package jnpf.dmsPermission;

import lombok.AllArgsConstructor;
import lombok.Data;
import org.springframework.stereotype.Component;

import java.nio.charset.StandardCharsets;
import java.sql.Timestamp;
import java.time.Instant;
import java.util.Base64;
import java.util.Date;
import java.util.UUID;

@Component
public class DmsCursorCodec {

    public String encode(Date time, UUID id) {
        String raw = time.toInstant().toString() + "|" + id;
        return Base64.getUrlEncoder().withoutPadding().encodeToString(raw.getBytes(StandardCharsets.UTF_8));
    }

    public Cursor decode(String value) {
        if (value == null || value.trim().isEmpty()) {
            return new Cursor(null, null);
        }
        try {
            String raw = new String(Base64.getUrlDecoder().decode(value), StandardCharsets.UTF_8);
            int separator = raw.indexOf('|');
            if (separator < 1) {
                throw new IllegalArgumentException("missing separator");
            }
            return new Cursor(Timestamp.from(Instant.parse(raw.substring(0, separator))),
                    UUID.fromString(raw.substring(separator + 1)));
        } catch (RuntimeException ex) {
            throw DmsPermissionException.of(DmsPermissionError.INVALID_REQUEST, "分页 cursor 无效");
        }
    }

    @Data
    @AllArgsConstructor
    public static class Cursor {
        private Date time;
        private UUID id;
    }
}