From c96ca310a019a892a717373677ded36dc0b9e2b3 Mon Sep 17 00:00:00 2001
From: René 'Necoro' Neumann <necoro@necoro.eu>
Date: Fri, 17 Apr 2020 20:57:01 +0200
Subject: Read and organize feeds

---
 go.mod  |   2 +-
 go.sum  |   4 +--
 main.go | 116 +++++++++++++++++++++++++++++++++++++++++++++++++++++++---------
 3 files changed, 103 insertions(+), 19 deletions(-)

diff --git a/go.mod b/go.mod
index 590d5c2..63d186d 100644
--- a/go.mod
+++ b/go.mod
@@ -2,4 +2,4 @@ module github.com/Necoro/feed2imap-go
 
 go 1.13
 
-require gopkg.in/yaml.v2 v2.2.8
+require gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c
diff --git a/go.sum b/go.sum
index 74b18ac..756b14d 100644
--- a/go.sum
+++ b/go.sum
@@ -1,4 +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 v2.2.8 h1:obN1ZagJSUGI0Ek/LBmuj4SNLPfIny3KsKFopxRdj10=
-gopkg.in/yaml.v2 v2.2.8/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=
+gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c h1:dUUwHk2QECo/6vqA44rthZ8ie2QXMNeKRTHCNY2nXvo=
+gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
diff --git a/main.go b/main.go
index 9f20203..b238ff0 100644
--- a/main.go
+++ b/main.go
@@ -5,50 +5,134 @@ import (
 	"fmt"
 	"io/ioutil"
 	"log"
+	"os"
 
-	"gopkg.in/yaml.v2"
+	"gopkg.in/yaml.v3"
 )
 
 var cfg = flag.String("f", "config.yml", "configuration file")
 
 type ConfigMap map[string]interface{}
 
-type Feed struct {
+type configFeed struct {
 	Name      string
 	Url       string
 	MinFreq   int `yaml:"min-frequency"`
 	ConfigMap `yaml:",inline"`
 }
 
-type Group struct {
+type configGroup struct {
 	Group string
-	Feeds []GroupFeed
+	Feeds []configGroupFeed
 }
 
-type GroupFeed struct {
-	Target string
-	Feed   `yaml:",inline"`
-	Group  `yaml:",inline"`
+type configGroupFeed struct {
+	Target      *string
+	configFeed  `yaml:",inline"`
+	configGroup `yaml:",inline"`
 }
 
-type Yaml struct {
+func (grpFeed *configGroupFeed) isGroup() bool {
+	return grpFeed.configGroup.Group != ""
+}
+
+func (grpFeed *configGroupFeed) isFeed() bool {
+	return grpFeed.configFeed.Name != ""
+}
+
+func (grpFeed *configGroupFeed) target() string {
+	if grpFeed.Target != nil {
+		return *grpFeed.Target
+	}
+	if grpFeed.Name != "" {
+		return grpFeed.Name
+	}
+
+	return grpFeed.Group
+}
+
+type config struct {
 	GlobalConfig ConfigMap `yaml:",inline"`
-	Feeds        []GroupFeed
+	Feeds        []configGroupFeed
 }
 
-func main() {
+type feed struct {
+	name    string
+	target  string
+	url     string
+	minFreq int
+	config  ConfigMap
+}
+
+var feeds = make(map[string]*feed)
+
+func appTarget(target, app string) string {
+	if target == "" {
+		return app
+	}
+
+	if app == "" {
+		return target
+	}
+
+	return target + "/" + app
+}
+
+func buildFeeds(cfg []configGroupFeed, target string) error {
+	for _, f := range cfg {
+		target := appTarget(target, f.target())
+		switch {
+		case f.isFeed() && f.isGroup():
+			return fmt.Errorf("Entry with Target %s is both a feed and a group", target)
+		case f.isFeed():
+			name := f.Name
+			if _, ok := feeds[name]; !ok {
+				return fmt.Errorf("Duplicate feed name '%s'", name)
+			}
+			feeds[name] = &feed{
+				name:    name,
+				target:  target,
+				url:     f.Url,
+				minFreq: f.MinFreq,
+				config:  f.ConfigMap,
+			}
+		case f.isGroup():
+			if err := buildFeeds(f.Feeds, target); err != nil {
+				return err
+			}
+		}
+	}
+
+	return nil
+}
+
+func run() error {
 	log.Print("Starting up...")
 	flag.Parse()
 
 	log.Printf("Reading configuration file '%s'", *cfg)
 	buf, err := ioutil.ReadFile(*cfg)
 	if err != nil {
-		msg := fmt.Sprint("No file found: ", *cfg)
-		panic(msg)
+		return fmt.Errorf("while reading '%s': %w", *cfg, err)
 	}
 
-	var m Yaml
-	yaml.Unmarshal(buf, &m)
-	fmt.Printf("--- m:\n%+v\n\n", m)
+	var parsedCfg config
+	if err := yaml.Unmarshal(buf, &parsedCfg); err != nil {
+		return fmt.Errorf("while unmarshalling: %w", err)
+	}
+	fmt.Printf("--- parsedCfg:\n%+v\n\n", parsedCfg)
+
+	if err := buildFeeds(parsedCfg.Feeds, ""); err != nil {
+		return fmt.Errorf("while parsing: %w", err)
+	}
 
+	return nil
+}
+
+func main() {
+	if err := run(); err != nil {
+		log.SetOutput(os.Stderr)
+		log.Print("Error: ", err)
+		os.Exit(1)
+	}
 }
-- 
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