lib: expose GgufMetadataReader as interface only

examples/llama.android/app/src/main/java/com/example/llama/data/repository/ModelRepository.kt

@@ -107,6 +107,7 @@ class ModelRepositoryImpl @Inject constructor(
     @ApplicationContext private val context: Context,
     private val modelDao: ModelDao,
     private val huggingFaceRemoteDataSource: HuggingFaceRemoteDataSource,
+    private val ggufMetadataReader: GgufMetadataReader,
 ) : ModelRepository {
 
     private val modelsDir = File(context.filesDir, INTERNAL_STORAGE_PATH)
@@ -224,7 +225,7 @@ class ModelRepositoryImpl @Inject constructor(
             val metadata = try {
                 val filePath = modelFile.absolutePath
                 Log.i(TAG, "Extracting GGUF Metadata from $filePath")
-                GgufMetadata.fromDomain(GgufMetadataReader().readStructuredMetadata(filePath))
+                GgufMetadata.fromDomain(ggufMetadataReader.readStructuredMetadata(filePath))
             } catch (e: Exception) {
                 Log.e(TAG, "Cannot extract GGUF metadata: ${e.message}", e)
                 throw e

examples/llama.android/app/src/main/java/com/example/llama/di/AppModule.kt

@@ -3,6 +3,7 @@ package com.example.llama.di
 import android.content.Context
 import android.llama.cpp.InferenceEngine
 import android.llama.cpp.InferenceEngineLoader
+import android.llama.cpp.gguf.GgufMetadataReader
 import com.example.llama.data.local.AppDatabase
 import com.example.llama.data.remote.HuggingFaceApiService
 import com.example.llama.data.remote.HuggingFaceRemoteDataSource
@@ -82,6 +83,10 @@ internal abstract class AppModule {
         @Provides
         fun providesSystemPromptDao(appDatabase: AppDatabase) = appDatabase.systemPromptDao()
 
+        @Provides
+        @Singleton
+        fun providesGgufMetadataReader(): GgufMetadataReader = GgufMetadataReader.create()
+
         @Provides
         @Singleton
         fun provideOkhttpClient() = OkHttpClient.Builder()

examples/llama.android/llama/src/main/java/android/llama/cpp/gguf/GgufMetadataReader.kt

@@ -4,23 +4,62 @@ import java.io.File
 import java.io.IOException
 import java.io.InputStream
 
-private val DEFAULT_SKIP_KEYS = setOf(
+/**
+ * Interface for reading GGUF metadata from model files.
+ * Use `GgufMetadataReader.create()` to get an instance.
+ */
+interface GgufMetadataReader {
+    /**
+     * Reads and parses GGUF metadata from the specified file path.
+     *
+     * @param path The absolute path to the GGUF file
+     * @return Structured metadata extracted from the file
+     * @throws IOException if file cannot be read
+     * @throws IllegalArgumentException if file format is invalid
+     */
+    suspend fun readStructuredMetadata(path: String): GgufMetadata
+
+    companion object {
+        private val DEFAULT_SKIP_KEYS = setOf(
             "tokenizer.chat_template",
             "tokenizer.ggml.scores",
             "tokenizer.ggml.tokens",
             "tokenizer.ggml.token_type"
-)
+        )
+
+        /**
+         * Creates a default GgufMetadataReader instance
+         */
+        fun create(): GgufMetadataReader = GgufMetadataReaderImpl(
+            skipKeys = DEFAULT_SKIP_KEYS,
+            arraySummariseThreshold = 1_000
+        )
+
+        /**
+         * Creates a GgufMetadataReader with custom configuration
+         *
+         * @param skipKeys Keys whose value should be skipped entirely (not kept in the result map)
+         * @param arraySummariseThreshold If ≥0, arrays longer get summarised, not materialised;
+         *                                If -1, never summarise.
+         */
+        fun create(
+            skipKeys: Set<String> = DEFAULT_SKIP_KEYS,
+            arraySummariseThreshold: Int = 1_000
+        ): GgufMetadataReader = GgufMetadataReaderImpl(
+            skipKeys = skipKeys,
+            arraySummariseThreshold = arraySummariseThreshold
+        )
+    }
+}
 
 /**
  * Utility class to read GGUF model files and extract metadata key-value pairs.
  * This parser reads the header and metadata of a GGUF v3 file (little-endian) and skips tensor data.
  */
-class GgufMetadataReader(
-    /** Keys whose value should be skipped entirely (not kept in the resulting map). */
-    private val skipKeys: Set<String> = DEFAULT_SKIP_KEYS,
-    /** If ≥0, arrays longer than this get summarised instead of materialised.  -1 ⇒ never summarise. */
-    private val arraySummariseThreshold: Int = 1_000
-) {
+private class GgufMetadataReaderImpl(
+    private val skipKeys: Set<String>,
+    private val arraySummariseThreshold: Int,
+) : GgufMetadataReader {
     companion object {
         private const val ARCH_LLAMA = "llama"
     }
@@ -92,7 +131,7 @@ class GgufMetadataReader(
      * @throws IOException if the file is not GGUF, the version is unsupported,
      *         or the metadata block is truncated / corrupt.
      */
-    fun readStructuredMetadata(path: String): GgufMetadata {
+    override suspend fun readStructuredMetadata(path: String): GgufMetadata {
         File(path).inputStream().buffered().use { input ->
             // ── 1. header ──────────────────────────────────────────────────────────
                           // throws on mismatch