package useCases

import (
	"RenewCMS/internal/domain/audit"
	"RenewCMS/internal/domain/author"
	"context"
)

type ReassignMode int

const (
	ReassignAbsent ReassignMode = iota
	ReassignNone
	ReassignToAuthor
	ReassignMalformed
)

type Reassignment struct {
	Mode        ReassignMode
	Destination uint32
}

type DeleteAuthorUseCase struct {
	authors  author.Repository
	recorder audit.Recorder
}

func NewDeleteAuthorUseCase(authors author.Repository, recorder audit.Recorder) *DeleteAuthorUseCase {
	return &DeleteAuthorUseCase{authors: authors, recorder: recorder}
}

func (u *DeleteAuthorUseCase) Delete(ctx context.Context, id uint32, reassignment Reassignment) error {
	target, err := u.authors.Get(id)
	if err != nil {
		return err
	}

	event := audit.NewEvent(audit.ActionAuthorDelete, audit.CategoryAuthors)
	event.Target = authorTarget(target)
	if err := u.delete(target, reassignment); err != nil {
		recordFailure(ctx, u.recorder, event, err)
		return err
	}
	u.recorder.Record(ctx, event)
	return nil
}

func (u *DeleteAuthorUseCase) delete(target author.Author, reassignment Reassignment) error {
	if reassignment.Mode == ReassignNone {
		return u.authors.DeleteUncrediting(target.ID)
	}
	if target.ArticleCount == 0 {
		return u.authors.DeleteMovingCredits(target.ID, nil)
	}
	destination, err := u.destination(target, reassignment)
	if err != nil {
		return err
	}
	return u.authors.DeleteMovingCredits(target.ID, &destination)
}

func (u *DeleteAuthorUseCase) destination(target author.Author, reassignment Reassignment) (uint32, error) {
	switch reassignment.Mode {
	case ReassignAbsent:
		return 0, author.ErrAuthorHasArticles
	case ReassignMalformed:
		return 0, author.ErrInvalidReassign
	}
	if reassignment.Destination == 0 || reassignment.Destination == target.ID {
		return 0, author.ErrInvalidReassign
	}
	if _, err := u.authors.Get(reassignment.Destination); err != nil {
		return 0, err
	}
	return reassignment.Destination, nil
}