Phase 4: plugin manifest, permissions and event hooks

app/src/main/java/io/github/abrarul/modularai/plugin/PluginHost.kt

@@ -0,0 +1,46 @@
+package io.github.abrarul.modularai.plugin
+
+import android.content.Context
+import io.github.abrarul.modularai.bridge.TermuxBridge
+import org.json.JSONObject
+import java.io.File
+
+/**
+ * Plugin layout: filesDir/plugins/<id>/plugin.json + entry script.
+ * plugin.json: {"id","name","version","entry":"run.sh","permissions":["net","shell"],"hooks":["on_capture","on_model_loaded"]}
+ * A plugin only runs hooks for permissions the user has explicitly granted.
+ */
+data class Plugin(
+    val id: String, val name: String, val version: String,
+    val entry: String, val permissions: Set<String>, val hooks: Set<String>, val dir: File
+)
+
+class PluginHost(private val ctx: Context) {
+    private val root = File(ctx.filesDir, "plugins").apply { mkdirs() }
+    private val granted = ctx.getSharedPreferences("plugin_grants", Context.MODE_PRIVATE)
+
+    fun installed(): List<Plugin> = root.listFiles()?.mapNotNull { load(it) } ?: emptyList()
+
+    private fun load(d: File): Plugin? = try {
+        val j = JSONObject(File(d, "plugin.json").readText())
+        fun set(k: String) = j.optJSONArray(k)?.let { a -> (0 until a.length()).map { a.getString(it) }.toSet() } ?: emptySet()
+        Plugin(j.getString("id"), j.getString("name"), j.getString("version"),
+            j.getString("entry"), set("permissions"), set("hooks"), d)
+    } catch (_: Exception) { null }
+
+    fun grant(id: String, perms: Set<String>) = granted.edit().putStringSet(id, perms).apply()
+    fun isGranted(p: Plugin) = granted.getStringSet(p.id, emptySet())!!.containsAll(p.permissions)
+    fun remove(p: Plugin) { p.dir.deleteRecursively(); granted.edit().remove(p.id).apply() }
+
+    /** Fires [event]; payload is passed as the first script argument. */
+    fun emit(event: String, payload: String = "") {
+        installed().filter { event in it.hooks && isGranted(it) }.forEach { p ->
+            // Entry paths must stay inside the plugin dir.
+            val entry = File(p.dir, p.entry).canonicalFile
+            if (!entry.path.startsWith(p.dir.canonicalPath)) return@forEach
+            if ("shell" in p.permissions) {
+                TermuxBridge.run(ctx, "sh '${entry.path}' '$event' \"\$1\"", arrayOf("_", payload))
+            }
+        }
+    }
+}