Add linter

src/main/kotlin/dev/jellylink/jellyfin/client/JellyfinResponseParser.kt

@@ -0,0 +1,123 @@
+package dev.jellylink.jellyfin.client
+
+import dev.jellylink.jellyfin.model.JellyfinMetadata
+import kotlinx.serialization.json.Json
+import kotlinx.serialization.json.contentOrNull
+import kotlinx.serialization.json.jsonArray
+import kotlinx.serialization.json.jsonObject
+import kotlinx.serialization.json.jsonPrimitive
+import kotlinx.serialization.json.longOrNull
+import org.slf4j.LoggerFactory
+
+/**
+ * Stateless parser for Jellyfin API JSON responses.
+ *
+ * Converts raw JSON strings into domain objects used by the plugin.
+ */
+class JellyfinResponseParser(
+    private val json: Json = Json { ignoreUnknownKeys = true },
+) {
+    /**
+     * Result of parsing an authentication response.
+     */
+    data class AuthResult(
+        val accessToken: String,
+        val userId: String,
+    )
+
+    /**
+     * Extract [AuthResult] from the Jellyfin AuthenticateByName response body.
+     *
+     * @return parsed result, or `null` if the required fields are missing
+     */
+    fun parseAuthResponse(body: String): AuthResult? {
+        val root = json.parseToJsonElement(body).jsonObject
+        val token = root["AccessToken"]?.jsonPrimitive?.contentOrNull
+        val userId =
+            root["User"]
+                ?.jsonObject
+                ?.get("Id")
+                ?.jsonPrimitive
+                ?.contentOrNull
+
+        if (token == null || userId == null) {
+            log.error("Jellyfin auth response missing AccessToken or User.Id")
+            return null
+        }
+
+        return AuthResult(accessToken = token, userId = userId)
+    }
+
+    /**
+     * Parse the Items array from a Jellyfin search response and return the first audio item.
+     *
+     * @param body       raw JSON response body
+     * @param baseUrl    Jellyfin server base URL (used for artwork URL construction)
+     * @return the first [JellyfinMetadata] found, or `null`
+     */
+    fun parseFirstAudioItem(
+        body: String,
+        baseUrl: String,
+    ): JellyfinMetadata? {
+        val root = json.parseToJsonElement(body).jsonObject
+        val items = root["Items"]?.jsonArray
+
+        if (items.isNullOrEmpty()) {
+            return null
+        }
+
+        return parseAudioItem(items[0].jsonObject, baseUrl)
+    }
+
+    /**
+     * Convert a single Jellyfin item JSON object into [JellyfinMetadata].
+     */
+    private fun parseAudioItem(
+        item: kotlinx.serialization.json.JsonObject,
+        baseUrl: String,
+    ): JellyfinMetadata? {
+        val id = item["Id"]?.jsonPrimitive?.contentOrNull ?: return null
+        val title = item["Name"]?.jsonPrimitive?.contentOrNull
+        val artist = item["AlbumArtist"]?.jsonPrimitive?.contentOrNull
+            ?: item["Artists"]
+                ?.jsonArray
+                ?.firstOrNull()
+                ?.jsonPrimitive
+                ?.contentOrNull
+
+        val album = item["Album"]?.jsonPrimitive?.contentOrNull
+
+        val runTimeTicks = item["RunTimeTicks"]?.jsonPrimitive?.longOrNull
+        val lengthMs = runTimeTicks?.let { it / TICKS_PER_MILLISECOND }
+
+        val imageTag = item["ImageTags"]
+            ?.jsonObject
+            ?.get("Primary")
+            ?.jsonPrimitive
+            ?.contentOrNull
+
+        val normalizedBase = baseUrl.trimEnd('/')
+        val artUrl =
+            if (imageTag != null) {
+                "$normalizedBase/Items/$id/Images/Primary?tag=$imageTag"
+            } else {
+                "$normalizedBase/Items/$id/Images/Primary"
+            }
+
+        log.info("Jellyfin artwork URL: {} (tag={})", artUrl, imageTag)
+
+        return JellyfinMetadata(
+            id = id,
+            title = title,
+            artist = artist,
+            album = album,
+            lengthMs = lengthMs,
+            artworkUrl = artUrl,
+        )
+    }
+
+    companion object {
+        private val log = LoggerFactory.getLogger(JellyfinResponseParser::class.java)
+        private const val TICKS_PER_MILLISECOND = 10_000L
+    }
+}