import { and, asc, eq, inArray, or, sql } from "drizzle-orm";
import type { Metadata } from "next";
import { notFound } from "next/navigation";
import { getTranslations } from "next-intl/server";
import type { CSSProperties } from "react";
import { postComment } from "@/actions/article-comments";
import { toggleReaction } from "@/actions/article-reactions";
import Link from "@/components/link";
import { ContentCard, EmptyState } from "@/components/public/ui";
import { SanitizedHtml } from "@/components/shared/sanitized-html";
import { auth } from "@/lib/auth";
import { cachedQuery } from "@/lib/cached-db";
import {
	db,
	User,
	WebsiteArticleComments,
	WebsiteArticleReactions,
	WebsiteArticles,
} from "@/lib/db";
import { excerpt } from "@/lib/format";
import { formatDate } from "@/lib/format-date";
import { sanitize } from "@/lib/sanitize";

type SearchParams = Promise<{
	comment?: string;
	reaction?: string;
	error?: string;
}>;

function feedbackStyle(tone: "success" | "error"): CSSProperties {
	const accent =
		tone === "error" ? "var(--color-danger)" : "var(--color-primary)";
	return {
		margin: 0,
		padding: "0.85rem 1rem",
		borderRadius: "var(--radius-md)",
		border: `1px solid ${accent}`,
		color: "var(--color-text-readable, var(--color-text))",
		fontSize: "0.9rem",
		fontWeight: 600,
		background: "var(--color-surface)",
		borderLeft: `4px solid ${accent}`,
	};
}

export async function generateMetadata({
	params,
}: {
	params: Promise<{ slug: string }>;
}): Promise<Metadata> {
	const appUrl = process.env.APP_URL ?? "http://localhost:3000";
	const { slug } = await params;
	const [article] = await db
		.select({
			title: WebsiteArticles.title,
			shortStory: WebsiteArticles.shortStory,
		})
		.from(WebsiteArticles)
		.where(
			and(
				eq(WebsiteArticles.slug, slug),
				eq(WebsiteArticles.status, "published"),
				or(
					sql`${WebsiteArticles.publishAt} IS NULL`,
					sql`${WebsiteArticles.publishAt} <= NOW()`,
				),
			),
		)
		.limit(1)
		.catch(() => []);
	if (!article) return { title: "Article" };
	return {
		title: article.title,
		description: excerpt(article.shortStory, 160),
		alternates: { canonical: `${appUrl}/news/${slug}` },
		openGraph: {
			title: article.title,
			description: excerpt(article.shortStory, 160),
			type: "article",
			url: `${appUrl}/news/${slug}`,
		},
		twitter: { card: "summary", title: article.title },
	};
}

// The reaction set offered by the voting UI. Must stay in sync with
// ALLOWED_REACTIONS in src/actions/article-reactions.ts.
const REACTIONS: { key: string; emoji: string }[] = [
	{ key: "like", emoji: "👍" },
	{ key: "love", emoji: "❤️" },
	{ key: "wow", emoji: "😮" },
];

export default async function ArticlePage({
	params,
	searchParams,
}: {
	params: Promise<{ slug: string }>;
	searchParams: SearchParams;
}) {
	const { slug } = await params;
	const { comment, reaction, error } = await searchParams;
	const t = await getTranslations("pages.article");

	const article = await cachedQuery(
		`article:slug:${slug}`,
		async () => {
			const [row] = await db
				.select({
					id: WebsiteArticles.id,
					slug: WebsiteArticles.slug,
					title: WebsiteArticles.title,
					shortStory: WebsiteArticles.shortStory,
					fullStory: WebsiteArticles.fullStory,
					image: WebsiteArticles.image,
					createdAt: WebsiteArticles.createdAt,
					updatedAt: WebsiteArticles.updatedAt,
				})
				.from(WebsiteArticles)
				.where(
					and(
						eq(WebsiteArticles.slug, slug),
						eq(WebsiteArticles.status, "published"),
						or(
							sql`${WebsiteArticles.publishAt} IS NULL`,
							sql`${WebsiteArticles.publishAt} <= NOW()`,
						),
					),
				)
				.limit(1)
				.catch(() => []);
			return row ?? null;
		},
		60,
	);
	if (!article) notFound();

	const articleId = article.id;

	const session = await auth();
	const loggedIn = Boolean(session?.user?.id);
	const sessionUserId = session?.user?.id ? Number(session.user.id) : null;

