[WIP] Initial commit

internal/serverConfig/readConfig.go

@@ -0,0 +1,100 @@
+package serverSonfig
+
+import (
+	"encoding/json"
+	"fmt"
+	"os"
+
+	"doll/internal/log"
+
+	hjson "github.com/hjson/hjson-go/v4"
+)
+
+// MyConfig config structure prototype.
+type MyConfig struct {
+	Loglevel string `json:"loglevel,omitempty"`
+	Logfile  string `json:"logfile,omitempty"`
+}
+
+var (
+	// Config contains application running config data.
+	Config MyConfig
+)
+
+// ReadConfig reads and validates config file. Setups defaults where possible if values are not provided.
+func ReadConfig(location string) error { //nolint:gocognit,gocyclo
+	var (
+		err          error
+		configLoaded bool
+	)
+
+	fileInfo, err := os.Stat(location)
+
+	if err != nil {
+		return fmt.Errorf("unable to read %s: %w", location, err)
+	}
+
+	// Config file seems to be too long for valid config.
+	if fileInfo.Size() > 65535 {
+		return fmt.Errorf("config file %s is too long for config, skipping", location)
+	}
+
+	buf, err := os.ReadFile(location)
+
+	// Config file is unreadable for some reasons.
+	if err != nil {
+		return fmt.Errorf("Skip reading config file %s: %s", location, err)
+	}
+
+	// According to docs hjson claims to be able to pase bad json, but parses it to go map.
+	// It is more interesting to get strict as result, so we parse data to go map, then make json out of this map and
+	// then parse this json to struct. It is not the most effective and speedy solution but it works and this action
+	// been performed not so often.
+	var (
+		sampleConfig MyConfig
+		tmp          map[string]interface{}
+	)
+
+	err = hjson.Unmarshal(buf, &tmp)
+
+	// Unable to parse json to map, that is unfortunate.
+	if err != nil {
+		return fmt.Errorf("Skip parsing config file %s: %s", location, err)
+	}
+
+	tmpJSON, err := json.Marshal(tmp)
+
+	// Unable to parse map to json, well, we can nothing to with that.
+	if err != nil {
+		return fmt.Errorf("Skip parsing config file %s: %s", location, err)
+	}
+
+	// Unable to parse json to struct, just bail it here.
+	if err := json.Unmarshal(tmpJSON, &sampleConfig); err != nil {
+		return fmt.Errorf("Skip parsing config file %s: %s", location, err)
+	}
+
+	// Time to validate config values here.
+	if sampleConfig.Loglevel == "" {
+		sampleConfig.Loglevel = "info"
+
+		log.Info("loglevel not defined in config, using info")
+	}
+
+	// sampleConfig.Log = "" if not set
+
+	// TODO: validate the rest values fron config.
+
+	Config = sampleConfig
+	configLoaded = true
+
+	log.Infof("Using %s as config file", location)
+
+	if !configLoaded {
+		return fmt.Errorf("config was not loaded!") //nolint:goerr113,revive,stylecheck
+	}
+
+	return err //nolint:wrapcheck
+}
+
+/* vim: set ft=go noet ai ts=4 sw=4 sts=4: */