package com.xly.erp.common.security;

import com.xly.erp.common.exception.BizException;
import com.xly.erp.common.response.ErrorCode;
import io.jsonwebtoken.Claims;
import io.jsonwebtoken.JwtException;
import io.jsonwebtoken.Jwts;
import io.jsonwebtoken.security.Keys;
import jakarta.annotation.PostConstruct;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Component;

import javax.crypto.SecretKey;
import java.nio.charset.StandardCharsets;
import java.util.Date;
import java.util.HashMap;
import java.util.Map;
import java.util.UUID;

/**
 * JWT 签发与验证工具。HS256，密钥来自 ${JWT_SECRET}。
 * docs/04 § 1.6。
 */
@Component
public class JwtUtil {

    @Value("${jwt.secret}")
    private String secret;

    private SecretKey key;

    @PostConstruct
    void init() {
        byte[] bytes = secret.getBytes(StandardCharsets.UTF_8);
        if (bytes.length < 32) {
            throw new IllegalStateException(
                    "JWT_SECRET 长度不足 32 字节（HS256 要求），实际 " + bytes.length
                            + " 字节。请在 .env.local 配置至少 256 位的随机字符串。");
        }
        this.key = Keys.hmacShaKeyFor(bytes);
    }

    public String issue(Map<String, Object> claims, long ttlSec) {
        long now = System.currentTimeMillis();
        Map<String, Object> all = new HashMap<>(claims);
        String sub = String.valueOf(all.remove("sub"));
        String jti = UUID.randomUUID().toString();
        return Jwts.builder()
                .subject(sub)
                .claims(all)
                .id(jti)
                .issuedAt(new Date(now))
                .expiration(new Date(now + ttlSec * 1000L))
                .signWith(key)
                .compact();
    }

    public Map<String, Object> parse(String token) {
        try {
            Claims claims = Jwts.parser()
                    .verifyWith(key)
                    .build()
                    .parseSignedClaims(token)
                    .getPayload();
            Map<String, Object> out = new HashMap<>(claims);
            out.put("sub", claims.getSubject());
            out.put("jti", claims.getId());
            out.put("iat", claims.getIssuedAt() != null ? claims.getIssuedAt().getTime() / 1000 : null);
            out.put("exp", claims.getExpiration() != null ? claims.getExpiration().getTime() / 1000 : null);
            return out;
        } catch (JwtException e) {
            throw new BizException(ErrorCode.BAD_CREDENTIALS, "token 无效或已过期");
        }
    }
}