use anyhow::Result;
use chrono::{DateTime, Utc};
use uuid::Uuid;

/// Cron-based wipe schedule management.
///
/// Manages wipe schedules backed by `tokio-cron-scheduler`. Each schedule
/// maps a cron expression + timezone to a wipe profile. When a schedule
/// fires, it creates a wipe_history record and dispatches execution to
/// the WipeEngine.
pub struct SchedulerService {
    // TODO: Add fields:
    // - db: sqlx::PgPool
    // - nats: async_nats::Client
    // - scheduler: tokio_cron_scheduler::JobScheduler
}

impl SchedulerService {
    /// Start the scheduler, loading all active schedules from the database.
    pub async fn start(&self) -> Result<()> {
        // TODO: Query all active wipe_schedules from DB
        // TODO: Register each as a cron job in tokio-cron-scheduler
        // TODO: Start the scheduler event loop
        todo!()
    }

    /// Register a wipe schedule as a cron job.
    pub async fn register_wipe_schedule(&self, _schedule_id: Uuid) -> Result<()> {
        // TODO: Load WipeSchedule from DB
        // TODO: Parse cron_expression with timezone
        // TODO: Create tokio-cron-scheduler job that:
        //   1. Creates a wipe_history record
        //   2. Publishes wipe execution event to NATS
        // TODO: Store job handle for later removal
        todo!()
    }

    /// Remove a schedule from the running scheduler.
    pub async fn remove_schedule(&self, _schedule_id: Uuid) -> Result<()> {
        // TODO: Look up job handle by schedule_id
        // TODO: Remove from tokio-cron-scheduler
        todo!()
    }

    /// Calculate the next N scheduled run times for a given schedule.
    pub async fn get_next_runs(
        &self,
        _schedule_id: Uuid,
        _count: usize,
    ) -> Result<Vec<DateTime<Utc>>> {
        // TODO: Load cron_expression and timezone from DB
        // TODO: Iterate cron expression to compute next N fire times
        // TODO: Convert to UTC and return
        todo!()
    }
}
