~handlerug/handlebot

ref: 5c3342e9f8fd6f47e7bc4ff496b631441fce047a handlebot/handler.go -rw-r--r-- 3.6 KiB
5c3342e9Umar Getagazov Update README.md 3 months ago
                                                                                
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package main

import (
	"context"
	"errors"
	"fmt"
	"log"
	"strings"

	"git.sr.ht/~handlerug/girc"
)

type PublicError interface {
	Public()
}

type HandlerFunc func(ctx context.Context, req HandlerRequest) (string, error)

type Handlers struct {
	client     *girc.Client
	cmdPrefix  string
	serverHost string

	cmdNames []string
	cmds     map[string]command
}

type HandlersOpts struct {
	Client     *girc.Client
	ServerHost string
	CmdPrefix  string
}

type HandlerRequest struct {
	Client     *girc.Client
	Event      girc.Event
	ServerHost string
	Args       string
}

type command struct {
	name    string
	aliases []string
	handler HandlerFunc
	help    string
}

func NewHandlers(opts HandlersOpts) Handlers {
	h := Handlers{
		client:     opts.Client,
		cmdPrefix:  opts.CmdPrefix,
		serverHost: opts.ServerHost,
		cmdNames:   make([]string, 0),
		cmds:       make(map[string]command),
	}
	h.Add("help", nil, h.helpHandler, "")
	return h
}

func (h *Handlers) Add(name string, aliases []string, handler HandlerFunc, help string) {
	cmd := command{
		name:    name,
		aliases: aliases,
		handler: handler,
		help:    help,
	}
	if help != "" {
		h.cmdNames = append(h.cmdNames, name)
	}
	h.cmds[name] = cmd
	for _, alias := range aliases {
		h.cmds[alias] = cmd
	}
}

func (h *Handlers) Handle(ctx context.Context, e girc.Event) bool {
	text := strings.TrimSpace(e.Last())
	if strings.HasPrefix(text, h.cmdPrefix) {
		var cmdName, args string
		parts := strings.SplitN(text[len(h.cmdPrefix):], " ", 2)
		if len(parts) >= 1 {
			cmdName = parts[0]
		}
		if len(parts) >= 2 {
			args = strings.TrimSpace(parts[1])
		}

		req := HandlerRequest{
			Client:     h.client,
			Event:      e,
			ServerHost: h.serverHost,
			Args:       args,
		}
		if cmd, ok := h.cmds[cmdName]; ok {
			resp, err := cmd.handler(ctx, req)
			resp = handleError(resp, err)
			if resp != "" {
				h.client.Cmd.Reply(e, resp)
			}
			return true
		}
	}

	return false
}

func (h *Handlers) helpHandler(ctx context.Context, req HandlerRequest) (string, error) {
	resp := h.getHelp(req.Args)
	for len(resp) > 0 {
		var line string
		if idx := strings.Index(resp, "\n"); idx >= 0 {
			line = resp[:idx]
			resp = resp[len(line)+1:]
		} else {
			line = resp
			resp = resp[:0]
		}
		line = strings.TrimSpace(line)
		req.Client.Cmd.Reply(req.Event, fmt.Sprintf("%s: %s", BotName, line))
	}
	return "", nil
}

func (h *Handlers) getHelp(args string) string {
	if args == "" {
		var b strings.Builder
		for i, name := range h.cmdNames {
			if i > 0 {
				b.WriteString(", ")
			}
			b.WriteString(h.cmdPrefix + name)
		}
		fmt.Fprintf(&b, "\nRequest help for a specific command "+
			"using %shelp <command>", h.cmdPrefix)
		return b.String()
	}
	args = strings.TrimPrefix(args, h.cmdPrefix)
	cmd, ok := h.cmds[args]
	if !ok {
		// We don't have this command, but there's a chance it was
		// addressed to another bot, so don't complain loudly
		return ""
	}

	var b strings.Builder
	fmt.Fprintf(&b, "Help for command %s%s", h.cmdPrefix, cmd.name)
	for _, alias := range cmd.aliases {
		fmt.Fprintf(&b, ", %s%s", h.cmdPrefix, alias)
	}
	b.WriteString(":\n")
	b.WriteString(strings.TrimSpace(cmd.help))
	return b.String()
}

func handleError(resp string, err error) string {
	if err != nil {
		if resp == "" {
			if errors.Is(err, context.DeadlineExceeded) {
				resp = errorMsg("Command timed out", nil)
			} else {
				resp = errorMsg("An error occured during handler execution", err)
			}
		}
		log.Println(err)
	}
	return resp
}

func errorMsg(msg string, err error) string {
	if _, ok := err.(PublicError); ok {
		return fmt.Sprintf("%s: %v", msg, err)
	}
	return fmt.Sprintf("%s; check the logs for more info.", msg)
}