	// Reaction counts grouped by reaction type for this article, plus the
	// signed-in user's currently-active reaction (so its button reads as pressed).
	let reactionCounts = new Map<string, number>();
	let myReaction: string | null = null;
	try {
		const rows = await db
			.select({
				reaction: WebsiteArticleReactions.reaction,
				userId: WebsiteArticleReactions.userId,
			})
			.from(WebsiteArticleReactions)
			.where(
				and(
					eq(WebsiteArticleReactions.articleId, articleId),
					eq(WebsiteArticleReactions.active, true),
				),
			);
		for (const r of rows) {
			reactionCounts.set(r.reaction, (reactionCounts.get(r.reaction) ?? 0) + 1);
			if (sessionUserId !== null && r.userId === sessionUserId)
				myReaction = r.reaction;
		}
	} catch {
		reactionCounts = new Map();
		myReaction = null;
	}

	// Comments for this article (oldest first).
	let comments: (typeof WebsiteArticleComments.$inferSelect)[] = [];
	try {
		comments = await db
			.select()
			.from(WebsiteArticleComments)
			.where(eq(WebsiteArticleComments.articleId, articleId))
			.orderBy(asc(WebsiteArticleComments.createdAt))
			.limit(200);
	} catch {
		comments = [];
	}

	// Resolve usernames for the commenters (userId is the emulator users.id, Int).
	const commenterIds = Array.from(new Set(comments.map((c) => c.userId)));
	let usernameById = new Map<number, string>();
	if (commenterIds.length > 0) {
		try {
			const users = await db
				.select({ id: User.id, username: User.username })
				.from(User)
				.where(inArray(User.id, commenterIds));
			usernameById = new Map(users.map((u) => [u.id, u.username]));
		} catch {
			usernameById = new Map();
		}
	}

	const errorMessage =
		error === "empty"
			? t("errors.empty")
			: error === "moderated"
				? t("errors.moderated")
				: error === "ratelimit"
					? t("errors.ratelimit")
					: error === "invalid"
						? t("errors.invalid")
						: error === "not_found"
							? t("errors.notFound")
							: error
								? t("errors.error")
								: null;

	return (
		<main className="page-grid">
			{comment === "posted" ? (
				<div role="status" style={feedbackStyle("success")}>
					{t("success.posted")}
				</div>
			) : null}
			{reaction === "1" ? (
				<div role="status" style={feedbackStyle("success")}>
					{t("success.reaction")}
				</div>
			) : null}
			{errorMessage ? (
				<div role="alert" style={feedbackStyle("error")}>
					{errorMessage}
				</div>
			) : null}

			<ContentCard
				icon="📰"
				title={article.title}
				subtitle={
					article.createdAt ? formatDate(article.createdAt, "date") : undefined
				}
				action={
					<Link className="btn btn-outline" href="/news">
						{t("backToNews")}
					</Link>
				}
			>
				{article.image ? (
					// eslint-disable-next-line @next/next/no-img-element
					<img
						src={article.image}
						alt=""
						decoding="async"
						style={{ width: "100%", borderRadius: 10, margin: "0 0 1rem" }}
					/>
				) : null}
				{/* Article body is rich HTML (atom uses TinyMCE) — sanitised server-side. */}
				<SanitizedHtml
					html={sanitize(article.fullStory)}
					className="article-body"
				/>
			</ContentCard>

