"""Create post use case."""

from app.application.dtos.post import CreatePostDTO, PostResponseDTO
from app.application.interfaces import TransactionManager
from app.domain.entities import Post
from app.domain.exceptions import AlreadyExistsException
from app.domain.repositories import PostRepository


class CreatePostUseCase:
    """Use case for creating a new blog post."""

    def __init__(
        self,
        post_repo: PostRepository,
        tx_manager: TransactionManager,
    ) -> None:
        self._post_repo = post_repo
        self._tx_manager = tx_manager

    async def execute(self, dto: CreatePostDTO) -> PostResponseDTO:
        """Execute the use case."""
        # Generate slug from title
        from app.domain.value_objects import Slug

        slug = Slug.from_title(dto.title)

        # Check if slug already exists
        if await self._post_repo.slug_exists(slug.value):
            raise AlreadyExistsException(f"Post with slug '{slug.value}' already exists")

        # Create domain entity
        post = Post.create(
            title_str=dto.title,
            content_str=dto.content,
            author_id=dto.author_id,
            tags=dto.tags or [],
        )

        # Persist entity
        await self._post_repo.add(post)

        # Commit transaction
        await self._tx_manager.commit()

        return self._map_to_dto(post)

    def _map_to_dto(self, post: Post) -> PostResponseDTO:
        """Map domain entity to response DTO."""
        return PostResponseDTO(
            id=post.id,
            title=post.title.value,
            content=post.content.value,
            slug=post.slug.value,
            author_id=post.author_id,
            published=post.published,
            tags=post.tags.copy(),
            created_at=post.created_at,
            updated_at=post.updated_at,
        )