// appendMatchingImages updates matchingImages with image metadata records from images which belong to the
// specified region. If an image already exists in matchingImages, it is not overwritten.
func appendMatchingImages(source simplestreams.DataSource, matchingImages []interface{},
	images map[string]interface{}, cons simplestreams.LookupConstraint) ([]interface{}, error) {

	imagesMap := make(map[imageKey]*ImageMetadata, len(matchingImages))
	for _, val := range matchingImages {
		im := val.(*ImageMetadata)
		imagesMap[imageKey{im.VirtType, im.Arch, im.Version, im.RegionName, im.Storage}] = im
	}
	for _, val := range images {
		im := val.(*ImageMetadata)
		if cons != nil && cons.Params().Region != "" && cons.Params().Region != im.RegionName {
			continue
		}
		if _, ok := imagesMap[imageKey{im.VirtType, im.Arch, im.Version, im.RegionName, im.Storage}]; !ok {
			matchingImages = append(matchingImages, im)
		}
	}
	return matchingImages, nil
}

// appendMatchingTools updates matchingTools with tools metadata records from tools which belong to the
// specified series. If a tools record already exists in matchingTools, it is not overwritten.
func appendMatchingTools(source simplestreams.DataSource, matchingTools []interface{},
	tools map[string]interface{}, cons simplestreams.LookupConstraint) ([]interface{}, error) {

	toolsMap := make(map[version.Binary]*ToolsMetadata, len(matchingTools))
	for _, val := range matchingTools {
		tm := val.(*ToolsMetadata)
		binary, err := tm.binary()
		if err != nil {
			return nil, errors.Trace(err)
		}
		toolsMap[binary] = tm
	}
	for _, val := range tools {
		tm := val.(*ToolsMetadata)
		if !set.NewStrings(cons.Params().Series...).Contains(tm.Release) {
			continue
		}
		if toolsConstraint, ok := cons.(*ToolsConstraint); ok {
			tmNumber := version.MustParse(tm.Version)
			if toolsConstraint.Version == version.Zero {
				if toolsConstraint.MajorVersion >= 0 && toolsConstraint.MajorVersion != tmNumber.Major {
					continue
				}
				if toolsConstraint.MinorVersion >= 0 && toolsConstraint.MinorVersion != tmNumber.Minor {
					continue
				}
			} else {
				if toolsConstraint.Version != tmNumber {
					continue
				}
			}
		}
		binary, err := tm.binary()
		if err != nil {
			return nil, errors.Trace(err)
		}
		if _, ok := toolsMap[binary]; !ok {
			tm.FullPath, _ = source.URL(tm.Path)
			matchingTools = append(matchingTools, tm)
		}
	}
	return matchingTools, nil
}