package database

import (
	"database/sql"
	"time"

	_ "github.com/mattn/go-sqlite3"
)

// UserDevice is one of a user's MACs joined to its current liveness from the
// ARP table: IP and Online are populated only when the device was seen within
// the freshness window.
type UserDevice struct {
	Mac      string
	IP       string
	Online   bool
	LastSeen time.Time
}

// MACOwnedByUsername reports whether a MAC is bound to the user with the given
// username. Username matching is case-insensitive to suit DNS labels. This
// gates the resolver's dynamic <mac>.<username> device records.
func MACOwnedByUsername(db *sql.DB, mac, username string) (bool, error) {
	var one int
	err := db.QueryRow(`SELECT 1 FROM macs m JOIN users u ON u.id = m.user_id
		WHERE m.mac = ? AND u.username = ? COLLATE NOCASE`, mac, username).Scan(&one)
	if err == sql.ErrNoRows {
		return false, nil
	}
	return err == nil, err
}

// ListUserMacs returns every MAC bound to a user, newest-seen first, annotated
// with its current LAN IP when the device is live.
func ListUserMacs(db *sql.DB, userID string) ([]UserDevice, error) {
	fresh := time.Now().Add(-connectionFreshness)
	rows, err := db.Query(`
		SELECT m.mac, m.last_seen,
		       (SELECT c.ip FROM connections c
		        WHERE c.mac = m.mac AND c.updated_at > ?
		        ORDER BY c.updated_at DESC LIMIT 1) AS ip
		FROM macs m
		WHERE m.user_id = ?
		ORDER BY m.last_seen DESC`,
		fresh, userID,
	)
	if err != nil {
		return nil, err
	}
	defer rows.Close()

	devices := []UserDevice{}
	for rows.Next() {
		var d UserDevice
		var ip sql.NullString
		if err := rows.Scan(&d.Mac, &d.LastSeen, &ip); err != nil {
			return nil, err
		}
		d.IP = ip.String
		d.Online = ip.Valid
		devices = append(devices, d)
	}
	return devices, rows.Err()
}