Add Gotify notification client (#36)

Co-authored-by: Paul Götzinger <paul70079@gmail.com>

internal/notif/gotify/client.go

@@ -0,0 +1,101 @@
+package gotify
+
+import (
+	"bytes"
+	"encoding/json"
+	"fmt"
+	"net/http"
+	"net/url"
+	"path"
+	"strconv"
+	"strings"
+	"text/template"
+	"time"
+
+	"github.com/crazy-max/diun/internal/model"
+	"github.com/crazy-max/diun/internal/notif/notifier"
+)
+
+// Client represents an active gotify notification object
+type Client struct {
+	*notifier.Notifier
+	cfg model.NotifGotify
+	app model.App
+}
+
+// New creates a new gotify notification instance
+func New(config model.NotifGotify, app model.App) notifier.Notifier {
+	return notifier.Notifier{
+		Handler: &Client{
+			cfg: config,
+			app: app,
+		},
+	}
+}
+
+// Name returns notifier's name
+func (c *Client) Name() string {
+	return "gotify"
+}
+
+// Send creates and sends a gotify notification with an entry
+func (c *Client) Send(entry model.NotifEntry) error {
+	hc := http.Client{
+		Timeout: time.Duration(c.cfg.Timeout) * time.Second,
+	}
+
+	title := fmt.Sprintf("Image update for %s", entry.Image.String())
+	if entry.Status == model.ImageStatusNew {
+		title = fmt.Sprintf("New image %s has been added", entry.Image.String())
+	}
+
+	var msgBuf bytes.Buffer
+	msgTpl := template.Must(template.New("gotify").Parse(`Docker 🐳 tag {{ .Image.Domain }}/{{ .Image.Path }}:{{ .Image.Tag }} which you subscribed to through {{ .Provider }} provider has been {{ if (eq .Status "new") }}newly added{{ else }}updated{{ end }}.`))
+	if err := msgTpl.Execute(&msgBuf, entry); err != nil {
+		return err
+	}
+
+	data := url.Values{}
+	data.Set("message", msgBuf.String())
+	data.Set("title", title)
+	data.Set("priority", strconv.Itoa(c.cfg.Priority))
+
+	u, err := url.Parse(c.cfg.Endpoint)
+	if err != nil {
+		return err
+	}
+	u.Path = path.Join(u.Path, "message")
+
+	q := u.Query()
+	q.Set("token", c.cfg.Token)
+	u.RawQuery = q.Encode()
+
+	req, err := http.NewRequest("POST", u.String(), strings.NewReader(data.Encode()))
+	if err != nil {
+		return err
+	}
+
+	req.Header.Set("Content-Type", "application/x-www-form-urlencoded")
+	req.Header.Add("Content-Length", strconv.Itoa(len(data.Encode())))
+	req.Header.Set("User-Agent", fmt.Sprintf("%s %s", c.app.Name, c.app.Version))
+
+	resp, err := hc.Do(req)
+	if err != nil {
+		return err
+	}
+
+	if resp.StatusCode != http.StatusOK {
+		var errBody struct {
+			Error            string `json:"error"`
+			ErrorCode        int    `json:"errorCode"`
+			ErrorDescription string `json:"errorDescription"`
+		}
+		err := json.NewDecoder(resp.Body).Decode(&errBody)
+		if err != nil {
+			return err
+		}
+		return fmt.Errorf("%d %s: %s", errBody.ErrorCode, errBody.Error, errBody.ErrorDescription)
+	}
+
+	return nil
+}