import { type CollectionEntry, getCollection } from "astro:content";
import { collectionDateSort } from "@/utils/date";

/** filter out draft posts based on the environment and optionally archived posts */
export async function getAllPosts(includeArchived = false): Promise<CollectionEntry<"post">[]> {
	const posts = await getCollection("post", ({ data }) => {
		const isDraftFilter = import.meta.env.PROD ? !data.draft : true;
		const isArchivedFilter = includeArchived || !data.tags.includes("archived");
		return isDraftFilter && isArchivedFilter;
	});

	// Fetch pleroma posts and cast them to post type since schemas are now compatible
	const pleromaPosts = await getCollection("pleroma").catch(() => []);
	const pleromaAsPost = pleromaPosts as unknown as CollectionEntry<"post">[];

	return [...posts, ...pleromaAsPost];
}

/** Get tag metadata by tag name */
export async function getTagMeta(tag: string): Promise<CollectionEntry<"tag"> | undefined> {
	const tagEntries = await getCollection("tag", (entry) => {
		return entry.id === tag;
	});
	return tagEntries[0];
}

/** groups posts by year (based on option siteConfig.sortPostsByUpdatedDate), using the year as the key
 *  Note: This function doesn't filter draft posts, pass it the result of getAllPosts above to do so.
 */
export function groupPostsByYear(posts: CollectionEntry<"post">[]) {
	return posts.reduce<Record<string, CollectionEntry<"post">[]>>((acc, post) => {
		const year = post.data.publishDate.getFullYear();
		if (!acc[year]) {
			acc[year] = [];
		}
		acc[year]?.push(post);
		return acc;
	}, {});
}

/** returns all tags created from posts (inc duplicate tags)
 *  Note: This function doesn't filter draft posts, pass it the result of getAllPosts above to do so.
 *  */
export function getAllTags(posts: CollectionEntry<"post">[]) {
	return posts.flatMap((post) => [...post.data.tags]);
}

/** returns all unique tags created from posts
 *  Note: This function doesn't filter draft posts, pass it the result of getAllPosts above to do so.
 *  */
export function getUniqueTags(posts: CollectionEntry<"post">[]) {
	return [...new Set(getAllTags(posts))];
}

/** returns a count of each unique tag - [[tagName, count], ...]
 *  Note: This function doesn't filter draft posts, pass it the result of getAllPosts above to do so.
 *  */
export function getUniqueTagsWithCount(posts: CollectionEntry<"post">[]): [string, number][] {
	return [
		...getAllTags(posts).reduce(
			(acc, t) => acc.set(t, (acc.get(t) ?? 0) + 1),
			new Map<string, number>(),
		),
	].sort((a, b) => b[1] - a[1]);
}

export type PostCategory = "regular" | "microblog" | "archived";

/** Determine the category of a post based on its tags. "archived" takes precedence over "microblog". */
export function getPostCategory(post: CollectionEntry<"post">): PostCategory {
	const tags = post.data.tags;
	if (tags.includes("archived")) return "archived";
	if (tags.includes("microblog")) return "microblog";
	return "regular";
}

export interface PostNavigation {
	prevPost: CollectionEntry<"post"> | null;
	nextPost: CollectionEntry<"post"> | null;
}

/** Get previous (newer) and next (older) posts within the same category.
 *  Posts are sorted newest-first. prevPost = newer, nextPost = older.
 */
export function getPostNavigation(
	allPosts: CollectionEntry<"post">[],
	currentPost: CollectionEntry<"post">,
): PostNavigation {
	const category = getPostCategory(currentPost);
	const sameCategoryPosts = allPosts
		.filter((p) => getPostCategory(p) === category)
		.sort(collectionDateSort);

	const currentIndex = sameCategoryPosts.findIndex((p) => p.id === currentPost.id);

	return {
		prevPost: currentIndex > 0 ? (sameCategoryPosts[currentIndex - 1] ?? null) : null,
		nextPost:
			currentIndex < sameCategoryPosts.length - 1
				? (sameCategoryPosts[currentIndex + 1] ?? null)
				: null,
	};
}