package sitereader

import (
	"bytes"
	"io"
	"io/fs"
	"time"

	"gopkg.in/yaml.v3"
	"lmika.dev/lmika/weiro/models"
)

type Provider struct {
	fs fs.FS
}

func New(fs fs.FS) *Provider {
	return &Provider{
		fs: fs,
	}
}

func (p *Provider) ReadSite() (ReadSiteModels, error) {
	posts, err := p.ListPosts()
	if err != nil {
		return ReadSiteModels{}, err
	}

	meta := siteMeta{}
	metaBytes, err := fs.ReadFile(p.fs, "site.yaml")
	if err != nil {
		return ReadSiteModels{}, err
	}
	if err := yaml.Unmarshal(metaBytes, &meta); err != nil {
		return ReadSiteModels{}, err
	}

	site := models.Site{
		Title:   meta.Title,
		Tagline: meta.Tagline,
	}
	publishTarget := models.SitePublishTarget{
		BaseURL: meta.BaseURL,
	}

	return ReadSiteModels{
		Site:   site,
		Target: publishTarget,
		Posts:  posts,
	}, nil
}

func (p *Provider) ListPosts() (posts []*models.Post, err error) {
	err = fs.WalkDir(p.fs, "posts", func(path string, d fs.DirEntry, err error) error {
		if err != nil {
			return err
		} else if d.IsDir() {
			return nil
		}

		post, err := p.ReadPost(path)
		if err != nil {
			return err
		}
		posts = append(posts, post)
		return nil
	})
	return posts, err
}

func (p *Provider) ReadPost(path string) (*models.Post, error) {
	data, err := fs.ReadFile(p.fs, path)
	if err != nil {
		return nil, err
	}

	// Split front matter and content
	parts := bytes.SplitN(data, []byte("---"), 3)
	if len(parts) < 3 {
		return nil, io.ErrUnexpectedEOF
	}

	var meta postMeta
	if err := yaml.Unmarshal(parts[1], &meta); err != nil {
		return nil, err
	}

	post := models.Post{
		Slug:        meta.Slug,
		Title:       meta.Title,
		GUID:        meta.ID,
		PublishedAt: meta.Date,
		CreatedAt:   time.Now(),
	}

	post.Body = string(bytes.TrimPrefix(parts[2], []byte("\n")))
	return &post, nil
}