package domain

import (
	"path/filepath"
	"regexp"
	"strings"
	"time"
)

type Note struct {
	path         string
	content      string
	frontmatter  *Frontmatter
	outlinks     []*WikiLink
	tags         []*Tag
	createdAt    time.Time
	modifiedAt   time.Time
}

func NewNote(path, content string) (*Note, error) {
	if err := validatePath(path); err != nil {
		return nil, err
	}

	note := &Note{
		path:        path,
		content:     content,
		frontmatter: NewFrontmatter(),
		outlinks:    make([]*WikiLink, 0),
		tags:        make([]*Tag, 0),
		createdAt:   time.Now(),
		modifiedAt:  time.Now(),
	}

	if err := note.extractLinks(); err != nil {
		return nil, err
	}

	if err := note.extractTags(); err != nil {
		return nil, err
	}

	return note, nil
}

func (n *Note) Path() string {
	return n.path
}

func (n *Note) Content() string {
	return n.content
}

func (n *Note) Frontmatter() *Frontmatter {
	return n.frontmatter
}

func (n *Note) Outlinks() []*WikiLink {
	return n.outlinks
}

func (n *Note) Tags() []*Tag {
	return n.tags
}

func (n *Note) CreatedAt() time.Time {
	return n.createdAt
}

func (n *Note) ModifiedAt() time.Time {
	return n.modifiedAt
}

func (n *Note) UpdateContent(content string) error {
	n.content = content
	n.modifiedAt = time.Now()

	n.outlinks = make([]*WikiLink, 0)
	n.tags = make([]*Tag, 0)

	if err := n.extractLinks(); err != nil {
		return err
	}

	return n.extractTags()
}

func (n *Note) SetFrontmatter(fm *Frontmatter) {
	n.frontmatter = fm
	n.modifiedAt = time.Now()
}

func (n *Note) AddTag(tag *Tag) error {
	for _, existingTag := range n.tags {
		if existingTag.Name() == tag.Name() {
			return nil
		}
	}

	n.tags = append(n.tags, tag)
	n.modifiedAt = time.Now()
	return nil
}

func (n *Note) RemoveTag(tagName string) error {
	for i, tag := range n.tags {
		if tag.Name() == tagName {
			n.tags = append(n.tags[:i], n.tags[i+1:]...)
			n.modifiedAt = time.Now()
			return nil
		}
	}
	return nil
}

func (n *Note) HasTag(tagName string) bool {
	for _, tag := range n.tags {
		if tag.Name() == tagName {
			return true
		}
	}
	return false
}

func (n *Note) ExtractLinks() []*WikiLink {
	return n.outlinks
}

func (n *Note) WordCount() int {
	words := strings.Fields(n.content)
	return len(words)
}

func (n *Note) CharacterCount() int {
	return len(n.content)
}

func (n *Note) extractLinks() error {
	linkRegex := regexp.MustCompile(`\[\[([^\]]+)\]\]`)
	matches := linkRegex.FindAllStringSubmatch(n.content, -1)

	for _, match := range matches {
		if len(match) >= 2 {
			link, err := ParseWikiLink(match[1])
			if err != nil {
				continue
			}
			n.outlinks = append(n.outlinks, link)
		}
	}

	return nil
}

func (n *Note) extractTags() error {
	tagRegex := regexp.MustCompile(`#([a-zA-Z0-9_/]+)`)
	matches := tagRegex.FindAllStringSubmatch(n.content, -1)

	for _, match := range matches {
		if len(match) >= 2 {
			tag, err := NewTag(match[1])
			if err != nil {
				continue
			}
			n.AddTag(tag)
		}
	}

	return nil
}

func validatePath(path string) error {
	if path == "" {
		return ErrInvalidPath
	}

	if !strings.HasSuffix(path, ".md") {
		return ErrInvalidPath
	}

	if strings.Contains(path, "..") {
		return ErrInvalidPath
	}

	if !filepath.IsAbs(path) && strings.HasPrefix(path, "/") {
		return ErrInvalidPath
	}

	return nil
}