//! The sync protocol v1 (SPEC §14.4): pull ([`pull`]), push processing ([`push`]) with the validation of step 8
//! ([`check`]), and the daily pruning of `sync_mutations` ([`prune_mutations`]). The HTTP handlers are in
//! `api/sync.rs`.

pub mod check;
pub mod pull;
pub mod push;

use chrono::{DateTime, Duration, Utc};

use crate::db::{self, Db};
use crate::error::AppError;
use crate::time::format_ts;

/// How long `sync_mutations` rows are kept (SPEC §14.4.9, D-021).
pub const MUTATION_RETENTION: Duration = Duration::days(90);

/// Deletes the `sync_mutations` rows whose `received_at` is older than 90 days before `now` (SPEC §14.1). Returns
/// the number of rows deleted. Timestamps are in the fixed RFC 3339 form, so text order is time order.
pub async fn prune_mutations(db: &Db, now: DateTime<Utc>) -> Result<u64, AppError> {
    let cutoff = format_ts(now - MUTATION_RETENTION);
    let mut tx = db::begin_immediate(db).await?;
    let deleted = sqlx::query("DELETE FROM sync_mutations WHERE received_at < ?")
        .bind(cutoff)
        .execute(&mut *tx)
        .await?
        .rows_affected();
    tx.commit().await?;
    Ok(deleted)
}