			{/* ── Reactions ─────────────────────────────────────────── */}
			<ContentCard
				icon="💬"
				title={t("reactionsTitle")}
				subtitle={t("reactionsSubtitle")}
			>
				{loggedIn ? (
					<div style={{ display: "flex", gap: "0.5rem", flexWrap: "wrap" }}>
						{REACTIONS.map((r) => {
							const active = myReaction === r.key;
							const count = reactionCounts.get(r.key) ?? 0;
							const label = `${r.emoji} ${t(`reaction.${r.key}`)}`;
							return (
								<form key={r.key} action={toggleReaction} style={{ margin: 0 }}>
									<input
										type="hidden"
										name="articleId"
										value={String(articleId)}
									/>
									<input type="hidden" name="slug" value={article.slug} />
									<input type="hidden" name="reaction" value={r.key} />
									<button
										type="submit"
										aria-pressed={active}
										className={`btn ${active ? "btn-primary" : "btn-outline"}`}
										title={
											active
												? t("removeReaction")
												: t("reactWith", { reaction: r.key })
										}
									>
										<span>{label}</span>
										<span
											className="muted"
											style={{
												fontSize: "0.85rem",
												color: "inherit",
												opacity: 0.85,
											}}
										>
											{count}
										</span>
									</button>
								</form>
							);
						})}
					</div>
				) : reactionCounts.size === 0 ? (
					<EmptyState icon="💬">
						{t("noReactions")} <Link href="/login">{t("logIn")}</Link>{" "}
						{t("toReact")}
					</EmptyState>
				) : (
					<>
						<div style={{ display: "flex", gap: "0.5rem", flexWrap: "wrap" }}>
							{REACTIONS.filter(
								(r) => (reactionCounts.get(r.key) ?? 0) > 0,
							).map((r) => (
								<span key={r.key} className="currency">
									<span
										style={{ fontWeight: 800 }}
									>{`${r.emoji} ${t(`reaction.${r.key}`)}`}</span>
									<span className="muted" style={{ fontSize: "0.85rem" }}>
										{reactionCounts.get(r.key) ?? 0}
									</span>
								</span>
							))}
						</div>
						<p className="muted" style={{ marginTop: "0.6rem" }}>
							<Link href="/login">{t("logIn")}</Link> {t("toReact")}
						</p>
					</>
				)}
			</ContentCard>

			{/* ── Comments ──────────────────────────────────────────── */}
			<ContentCard
				icon="🗨️"
				title={t("commentsTitle")}
				subtitle={
					comments.length > 0
						? t("commentsCount", { count: comments.length })
						: t("commentsSubtitle")
				}
			>
				{comments.length === 0 ? (
					<EmptyState icon="🗨️">{t("noComments")}</EmptyState>
				) : (
					<div className="grid" style={{ marginBottom: "1.5rem" }}>
						{comments.map((c) => {
							const name = usernameById.get(c.userId);
							return (
								<article key={String(c.id)} className="card">
									<p
										className="muted"
										style={{ marginTop: 0, marginBottom: "0.35rem" }}
									>
										{name ? (
											<Link href={`/u/${name}`}>{name}</Link>
										) : (
											<span>{t("userNumber", { id: c.userId })}</span>
										)}
										{c.createdAt ? (
											<span> · {formatDate(c.createdAt, "date", "")}</span>
										) : null}
									</p>
									<p style={{ margin: 0, whiteSpace: "pre-wrap" }}>
										{c.comment}
									</p>
								</article>
							);
						})}
					</div>
				)}

				{loggedIn ? (
					<form action={postComment} className="card">
						<input type="hidden" name="articleId" value={String(articleId)} />
						<input type="hidden" name="slug" value={slug} />
						<label
							htmlFor="comment"
							style={{
								display: "block",
								fontWeight: 700,
								marginBottom: "0.5rem",
							}}
						>
							{t("addComment")}
						</label>
						<textarea
							id="comment"
							name="comment"
							required
							maxLength={255}
							rows={3}
							placeholder={t("commentPlaceholder")}
							style={{ width: "100%", resize: "vertical" }}
						/>
						<div style={{ marginTop: "0.75rem" }}>
							<button type="submit" className="btn btn-primary">
								{t("postComment")}
							</button>
						</div>
					</form>
				) : (
					<p className="muted">
						<Link href="/login">{t("logIn")}</Link> {t("toComment")}
					</p>
				)}
			</ContentCard>
		</main>
	);
}