Pull request 2111: 6545-schema-version

Updates #6545.

Squashed commit of the following:

commit b1969128a99ff21c97feb4e7805b4b8133d7122f
Author: Ainar Garipov <A.Garipov@AdGuard.COM>
Date:   Fri Dec 15 20:04:37 2023 +0300

    home: fix import

commit 872ccea1491a8da76cc24db79247438d0ce4d256
Author: Ainar Garipov <A.Garipov@AdGuard.COM>
Date:   Fri Dec 15 20:01:15 2023 +0300

    all: output schema version

internal/configmigrate/v16.go

@@ -0,0 +1,78 @@
+package configmigrate
+
+// migrateTo16 performs the following changes:
+//
+//	# BEFORE:
+//	'schema_version': 15
+//	'dns':
+//	  # …
+//	  'statistics_interval': 1
+//	'statistics':
+//	  # …
+//	# …
+//
+//	# AFTER:
+//	'schema_version': 16
+//	'dns':
+//	  # …
+//	'statistics':
+//	  'enabled': true
+//	  'interval': 1
+//	  'ignored': []
+//	  # …
+//	# …
+//
+// If statistics were disabled:
+//
+//	# BEFORE:
+//	'schema_version': 15
+//	'dns':
+//	  # …
+//	  'statistics_interval': 0
+//	'statistics':
+//	  # …
+//	# …
+//
+//	# AFTER:
+//	'schema_version': 16
+//	'dns':
+//	  # …
+//	'statistics':
+//	  'enabled': false
+//	  'interval': 1
+//	  'ignored': []
+//	  # …
+//	# …
+func migrateTo16(diskConf yobj) (err error) {
+	diskConf["schema_version"] = 16
+
+	dns, ok, err := fieldVal[yobj](diskConf, "dns")
+	if !ok {
+		return err
+	}
+
+	stats := yobj{
+		"enabled":  true,
+		"interval": 1,
+		"ignored":  yarr{},
+	}
+	diskConf["statistics"] = stats
+
+	const field = "statistics_interval"
+
+	statsIvl, ok, err := fieldVal[int](dns, field)
+	if !ok {
+		return err
+	}
+
+	if statsIvl == 0 {
+		// Set the interval to the default value of one day to make sure
+		// that it passes the validations.
+		stats["enabled"] = false
+	} else {
+		stats["interval"] = statsIvl
+	}
+	delete(dns, field)
+
+	return nil
+}