package useCases

import (
	"RenewCMS/internal/domain/audit"
	"RenewCMS/internal/domain/author"
	"RenewCMS/internal/domain/user"
	"context"
	"errors"
	"strings"
)

const maxOwnSlugAttempts = 50

type CreateMyAuthorUseCase struct {
	authors  author.Repository
	users    user.Repository
	recorder audit.Recorder
}

func NewCreateMyAuthorUseCase(authors author.Repository, users user.Repository, recorder audit.Recorder) *CreateMyAuthorUseCase {
	return &CreateMyAuthorUseCase{authors: authors, users: users, recorder: recorder}
}

func (u *CreateMyAuthorUseCase) Create(ctx context.Context, userID uint32) (author.Author, error) {
	caller, err := u.users.Get(userID)
	if err != nil {
		return author.Author{}, err
	}
	name := authorNameOf(caller)
	event := audit.NewEvent(audit.ActionAuthorCreate, audit.CategoryAuthors)
	event.Target = audit.Target{Type: audit.TargetAuthor, Name: name}
	created, err := u.create(caller, name)
	if err != nil {
		recordFailure(ctx, u.recorder, event, err)
		return author.Author{}, err
	}
	event.Target = authorTarget(created)
	u.recorder.Record(ctx, event)
	return created, nil
}

func authorNameOf(caller user.User) string {
	name := strings.TrimSpace(caller.DisplayName)
	if name == "" {
		name = strings.TrimSpace(caller.Username)
	}
	runes := []rune(name)
	return string(runes[:min(len(runes), author.MaxNameRunes)])
}

func (u *CreateMyAuthorUseCase) create(caller user.User, name string) (author.Author, error) {
	_, err := u.authors.GetByUserID(caller.ID)
	if err == nil {
		return author.Author{}, author.ErrUserAlreadyLinked
	}
	if !errors.Is(err, author.ErrAuthorNotFound) {
		return author.Author{}, err
	}
	return u.createWithFreeSlug(caller.ID, name)
}

func (u *CreateMyAuthorUseCase) createWithFreeSlug(userID uint32, name string) (author.Author, error) {
	base := author.GenerateSlug(name)
	for attempt := 1; attempt <= maxOwnSlugAttempts; attempt++ {
		slug := author.SlugWithSuffix(base, attempt)
		taken, err := isSlugTaken(u.authors, slug)
		if err != nil {
			return author.Author{}, err
		}
		if taken {
			continue
		}
		created, err := u.authors.Create(author.Author{Name: name, Slug: slug, SocialLinks: []author.SocialLink{}, UserID: &userID, IsLinked: true})
		if errors.Is(err, author.ErrSlugTaken) {
			continue
		}
		return created, err
	}
	return author.Author{}, author.ErrSlugTaken
}