/
handler.go
291 lines (226 loc) · 6.75 KB
/
handler.go
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package chatcommand
import (
"errors"
"fmt"
"sort"
"strings"
"sync"
"awesome-dragon.science/go/irc/event"
"awesome-dragon.science/go/irc/permissions"
"awesome-dragon.science/go/irc/user"
"github.com/op/go-logging"
)
var log = logging.MustGetLogger("irc") //nolint:gochecknoglobals // logger is fine :P
// Handler implements a chat message command system. You must provide a prefix and MessageFunc for replies
type Handler struct {
Prefix string
mu sync.Mutex // Protects callbacks
callbacks map[string]*command
// Function used to send messages. It is expected that this can handle overlong lines cleanly.
MessageFunc func(string, string) error
// A permission system to use. If nil, no permission checks take place
PermissionHandler permissions.Handler
}
// AddCommand errors
var (
ErrCmdExists = errors.New("command exists")
ErrCmdNoExist = errors.New("command does not exist")
ErrInvalidCmdName = errors.New("invalid command name")
ErrNoHelp = errors.New("cannot add a command with no help message")
)
// AddCommand adds a new command to the Handler
func (h *Handler) AddCommand(
name, help string, requiredPermissions []string, requiredArgs int, callback Callback,
) error {
name = strings.ToUpper(strings.TrimSpace(name))
if name == "" || strings.ContainsAny(name, " ") {
return fmt.Errorf("%w: %q", ErrInvalidCmdName, name)
}
upperName := strings.ToUpper(name)
c := &command{
name: upperName,
help: help,
requiredArgs: requiredArgs,
requiredPermissions: requiredPermissions,
callback: callback,
}
h.mu.Lock()
defer h.mu.Unlock()
if h.callbacks == nil {
h.callbacks = make(map[string]*command)
}
_, exists := h.callbacks[upperName]
if exists {
return fmt.Errorf("%w: %s", ErrCmdExists, upperName)
}
h.callbacks[upperName] = c
return nil
}
func (h *Handler) RemoveCommand(name string) error {
name = strings.ToUpper(strings.TrimSpace(name))
if name == "" {
return fmt.Errorf("%w: %q", ErrInvalidCmdName, name)
}
h.mu.Lock()
defer h.mu.Unlock()
_, exists := h.callbacks[name]
if !exists {
return fmt.Errorf("%w: %q", ErrCmdNoExist, name)
}
delete(h.callbacks, name)
return nil
}
// OnMessage implements event.MessageHandler
func (h *Handler) OnMessage(msg *event.Message) error {
if msg.Raw.Command != "PRIVMSG" {
return nil
}
message := msg.Raw.Params[len(msg.Raw.Params)-1]
messageTarget := msg.Raw.Params[0]
replyTarget := messageTarget
if replyTarget == msg.CurrentNick {
replyTarget = msg.SourceUser.Name
}
return h.executeCommandIfExists(message, messageTarget, replyTarget, msg)
}
func (h *Handler) getCommand(splitMsg []string, currentNick string) (cmd *command, args []string) {
if len(splitMsg) == 0 {
return nil, nil
}
cmdName := splitMsg[0]
args = splitMsg[1:]
switch {
case currentNick != "" && strings.HasPrefix(cmdName, currentNick):
if len(splitMsg) < 2 {
return nil, nil // Cant extract a command here
}
cmdName = splitMsg[1]
args = splitMsg[2:]
case strings.HasPrefix(cmdName, h.Prefix):
cmdName = strings.TrimPrefix(cmdName, h.Prefix)
default:
return nil, nil
}
h.mu.Lock()
defer h.mu.Unlock()
res, exists := h.callbacks[strings.ToUpper(cmdName)]
if !exists {
if strings.EqualFold(cmdName, "help") {
return &command{
name: "help",
help: "Helps with commands",
requiredArgs: 0,
requiredPermissions: nil,
callback: h.helpCommandCallback,
}, args
}
return nil, nil
}
return res, args
}
func (h *Handler) helpCommandCallback(args *Argument) error {
name := ""
if len(args.Arguments) > 0 {
name = args.Arguments[0]
}
help := h.DoHelp(name)
if strings.Contains(help, "\n") {
for _, l := range strings.Split(help, "\n") {
args.Reply(l)
}
return nil
}
args.Reply(help)
return nil
}
// DoHelp generates the help message for a given command, or a general help message if the command is ""
func (h *Handler) DoHelp(commandName string) string {
h.mu.Lock()
defer h.mu.Unlock()
if commandName == "" {
keys := make([]string, 0, len(h.callbacks))
for k := range h.callbacks {
keys = append(keys, "\x02"+k+"\x02")
}
sort.Strings(keys)
// all commands
return "Available commands: " + strings.Join(keys, ", ")
}
commandName = strings.ToUpper(commandName)
// particular command
cmd, exists := h.callbacks[commandName]
if !exists {
return fmt.Sprintf("\x02%s\x02 does not exist, try %shelp", commandName, h.Prefix)
}
if !strings.Contains(cmd.help, "\n") {
return fmt.Sprintf("Help for command \x02%s\x02: %s", commandName, cmd.help)
}
out := &strings.Builder{}
for _, l := range strings.Split(cmd.help, "\n") {
out.WriteString(fmt.Sprintf("Help for \x02%s\x02: %s\n", commandName, l))
}
return out.String()
}
func (h *Handler) reply(target, message string) {
if err := h.MessageFunc(target, message); err != nil {
log.Errorf("Failed to send message %q to %q: %s", target, message, err)
}
}
func (h *Handler) replyf(target, format string, args ...interface{}) {
h.reply(target, fmt.Sprintf(format, args...))
}
func (h *Handler) callOK(cmd *command, replyTarget string, sourceUser *user.EphemeralUser, args []string) bool {
if cmd == nil {
return false
}
if h.PermissionHandler != nil {
// Next up, permissions
allowed, err := h.PermissionHandler.IsAuthorised(sourceUser, cmd.requiredPermissions)
if err != nil {
log.Infof("Permission check for %#v on command %q errored: %s", sourceUser, cmd.name, err)
}
if !allowed {
h.reply(replyTarget, "Access denied.")
return false
}
} else {
log.Debug("Permissions handler is nil. Skipping all permissions checks.")
}
if cmd.requiredArgs != -1 && len(args) < cmd.requiredArgs {
h.replyf(replyTarget, "\x02%s\x02 Requires at least \x02%d\x02 arguments.", cmd.name, cmd.requiredArgs)
return false
}
return true
}
func (h *Handler) executeCommandIfExists(
message, target, replyTarget string, ev *event.Message,
) (outErr error) {
splitMsg := strings.Split(message, " ")
cmd, args := h.getCommand(splitMsg, ev.CurrentNick)
if !h.callOK(cmd, replyTarget, ev.SourceUser, args) {
return nil
}
argsToSend := &Argument{
CommandName: cmd.name,
Arguments: args,
Event: ev,
Target: target,
Reply: func(msg string) { h.reply(replyTarget, msg) },
}
defer func() {
if res := recover(); res != nil {
log.Criticalf("Caught panic while running command! %#v", res)
outErr = &CommandPanicedError{
CommandName: cmd.name,
line: ev.Raw,
PanicData: res,
}
}
}()
log.Infof("Executing command %q for user %s", cmd.name, ev.SourceUser.Mask())
if err := cmd.callback(argsToSend); err != nil {
log.Errorf("Error while running command %q's callback: %s", cmd.name, err)
return err
}
return nil
}