package useCases

import (
	"RenewCMS/internal/domain/article"
	"RenewCMS/internal/domain/audit"
	"RenewCMS/internal/domain/author"
	"RenewCMS/internal/domain/image"
	"RenewCMS/internal/domain/site"
	"context"
	"slices"
	"strconv"
	"strings"
)

type UpdateArticleUseCase struct {
	articleRepository article.Repository
	bodyRenderer      article.BodyRenderer
	recorder          audit.Recorder
	sites             site.Repository
	authors           author.Repository
	images            image.Repository
}

type UpdateArticleCommand struct {
	Body              *string
	SiteID            *uint32
	AuthorIDs         *[]uint32
	Slug              *string
	Excerpt           *string
	SEOTitle          *string
	SEODescription    *string
	CoverImageID      article.Nullable[uint32]
	CoverImageAlt     *string
	SocialTitle       *string
	SocialDescription *string
	SocialImageID     article.Nullable[uint32]
	CanonicalURL      *string
	Noindex           *bool
	SEODismissed      *[]string
	Format            article.BodyFormat
}

func NewUpdateArticleUseCase(articleRepository article.Repository, bodyRenderer article.BodyRenderer, recorder audit.Recorder, sites site.Repository, authors author.Repository, images image.Repository) *UpdateArticleUseCase {
	return &UpdateArticleUseCase{articleRepository: articleRepository, bodyRenderer: bodyRenderer, recorder: recorder, sites: sites, authors: authors, images: images}
}

func (g *UpdateArticleUseCase) UpdateBody(ctx context.Context, id uint32, body string, format article.BodyFormat) (article.Article, error) {
	return g.Update(ctx, id, UpdateArticleCommand{Body: &body, Format: format})
}

func (g *UpdateArticleUseCase) Update(ctx context.Context, id uint32, command UpdateArticleCommand) (article.Article, error) {
	before, err := g.articleRepository.Get(id)
	if err != nil {
		return article.Article{}, err
	}
	destination, err := g.destinationSite(command)
	if err != nil {
		return article.Article{}, err
	}
	if err := g.ensureAuthorsExist(command.AuthorIDs); err != nil {
		return article.Article{}, err
	}
	if err := g.validateSEO(command); err != nil {
		return article.Article{}, err
	}
	update := command.toUpdate()
	slug, err := g.resolveSlug(before, command)
	if err != nil {
		g.recordFailure(ctx, audit.ActionArticleEdit, before, err)
		return article.Article{}, err
	}
	update.Slug = slug
	updated, err := g.articleRepository.Update(id, update)
	if isSlugTakenError(err) {
		err = g.raceConflict(before, command, slug)
	}
	if err != nil {
		g.recordFailure(ctx, audit.ActionArticleEdit, before, err)
		return article.Article{}, err
	}
	g.recordEdit(ctx, before, updated, destination)
	return renderArticle(g.bodyRenderer, updated, command.Format)
}

func (c UpdateArticleCommand) toUpdate() article.Update {
	update := article.Update{
		Body:              c.Body,
		SiteID:            c.SiteID,
		AuthorIDs:         c.AuthorIDs,
		Excerpt:           c.Excerpt,
		SEOTitle:          c.SEOTitle,
		SEODescription:    c.SEODescription,
		CoverImageID:      c.CoverImageID,
		CoverImageAlt:     c.CoverImageAlt,
		SocialTitle:       c.SocialTitle,
		SocialDescription: c.SocialDescription,
		SocialImageID:     c.SocialImageID,
		CanonicalURL:      c.CanonicalURL,
		Noindex:           c.Noindex,
	}
	if c.SEODismissed != nil {
		normalized := article.NormalizeDismissed(*c.SEODismissed)
		update.SEODismissed = &normalized
	}
	return update
}

func (g *UpdateArticleUseCase) validateSEO(command UpdateArticleCommand) error {
	if command.Slug != nil && *command.Slug != "" && !article.IsValidSlug(*command.Slug) {
		return article.ErrInvalidSlug
	}
	if command.CanonicalURL != nil {
		if err := article.ValidateCanonicalURL(*command.CanonicalURL); err != nil {
			return err
		}
	}
	if command.CoverImageID.Set {
		if err := ensureImageExists(g.images, command.CoverImageID.Value); err != nil {
			return err
		}
	}
	if command.SocialImageID.Set {
		return ensureImageExists(g.images, command.SocialImageID.Value)
	}
	return nil
}

func targetSiteID(before article.Article, command UpdateArticleCommand) uint32 {
	if command.SiteID != nil {
		return *command.SiteID
	}
	return before.SiteID
}

func requestedSlug(before article.Article, command UpdateArticleCommand) string {
	if command.Slug == nil {
		return before.Slug
	}
	if *command.Slug == "" {
		return article.GenerateSlug(before.Title)
	}
	return *command.Slug
}

