zesdex/crates/zesdex-cms/src/application/conversation_service.rs

//! Conversation use-case implementations.
//!
//! `ConversationServiceImpl` is generic over `R: ConversationRepository`,
//! delegating all persistence to that adapter.

use anyhow::{Context, Result};

use crate::domain::conversation::{ChatMessage, Conversation};
use crate::domain::repository::ConversationRepository;
use crate::domain::service::ConversationService;

/// Generic conversation service backed by an injected repository.
pub struct ConversationServiceImpl<R> {
    pub repo: R,
    pub sessions_dir: std::path::PathBuf,
}

impl<R: ConversationRepository> ConversationServiceImpl<R> {
    /// Create a new service with the given repository and sessions directory.
    pub fn new(repo: R, sessions_dir: impl Into<std::path::PathBuf>) -> Self {
        Self {
            repo,
            sessions_dir: sessions_dir.into(),
        }
    }

    /// Compute the session directory for a given session id.
    fn session_dir(&self, session_id: &str) -> std::path::PathBuf {
        self.sessions_dir.join(session_id)
    }
}

impl<R: ConversationRepository> ConversationService for ConversationServiceImpl<R> {
    fn load_conversation(&self, session_id: &str) -> Result<Conversation> {
        let dir = self.session_dir(session_id);
        self.repo
            .load(&dir)
            .with_context(|| format!("failed to load conversation for session '{session_id}'"))
    }

    fn save_conversation(&self, conv: &Conversation) -> Result<()> {
        let dir = self.session_dir(&conv.session_id);
        self.repo.save(&dir, conv).with_context(|| {
            format!(
                "failed to save conversation for session '{}'",
                conv.session_id
            )
        })
    }

    fn add_message(&self, conv: &mut Conversation, msg: ChatMessage) -> Result<()> {
        conv.push(msg);
        let dir = self.session_dir(&conv.session_id);
        self.repo.save(&dir, conv).with_context(|| {
            format!(
                "failed to persist conversation after adding message for session '{}'",
                conv.session_id
            )
        })
    }
}