1 files changed, 58 insertions, 0 deletions
diff --git a/core/src/main/kotlin/ca/allanwang/kau/permissions/PermissionManager.kt b/core/src/main/kotlin/ca/allanwang/kau/permissions/PermissionManager.kt
new file mode 100644
index 0000000..6f93c9f
--- /dev/null
+++ b/core/src/main/kotlin/ca/allanwang/kau/permissions/PermissionManager.kt
@@ -0,0 +1,58 @@
+package ca.allanwang.kau.permissions
+
+import android.app.Activity
+import android.content.Context
+import android.support.v4.app.ActivityCompat
+import ca.allanwang.kau.logging.KL
+import ca.allanwang.kau.utils.KauException
+import ca.allanwang.kau.utils.buildIsMarshmallowAndUp
+import ca.allanwang.kau.utils.hasPermission
+import java.lang.ref.WeakReference
+
+/**
+ * Created by Allan Wang on 2017-07-03.
+ */
+internal object PermissionManager {
+
+    var requestInProgress = false
+    val pendingResults: MutableList<WeakReference<PermissionResult>> by lazy { mutableListOf<WeakReference<PermissionResult>>() }
+
+    operator fun invoke(context: Context, permissions: Array<out String>, callback: (granted: Boolean, deniedPerm: String?) -> Unit) {
+        KL.d("Requesting permissions: ${permissions.contentToString()}")
+        if (!buildIsMarshmallowAndUp) return callback(true, null)
+        val missingPermissions = permissions.filter { !context.hasPermission(it) }
+        if (missingPermissions.isEmpty()) return callback(true, null)
+        pendingResults.add(WeakReference(PermissionResult(permissions, callback = callback)))
+        if (!requestInProgress) {
+            requestInProgress = true
+            requestPermissions(context, missingPermissions.toTypedArray())
+        } else KL.d("Request is postponed since another one is still in progress; did you remember to override onRequestPermissionsResult?")
+    }
+
+    @Synchronized internal fun requestPermissions(context: Context, permissions: Array<out String>) {
+        val activity = (context as? Activity) ?: throw KauException("Context is not an instance of an activity; cannot request permissions")
+        ActivityCompat.requestPermissions(activity, permissions, 1)
+    }
+
+    fun onRequestPermissionsResult(context: Context, permissions: Array<out String>, grantResults: IntArray) {
+        val count = Math.min(permissions.size, grantResults.size)
+        val iter = pendingResults.iterator()
+        while (iter.hasNext()) {
+            val action = iter.next().get()
+            if ((0 until count).any { action?.onResult(permissions[it], grantResults[it]) ?: true })
+                iter.remove()
+        }
+        if (pendingResults.isEmpty())
+            requestInProgress = false
+        else {
+            val action = pendingResults.map { it.get() }.firstOrNull { it != null }
+            if (action == null) { //actions have been unlinked from their weak references
+                pendingResults.clear()
+                requestInProgress = false
+                return
+            }
+            requestPermissions(context, action.permissions.toTypedArray())
+        }
+    }
+
+}
+\ No newline at end of file