2 files changed, 91 insertions, 5 deletions

diff --git a/config/config.go b/config/config.go
index 2ec6706..cd2883b 100644
--- a/config/config.go
+++ b/config/config.go
@@ -1,9 +1,11 @@
 package config
 
 import (
+	"fmt"
 	"github.com/pkg/errors"
 	"io/ioutil"
 
+	"github.com/santhosh-tekuri/jsonschema"
 	"gopkg.in/yaml.v2"
 )
 
@@ -47,7 +49,7 @@ type TelegramTdlibClientConfig struct {
 	UseChatInfoDatabase bool   `yaml:":use_chat_info_database"`
 }
 
-func ReadConfig(path string) (Config, error) {
+func ReadConfig(path string, schema_path string) (Config, error) {
 	var config Config
 
 	file, err := ioutil.ReadFile(path)
@@ -60,5 +62,85 @@ func ReadConfig(path string) (Config, error) {
 		return config, errors.Wrap(err, "Error parsing config")
 	}
 
+	err = validateConfig(file, schema_path)
+	if err != nil {
+		return config, errors.Wrap(err, "Validation error")
+	}
+
 	return config, nil
 }
+
+func validateConfig(file []byte, schema_path string) error {
+	schema, err := jsonschema.Compile(schema_path)
+	if err != nil {
+		return errors.Wrap(err, "Corrupted JSON schema")
+	}
+
+	var config_generic interface{}
+
+	err = yaml.Unmarshal(file, &config_generic)
+	if err != nil {
+		return errors.Wrap(err, "Error re-parsing config")
+	}
+
+	config_generic, err = convertToStringKeysRecursive(config_generic, "")
+	if err != nil {
+		return errors.Wrap(err, "Config conversion error")
+	}
+
+	err = schema.ValidateInterface(config_generic)
+	if err != nil {
+		return errors.Wrap(err, "Config validation error")
+	}
+
+	return nil
+}
+
+// copied and adapted from https://github.com/docker/docker-ce/blob/de14285fad39e215ea9763b8b404a37686811b3f/components/cli/cli/compose/loader/loader.go#L330
+func convertToStringKeysRecursive(value interface{}, keyPrefix string) (interface{}, error) {
+	if mapping, ok := value.(map[interface{}]interface{}); ok {
+		dict := make(map[string]interface{})
+		for key, entry := range mapping {
+			str, ok := key.(string)
+			if !ok {
+				return nil, formatInvalidKeyError(keyPrefix, key)
+			}
+			var newKeyPrefix string
+			if keyPrefix == "" {
+				newKeyPrefix = str
+			} else {
+				newKeyPrefix = fmt.Sprintf("%s.%s", keyPrefix, str)
+			}
+			convertedEntry, err := convertToStringKeysRecursive(entry, newKeyPrefix)
+			if err != nil {
+				return nil, err
+			}
+			dict[str] = convertedEntry
+		}
+		return dict, nil
+	}
+	if list, ok := value.([]interface{}); ok {
+		var convertedList []interface{}
+		for index, entry := range list {
+			newKeyPrefix := fmt.Sprintf("%s[%d]", keyPrefix, index)
+			convertedEntry, err := convertToStringKeysRecursive(entry, newKeyPrefix)
+			if err != nil {
+				return nil, err
+			}
+			convertedList = append(convertedList, convertedEntry)
+		}
+		return convertedList, nil
+	}
+
+	return value, nil
+}
+
+func formatInvalidKeyError(keyPrefix string, key interface{}) error {
+	var location string
+	if keyPrefix == "" {
+		location = "at top level"
+	} else {
+		location = fmt.Sprintf("in %s", keyPrefix)
+	}
+	return errors.Errorf("Non-string key %s: %#v", location, key)
+}
diff --git a/config/config_test.go b/config/config_test.go
index 34009d7..6fce23b 100644
--- a/config/config_test.go
+++ b/config/config_test.go
@@ -4,23 +4,27 @@ import (
 	"testing"
 )
 
+const SCHEMA_PATH string = "../config_schema.json"
+
 func TestNoConfig(t *testing.T) {
-	_, err := ReadConfig("../test/sfklase.yml")
+	_, err := ReadConfig("../test/sfklase.yml", SCHEMA_PATH)
 	if err == nil {
 		t.Errorf("Non-existent config was successfully read")
 	}
 }
 
 func TestGoodConfig(t *testing.T) {
-	_, err := ReadConfig("../test/good_config.yml")
+	_, err := ReadConfig("../test/good_config.yml", SCHEMA_PATH)
 	if err != nil {
 		t.Errorf("Good config is not accepted: %v", err)
 	}
 }
 
 func TestBadConfig(t *testing.T) {
-	_, err := ReadConfig("../test/bad_config.yml")
+	_, err := ReadConfig("../test/bad_config.yml", SCHEMA_PATH)
 	if err == nil {
-		t.Errorf("Bad config is accepted but it shoudn't!")
+		t.Errorf("Bad config is accepted but it shouldn't!")
+	} else {
+		t.Log(err)
 	}
 }