<script lang="ts">
import type { TranscriptionBlockData } from '$lib/types';
import type { components } from '$lib/generated/api';
import { splitByMarkers } from '$lib/utils/transcriptionMarkers';
import { renderTranscriptionBody } from '$lib/utils/mention';
import PersonHoverCard from './PersonHoverCard.svelte';
import type { HoverData, LoadState } from '$lib/types/personHoverCard';
import { goto } from '$app/navigation';
import { SvelteMap, SvelteSet } from 'svelte/reactivity';

type Person = components['schemas']['Person'];
type RelationshipDTO = components['schemas']['RelationshipDTO'];

interface Props {
	blocks: TranscriptionBlockData[];
	onParagraphClick: (annotationId: string) => void;
	highlightBlockId?: string | null;
}

let { blocks, onParagraphClick, highlightBlockId = null }: Props = $props();

let sorted = $derived([...blocks].sort((a, b) => a.sortOrder - b.sortOrder));

// Per-page in-memory cache: a sweep across 20 mentions of the same person
// must not fire 20 backend calls (B15.5). The Promise<HoverData | null> shape
// lets simultaneous hovers share the same in-flight fetch.
const hoverCache = new SvelteMap<string, Promise<HoverData | null>>();
const deletedPersonIds = new SvelteSet<string>();

let activeCard: {
	personId: string;
	cardId: string;
	state: LoadState;
	position: { top: number; left: number };
} | null = $state(null);

const CARD_WIDTH = 320;
const CARD_HEIGHT = 180;
const CARD_GAP = 6;

// Compose splitByMarkers with renderTranscriptionBody. Markers are pre-rendered
// as <em data-marker> tags; text segments run through HTML-escaping + mention
// substitution. The two are concatenated to preserve marker boundaries — markers
// never end up nested inside an anchor (Felix #5324 B19b).
function renderBlockHtml(block: TranscriptionBlockData): string {
	return splitByMarkers(block.text)
		.map((segment) => {
			if (segment.type === 'marker') {
				return `<em data-marker class="text-ink-2 italic">${segment.text}</em>`;
			}
			return renderTranscriptionBody(segment.text, block.mentionedPersons ?? []);
		})
		.join('');
}

function fetchHoverData(personId: string): Promise<HoverData | null> {
	let cached = hoverCache.get(personId);
	if (cached) return cached;

	cached = (async () => {
		const personRes = await fetch(`/api/persons/${personId}`);
		if (personRes.status === 404) return null;
		if (!personRes.ok) throw new Error(`person fetch failed: ${personRes.status}`);
		const person = (await personRes.json()) as Person;

		const relRes = await fetch(`/api/persons/${personId}/relationships`);
		const relationships: RelationshipDTO[] = relRes.ok
			? ((await relRes.json()) as RelationshipDTO[])
			: [];
		return { person, relationships };
	})();

	hoverCache.set(personId, cached);
	return cached;
}

function computeCardPosition(rect: DOMRect): { top: number; left: number } {
	const vw = window.innerWidth;
	const vh = window.innerHeight;

	let top = rect.bottom + CARD_GAP;
	let left = rect.left;

	// Flip up if the card would overflow the bottom edge OR the mention sits in
	// the bottom 30% of the viewport (Leonie #5329).
	if (vh - rect.bottom < CARD_HEIGHT + CARD_GAP || rect.top > vh * 0.7) {
		top = rect.top - CARD_HEIGHT - CARD_GAP;
	}

