// This file is part of arduino-cli.
//
// Copyright 2020 ARDUINO SA (http://www.arduino.cc/)
//
// This software is released under the GNU General Public License version 3,
// which covers the main part of arduino-cli.
// The terms of this license can be found at:
// https://www.gnu.org/licenses/gpl-3.0.en.html
//
// You can be released from the requirements of the above licenses by purchasing
// a commercial license. Buying such a license is mandatory if you want to
// modify or otherwise use the software for commercial activities involving the
// Arduino software without disclosing the source code of your own applications.
// To purchase a commercial license, send an email to license@arduino.cc.

package po

// Merge merges two message catalogs, preserving only keys present in source
func Merge(source MessageCatalog, destination MessageCatalog) MessageCatalog {
	catalog := MessageCatalog{}
	for _, k := range source.SortedKeys() {
		if k == "" {
			sourceMessage := source.Messages[k]
			destinationMessage := destination.Messages[k]

			if destinationMessage != nil {
				catalog.AddMessage(k, *destinationMessage)
			} else {
				catalog.AddMessage(k, *sourceMessage)
			}

			continue
		}

		if destination.Messages[k] != nil {
			catalog.Add(k, destination.Messages[k].Value, source.Messages[k].Comments)
		} else {
			catalog.Add(k, "", source.Messages[k].Comments)
		}
	}
	return catalog
}