client

README

client

Typed Go client for interacting with a factop server over NATS.

Architecture

client/
├── client.go              # Shared Conn type (NATS + RCON-over-NATS)
├── tiles/tiles.go         # Client for softmod/factop/tiles.lua commands
├── entities/entities.go   # Client for softmod/factop/entities.lua commands
├── surface/surface.go     # Client for softmod/factop/surface.lua commands
├── resources/resources.go # Client for softmod/factop/resources.lua commands
└── README.md

Naming Convention

Each softmod/factop/<name>.lua file that registers RCON commands gets a corresponding client/<name>/ Go package:

Lua module	Go package	Client type
softmod/factop/tiles.lua	client/tiles	tiles.Client
softmod/factop/entities.lua	client/entities	entities.Client
softmod/factop/surface.lua	client/surface	surface.Client
softmod/factop/resources.lua	client/resources	resources.Client

When creating a new softmod command module:

1. Use apidoc/factorio-api.md as the API reference for Factorio Lua calls. Generate or update it with go run ./apidoc if needed.
2. Create softmod/factop/<name>.lua following the patterns in softmod/README.md (RCON-only guard, on_init/on_load registration, compact wire format).
3. Create client/<name>/ with a Client struct, a New(conn) constructor, typed methods for each command, and a Parse function for any structured response format.
4. The Lua command names and Go method names should mirror each other: /tiles-fill → tiles.Client.Fill(), /entities-create → entities.Client.Create().

Connection

All sub-packages share a *client.Conn which wraps the NATS connection. The server address is configured once at dial time:

conn, err := client.Dial("nats://factorio:4222")
defer conn.Close()

tc := tiles.New(conn)
ec := entities.New(conn)

Options:

• client.WithTimeout(30 * time.Second) — RCON request timeout (default 10s)

Wire Formats

Commands use compact text formats to minimize RCON payload size. Each client/<name>/ package includes a Parse function that converts the wire format into typed Go structs.

Module	Wire format	Example
tiles-read	name:x:y,...	concrete:0:0,grass-1:1:0
entities-find	name:x:y:unit_number,...	iron-chest:5.5:10.5:42
surface-list	name:index,...	nauvis:1,vulcanus:2
surface-info	key:value,...	name:nauvis,always_day:false,...
resources-count	name:count,...	iron-ore:12345,copper-ore:6789
resources-find	name:x:y:amount,...	iron-ore:10.5:20.5:1500
pollution-get	float	123.45
pollution-total	float	5678.90

Filter Placeholders

For commands with optional positional arguments, use _ to skip a filter field. The Lua side treats _ as "no filter". The Go client handles this automatically through the typed options structs.

Design Decisions

• NATS, not direct RCON: The client talks to NATS, which routes to the factop service's RCON handler. This keeps the RCON password internal to the server and allows the same NATS bus for all factop communication.
• Compact wire formats over JSON: Lua has no built-in JSON encoder. Custom compact formats are trivially parseable on both sides and keep RCON payloads small.
• One package per Lua module: Keeps Go imports focused. You only pull in the client code for the commands you actually use.
• Parse functions are exported: Useful for testing or processing raw RCON output from other sources.

Documentation

Overview

Package client provides a typed Go client for interacting with a factop server over NATS. It handles the RCON-over-NATS connection and provides the base for command-specific sub-packages.

Convention: each softmod/factop/<name>.lua that registers custom commands gets a corresponding client/<name>/ package. The Lua file defines the server-side commands; the Go package provides the typed client methods.

softmod/factop/tiles.lua  →  client/tiles/  (TilesClient)
softmod/factop/foo.lua    →  client/foo/    (FooClient)

All sub-packages accept a *client.Conn and use its Rcon method to send commands to the factop server.

Index

• Constants
• type Conn
  • func Dial(natsURL string, opts ...Option) (*Conn, error)
  • func (c *Conn) Close()
  • func (c *Conn) Rcon(command string) (string, error)
• type Option
  • func WithTimeout(d time.Duration) Option

Constants

const (
	DefaultTimeout = 10 * time.Second
	RconSubject    = "factop.rcon"
)

Types

type Conn

type Conn struct {
	// contains filtered or unexported fields
}

Conn wraps a NATS connection for communicating with a factop server.

func Dial

func Dial(natsURL string, opts ...Option) (*Conn, error)

Dial connects to the NATS server at the given URL and returns a Conn.

func (*Conn) Close

func (c *Conn) Close()

Close closes the underlying NATS connection.

func (*Conn) Rcon

func (c *Conn) Rcon(command string) (string, error)

Rcon sends a raw RCON command string to the factop server and returns the response. This is the low-level method used by all sub-packages.

type Option

type Option func(*Conn)

Option configures a Conn.

func WithTimeout

func WithTimeout(d time.Duration) Option

WithTimeout sets the RCON request timeout.