initial

.github/workflows/ci.yaml

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+name: Golang CI
+
+on:
+  push:
+    branches: [main]
+  pull_request:
+    types: [opened, reopened, synchronize]
+  schedule:
+  - cron: '15 3 * * 0'
+
+jobs:
+  build:
+    name: Test and Build
+    runs-on: ubuntu-latest
+    steps:
+    - name: Checkout code
+      uses: actions/checkout@v3
+      with:
+        fetch-depth: 0
+
+    - name: Setup Go
+      uses: actions/setup-go@v4
+      with:
+        go-version: '1.20'
+
+    - name: Fetch vendor
+      run: go mod vendor
+
+    - name: Test and build
+      run: go run github.com/rebuy-de/rebuy-go-sdk/v5/cmd/buildutil

.github/workflows/release.yaml

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+name: Release Binaries
+
+on:
+  release:
+    types: [created]
+permissions:
+  contents: write
+
+jobs:
+  build:
+    name: Release
+    runs-on: ubuntu-latest
+    steps:
+    - name: Checkout code
+      uses: actions/checkout@v3
+      with:
+        fetch-depth: 0
+
+    - name: Setup Go
+      uses: actions/setup-go@v3
+      with:
+        go-version: '1.20'
+
+    - name: Fetch vendor
+      run: go mod vendor
+
+    - name: Test and build
+      run: |
+        go run github.com/rebuy-de/rebuy-go-sdk/v5/cmd/buildutil \
+          --compress \
+          -x linux/amd64 \
+          -x linux/arm64 \
+          -x darwin/arm64
+
+    # The symlinks cause duplicate files on the GitHub releases page. Perhaps
+    # we should fix this in buildutil.
+    - name: Clean dist directory
+      run: |
+        cd dist && rm $(find . -type l)
+
+    - name: Upload binaries to release
+      uses: svenstaro/upload-release-action@v2
+      with:
+        repo_token: ${{ secrets.GITHUB_TOKEN }}
+        file: dist/i3block-mqtt-*.tar.gz
+        tag: ${{ github.ref }}
+        overwrite: true
+        file_glob: true

.gitignore

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+/vendor
+/dist

LICENSE

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+MIT License
+
+Copyright (c) 2023 Sven Walter
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

README.md

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+# i3blocks-mqtt
+
+Command for templating message for MQTT to use in [i3blocks](https://github.com/vivien/i3blocks).
+
+> **Development Status:** Currently, I am only using this myself.
+
+> This project is open source, but not open for contribution, since helping contributors to ship a PR usually takes more time than doing it myself. Please drop an issue, if you want something changed. Also of course it is possible to fork the whole project.
+
+## Example
+
+```
+[temperature-inside]
+label=In:
+interval=persist
+format=json
+command=i3block-mqtt subscribe
+BLOCKS_BROKER=mqtt://localhost:1883
+BLOCKS_TOPIC=wadra/dashboard/temperature/wohnzimmer
+BLOCKS_JSON=true
+BLOCKS_TEMPLATE_FULL={{. | printf "%.1f"}}°C
+BLOCKS_TEMPLATE_COLOR={{if gt . 24.}}#cc0000{{end}}{{if lt . .20}}#73d216{{end}}
+```
+
+Prints lines like this to stdout:
+
+```
+{"full_text":"27.6°C","color":"#cc0000"}
+```
+
+Which show `In:27.6°C` in a red color in the i3 bar.

buildutil

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+#!/usr/bin/env sh
+set -eu
+go mod vendor
+go generate ./...
+exec go run github.com/rebuy-de/rebuy-go-sdk/v5/cmd/buildutil "$@"

cmd/autoenv.go

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+package cmd
+
+import (
+	"os"
+	"regexp"
+	"strings"
+
+	"github.com/spf13/cobra"
+	"github.com/spf13/pflag"
+)
+
+func AutoEnv(cmd *cobra.Command, args []string) {
+	cmd.PersistentFlags().VisitAll(func(flag *pflag.Flag) {
+		if !flag.Changed {
+			var (
+				envName  = "BLOCKS_" + ConvertToValidEnvVarName(flag.Name)
+				envValue = os.Getenv(envName)
+			)
+
+			if envValue == "" {
+				return
+			}
+
+			flag.Value.Set(envValue)
+		}
+	})
+}
+
+func ConvertToValidEnvVarName(s string) string {
+	// Remove non-alphanumeric characters and replace them with underscores
+	re := regexp.MustCompile(`[^a-zA-Z0-9]+`)
+	s = re.ReplaceAllString(s, "_")
+
+	// Remove leading and trailing underscores
+	s = strings.Trim(s, "_")
+
+	// Convert to uppercase
+	s = strings.ToUpper(s)
+
+	return s
+}

cmd/root.go

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+package cmd
+
+import (
+	"context"
+
+	"github.com/rebuy-de/rebuy-go-sdk/v5/pkg/cmdutil"
+	"github.com/spf13/cobra"
+)
+
+type RunnerFunc func(ctx context.Context) error
+
+func (r RunnerFunc) Bind(cmd *cobra.Command) error {
+	return nil
+}
+
+func (r RunnerFunc) Run(ctx context.Context) error {
+	return r(ctx)
+}
+
+func NewRootCommand() *cobra.Command {
+	return cmdutil.New(
+		"i3blocks-mqtt", "Tools for adding MQTT support to i3blocks",
+		cmdutil.WithLogVerboseFlag(),
+		cmdutil.WithVersionCommand(),
+
+		cmdutil.WithSubCommand(cmdutil.New(
+			"subscribe", "Subscribes to a single topic and output the data to stdout",
+			cmdutil.WithRunner(new(SubscribeRunner)),
+		)),
+	)
+}

