Add LlmGuardian

Author: SplotyCode

engine/src/main/kotlin/de/tuda/stg/securecoder/engine/guardian/LlmGuardian.kt

@@ -0,0 +1,61 @@
+package de.tuda.stg.securecoder.engine.guardian
+
+import de.tuda.stg.securecoder.engine.llm.ChatMessage
+import de.tuda.stg.securecoder.engine.llm.LlmClient
+import de.tuda.stg.securecoder.engine.llm.chatStructured
+import de.tuda.stg.securecoder.guardian.AnalyzeRequest
+import de.tuda.stg.securecoder.guardian.AnalyzeResponse
+import de.tuda.stg.securecoder.guardian.Guardian
+
+class LlmGuardian(
+    private val client: LlmClient,
+    private val systemPrompt: String = DEFAULT_SYSTEM_PROMPT,
+) : Guardian {
+    override suspend fun run(req: AnalyzeRequest): AnalyzeResponse {
+        val messages = buildMessages(req)
+        val llmResp = client.chatStructured<LlmAnalyzeResponse>(
+            messages = messages,
+            params = LlmClient.GenerationParams(
+                temperature = 0.0
+            )
+        )
+        return llmResp.toApi()
+    }
+
+    private fun buildMessages(req: AnalyzeRequest): List<ChatMessage> {
+        return listOf(
+            ChatMessage(ChatMessage.Role.System, systemPrompt),
+            ChatMessage(ChatMessage.Role.User, buildString {
+                appendLine("You are given a set of source files to analyze for security issues.")
+                appendLine("Only consider the provided files; do not assume hidden context.")
+                appendLine()
+                req.files.forEach { file ->
+                    appendLine("===== FILE: ${file.name} =====")
+                    appendLine(withLineNumbers(file.content))
+                    appendLine("===== END FILE: ${file.name} =====")
+                    appendLine()
+                }
+                appendLine("Return your analysis strictly using the structured schema provided by the tool.")
+            })
+        )
+    }
+
+    private fun withLineNumbers(text: String): String = buildString {
+        text.lineSequence().forEachIndexed { idx, line ->
+            append(idx + 1)
+            append(": ")
+            append(line)
+            append('\n')
+        }
+    }.removeSuffix("\n")
+
+    companion object {
+        private const val DEFAULT_SYSTEM_PROMPT: String =
+            """
+            You are SecureCoder Guardian. Analyze code for security vulnerabilities.
+            Use conservative judgment; highlight clear issues or suspicious patterns.
+            Provide precise file and line locations when possible. If unsure, leave
+            optional fields null. Do not include any prose outside the structured result.
+            """
+    }
+}