exo/system.go

package main

import (
	"database/sql"
	"fmt"
	"math"
	"math/rand"
	"time"
)

var (
	index     map[int]*System
	nameIndex map[string]*System
)

type System struct {
	id          int
	x, y, z     float64
	planets     int
	name        string
	players     map[*Connection]bool
	miningRate  float64
	colonizedBy *Connection
	distances   []Ray
}

func (s *System) Arrive(conn *Connection) {
	conn.SetSystem(s)
	log_info("player %s has arrived at system %s", conn.PlayerName(), s.name)
	if s.players == nil {
		s.players = make(map[*Connection]bool, 8)
	}
	s.players[conn] = true
	if s.planets == 1 {
		fmt.Fprintf(conn, "you are in the system %s. There is %d planet here.\n", s.name, s.planets)
	} else {
		fmt.Fprintf(conn, "you are in the system %s. There are %d planets here.\n", s.name, s.planets)
	}
}

func (s *System) Leave(p *Connection) {
	delete(s.players, p)
	p.location = nil
}

func (s *System) NotifyInhabitants(template string, args ...interface{}) {
	s.EachConn(func(conn *Connection) {
		fmt.Fprintf(conn, template, args...)
	})
}

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("unable to store system: %v", err)
	}
}

func (s *System) DistanceTo(other *System) float64 {
	return dist3d(s.x, s.y, s.z, other.x, other.y, other.z)
}

func (s *System) LightTimeTo(other *System) time.Duration {
	return time.Duration(int64(s.DistanceTo(other) * 100000000))
}

func (s *System) BombTimeTo(other *System) time.Duration {
	return time.Duration(int64(s.DistanceTo(other) * 110000000))
}

func (s *System) TravelTimeTo(other *System) time.Duration {
	return time.Duration(int64(s.DistanceTo(other) * 125000000))
}

type Ray struct {
	s    *System
	dist float64 // distance in parsecs
}

func (s *System) Distances() []Ray {
	if s.distances == nil {
		s.distances = make([]Ray, 0, 551)
		rows, err := db.Query(`
            select edges.id_2, edges.distance
            from edges
            where edges.id_1 = ?
            order by distance
        ;`, s.id)
		if err != nil {
			log_error("unable to query for system distances: %v", err)
			return nil
		}
		for rows.Next() {
			var (
				r    Ray
				id   int
				dist float64
			)
			if err := rows.Scan(&id, &dist); err != nil {
				log_error("unable to unpack Ray from sql result: %v", err)
				continue
			}
			r.s = index[id]
			r.dist = dist
			s.distances = append(s.distances, r)
		}
	}
	return s.distances
}

func (s *System) Bombed(bomber *Connection) {
	s.EachConn(func(conn *Connection) {
		conn.Die()
		bomber.MadeKill(conn)
	})
	if s.colonizedBy != nil {
		fmt.Fprintf(s.colonizedBy, "your mining colony on %s has been destroyed!\n", s.name)
		s.colonizedBy = nil
	}

	for id, _ := range index {
		if id == s.id {
			continue
		}
		delay := s.BombTimeTo(index[id])
		id2 := id
		After(delay, func() {
			bombNotice(id2, s.id)
		})
	}
}

func bombNotice(to_id, from_id int) {
	to := index[to_id]
	from := index[from_id]
	to.EachConn(func(conn *Connection) {
		fmt.Fprintf(conn, "a bombing has been observed on %s\n", from.name)
	})
}

// for players to read.
func (s System) Label() string {
	return fmt.Sprintf("%s (id: %v)", s.name, s.id)
}

func (e System) String() string {
	return fmt.Sprintf("<name: %s x: %v y: %v z: %v planets: %v>", 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)
	nameIndex = make(map[string]*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
		nameIndex[p.name] = &p
		p.miningRate = rand.Float64()
	}
	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
}

func deliverMessage(to_id, from_id int, msg string) {
	to := index[to_id]
	from := index[from_id]
	to.EachConn(func(conn *Connection) {
		fmt.Fprintf(conn, "Message from %s: %s", from.name, msg)
	})
}