package processing

import (
	"context"
	"fmt"

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

// RetentionAgeInterval is the shared SQL age used by CleanupExpired /
// CleanupExpiredSyncJobs to prune terminal job history.
const RetentionAgeInterval = "30 days"

// RetentionBatchLimit caps rows deleted per cleanup call to avoid long locks.
const RetentionBatchLimit = 5000

// RetentionCleanupResult counts rows deleted by retention cleanups.
type RetentionCleanupResult struct {
	JobsDeleted     int64
	SyncJobsDeleted int64
}

// CleanupExpired deletes terminal processing_jobs older than RetentionAgeInterval.
// Child processing_job_products rows are removed via ON DELETE CASCADE.
// Pending/running jobs are never deleted.
// Migrated history (ai_provider_mode='migrated') is retained indefinitely.
func CleanupExpired(ctx context.Context, pool *pgxpool.Pool) (RetentionCleanupResult, error) {
	var out RetentionCleanupResult
	if pool == nil {
		return out, fmt.Errorf("cleanup expired: nil pool")
	}

	ct, err := pool.Exec(ctx, `
		WITH doomed AS (
			SELECT id
			FROM processing_jobs
			WHERE status IN ('completed', 'failed', 'cancelled')
			  AND COALESCE(ai_provider_mode, '') <> 'migrated'
			  AND COALESCE(completed_at, updated_at) < now() - interval '`+RetentionAgeInterval+`'
			ORDER BY COALESCE(completed_at, updated_at) ASC
			LIMIT $1
		)
		DELETE FROM processing_jobs
		WHERE id IN (SELECT id FROM doomed)`, RetentionBatchLimit)
	if err != nil {
		return out, fmt.Errorf("cleanup expired jobs: %w", err)
	}
	out.JobsDeleted = ct.RowsAffected()
	return out, nil
}

// CleanupExpiredSyncJobs deletes terminal feed_sync_jobs older than RetentionAgeInterval.
// Keeps the newest completed job that still has a content_hash per feed so
// lastContentHash skip-unchanged continues to work after cleanup.
// raw_products.sync_job_id is ON DELETE SET NULL, so product rows are preserved.
func CleanupExpiredSyncJobs(ctx context.Context, pool *pgxpool.Pool) (RetentionCleanupResult, error) {
	var out RetentionCleanupResult
	if pool == nil {
		return out, fmt.Errorf("cleanup expired sync jobs: nil pool")
	}

	ct, err := pool.Exec(ctx, `
		WITH keep AS (
			SELECT DISTINCT ON (feed_id) id
			FROM feed_sync_jobs
			WHERE status = 'completed'
			  AND content_hash IS NOT NULL
			  AND content_hash <> ''
			ORDER BY feed_id, completed_at DESC NULLS LAST
		),
		doomed AS (
			SELECT id
			FROM feed_sync_jobs
			WHERE status IN ('completed', 'failed')
			  AND COALESCE(completed_at, updated_at) < now() - interval '`+RetentionAgeInterval+`'
			  AND id NOT IN (SELECT id FROM keep)
			ORDER BY COALESCE(completed_at, updated_at) ASC
			LIMIT $1
		)
		DELETE FROM feed_sync_jobs
		WHERE id IN (SELECT id FROM doomed)`, RetentionBatchLimit)
	if err != nil {
		return out, fmt.Errorf("cleanup expired sync jobs: %w", err)
	}
	out.SyncJobsDeleted = ct.RowsAffected()
	return out, nil
}