added jwt auth to service

src/main/java/zw/qantra/tm/utils/JwtUtils.java

@@ -0,0 +1,72 @@
+package zw.qantra.tm.utils;
+
+import io.jsonwebtoken.*;
+import io.jsonwebtoken.security.Keys;
+import org.springframework.beans.factory.annotation.Value;
+import org.springframework.security.core.userdetails.UserDetails;
+import org.springframework.stereotype.Component;
+
+import javax.crypto.SecretKey;
+import java.util.Date;
+import java.util.HashMap;
+import java.util.Map;
+import java.util.function.Function;
+
+@Component
+public class JwtUtils {
+
+    @Value("${jwt.secret:defaultSecretKey123456789012345678901234567890}")
+    private String secret;
+
+    @Value("${jwt.expiration:86400000}")
+    private Long expiration;
+
+    private SecretKey getSigningKey() {
+        return Keys.hmacShaKeyFor(secret.getBytes());
+    }
+
+    public String extractUsername(String token) {
+        return extractClaim(token, Claims::getSubject);
+    }
+
+    public Date extractExpiration(String token) {
+        return extractClaim(token, Claims::getExpiration);
+    }
+
+    public <T> T extractClaim(String token, Function<Claims, T> claimsResolver) {
+        final Claims claims = extractAllClaims(token);
+        return claimsResolver.apply(claims);
+    }
+
+    private Claims extractAllClaims(String token) {
+        return Jwts.parser()
+                .verifyWith(getSigningKey())
+                .build()
+                .parseSignedClaims(token)
+                .getPayload();
+    }
+
+    private Boolean isTokenExpired(String token) {
+        return extractExpiration(token).before(new Date());
+    }
+
+    public String generateToken(UserDetails userDetails) {
+        Map<String, Object> claims = new HashMap<>();
+        return createToken(claims, userDetails.getUsername());
+    }
+
+    private String createToken(Map<String, Object> claims, String subject) {
+        return Jwts.builder()
+                .setClaims(claims)
+                .setSubject(subject)
+                .setIssuedAt(new Date(System.currentTimeMillis()))
+                .setExpiration(new Date(System.currentTimeMillis() + expiration))
+                .signWith(getSigningKey(), SignatureAlgorithm.HS256)
+                .compact();
+    }
+
+    public Boolean validateToken(String token, UserDetails userDetails) {
+        final String username = extractUsername(token);
+        return (username.equals(userDetails.getUsername()) && !isTokenExpired(token));
+    }
+}