thoughts/crates/application/src/use_cases/social.rs

use chrono::Utc;
use domain::{
    errors::DomainError,
    events::DomainEvent,
    models::social::{Block, Boost, Follow, FollowState, Like},
    ports::{BlockRepository, BoostRepository, EventPublisher, FollowRepository, LikeRepository},
    value_objects::{BoostId, LikeId, ThoughtId, UserId},
};

pub async fn like_thought(likes: &dyn LikeRepository, events: &dyn EventPublisher, user_id: &UserId, thought_id: &ThoughtId) -> Result<(), DomainError> {
    let like = Like { id: LikeId::new(), user_id: user_id.clone(), thought_id: thought_id.clone(), ap_id: None, created_at: Utc::now() };
    likes.save(&like).await?;
    events.publish(&DomainEvent::LikeAdded { like_id: like.id, user_id: user_id.clone(), thought_id: thought_id.clone() }).await?;
    Ok(())
}

pub async fn unlike_thought(likes: &dyn LikeRepository, events: &dyn EventPublisher, user_id: &UserId, thought_id: &ThoughtId) -> Result<(), DomainError> {
    likes.delete(user_id, thought_id).await?;
    events.publish(&DomainEvent::LikeRemoved { user_id: user_id.clone(), thought_id: thought_id.clone() }).await?;
    Ok(())
}

pub async fn boost_thought(boosts: &dyn BoostRepository, events: &dyn EventPublisher, user_id: &UserId, thought_id: &ThoughtId) -> Result<(), DomainError> {
    let boost = Boost { id: BoostId::new(), user_id: user_id.clone(), thought_id: thought_id.clone(), ap_id: None, created_at: Utc::now() };
    boosts.save(&boost).await?;
    events.publish(&DomainEvent::BoostAdded { boost_id: boost.id, user_id: user_id.clone(), thought_id: thought_id.clone() }).await?;
    Ok(())
}

pub async fn unboost_thought(boosts: &dyn BoostRepository, events: &dyn EventPublisher, user_id: &UserId, thought_id: &ThoughtId) -> Result<(), DomainError> {
    boosts.delete(user_id, thought_id).await?;
    events.publish(&DomainEvent::BoostRemoved { user_id: user_id.clone(), thought_id: thought_id.clone() }).await?;
    Ok(())
}

pub async fn follow_user(follows: &dyn FollowRepository, events: &dyn EventPublisher, follower_id: &UserId, following_id: &UserId) -> Result<(), DomainError> {
    if follower_id == following_id { return Err(DomainError::InvalidInput("cannot follow yourself".into())); }
    let follow = Follow { follower_id: follower_id.clone(), following_id: following_id.clone(), state: FollowState::Accepted, ap_id: None, created_at: Utc::now() };
    follows.save(&follow).await?;
    events.publish(&DomainEvent::FollowAccepted { follower_id: follower_id.clone(), following_id: following_id.clone() }).await?;
    Ok(())
}

pub async fn unfollow_user(follows: &dyn FollowRepository, events: &dyn EventPublisher, follower_id: &UserId, following_id: &UserId) -> Result<(), DomainError> {
    follows.delete(follower_id, following_id).await?;
    events.publish(&DomainEvent::Unfollowed { follower_id: follower_id.clone(), following_id: following_id.clone() }).await?;
    Ok(())
}

pub async fn accept_follow(follows: &dyn FollowRepository, events: &dyn EventPublisher, follower_id: &UserId, following_id: &UserId) -> Result<(), DomainError> {
    follows.update_state(follower_id, following_id, &FollowState::Accepted).await?;
    events.publish(&DomainEvent::FollowAccepted { follower_id: follower_id.clone(), following_id: following_id.clone() }).await?;
    Ok(())
}

pub async fn reject_follow(follows: &dyn FollowRepository, events: &dyn EventPublisher, follower_id: &UserId, following_id: &UserId) -> Result<(), DomainError> {
    follows.update_state(follower_id, following_id, &FollowState::Rejected).await?;
    events.publish(&DomainEvent::FollowRejected { follower_id: follower_id.clone(), following_id: following_id.clone() }).await?;
    Ok(())
}

pub async fn block_user(blocks: &dyn BlockRepository, events: &dyn EventPublisher, blocker_id: &UserId, blocked_id: &UserId) -> Result<(), DomainError> {
    if blocker_id == blocked_id { return Err(DomainError::InvalidInput("cannot block yourself".into())); }
    let block = Block { blocker_id: blocker_id.clone(), blocked_id: blocked_id.clone(), created_at: Utc::now() };
    blocks.save(&block).await?;
    events.publish(&DomainEvent::UserBlocked { blocker_id: blocker_id.clone(), blocked_id: blocked_id.clone() }).await?;
    Ok(())
}

pub async fn unblock_user(
    blocks: &dyn BlockRepository,
    events: &dyn EventPublisher,
    blocker_id: &UserId,
    blocked_id: &UserId,
) -> Result<(), DomainError> {
    blocks.delete(blocker_id, blocked_id).await?;
    events.publish(&DomainEvent::UserUnblocked {
        blocker_id: blocker_id.clone(),
        blocked_id: blocked_id.clone(),
    }).await?;
    Ok(())
}

#[cfg(test)]
mod tests {
    use super::*;
    use domain::{
        models::{thought::{Thought, Visibility}, user::User},
        testing::TestStore,
        value_objects::*,
    };

    fn user(name: &str) -> User {
        User::new_local(UserId::new(), Username::new(name).unwrap(), Email::new(format!("{name}@ex.com")).unwrap(), PasswordHash("h".into()))
    }

    #[tokio::test]
    async fn like_and_unlike() {
        let store = TestStore::default();
        let alice = user("alice");
        let tid = ThoughtId::new();
        store.thoughts.lock().unwrap().push(Thought::new_local(tid.clone(), alice.id.clone(), Content::new_local("hi").unwrap(), None, Visibility::Public, None, false));
        like_thought(&store, &store, &alice.id, &tid).await.unwrap();
        assert_eq!(store.likes.lock().unwrap().len(), 1);
        unlike_thought(&store, &store, &alice.id, &tid).await.unwrap();
        assert!(store.likes.lock().unwrap().is_empty());
    }

    #[tokio::test]
    async fn follow_and_unfollow() {
        let store = TestStore::default();
        let alice = user("alice"); let bob = user("bob");
        follow_user(&store, &store, &alice.id, &bob.id).await.unwrap();
        assert_eq!(store.follows.lock().unwrap().len(), 1);
        unfollow_user(&store, &store, &alice.id, &bob.id).await.unwrap();
        assert!(store.follows.lock().unwrap().is_empty());
    }

    #[tokio::test]
    async fn cannot_follow_self() {
        let store = TestStore::default();
        let alice = user("alice");
        let err = follow_user(&store, &store, &alice.id, &alice.id).await.unwrap_err();
        assert!(matches!(err, DomainError::InvalidInput(_)));
    }

    #[tokio::test]
    async fn unblock_user_publishes_event() {
        let store = TestStore::default();
        let alice = user("alice");
        let bob = user("bob");
        block_user(&store, &store, &alice.id, &bob.id).await.unwrap();
        store.events.lock().unwrap().clear();
        unblock_user(&store, &store, &alice.id, &bob.id).await.unwrap();
        let events = store.events.lock().unwrap();
        assert_eq!(events.len(), 1);
        assert!(matches!(events[0], DomainEvent::UserUnblocked { .. }));
    }
}