commit 0c0aeb29440a04cd570d0b1a086040ffeee732f5
Author: Robert Gerus <ar@bash.org.pl>
Date:   Mon Jan 3 22:27:52 2022 +0100

    initial working version

diff --git a/go.mod b/go.mod
new file mode 100644
index 0000000..03dcbe1
--- /dev/null
+++ b/go.mod
@@ -0,0 +1,5 @@
+module code.hackerspace.pl/ar/notbot
+
+go 1.16
+
+require gopkg.in/irc.v3 v3.1.4
diff --git a/go.sum b/go.sum
new file mode 100644
index 0000000..12af36d
--- /dev/null
+++ b/go.sum
@@ -0,0 +1,13 @@
+github.com/davecgh/go-spew v1.1.0 h1:ZDRjVQ15GmhC3fiQ8ni8+OwkZQO4DARzQgrnXU1Liz8=
+github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
+github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
+github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
+github.com/stretchr/testify v1.4.0 h1:2E4SXV/wtOkTonXsotYi4li6zVWxYlZuYNCXe9XRJyk=
+github.com/stretchr/testify v1.4.0/go.mod h1:j7eGeouHqKxXV5pUuKE4zz7dFj8WfuZ+81PSLYec5m4=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/irc.v3 v3.1.4 h1:DYGMRFbtseXEh+NadmMUFzMraqyuUj4I3iWYFEzDZPc=
+gopkg.in/irc.v3 v3.1.4/go.mod h1:shO2gz8+PVeS+4E6GAny88Z0YVVQSxQghdrMVGQsR9s=
+gopkg.in/yaml.v2 v2.2.2/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=
+gopkg.in/yaml.v2 v2.2.8 h1:obN1ZagJSUGI0Ek/LBmuj4SNLPfIny3KsKFopxRdj10=
+gopkg.in/yaml.v2 v2.2.8/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=
diff --git a/notifier.go b/notifier.go
new file mode 100644
index 0000000..de98f39
--- /dev/null
+++ b/notifier.go
@@ -0,0 +1,179 @@
+package main
+
+import (
+	"encoding/json"
+	"fmt"
+	"io"
+	"log"
+	"net"
+	"net/http"
+	"time"
+
+	"gopkg.in/irc.v3"
+)
+
+type atMonitor struct {
+	previousUserList []string
+}
+
+type atUsers struct {
+	Login      string
+	Timestamp  float64
+	PrettyTime string `json:"pretty_time"`
+}
+
+type atResponse struct {
+	Users   []atUsers
+	Esps    uint
+	Kektops uint
+	Vms     uint
+	Unknown uint
+}
+
+func (a *atResponse) UserList() (ret []string) {
+	for _, user := range a.Users {
+		ret = append(ret, user.Login)
+	}
+
+	return ret
+}
+
+func listSubstract(a, b []string) (ret []string) {
+	mb := make(map[string]bool, len(b))
+
+	for _, x := range b {
+		mb[x] = true
+	}
+
+	for _, x := range a {
+		if _, found := mb[x]; !found {
+			ret = append(ret, x)
+		}
+	}
+
+	return ret
+}
+
+func (a *atMonitor) Run(c *irc.Client, done chan bool) {
+	ticker := time.NewTicker(10 * time.Second)
+
+	for {
+		select {
+		case <-done:
+			return
+		case <-ticker.C:
+			var diffText string
+			atHS, err := at()
+
+			if err != nil {
+				log.Println(err)
+				break
+			}
+
+			current := atHS.UserList()
+
+			arrived := listSubstract(current, a.previousUserList)
+			left := listSubstract(a.previousUserList, current)
+
+			if len(arrived) > 0 {
+				diffText = fmt.Sprint(" +", arrived)
+			}
+
+			if len(left) > 0 {
+				diffText = fmt.Sprint(" -", left)
+			}
+
+			if len(diffText) > 0 {
+				msg := fmt.Sprintf("NOTICE #hswaw-bottest :%s\n", diffText)
+				log.println(diffText)
+				c.Write(msg)
+				a.previousUserList = current
+			}
+		}
+	}
+}
+
+func genericHandler(c *irc.Client, m *irc.Message) {
+	log.Println(m)
+	if m.Command == "001" {
+		c.Write("JOIN #hswaw-bottest")
+	}
+}
+
+func main() {
+	done := make(chan bool)
+	var a atMonitor
+
+	conn, err := net.Dial("tcp", "irc.libera.chat:6667")
+	if err != nil {
+		log.Fatalln(err)
+	}
+
+	config := irc.ClientConfig{
+		Nick:    "notbot",
+		Pass:    "***",
+		User:    "bot",
+		Name:    "notbot",
+		Handler: irc.HandlerFunc(genericHandler),
+	}
+
+	client := irc.NewClient(conn, config)
+	go a.Run(client, done)
+
+	err = client.Run()
+	if err != nil {
+		done <- true
+		log.Fatalln(err)
+	}
+}
+
+func at() (at atResponse, err error) {
+	var values atResponse = atResponse{}
+
+	data, err := httpGet("https://at.hackerspace.pl/api")
+	if err != nil {
+		return values, fmt.Errorf("Unable to access checkinator api:", err)
+	}
+
+	err = json.Unmarshal(data, &values)
+	if err != nil {
+		return values, fmt.Errorf("Unable to decode checkinator response:", err)
+	}
+
+	return values, nil
+}
+
+func httpGet(link string) ([]byte, error) {
+	var buf []byte
+	tr := &http.Transport{
+		TLSHandshakeTimeout:   20 * time.Second,
+		ResponseHeaderTimeout: 20 * time.Second,
+	}
+	client := &http.Client{
+		Transport: tr,
+	}
+
+	req, err := http.NewRequest("GET", link, nil)
+	if err != nil {
+		return []byte{}, err
+	}
+
+	resp, err := client.Do(req)
+	if err != nil {
+		return []byte{}, err
+	}
+	defer resp.Body.Close()
+
+	// Limit response to 5MiB
+	limitedResponse := http.MaxBytesReader(nil, resp.Body, 5*1024*1024)
+	buf = make([]byte, 5*1024*1024)
+
+	i, err := io.ReadFull(limitedResponse, buf)
+	if err == io.ErrUnexpectedEOF {
+		buf = buf[:i]
+	} else if err != nil {
+		return []byte{}, err
+	}
+
+	return buf, nil
+}