	// Flip left if <300px from the right edge.
	if (vw - rect.left < 300) {
		left = rect.right - CARD_WIDTH;
	}

	return {
		top: Math.max(0, top + window.scrollY),
		left: Math.max(0, left + window.scrollX)
	};
}

async function handleMentionEnter(event: Event) {
	const link = event.target as HTMLAnchorElement;
	const personId = link.dataset.personId;
	if (!personId) return;
	if (deletedPersonIds.has(personId)) return;

	const cardId = `person-hover-card-${personId}`;
	link.setAttribute('aria-describedby', cardId);

	const rect = link.getBoundingClientRect();
	const position = computeCardPosition(rect);

	activeCard = { personId, cardId, position, state: { status: 'loading' } };

	try {
		const data = await fetchHoverData(personId);
		// Bail if a different mention is now active
		if (!activeCard || activeCard.personId !== personId) return;

		if (data === null) {
			deletedPersonIds.add(personId);
			link.setAttribute('data-person-deleted', 'true');
			activeCard = null;
			return;
		}

		activeCard = {
			personId,
			cardId,
			position,
			state: { status: 'loaded', person: data.person, relationships: data.relationships }
		};
	} catch {
		if (!activeCard || activeCard.personId !== personId) return;
		activeCard = { personId, cardId, position, state: { status: 'error' } };
	}
}

function handleMentionLeave(event: Event) {
	const link = event.target as HTMLAnchorElement;
	link.removeAttribute('aria-describedby');
	activeCard = null;
}

async function handleMentionClick(event: MouseEvent) {
	const link = event.target as HTMLAnchorElement;
	const personId = link.dataset.personId;
	if (!personId) return;
	if (deletedPersonIds.has(personId)) {
		event.preventDefault();
		return;
	}
	event.preventDefault();
	await goto(`/persons/${personId}`);
}

// Attach delegated event listeners on each rendered block. Using {@html ...}
// for the body means we cannot bind events declaratively to the injected
// anchors, so we hook up listeners via a Svelte action when the wrapper mounts.
function attachMentionHandlers(node: HTMLElement) {
	function onEnter(e: Event) {
		const t = e.target as HTMLElement;
		if (t.matches?.('a.person-mention')) handleMentionEnter(e);
	}
	function onLeave(e: Event) {
		const t = e.target as HTMLElement;
		if (t.matches?.('a.person-mention')) handleMentionLeave(e);
	}
	function onClick(e: MouseEvent) {
		const t = e.target as HTMLElement;
		if (t.matches?.('a.person-mention')) handleMentionClick(e);
	}
	// mouseenter does not bubble — capture it.
	node.addEventListener('mouseenter', onEnter, true);
	node.addEventListener('mouseleave', onLeave, true);
	node.addEventListener('click', onClick);

	return {
		destroy() {
			node.removeEventListener('mouseenter', onEnter, true);
			node.removeEventListener('mouseleave', onLeave, true);
			node.removeEventListener('click', onClick);
		}
	};
}
</script>

<article class="px-6 py-8" use:attachMentionHandlers>
	{#each sorted as block (block.id)}
		<div
			class="-mx-2 mb-6 cursor-pointer rounded-sm px-2 py-1 font-serif text-[16px] leading-[1.85] text-ink transition-colors hover:bg-turquoise/10"
			class:flash-highlight={highlightBlockId === block.id}
			data-block-id={block.id}
			onclick={() => onParagraphClick(block.annotationId)}
			role="button"
			tabindex="0"
			onkeydown={(e) => {
				if (e.key === 'Enter' || e.key === ' ') onParagraphClick(block.annotationId);
			}}
		>
			<!-- eslint-disable-next-line svelte/no-at-html-tags -- renderTranscriptionBody escapes all HTML before injecting mention links; mirrors CommentMessage.svelte -->
			{@html renderBlockHtml(block)}
		</div>
	{/each}
</article>

{#if activeCard}
	<PersonHoverCard
		personId={activeCard.personId}
		cardId={activeCard.cardId}
		position={activeCard.position}
		state={activeCard.state}
	/>
{/if}

<style>
@keyframes flash {
	0% {
		background-color: color-mix(in srgb, var(--color-turquoise) 18%, transparent);
	}
	100% {
		background-color: transparent;
	}
}

.flash-highlight {
	animation: flash 1.2s ease-out;
}

@media (prefers-reduced-motion: reduce) {
	.flash-highlight {
		animation: none;
		background-color: color-mix(in srgb, var(--color-turquoise) 18%, transparent);
	}
}
</style>
