import type { CollectionConfig } from 'payload';
import { revalidatePath } from 'next/cache';
import { lexicalEditor, BlocksFeature } from '@payloadcms/richtext-lexical';
import { Callout } from '@/blocks/Callout';

/**
 * Drop the cached copy of a post page when it changes.
 *
 * Only the post page needs this. The blog index, the RSS feed and the content
 * sitemap are force-dynamic — they have no dynamic params, so Next would
 * prerender them at build time, where CI has no database — which means they
 * already reflect a change on the next request.
 *
 * /blog/[slug] is ISR: generated on first request and cached, so without this
 * an edit to an already-published post would not appear until the revalidate
 * window expired — up to an hour of a writer concluding that saving is broken.
 *
 * Payload runs in the same process as Next, so this is a direct revalidatePath
 * call: no webhook, no shared secret, no network hop to get wrong.
 */
function revalidatePost(slug: string) {
  revalidatePath(`/blog/${slug}`);
}

export const Posts: CollectionConfig = {
  slug: 'posts',
  access: {
    /*
     * Drafts must be hidden here, not in the pages that query this collection.
     *
     * From Payload's own documentation: "The `draft` argument alone does not
     * restrict documents with `_status: 'draft'` from being returned by the
     * API." The blog index and post page both filter on `_status`, but that
     * is a convenience, not a control — a direct GET /cms-api/posts would
     * hand every unpublished draft to any visitor.
     *
     * Returning a query constraint rather than a boolean is the documented
     * mechanism: Payload merges it into every read for an anonymous caller.
     */
    read: ({ req }) => {
      if (req.user) return true;
      return { _status: { equals: 'published' } };
    },
  },
  admin: {
    useAsTitle: 'title',
    defaultColumns: ['title', 'publishedAt', '_status'],
  },
  versions: {
    // Posts get written across several sittings and previewed before they go
    // live. Without drafts, saving is publishing.
    drafts: true,
  },
  hooks: {
    afterChange: [({ doc }) => { revalidatePost(String(doc.slug)); }],
    afterDelete: [({ doc }) => { revalidatePost(String(doc.slug)); }],
  },
  fields: [
    { name: 'title', type: 'text', required: true },
    {
      name: 'slug',
      type: 'text',
      required: true,
      unique: true,
      index: true,
      admin: {
        position: 'sidebar',
        description: 'The URL segment. Never change it after publishing.',
      },
    },
    {
      name: 'publishedAt',
      type: 'date',
      required: true,
      admin: { position: 'sidebar', date: { pickerAppearance: 'dayOnly' } },
    },
    {
      name: 'excerpt',
      type: 'textarea',
      required: true,
      maxLength: 200,
      admin: {
        description: 'Shown on the index and used as the meta description.',
      },
    },
    { name: 'heroImage', type: 'upload', relationTo: 'media' },
    {
      name: 'content',
      type: 'richText',
      required: true,
      editor: lexicalEditor({
        features: ({ defaultFeatures }) => [
          ...defaultFeatures,
          BlocksFeature({ blocks: [Callout] }),
        ],
      }),
    },
  ],
};