From 858421789ff779483a71df59fb5148aa02ea457c Mon Sep 17 00:00:00 2001
From: Timon Ringwald <timon.ringwald@mequen.de>
Date: Sun, 18 Sep 2022 19:39:45 +0200
Subject: [PATCH] error handling

---
 errors.go          |  9 +++++++++
 go.mod             |  5 ++++-
 go.sum             |  2 ++
 handle_template.go |  2 +-
 main.go            | 11 +++++++----
 parse_templates.go |  2 +-
 6 files changed, 24 insertions(+), 7 deletions(-)
 create mode 100644 errors.go

diff --git a/errors.go b/errors.go
new file mode 100644
index 0000000..769402d
--- /dev/null
+++ b/errors.go
@@ -0,0 +1,9 @@
+package main
+
+import "git.milar.in/milarin/adverr"
+
+var (
+	ErrInvalidTemplateSyntax   = adverr.NewErrTmpl("ErrInvalidTemplateSyntax", "parsing of template failed: %s")
+	ErrTemplateExecutionFailed = adverr.NewErrTmpl("ErrTemplateExecutionFailed", "execution of template failed: %s")
+	ErrDirectoryCreationFailed = adverr.NewErrTmpl("ErrDirectoryCreationFailed", "creation of target directory failed: %s")
+)
diff --git a/go.mod b/go.mod
index c00fb36..d31a214 100644
--- a/go.mod
+++ b/go.mod
@@ -2,4 +2,7 @@ module git.milar.in/milarin/cfgen
 
 go 1.19
 
-require gopkg.in/yaml.v2 v2.4.0
+require (
+	git.milar.in/milarin/adverr v1.1.0
+	gopkg.in/yaml.v2 v2.4.0
+)
diff --git a/go.sum b/go.sum
index dd0bc19..1d5040d 100644
--- a/go.sum
+++ b/go.sum
@@ -1,3 +1,5 @@
+git.milar.in/milarin/adverr v1.1.0 h1:jD9WnOvs40lfMhvqQ7cllOaRJNBMWr1f07/s9jAadp0=
+git.milar.in/milarin/adverr v1.1.0/go.mod h1:joU9sBb7ySyNv4SpTXB0Z4o1mjXsArBw4N27wjgzj9E=
 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=
diff --git a/handle_template.go b/handle_template.go
index 969f903..8656771 100644
--- a/handle_template.go
+++ b/handle_template.go
@@ -13,7 +13,7 @@ import (
 func HandleTemplate(tmpl *template.Template) error {
 	b := &bytes.Buffer{}
 	if err := tmpl.Execute(b, ConfigFile.Globals); err != nil {
-		return err
+		return ErrTemplateExecutionFailed.Wrap(err, tmpl.Name())
 	}
 
 	if len(strings.TrimSpace(b.String())) == 0 {
diff --git a/main.go b/main.go
index 448f64d..431538d 100644
--- a/main.go
+++ b/main.go
@@ -3,9 +3,11 @@ package main
 import (
 	"errors"
 	"flag"
+	"fmt"
 	"os"
 	"text/template"
 
+	"git.milar.in/milarin/adverr"
 	"gopkg.in/yaml.v2"
 )
 
@@ -17,21 +19,22 @@ func main() {
 	flag.Parse()
 
 	if err := ReadConfigFile(); err != nil {
-		panic(err)
+		fmt.Fprintln(os.Stderr, "no config file provided")
+		os.Exit(1)
 	}
 
 	tmplMap, err := ParseTemplates(template.New("template"), ConfigFile.TemplateDir)
 	if err != nil {
-		panic(err)
+		adverr.Fatalln(err, 2)
 	}
 
 	if err := os.MkdirAll(ConfigFile.TargetDir, 0755); err != nil {
-		panic(err)
+		adverr.Fatalln(ErrDirectoryCreationFailed.Wrap(err, ConfigFile.TargetDir), 3)
 	}
 
 	for _, tmpl := range tmplMap {
 		if err := HandleTemplate(tmpl); err != nil {
-			panic(err)
+			adverr.Fatalln(err, 4)
 		}
 	}
 }
diff --git a/parse_templates.go b/parse_templates.go
index c564c83..100a168 100644
--- a/parse_templates.go
+++ b/parse_templates.go
@@ -48,7 +48,7 @@ func parseTemplates(tmpl *template.Template, tmplMap map[string]*template.Templa
 
 		tmpl, err = tmpl.New(tmplName).Parse(string(data))
 		if err != nil {
-			return err
+			return ErrInvalidTemplateSyntax.Wrap(err, tmplName)
 		}
 
 		tmplMap[tmplName] = tmpl