package useCases

import (
	"RenewCMS/internal/domain/article"
	"RenewCMS/internal/domain/audit"
	"RenewCMS/internal/domain/author"
	"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
}

type UpdateArticleCommand struct {
	Body      *string
	SiteID    *uint32
	AuthorIDs *[]uint32
	Format    article.BodyFormat
}

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

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
	}
	updated, err := g.articleRepository.Update(id, article.Update{Body: command.Body, SiteID: command.SiteID, AuthorIDs: command.AuthorIDs})
	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 (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 := bylineIDs(before.Authors)
	afterIDs := 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 bylineIDs(bylines []author.Byline) []uint32 {
	ids := make([]uint32, 0, len(bylines))
	for _, byline := range bylines {
		ids = append(ids, byline.ID)
	}
	return ids
}

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)
	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) 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)
}