"use server";

import { revalidatePath } from "next/cache";
import { auth } from "@/lib/auth";
import { prisma } from "@/lib/prisma";

// The reaction set the UI offers. The action rejects anything outside this list
// so the website_article_reactions.reaction VARCHAR(50) only ever holds known
// values. Keep this in sync with REACTIONS in src/app/news/[slug]/page.tsx.
const ALLOWED_REACTIONS = new Set(["like", "love", "wow"]);

/**
 * Toggle the SIGNED-IN user's reaction on a news article.
 *
 * The voter id is read from the session (re-fetched via auth()), never from the
 * submitted FormData, so a crafted form cannot vote as another account. A user
 * has at most one ACTIVE reaction per article:
 *   - clicking the reaction they already have active -> deactivates it (un-vote)
 *   - clicking a different reaction -> that reaction becomes active and any other
 *     reaction rows for this user/article are deactivated
 *   - first-ever reaction of a type -> a new active row is created
 *
 * Rows are toggled (active flag) rather than deleted so a user's history of
 * reaction types is preserved. website_article_reactions has no composite
 * unique key, so we resolve the existing row with findFirst rather than upsert.
 */
export async function toggleReaction(formData: FormData): Promise<void> {
  const session = await auth();
  if (!session?.user?.id) return;

  const userId = Number(session.user.id);
  if (!Number.isFinite(userId)) return;

  const reaction = String(formData.get("reaction") ?? "")
    .trim()
    .toLowerCase();
  if (!ALLOWED_REACTIONS.has(reaction)) return;

  const articleIdRaw = String(formData.get("articleId") ?? "").trim();
  if (!/^\d+$/.test(articleIdRaw)) return;

  let articleId: bigint;
  try {
    articleId = BigInt(articleIdRaw);
  } catch {
    return;
  }

  let slug: string | null;
  try {
    // Confirm the article exists (and grab its slug for revalidation).
    const article = await prisma.websiteArticles.findUnique({
      where: { id: articleId },
      select: { slug: true },
    });
    if (!article) return;
    slug = article.slug;

    // The user's current row for THIS reaction on THIS article, if any.
    const existing = await prisma.websiteArticleReactions.findFirst({
      where: { userId, articleId, reaction },
      select: { id: true, active: true },
    });

    if (existing?.active) {
      // Already reacting with this exact reaction -> un-vote (deactivate it).
      await prisma.websiteArticleReactions.update({
        where: { id: existing.id },
        data: { active: false },
      });
    } else {
      // Switching to (or first-time picking) this reaction: clear any other
      // active reaction by this user on this article, then activate this one.
      await prisma.websiteArticleReactions.updateMany({
        where: { userId, articleId, active: true },
        data: { active: false },
      });

      if (existing) {
        await prisma.websiteArticleReactions.update({
          where: { id: existing.id },
          data: { active: true },
        });
      } else {
        await prisma.websiteArticleReactions.create({
          data: { userId, articleId, reaction, active: true },
        });
      }
    }
  } catch {
    // DB unavailable — fail soft; nothing to persist.
    return;
  }

  if (slug) revalidatePath(`/news/${slug}`);
}