package author

import (
	"context"
	"errors"
	"tercul/internal/domain"
)

// AuthorCommands contains the command handlers for the author aggregate.
type AuthorCommands struct {
	repo domain.AuthorRepository
}

// NewAuthorCommands creates a new AuthorCommands handler.
func NewAuthorCommands(repo domain.AuthorRepository) *AuthorCommands {
	return &AuthorCommands{
		repo: repo,
	}
}

// CreateAuthorInput represents the input for creating a new author.
type CreateAuthorInput struct {
	Name     string
	Language string
}

// CreateAuthor creates a new author.
func (c *AuthorCommands) CreateAuthor(ctx context.Context, input CreateAuthorInput) (*domain.Author, error) {
	if input.Name == "" {
		return nil, errors.New("author name cannot be empty")
	}
	if input.Language == "" {
		return nil, errors.New("author language cannot be empty")
	}

	author := &domain.Author{
		Name: input.Name,
		TranslatableModel: domain.TranslatableModel{
			Language: input.Language,
		},
	}

	err := c.repo.Create(ctx, author)
	if err != nil {
		return nil, err
	}

	return author, nil
}

// UpdateAuthorInput represents the input for updating an existing author.
type UpdateAuthorInput struct {
	ID       uint
	Name     string
	Language string
}

// UpdateAuthor updates an existing author.
func (c *AuthorCommands) UpdateAuthor(ctx context.Context, input UpdateAuthorInput) (*domain.Author, error) {
	if input.ID == 0 {
		return nil, errors.New("author ID cannot be zero")
	}
	if input.Name == "" {
		return nil, errors.New("author name cannot be empty")
	}
	if input.Language == "" {
		return nil, errors.New("author language cannot be empty")
	}

	// Fetch the existing author
	author, err := c.repo.GetByID(ctx, input.ID)
	if err != nil {
		return nil, err
	}
	if author == nil {
		return nil, errors.New("author not found")
	}

	// Update fields
	author.Name = input.Name
	author.Language = input.Language

	err = c.repo.Update(ctx, author)
	if err != nil {
		return nil, err
	}

	return author, nil
}

// DeleteAuthor deletes an author by ID.
func (c *AuthorCommands) DeleteAuthor(ctx context.Context, id uint) error {
	if id == 0 {
		return errors.New("invalid author ID")
	}
	return c.repo.Delete(ctx, id)
}