Moved some code around and updated the README

config.go

@@ -0,0 +1,60 @@
+// Copyright (c) 2024 Julian Müller (ChaoticByte)
+
+package main
+
+import (
+	"errors"
+)
+
+type Config struct {
+	ApiFetchInterval int `json:"api_fetch_interval"` // in seconds
+	EnabledApiEndpoints []string `json:"enabled_api_endpoints"`
+	PersistentDataFilePath string `json:"datafile"`
+	LogLevel int `json:"loglevel"`
+	Recipients []Recipient `json:"recipients"`
+	SmtpConfiguration SmtpSettings `json:"smtp"`
+	Template MailTemplateConfig `json:"template"`
+}
+
+func NewConfig() Config {
+	// Initial config
+	c := Config{
+		ApiFetchInterval: 60 * 10, // every 10 minutes,
+		EnabledApiEndpoints: []string{"bay", "bund"},
+		PersistentDataFilePath: "data.json",
+		LogLevel: 2,
+		Recipients: []Recipient{},
+		SmtpConfiguration: SmtpSettings{
+			From: "from@example.org",
+			User: "from@example.org",
+			Password: "SiEhAbEnMiChInSgEsIcHtGeFiLmTdAsDüRfEnSiEnIcHt",
+			ServerHost: "example.org",
+			ServerPort: 587},
+		Template: MailTemplateConfig{
+			SubjectTemplate: "",
+			BodyTemplate: "",
+		},
+	}
+	return c
+}
+
+func checkConfig(config Config) {
+	if len(config.Recipients) < 1 {
+		logger.error("Configuration is incomplete")
+		panic(errors.New("no recipients are configured"))
+	}
+	for _, r := range config.Recipients {
+		if !mailAddressIsValid(r.Address) {
+			logger.error("Configuration includes invalid data")
+			panic(errors.New("'" + r.Address + "' is not a valid e-mail address"))
+		}
+		if len(r.Filters) < 1 {
+			logger.error("Configuration is incomplete")
+			panic(errors.New("recipient " + r.Address + " has no filter defined - at least {'any': true/false} should be configured"))
+		}
+	}
+	if !mailAddressIsValid(config.SmtpConfiguration.From) {
+		logger.error("Configuration includes invalid data")
+		panic(errors.New("'" + config.SmtpConfiguration.From + "' is not a valid e-mail address"))
+	}
+}