// Per-device allow and block lists, and device lookup by MQTT topic
// (AGENTS.md §7 blocklist/allowlist, §11 Phase 3).
//
// The editors for these lists arrive in Phase 6. Phase 3 already publishes them
// in the device config, so a device that is onboarded later gets the real lists
// without another protocol change. Migration 001 created both tables.
package store

import (
	"context"
	"database/sql"
	"errors"
	"fmt"
	"strings"
)

// DeviceLists returns the site/app values that stay allowed and the values that
// are blocked for one device. A row with a NULL device_id applies to every
// device (§7). Rows are returned in insertion order, de-duplicated.
func (s *Store) DeviceLists(ctx context.Context, id int64) (allow, block []string, err error) {
	if allow, err = s.listValues(ctx, "allowlist", id); err != nil {
		return nil, nil, err
	}
	if block, err = s.listValues(ctx, "blocklist", id); err != nil {
		return nil, nil, err
	}
	return allow, block, nil
}

func (s *Store) listValues(ctx context.Context, table string, id int64) ([]string, error) {
	// The table name is a package constant, never caller input.
	rows, err := s.db.QueryContext(ctx,
		`SELECT value FROM `+table+` WHERE device_id = ? OR device_id IS NULL ORDER BY id`, id)
	if err != nil {
		return nil, fmt.Errorf("list %s: %w", table, err)
	}
	defer rows.Close()

	out := make([]string, 0, 4)
	seen := make(map[string]struct{}, 4)
	for rows.Next() {
		var v string
		if err := rows.Scan(&v); err != nil {
			return nil, fmt.Errorf("scan %s: %w", table, err)
		}
		v = strings.TrimSpace(v)
		if v == "" {
			continue
		}
		if _, dup := seen[v]; dup {
			continue
		}
		seen[v] = struct{}{}
		out = append(out, v)
	}
	if err := rows.Err(); err != nil {
		return nil, fmt.Errorf("list %s: %w", table, err)
	}
	return out, nil
}

// DeviceByConfigTopic finds a device from a topic the device wrote to, for
// example "restrict/harry_phone_2/status". Only the Control Service reads the
// topic table, so a topic the service does not know is ignored.
func (s *Store) DeviceByConfigTopic(ctx context.Context, topic string) (*Device, error) {
	dev, err := scanDevice(s.db.QueryRowContext(ctx, selectDevice+` WHERE d.topic = ?`, topic))
	if errors.Is(err, sql.ErrNoRows) {
		return nil, ErrNotFound
	}
	if err != nil {
		return nil, fmt.Errorf("device by topic: %w", err)
	}
	return dev, nil
}