import { blogPosts } from "./blog-data";
import { authors } from "./author-data";
import type { BlogPost, PillarKey, AuthorProfile } from "./types";

/**
 * Blog slugs that are 301-redirected in next.config.mjs.
 * They must not appear in the blog index, the learn pillars, the sitemap
 * or IndexNow submissions - linking to a redirect source wastes crawl budget
 * and passes link equity through an unnecessary hop.
 * Keep this in sync with the redirects() block in next.config.mjs.
 */
export const REDIRECTED_BLOG_SLUGS = new Set<string>([
    "qr-code-analytics",
    "qr-code-restaurant-menu",
    // Duplicate of the standalone /qr-code-print-size-guide, which is the version
    // Google actually ranks. Both were live and self-canonical until 2026-08-13.
    "qr-code-print-size-guide",
]);

export function isRedirectedSlug(slug: string): boolean {
    return REDIRECTED_BLOG_SLUGS.has(slug);
}

export function getPublishedPosts(): BlogPost[] {
    const currentDate = new Date();
    return blogPosts.filter(p => {
        if (!p.published) return false;
        if (REDIRECTED_BLOG_SLUGS.has(p.slug)) return false;
        const publishDate = p.datePublished ? new Date(p.datePublished) : new Date(p.date);
        return publishDate <= currentDate;
    });
}

export function getPostBySlug(slug: string): BlogPost | undefined {
    return blogPosts.find(p => p.slug === slug);
}

export function getPublishedPostBySlug(slug: string): BlogPost | undefined {
    const p = getPostBySlug(slug);
    if (!p?.published) return undefined;

    const currentDate = new Date();
    const publishDate = p.datePublished ? new Date(p.datePublished) : new Date(p.date);
    return publishDate <= currentDate ? p : undefined;
}

export function getPostsByPillar(pillar: PillarKey): BlogPost[] {
    return getPublishedPosts()
        .filter(p => p.pillar === pillar)
        .sort((a, b) => (new Date(a.datePublished).getTime() < new Date(b.datePublished).getTime() ? 1 : -1));
}

export function getAuthorBySlug(slug: string): AuthorProfile | undefined {
    return authors.find(a => a.slug === slug);
}

export function getPostsByAuthor(slug: string): BlogPost[] {
    return getPublishedPosts()
        .filter(p => p.authorSlug === slug)
        .sort((a, b) => (new Date(a.datePublished).getTime() < new Date(b.datePublished).getTime() ? 1 : -1));
}

export function getRelatedPosts(post: BlogPost, limit = 4): BlogPost[] {
    const published = getPublishedPosts();

    // explicit relatedSlugs first
    const explicit = (post.relatedSlugs ?? [])
        .map(s => published.find(p => p.slug === s))
        .filter((p): p is BlogPost => !!p);

    if (explicit.length >= limit) return explicit.slice(0, limit);

    // fallback: same pillar, not itself, newest
    const fallback = published
        .filter(p => p.slug !== post.slug && p.pillar === post.pillar)
        .slice(0, limit - explicit.length);

    return [...explicit, ...fallback];
}