package article

import (
	"RenewCMS/internal/domain/author"
	"RenewCMS/internal/domain/slug"
	"errors"
	"net/url"
	"slices"
	"strconv"
	"time"
	"unicode/utf8"
)

var (
	ErrInvalidTitle    = errors.New("article's title length should be between 3 and 200 caracters")
	ErrArticleNotFound = errors.New("article not found")
	ErrArticleOffline  = errors.New("article is offline")

	ErrInvalidSlug         = errors.New("invalid slug")
	ErrSlugTaken           = errors.New("another article on this site already uses that slug")
	ErrInvalidCanonicalURL = errors.New("invalid canonical url")
)

type SlugTakenError struct {
	Suggestion string
}

func (e *SlugTakenError) Error() string {
	return ErrSlugTaken.Error()
}

func (e *SlugTakenError) Is(target error) bool {
	return target == ErrSlugTaken
}

const (
	MinTitleRunes = 3
	MaxTitleRunes = 200

	MaxCanonicalURLRunes = 2048

	FallbackSlug = "article"
	DeletedSlug  = "#deleted-"

	DismissTitleLong  = "title_long"
	DismissTitleEmpty = "title_empty"
	DismissDescShort  = "desc_short"
	DismissDescLong   = "desc_long"
	DismissCoverAlt   = "cover_alt"
	DismissCoverNone  = "cover_none"
	DismissSlugLong   = "slug_long"
	DismissNoAuthor   = "no_au"
	DismissNoHeading  = "no_h"
	DismissBodyAlt    = "body_alt"
	DismissShort      = "short"
)

var dismissCodes = []string{
	DismissTitleLong, DismissTitleEmpty, DismissDescShort, DismissDescLong, DismissCoverAlt, DismissCoverNone,
	DismissSlugLong, DismissNoAuthor, DismissNoHeading, DismissBodyAlt, DismissShort,
}

func DismissCodes() []string {
	return slices.Clone(dismissCodes)
}

func NormalizeDismissed(codes []string) []string {
	normalized := make([]string, 0, len(codes))
	for _, code := range codes {
		if !slices.Contains(normalized, code) {
			normalized = append(normalized, code)
		}
	}
	return normalized
}

func IsValidSlug(candidate string) bool {
	return slug.IsValid(candidate)
}

func Tombstone(id uint32) string {
	return DeletedSlug + strconv.FormatUint(uint64(id), 10)
}

func GenerateSlug(title string) string {
	return slug.Generate(title, FallbackSlug)
}

func SlugWithSuffix(base string, attempt int) string {
	return slug.WithSuffix(base, attempt)
}

func ValidateCanonicalURL(raw string) error {
	if raw == "" {
		return nil
	}
	if utf8.RuneCountInString(raw) > MaxCanonicalURLRunes {
		return ErrInvalidCanonicalURL
	}
	parsed, err := url.Parse(raw)
	if err != nil || parsed.Scheme != "https" || parsed.Hostname() == "" {
		return ErrInvalidCanonicalURL
	}
	return nil
}

func ValidateTitle(title string) error {
	runeCount := utf8.RuneCountInString(title)
	if runeCount < MinTitleRunes || runeCount > MaxTitleRunes {
		return ErrInvalidTitle
	}
	return nil
}

type Article struct {
	ID                uint32          `json:"id"`
	Title             string          `json:"title"`
	Body              string          `json:"body"`
	IsOnline          bool            `json:"is_online"`
	SiteID            uint32          `json:"site_id"`
	Authors           []author.Byline `json:"authors"`
	Slug              string          `json:"slug"`
	Excerpt           string          `json:"excerpt"`
	SEOTitle          string          `json:"seo_title"`
	SEODescription    string          `json:"seo_description"`
	CoverImageID      *uint32         `json:"cover_image_id"`
	CoverImageAlt     string          `json:"cover_image_alt"`
	SocialTitle       string          `json:"social_title"`
	SocialDescription string          `json:"social_description"`
	SocialImageID     *uint32         `json:"social_image_id"`
	CanonicalURL      string          `json:"canonical_url"`
	Noindex           bool            `json:"noindex"`
	SEODismissed      []string        `json:"seo_dismissed"`
	CreatedAt         time.Time       `json:"created_at"`
	UpdatedAt         time.Time       `json:"updated_at"`
}

func (a Article) UsesImage(imageID uint32) bool {
	return a.CoverImageID != nil && *a.CoverImageID == imageID || a.SocialImageID != nil && *a.SocialImageID == imageID
}