package jobs

import (
	"context"
	"fmt"
	"log"

	"github.com/google/uuid"
	"github.com/jackc/pgx/v5/pgxpool"
)

// Queue enqueues processing and feed-sync work for the worker poller (SKIP LOCKED claim).
// ASSUMPTION: full River client + river migrations are deferred; Postgres pending
// jobs + FOR UPDATE SKIP LOCKED is the production queue for P0-4 MVP.
type Queue struct {
	Pool *pgxpool.Pool
}

func NewQueue(pool *pgxpool.Pool) *Queue {
	return &Queue{Pool: pool}
}

// EnqueueProcessingJob ensures the job is pending and wakes listeners via NOTIFY.
func (q *Queue) EnqueueProcessingJob(ctx context.Context, jobID uuid.UUID) error {
	if q == nil || q.Pool == nil {
		return fmt.Errorf("jobs queue not configured")
	}
	ct, err := q.Pool.Exec(ctx, `
		UPDATE processing_jobs
		SET status = 'pending', updated_at = now(),
			error = CASE WHEN status = 'failed' THEN NULL ELSE error END
		WHERE id = $1 AND status IN ('pending', 'failed')`, jobID)
	if err != nil {
		return err
	}
	if ct.RowsAffected() == 0 {
		// Already running/completed/cancelled — still notify in case worker is idle.
		var status string
		_ = q.Pool.QueryRow(ctx, `SELECT status FROM processing_jobs WHERE id = $1`, jobID).Scan(&status)
		log.Printf("jobs: enqueue %s status=%s (no status change)", jobID, status)
	}
	_, _ = q.Pool.Exec(ctx, `SELECT pg_notify('processing_jobs', $1)`, jobID.String())
	return nil
}

// EnqueueFeedSyncJob wakes listeners for an already-pending feed_sync_jobs row.
// Row creation + mapping gates live in feeds.EnqueueSync; this mirrors processing NOTIFY.
func (q *Queue) EnqueueFeedSyncJob(ctx context.Context, jobID uuid.UUID) error {
	if q == nil || q.Pool == nil {
		return fmt.Errorf("jobs queue not configured")
	}
	var status string
	err := q.Pool.QueryRow(ctx, `SELECT status FROM feed_sync_jobs WHERE id = $1`, jobID).Scan(&status)
	if err != nil {
		return err
	}
	if status != "pending" && status != "running" {
		log.Printf("jobs: feed sync enqueue %s status=%s (notify only)", jobID, status)
	}
	_, _ = q.Pool.Exec(ctx, `SELECT pg_notify('feed_sync_jobs', $1)`, jobID.String())
	return nil
}