:bg-white focus-within:ring-1 focus-within:ring-blue-200">
						<svg class="h-4 w-4 shrink-0 text-gray-400" fill="none" viewBox="0 0 24 24" stroke="currentColor" stroke-width="2">
							<path stroke-linecap="round" stroke-linejoin="round" d="M21 21l-5.197-5.197m0 0A7.5 7.5 0 1 0 5.196 5.196a7.5 7.5 0 0 0 10.607 10.607Z" />
						</svg>
						<input
							type="search"
							placeholder="Nutzer oder #Tag suchen…"
							bind:value={searchQuery}
							onfocus={() => (showAutocomplete = true)}
							onblur={() => setTimeout(() => (showAutocomplete = false), 150)}
							class="min-w-0 flex-1 bg-transparent text-sm text-gray-900 placeholder-gray-400 outline-none"
						/>
						{#if searchQuery}
							<button
								onclick={() => { searchQuery = ''; }}
								class="shrink-0 text-gray-400 hover:text-gray-600"
								aria-label="Suche löschen"
							>
								<svg class="h-4 w-4" fill="none" viewBox="0 0 24 24" stroke="currentColor" stroke-width="2">
									<path stroke-linecap="round" stroke-linejoin="round" d="M6 18 18 6M6 6l12 12" />
								</svg>
							</button>
						{/if}
					</div>

					<!-- Autocomplete dropdown -->
					{#if showAutocomplete && suggestions.length > 0}
						<div class="absolute left-0 right-0 top-full z-50 mt-1 overflow-hidden rounded-xl border border-gray-200 bg-white shadow-lg">
							{#each suggestions as item}
								<button
									class="flex w-full items-center gap-3 px-4 py-2.5 text-left text-sm hover:bg-gray-50"
									onmousedown={() => selectSuggestion(item)}
								>
									{#if item.type === 'user'}
										<svg class="h-4 w-4 shrink-0 text-gray-400" fill="none" viewBox="0 0 24 24" stroke="currentColor" stroke-width="1.5">
											<path stroke-linecap="round" stroke-linejoin="round" d="M15.75 6a3.75 3.75 0 1 1-7.5 0 3.75 3.75 0 0 1 7.5 0ZM4.501 20.118a7.5 7.5 0 0 1 14.998 0A17.933 17.933 0 0 1 12 21.75c-2.676 0-5.216-.584-7.499-1.632Z" />
										</svg>
										<span class="font-medium text-gray-900">{item.value}</span>
									{:else}
										<span class="text-blue-500 font-medium">#</span>
										<span class="font-medium text-gray-900">{item.value}</span>
									{/if}
								</button>
							{/each}
						</div>
					{/if}
				</div>

				<!-- Active filter chips -->
				{#if activeFilters.length > 0}
					<div class="mt-2 flex flex-wrap items-center gap-1.5">
						{#each activeFilters as filter}
							<span class="flex items-center gap-1 rounded-full bg-blue-100 px-2.5 py-0.5 text-xs font-medium text-blue-700">
								{filter.type === 'tag' ? '#' : ''}{filter.value}
								<button onclick={() => removeFilter(filter)} class="ml-0.5 hover:text-blue-900" aria-label="Filter entfernen">
									<svg class="h-3 w-3" fill="none" viewBox="0 0 24 24" stroke="currentColor" stroke-width="2.5">
										<path stroke-linecap="round" stroke-linejoin="round" d="M6 18 18 6M6 6l12 12" />
									</svg>
								</button>
							</span>
						{/each}
						{#if activeFilters.length >= 2}
							<button onclick={clearFilters} class="text-xs text-gray-400 hover:text-gray-600">
								Alle löschen
							</button>
						{/if}
					</div>
				{/if}
			</div>
		{/if}
	</div>

	<!-- Content -->
	{#if uploads.length === 0}
		<div class="py-20 text-center">
			<p class="text-lg text-gray-400">Noch keine Fotos.</p>
			<p class="mt-1 text-sm text-gray-400">Tippe auf den Plus-Button unten!</p>
		</div>
	{:else if viewMode === 'list'}
		<!-- List view: chronological full-width cards -->
		<div class="mx-auto max-w-2xl">
			{#each uploads as upload (upload.id)}
				<FeedListCard
					{upload}
					onlike={handleLike}
					oncomment={openComments}
					onselect={(u) => (selectedUpload = u)}
				/>
			{/each}
		</div>
	{:else}
		<!-- Grid view: 3-col, filters applied -->
		<div class="mx-auto max-w-2xl">
			{#if displayUploads.length === 0}
				<div class="py-16 text-center">
					<p class="text-sm text-gray-400">Keine Treffer für die gewählten Filter.</p>
					<button onclick={clearFilters} class="mt-2 text-sm text-blue-600 hover:underline">Filter zurücksetzen</button>
				</div>
			{:else}
				<FeedGrid
					uploads={displayUploads}
					onlike={handleLike}
					oncomment={openComments}
					onselect={(u) => (selectedUpload = u)}
					threeCol={true}
				/>
			{/if}
		</div>
	{/if}

	<!-- Infinite scroll sentinel -->
	<div class="mx-auto max-w-2xl">
		<div bind:this={sentinel} class="h-4"></div>
		{#if loadingMore}
			<div class="py-4 text-center">
				<div class="inline-block h-6 w-6 animate-spin rounded-full border-2 border-gray-300 border-t-blue-600"></div>
			</div>
		{/if}
	</div>
</div>

<!-- Lightbox -->
{#if selectedUpload}
	<LightboxModal
		upload={selectedUpload}
		onclose={() => (selectedUpload = null)}
		onlike={handleLike}
	/>
{/if}

<!-- First-visit onboarding guide -->
<OnboardingGuide />
