package auth

import (
	"strings"
)

// IsAuthTokenPayloadKey returns true if key is a credential or token lifecycle field
// that should not overwrite newly acquired OAuth credentials during metadata merge.
func IsAuthTokenPayloadKey(key string) bool {
	switch strings.ToLower(strings.TrimSpace(key)) {
	case "access_token", "refresh_token", "id_token", "session_id",
		"expired", "last_refresh", "expires_in", "timestamp",
		"token_type", "user_code", "verification_uri", "verification_uri_complete":
		return true
	default:
		return false
	}
}

// MergeExistingAuthMetadata merges user-configured metadata fields from existingMap
// into target.Metadata and target.Storage if target does not already define them.
func MergeExistingAuthMetadata(target *Auth, existingMap map[string]any) {
	if target == nil || len(existingMap) == 0 {
		return
	}
	if target.Metadata == nil {
		target.Metadata = make(map[string]any)
	}
	for k, v := range existingMap {
		if IsAuthTokenPayloadKey(k) {
			continue
		}
		if _, exists := target.Metadata[k]; !exists {
			target.Metadata[k] = v
		}
	}
	if setter, ok := target.Storage.(interface{ SetMetadata(map[string]any) }); ok {
		setter.SetMetadata(target.Metadata)
	}
}