package publisher

import (
	"context"
	"iter"

	"lmika.dev/lmika/weiro/models"
	"lmika.dev/lmika/weiro/providers/db"
)

// postIter returns a post iterator which returns posts in reverse chronological order.
func (s *Publisher) publishedPostIter(ctx context.Context, site int64) iter.Seq[models.Maybe[*models.Post]] {
	return func(yield func(models.Maybe[*models.Post]) bool) {
		paging := db.PagingParams{Offset: 0, Limit: 50}
		page, err := s.db.SelectPublishedPostsOfSite(ctx, site, paging)
		if err != nil {
			yield(models.Maybe[*models.Post]{Err: err})
			return
		}

		for {
			for _, post := range page {
				if post.State != models.StatePublished {
					continue
				}

				if !yield(models.Maybe[*models.Post]{Value: post}) {
					return
				}
			}
			paging.Offset += paging.Limit
			page, err = s.db.SelectPostsOfSite(ctx, site, false, paging)
			if err != nil {
				yield(models.Maybe[*models.Post]{Err: err})
				return
			} else if len(page) == 0 {
				return
			}
		}
	}
}

// postIterByCategory returns a post iterator for posts in a specific category.
func (s *Publisher) postIterByCategory(ctx context.Context, categoryID int64) iter.Seq[models.Maybe[*models.Post]] {
	return func(yield func(models.Maybe[*models.Post]) bool) {
		paging := db.PagingParams{Offset: 0, Limit: 50}
		for {
			page, err := s.db.SelectPublishedPostsOfCategory(ctx, categoryID, paging)
			if err != nil {
				yield(models.Maybe[*models.Post]{Err: err})
				return
			}
			if len(page) == 0 {
				return
			}
			for _, post := range page {
				if !yield(models.Maybe[*models.Post]{Value: post}) {
					return
				}
			}
			paging.Offset += paging.Limit
		}
	}
}