add PrivateJwtService

src/main/kotlin/ltd/hlaeja/jwt/service/PrivateJwtService.kt

@@ -0,0 +1,26 @@
+package ltd.hlaeja.jwt.service
+
+import io.jsonwebtoken.Jwts
+import java.security.interfaces.RSAPrivateKey
+import ltd.hlaeja.jwt.util.PrivateKeyProvider
+import org.springframework.beans.factory.annotation.Value
+import org.springframework.boot.autoconfigure.condition.ConditionalOnProperty
+import org.springframework.stereotype.Service
+
+@Service
+@ConditionalOnProperty(prefix = "jwt", name = ["private-key"])
+class PrivateJwtService(
+    @Value("\${jwt.private-key}") jwtPrivateKey: String,
+) {
+
+    private var privateKey: RSAPrivateKey = PrivateKeyProvider.load(jwtPrivateKey)
+
+    fun sign(
+        vararg claim: Pair<String, Any>,
+    ): String = Jwts.builder()
+        .claims()
+        .also { claims -> claim.forEach { claims.add(it.first, it.second) } }
+        .and()
+        .signWith(privateKey)
+        .compact()
+}

src/test/kotlin/ltd/hlaeja/jwt/service/PrivateJwtServiceTest.kt

@@ -0,0 +1,54 @@
+package ltd.hlaeja.jwt.service
+
+import java.util.Base64
+import org.assertj.core.api.Assertions.assertThat
+import org.junit.jupiter.api.BeforeEach
+import org.junit.jupiter.api.Test
+
+class PrivateJwtServiceTest {
+
+    private lateinit var service: PrivateJwtService
+
+    @BeforeEach
+    fun setup() {
+        service = PrivateJwtService("cert/valid-private-key.pem")
+    }
+
+    @Test
+    fun `make token with claims`() {
+        // given
+        val claim1 = "claim1" to "value1"
+        val claim2 = "claim2" to 123
+
+        // when
+        val token = service.sign(claim1, claim2)
+
+        // then
+        assertThat(token).isNotEmpty()
+
+        val parts = token.split("\\.".toRegex())
+        assertThat(parts).hasSize(3)
+
+        val header = String(Base64.getDecoder().decode(parts[0]))
+        val payload = String(Base64.getDecoder().decode(parts[1]))
+        assertThat(header).contains("RS256")
+        assertThat(payload).contains("\"claim1\":\"value1\"", "\"claim2\":123")
+    }
+
+    @Test
+    fun `make token with no claims`() {
+        // when
+        val token = service.sign()
+
+        // then
+        assertThat(token).isNotEmpty()
+
+        val parts = token.split("\\.".toRegex())
+        assertThat(parts).hasSize(3)
+
+        val header = String(Base64.getDecoder().decode(parts[0]))
+        val payload = String(Base64.getDecoder().decode(parts[1]))
+        assertThat(header).contains("RS256")
+        assertThat(payload).isEmpty()
+    }
+}