func (g *UpdateArticleUseCase) resolveSlug(before article.Article, command UpdateArticleCommand) (*string, error) {
	target := targetSiteID(before, command)
	slug := requestedSlug(before, command)
	if slug == "" || (slug == before.Slug && target == before.SiteID) {
		return nil, nil
	}
	taken, err := g.articleRepository.SlugTaken(target, slug, before.ID)
	if err != nil {
		return nil, err
	}
	if taken {
		return nil, slugConflict(g.articleRepository, target, slug, before.ID)
	}
	if slug == before.Slug {
		return nil, nil
	}
	return &slug, nil
}

func (g *UpdateArticleUseCase) raceConflict(before article.Article, command UpdateArticleCommand, chosen *string) error {
	slug := requestedSlug(before, command)
	if chosen != nil {
		slug = *chosen
	}
	return slugConflict(g.articleRepository, targetSiteID(before, command), slug, before.ID)
}

func (g *UpdateArticleUseCase) destinationSite(command UpdateArticleCommand) (*site.Site, error) {
	if command.SiteID == nil {
		return nil, nil
	}
	destination, err := g.sites.Get(*command.SiteID)
	if err != nil {
		return nil, err
	}
	return &destination, nil
}

func (g *UpdateArticleUseCase) ensureAuthorsExist(ids *[]uint32) error {
	if ids == nil {
		return nil
	}
	for _, id := range *ids {
		if _, err := g.authors.Get(id); err != nil {
			return err
		}
	}
	return nil
}

func authorsChange(before article.Article, after article.Article) (audit.Change, bool) {
	beforeIDs := author.BylineIDs(before.Authors)
	afterIDs := author.BylineIDs(after.Authors)
	if slices.Equal(beforeIDs, afterIDs) {
		return audit.Change{}, false
	}
	return audit.TextChange(audit.FieldAuthors, bylineNames(before.Authors), bylineNames(after.Authors)), true
}

func bylineNames(bylines []author.Byline) string {
	names := make([]string, 0, len(bylines))
	for _, byline := range bylines {
		names = append(names, byline.Name)
	}
	return strings.Join(names, authorChangeSeparator)
}

func (g *UpdateArticleUseCase) recordEdit(ctx context.Context, before article.Article, after article.Article, destination *site.Site) {
	changes := audit.ArticleChanges(before, after)
	changes = append(changes, audit.SEOChanges(before, after)...)
	changes = append(changes, g.imageChanges(before, after)...)
	if destination != nil && before.SiteID != after.SiteID {
		changes = append(changes, audit.TextChange(audit.FieldSite, g.siteName(before.SiteID), destination.Name))
	}
	if change, changed := authorsChange(before, after); changed {
		changes = append(changes, change)
	}
	if len(changes) == 0 {
		return
	}
	event := audit.NewEvent(audit.ActionArticleEdit, audit.CategoryArticles)
	event.Target = articleTarget(after)
	event.Changes = changes
	g.recorder.Record(ctx, event)
}

func (g *UpdateArticleUseCase) imageChanges(before article.Article, after article.Article) []audit.Change {
	changes := []audit.Change{}
	if !sameImage(before.CoverImageID, after.CoverImageID) {
		changes = append(changes, audit.TextChange(audit.FieldCoverImage, imageLabel(g.images, before.CoverImageID), imageLabel(g.images, after.CoverImageID)))
	}
	if !sameImage(before.SocialImageID, after.SocialImageID) {
		changes = append(changes, audit.TextChange(audit.FieldArticleSocialImage, imageLabel(g.images, before.SocialImageID), imageLabel(g.images, after.SocialImageID)))
	}
	return changes
}

func (g *UpdateArticleUseCase) siteName(id uint32) string {
	found, err := g.sites.Get(id)
	if err != nil {
		return strconv.FormatUint(uint64(id), 10)
	}
	return found.Name
}

func (g *UpdateArticleUseCase) UpdateIsOnline(ctx context.Context, id uint32, isOnline bool, format article.BodyFormat) (article.Article, error) {
	before, err := g.articleRepository.Get(id)
	if err != nil {
		return article.Article{}, err
	}
	updated, err := g.articleRepository.UpdateIsOnline(id, isOnline)
	if err != nil {
		g.recordFailure(ctx, publishAction(isOnline), before, err)
		return article.Article{}, err
	}
	g.recordChange(ctx, publishAction(isOnline), before, updated)
	return renderArticle(g.bodyRenderer, updated, format)
}

func publishAction(isOnline bool) string {
	if isOnline {
		return audit.ActionArticlePublish
	}
	return audit.ActionArticleUnpublish
}

func (g *UpdateArticleUseCase) recordChange(ctx context.Context, action string, before article.Article, after article.Article) {
	changes := audit.ArticleChanges(before, after)
	if len(changes) == 0 {
		return
	}
	event := audit.NewEvent(action, audit.CategoryArticles)
	event.Target = articleTarget(after)
	event.Changes = changes
	g.recorder.Record(ctx, event)
}

func (g *UpdateArticleUseCase) recordFailure(ctx context.Context, action string, before article.Article, cause error) {
	event := audit.NewEvent(action, audit.CategoryArticles)
	event.Target = articleTarget(before)
	recordFailure(ctx, g.recorder, event, cause)
}