use super::{PgPool, Uuid};

/// Batch-check which threads have at least one mention of the given user.
#[tracing::instrument(skip_all)]
pub async fn get_threads_with_mentions_for_user(
    pool: &PgPool,
    user_id: Uuid,
    thread_ids: &[Uuid],
) -> Result<Vec<Uuid>, sqlx::Error> {
    if thread_ids.is_empty() {
        return Ok(Vec::new());
    }
    sqlx::query_scalar!(
        "SELECT DISTINCT p.thread_id
         FROM post_mentions pm
         JOIN posts p ON p.id = pm.post_id
         WHERE pm.mentioned_user_id = $1
           AND p.thread_id = ANY($2)",
        user_id,
        thread_ids,
    )
    .fetch_all(pool)
    .await
}

/// Resolve usernames to user IDs, filtered to community members.
#[tracing::instrument(skip_all)]
pub async fn resolve_usernames_in_community(
    pool: &PgPool,
    community_id: Uuid,
    usernames: &[String],
) -> Result<std::collections::HashMap<String, Uuid>, sqlx::Error> {
    if usernames.is_empty() {
        return Ok(std::collections::HashMap::new());
    }
    let rows = sqlx::query!(
        "SELECT u.username, u.mnw_account_id
         FROM users u
         WHERE u.username = ANY($1)
           AND u.mnw_account_id IN (SELECT user_id FROM memberships WHERE community_id = $2)",
        usernames,
        community_id,
    )
    .fetch_all(pool)
    .await?;
    Ok(rows
        .into_iter()
        .map(|r| (r.username, r.mnw_account_id))
        .collect())
}