package main import ( "database/sql" "fmt" "math" "math/rand" ) var ( index map[int]*System ) type System struct { id int x, y, z float64 planets int name string players map[*Connection]bool } func (s *System) Arrive(p *Connection) { p.SetSystem(s) log_info("player %s has arrived at system %s", p.PlayerName(), s.name) if s.players == nil { s.players = make(map[*Connection]bool, 8) } s.players[p] = true } func (s *System) Leave(p *Connection) { delete(s.players, p) } func (s *System) EachConn(fn func(*Connection)) { if s.players == nil { return } for conn, _ := range s.players { fn(conn) } } func (s *System) NumInhabitants() int { if s.players == nil { return 0 } return len(s.players) } func (e System) Store(db *sql.DB) { _, err := db.Exec(` insert into planets (name, x, y, z, planets) values (?, ?, ?, ?, ?) ;`, e.name, e.x, e.y, e.z, e.planets) if err != nil { log_error("%v", err) } } func (s *System) DistanceTo(other *System) float64 { return dist3d(s.x, s.y, s.z, other.x, other.y, other.z) } func (e System) String() string { return fmt.Sprintf("", e.name, e.x, e.y, e.z, e.planets) } type Neighbor struct { id int distance float64 } func (e *System) Nearby(n int) ([]Neighbor, error) { rows, err := db.Query(` select planets.id, edges.distance from edges join planets on edges.id_2 = planets.id where edges.id_1 = ? order by distance limit ? ;`, e.id, n) if err != nil { log_error("unable to get nearby systems for %s: %v", e.name, err) return nil, err } neighbors := make([]Neighbor, 0, n) for rows.Next() { var neighbor Neighbor if err := rows.Scan(&neighbor.id, &neighbor.distance); err != nil { log_error("error unpacking row from nearby neighbors query: %v", err) continue } neighbors = append(neighbors, neighbor) } return neighbors, nil } func countSystems() (int, error) { row := db.QueryRow(`select count(*) from planets`) var n int err := row.Scan(&n) return n, err } func sq(x float64) float64 { return x * x } func dist3d(x1, y1, z1, x2, y2, z2 float64) float64 { return math.Sqrt(sq(x1-x2) + sq(y1-y2) + sq(z1-z2)) } func indexSystems() map[int]*System { rows, err := db.Query(`select * from planets`) if err != nil { log_error("unable to select all planets: %v", err) return nil } defer rows.Close() index = make(map[int]*System, 551) for rows.Next() { p := System{} if err := rows.Scan(&p.id, &p.name, &p.x, &p.y, &p.z, &p.planets); err != nil { log_info("unable to scan planet row: %v", err) continue } index[p.id] = &p } return index } func randomSystem() (*System, error) { n := len(index) if n == 0 { return nil, fmt.Errorf("no planets are known to exist") } pick := rand.Intn(n) planet := index[pick] return planet, nil }