cmd/subscribe.go

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+package cmd
+
+import (
+	"bytes"
+	"context"
+	"encoding/json"
+	"fmt"
+	"text/template"
+
+	mqtt "github.com/eclipse/paho.mqtt.golang"
+	"github.com/spf13/cobra"
+)
+
+type SubscribeRunner struct {
+	broker string
+	topic  string
+
+	json          bool
+	templateFull  string
+	templateShort string
+	templateColor string
+}
+
+func (r *SubscribeRunner) Bind(cmd *cobra.Command) error {
+	cmd.PersistentFlags().StringVar(
+		&r.broker, "broker", "",
+		`Specify the MQTT broker URI (e.g., tcp://10.10.1.1:1883)`)
+	cmd.PersistentFlags().StringVar(
+		&r.topic, "topic", "",
+		`Specify the topic to subscribe to`)
+
+	cmd.PersistentFlags().BoolVar(
+		&r.json, "json", false,
+		`Parse the message payload as JSON before passing to the template`)
+
+	cmd.PersistentFlags().StringVar(
+		&r.templateFull, "template-full", "{{.}}",
+		`Specify the Go template to format the full_text`)
+	cmd.PersistentFlags().StringVar(
+		&r.templateShort, "template-short", "",
+		`Specify the Go template to format the short_text`)
+	cmd.PersistentFlags().StringVar(
+		&r.templateColor, "template-color", "",
+		`Specify the Go template to format the color`)
+
+	cmd.PreRun = AutoEnv
+
+	return nil
+}
+
+func (r *SubscribeRunner) Run(ctx context.Context) error {
+	templateFull, err := template.New("full_text").Parse(r.templateFull)
+	if err != nil {
+		return fmt.Errorf("parse message_full: %w", err)
+	}
+
+	templateShort, err := template.New("short_text").Parse(r.templateShort)
+	if err != nil {
+		return fmt.Errorf("parse message_full: %w", err)
+	}
+
+	templateColor, err := template.New("message_full").Parse(r.templateColor)
+	if err != nil {
+		return fmt.Errorf("parse message_full: %w", err)
+	}
+
+	handler := SubscribeHandler{
+		TemplateFull:  templateFull,
+		TemplateShort: templateShort,
+		TemplateColor: templateColor,
+		ParseJSON:     r.json,
+	}
+
+	opts := mqtt.NewClientOptions()
+	opts.AddBroker(r.broker)
+	opts.SetAutoReconnect(true)
+
+	client := mqtt.NewClient(opts)
+	token := client.Connect()
+	token.Wait()
+	if token.Error() != nil {
+		return token.Error()
+	}
+
+	token = client.Subscribe(r.topic, 1, handler.Handle)
+	token.Wait()
+	if token.Error() != nil {
+		return token.Error()
+	}
+
+	<-ctx.Done()
+	return nil
+}
+
+type SubscribeHandler struct {
+	TemplateFull  *template.Template
+	TemplateShort *template.Template
+	TemplateColor *template.Template
+	ParseJSON     bool
+}
+
+func (h *SubscribeHandler) Handle(client mqtt.Client, message mqtt.Message) {
+	err := h.handle(message.Payload())
+	if err != nil {
+		fmt.Println(err)
+	}
+}
+
+type Line struct {
+	FullText  string `json:"full_text"`
+	ShortText string `json:"short_text,omitempty"`
+	Color     string `json:"color,omitempty"`
+}
+
+func (h *SubscribeHandler) handle(payload []byte) error {
+	var data any
+	if h.ParseJSON {
+		err := json.Unmarshal(payload, &data)
+		if err != nil {
+			return fmt.Errorf("parse json: %w", err)
+		}
+	} else {
+		data = string(payload)
+	}
+
+	var (
+		err    error
+		result Line
+	)
+
+	result.FullText, err = h.executeTemplate(h.TemplateFull, data)
+	if err != nil {
+		return fmt.Errorf("execute full_text: %w", err)
+	}
+
+	result.ShortText, err = h.executeTemplate(h.TemplateShort, data)
+	if err != nil {
+		return fmt.Errorf("execute short_text: %w", err)
+	}
+
+	result.Color, err = h.executeTemplate(h.TemplateColor, data)
+	if err != nil {
+		return fmt.Errorf("execute color: %w", err)
+	}
+
+	out, err := json.Marshal(result)
+	if err != nil {
+		return fmt.Errorf("encode JSON: %w", err)
+	}
+
+	fmt.Println(string(out))
+
+	return nil
+}
+
+func (h *SubscribeHandler) executeTemplate(t *template.Template, data any) (string, error) {
+	var buf bytes.Buffer
+	err := t.Execute(&buf, data)
+	if err != nil {
+		return "", err
+	}
+	return buf.String(), nil
+}