package blog

import (
	"errors"
	"os"
	"path/filepath"
	"sort"
	"strings"
)

// Store manages blog posts stored as markdown files on disk.
type Store struct {
	dir string
}

// NewStore creates a Store rooted at dir, creating the directory if needed.
func NewStore(dir string) (*Store, error) {
	if err := os.MkdirAll(dir, 0755); err != nil {
		return nil, err
	}
	return &Store{dir: dir}, nil
}

// All returns posts sorted by date descending.
// If includeDrafts is false, draft posts are excluded.
func (s *Store) All(includeDrafts bool) ([]*Post, error) {
	entries, err := os.ReadDir(s.dir)
	if err != nil {
		return nil, err
	}

	var posts []*Post
	for _, e := range entries {
		if e.IsDir() || !strings.HasSuffix(e.Name(), ".md") {
			continue
		}
		raw, err := os.ReadFile(filepath.Join(s.dir, e.Name()))
		if err != nil {
			continue
		}
		post, err := ParsePost(raw, e.Name())
		if err != nil {
			continue
		}
		if post.Draft && !includeDrafts {
			continue
		}
		posts = append(posts, post)
	}

	sort.Slice(posts, func(i, j int) bool {
		return posts[i].ParsedDate.After(posts[j].ParsedDate)
	})

	return posts, nil
}

// ByTag returns published posts matching a given tag.
func (s *Store) ByTag(tag string) ([]*Post, error) {
	all, err := s.All(false)
	if err != nil {
		return nil, err
	}
	var filtered []*Post
	for _, p := range all {
		for _, t := range p.Tags {
			if strings.EqualFold(t, tag) {
				filtered = append(filtered, p)
				break
			}
		}
	}
	return filtered, nil
}

// Get returns a single post by slug.
func (s *Store) Get(slug string) (*Post, error) {
	// Try filename = slug + ".md"
	raw, err := os.ReadFile(filepath.Join(s.dir, slug+".md"))
	if err == nil {
		return ParsePost(raw, slug+".md")
	}

	// Fall back: scan all posts
	posts, err := s.All(true)
	if err != nil {
		return nil, err
	}
	for _, p := range posts {
		if p.Slug == slug {
			return p, nil
		}
	}
	return nil, errors.New("post not found: " + slug)
}

// RawContent returns the raw markdown source for a post.
func (s *Store) RawContent(slug string) (string, error) {
	raw, err := os.ReadFile(filepath.Join(s.dir, slug+".md"))
	if err != nil {
		return "", err
	}
	return string(raw), nil
}

// Save writes raw markdown content to a file named slug+".md".
func (s *Store) Save(slug, content string) error {
	return os.WriteFile(filepath.Join(s.dir, slug+".md"), []byte(content), 0644)
}

// Delete removes the file for a given slug.
func (s *Store) Delete(slug string) error {
	return os.Remove(filepath.Join(s.dir, slug+".md"))
}

// Search returns published posts whose title, description, tags, or raw markdown
// content contain the query string (case-insensitive).
func (s *Store) Search(query string) ([]*Post, error) {
	posts, err := s.All(false)
	if err != nil {
		return nil, err
	}
	q := strings.ToLower(strings.TrimSpace(query))
	if q == "" {
		return posts, nil
	}
	seen := map[string]bool{}
	var results []*Post
	add := func(p *Post) {
		if !seen[p.Slug] {
			seen[p.Slug] = true
			results = append(results, p)
		}
	}
	for _, p := range posts {
		if strings.Contains(strings.ToLower(p.Title), q) {
			add(p)
			continue
		}
		if strings.Contains(strings.ToLower(p.Description), q) {
			add(p)
			continue
		}
		matched := false
		for _, t := range p.Tags {
			if strings.Contains(strings.ToLower(t), q) {
				matched = true
				break
			}
		}
		if matched {
			add(p)
			continue
		}
		// Fall back to raw markdown search (avoids rendering overhead)
		raw, err := s.RawContent(p.Slug)
		if err == nil && strings.Contains(strings.ToLower(raw), q) {
			add(p)
		}
	}
	return results, nil
}

// AllTags returns a deduplicated list of tags across all published posts.
func (s *Store) AllTags() ([]string, error) {
	posts, err := s.All(false)
	if err != nil {
		return nil, err
	}
	seen := map[string]bool{}
	var tags []string
	for _, p := range posts {
		for _, t := range p.Tags {
			if !seen[t] {
				seen[t] = true
				tags = append(tags, t)
			}
		}
	}
	sort.Strings(tags)
	return tags, nil
}