commit b730aca6cfb41c83218c2c8d50e5722ad88f3b59
Author: Timon Ringwald <timon.ringwald@mequen.de>
Date:   Sun Sep 18 19:28:34 2022 +0200

    initial commit

diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..5e8719d
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,3 @@
+*.yaml
+templates
+target
diff --git a/config_file.go b/config_file.go
new file mode 100644
index 0000000..463704b
--- /dev/null
+++ b/config_file.go
@@ -0,0 +1,7 @@
+package main
+
+type Config struct {
+	Globals     map[interface{}]interface{} `yaml:"globals"`
+	TemplateDir string                      `yaml:"templates"`
+	TargetDir   string                      `yaml:"target"`
+}
diff --git a/go.mod b/go.mod
new file mode 100644
index 0000000..c00fb36
--- /dev/null
+++ b/go.mod
@@ -0,0 +1,5 @@
+module git.milar.in/milarin/cfgen
+
+go 1.19
+
+require gopkg.in/yaml.v2 v2.4.0
diff --git a/go.sum b/go.sum
new file mode 100644
index 0000000..dd0bc19
--- /dev/null
+++ b/go.sum
@@ -0,0 +1,4 @@
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405 h1:yhCVgyC4o1eVCa2tZl7eS0r+SDo693bJlVdllGtEeKM=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/yaml.v2 v2.4.0 h1:D8xgwECY7CYvx+Y2n4sBz93Jn9JRvxdiyyo8CTfuKaY=
+gopkg.in/yaml.v2 v2.4.0/go.mod h1:RDklbk79AGWmwhnvt/jBztapEOGDOx6ZbXqjP6csGnQ=
diff --git a/handle_template.go b/handle_template.go
new file mode 100644
index 0000000..969f903
--- /dev/null
+++ b/handle_template.go
@@ -0,0 +1,42 @@
+package main
+
+import (
+	"bytes"
+	"fmt"
+	"io"
+	"os"
+	"path/filepath"
+	"strings"
+	"text/template"
+)
+
+func HandleTemplate(tmpl *template.Template) error {
+	b := &bytes.Buffer{}
+	if err := tmpl.Execute(b, ConfigFile.Globals); err != nil {
+		return err
+	}
+
+	if len(strings.TrimSpace(b.String())) == 0 {
+		return nil
+	}
+
+	tmplPath := filepath.Join(ConfigFile.TargetDir, tmpl.Name())
+
+	if err := os.MkdirAll(filepath.Dir(tmplPath), 0755); err != nil {
+		return err
+	}
+
+	file, err := os.Create(tmplPath)
+	if err != nil {
+		return err
+	}
+	defer file.Close()
+
+	if _, err := io.Copy(file, b); err != nil {
+		return err
+	}
+
+	fmt.Println(tmplPath)
+
+	return nil
+}
diff --git a/main.go b/main.go
new file mode 100644
index 0000000..448f64d
--- /dev/null
+++ b/main.go
@@ -0,0 +1,81 @@
+package main
+
+import (
+	"errors"
+	"flag"
+	"os"
+	"text/template"
+
+	"gopkg.in/yaml.v2"
+)
+
+var (
+	ConfigFile = &Config{}
+)
+
+func main() {
+	flag.Parse()
+
+	if err := ReadConfigFile(); err != nil {
+		panic(err)
+	}
+
+	tmplMap, err := ParseTemplates(template.New("template"), ConfigFile.TemplateDir)
+	if err != nil {
+		panic(err)
+	}
+
+	if err := os.MkdirAll(ConfigFile.TargetDir, 0755); err != nil {
+		panic(err)
+	}
+
+	for _, tmpl := range tmplMap {
+		if err := HandleTemplate(tmpl); err != nil {
+			panic(err)
+		}
+	}
+}
+
+func ReadConfigFile() error {
+	filename := flag.Arg(0)
+	if filename == "" {
+		return errors.New("no config file provided")
+	}
+
+	file, err := os.Open(filename)
+	if err != nil {
+		return err
+	}
+	defer file.Close()
+
+	if err := yaml.NewDecoder(file).Decode(ConfigFile); err != nil {
+		return err
+	}
+
+	RecursiveEnvLookupForMap(ConfigFile.Globals)
+	return nil
+}
+
+func RecursiveEnvLookupForMap(m map[interface{}]interface{}) {
+	for k, v := range m {
+		if str, ok := v.(string); ok {
+			m[k] = os.ExpandEnv(str)
+		} else if m2, ok := v.(map[interface{}]interface{}); ok {
+			RecursiveEnvLookupForMap(m2)
+		} else if arr, ok := v.([]interface{}); ok {
+			RecursiveEnvLookupForSlice(arr)
+		}
+	}
+}
+
+func RecursiveEnvLookupForSlice(s []interface{}) {
+	for i, v := range s {
+		if str, ok := v.(string); ok {
+			s[i] = os.ExpandEnv(str)
+		} else if m, ok := v.(map[interface{}]interface{}); ok {
+			RecursiveEnvLookupForMap(m)
+		} else if arr, ok := v.([]interface{}); ok {
+			RecursiveEnvLookupForSlice(arr)
+		}
+	}
+}
diff --git a/parse_templates.go b/parse_templates.go
new file mode 100644
index 0000000..c564c83
--- /dev/null
+++ b/parse_templates.go
@@ -0,0 +1,58 @@
+package main
+
+import (
+	"os"
+	"path/filepath"
+	"strings"
+	"text/template"
+)
+
+func ParseTemplates(tmpl *template.Template, path string) (map[string]*template.Template, error) {
+	tmplMap := map[string]*template.Template{}
+
+	err := parseTemplates(tmpl, tmplMap, path, path)
+	if err != nil {
+		return nil, err
+	}
+
+	return tmplMap, nil
+}
+
+func parseTemplates(tmpl *template.Template, tmplMap map[string]*template.Template, path string, trimPrefix string) error {
+	var err error
+
+	dirEntries, err := os.ReadDir(path)
+	if err != nil {
+		return err
+	}
+
+	for _, dirEntry := range dirEntries {
+		entryPath := filepath.Join(path, dirEntry.Name())
+		if dirEntry.IsDir() {
+			err = parseTemplates(tmpl, tmplMap, entryPath, trimPrefix)
+			if err != nil {
+				return err
+			}
+			continue
+		}
+
+		data, err := ReadFileString(entryPath)
+		if err != nil {
+			return err
+		}
+
+		tmplName := filepath.Clean(strings.TrimPrefix(entryPath, trimPrefix))
+		if tmplName[0] == '/' {
+			tmplName = tmplName[1:]
+		}
+
+		tmpl, err = tmpl.New(tmplName).Parse(string(data))
+		if err != nil {
+			return err
+		}
+
+		tmplMap[tmplName] = tmpl
+	}
+
+	return nil
+}
diff --git a/utils.go b/utils.go
new file mode 100644
index 0000000..df44c78
--- /dev/null
+++ b/utils.go
@@ -0,0 +1,20 @@
+package main
+
+import (
+	"io"
+	"os"
+)
+
+func ReadFile(path string) ([]byte, error) {
+	file, err := os.Open(path)
+	if err != nil {
+		return nil, err
+	}
+	defer file.Close()
+	return io.ReadAll(file)
+}
+
+func ReadFileString(path string) (string, error) {
+	data, err := ReadFile(path)
+	return string(data), err
+}