use actix_web::{HttpResponse, Result, web};
use service::error::AppError;
use session::Session;
use uuid::Uuid;

use crate::ApiResponse;
use crate::error::ApiError;

#[derive(Debug, serde::Serialize, utoipa::ToSchema)]
pub struct ForkConversationResponse {
    pub id: Uuid,
    pub title: Option<String>,
    pub model: String,
    pub created_at: chrono::DateTime<chrono::Utc>,
}

/// Fork a conversation from a specific message, creating a new conversation
/// with all messages up to and including the source message.
#[utoipa::path(
    post,
    path = "/api/ai/conversations/{conversation_id}/messages/{message_id}/fork",
    operation_id = "ai_conversation_fork",
    params(
        ("conversation_id" = Uuid, Path, description = "Conversation ID"),
        ("message_id" = Uuid, Path, description = "Source message ID to fork from"),
    ),
    responses(
        (status = 200, description = "Conversation forked", body = ApiResponse<ForkConversationResponse>),
    ),
    tag = "AI Chat"
)]
pub async fn message_fork(
    service: web::Data<service::AppService>,
    session: Session,
    path: web::Path<(Uuid, Uuid)>,
) -> Result<HttpResponse, ApiError> {
    let user_id = session
        .user()
        .ok_or_else(|| ApiError::from(AppError::Unauthorized))?;
    let (conversation_id, source_message_id) = path.into_inner();

    let new_conv = service
        .fork_conversation_from_message(user_id, conversation_id, source_message_id)
        .await?;

    let resp = ForkConversationResponse {
        id: new_conv.id,
        title: new_conv.title,
        model: new_conv.model,
        created_at: new_conv.created_at,
    };

    Ok(ApiResponse::ok(resp).to_response())
}

#[derive(Debug, serde::Serialize, utoipa::ToSchema)]
pub struct ForkListResponse {
    pub forks: Vec<ForkConversationResponse>,
}

/// List all forks created from a specific message.
pub async fn message_forks(
    service: web::Data<service::AppService>,
    session: Session,
    path: web::Path<(Uuid, Uuid)>,
) -> Result<HttpResponse, ApiError> {
    let user_id = session
        .user()
        .ok_or_else(|| ApiError::from(AppError::Unauthorized))?;
    let (conversation_id, source_message_id) = path.into_inner();

    let forks = service
        .list_forks(conversation_id, user_id, source_message_id)
        .await?;

    let fork_responses: Vec<ForkConversationResponse> = forks
        .into_iter()
        .map(|f| ForkConversationResponse {
            id: f.fork_message_id,
            title: None,
            model: String::new(),
            created_at: f.created_at,
        })
        .collect();

    Ok(ApiResponse::ok(ForkListResponse {
        forks: fork_responses,
    })
    .to_response())
}