more KMP targets

src/wasmJsMain/kotlin/net.sergeych.bintools/KVStorage.wasmJs.kt

@@ -0,0 +1,63 @@
+package net.sergeych.bintools
+
+import kotlinx.browser.localStorage
+import net.sergeych.mp_tools.decodeBase64Compact
+import net.sergeych.mp_tools.encodeToBase64Compact
+import org.w3c.dom.Storage
+import org.w3c.dom.set
+
+
+/**
+ * Create per-platform default named storage.
+ *
+ * - In the browser, it uses the `Window.localStorage` prefixing items
+ *   by a string containing the [name]
+ *
+ * - In the JVM environment it uses folder-based storage on the file system. The name
+ *   is considered to be a folder name (the whole path which will be automatically created)
+ *   using the following rules:
+ *    - when the name starts with slash (`/`) it is treated as an absolute path to a folder
+ *    - when the name contains slash, it is considered to be a relative folder to the
+ *      `User.home` directory, like "`~/`" on unix systems.
+ *    - otherwise, the folder will be created in "`~/.local_storage`" parent directory
+ *      (which also will be created if needed).
+ *
+ *  - For the native platorms it is not yet implemented (but will be soon).
+ *
+ *  See [DataKVStorage] and [DataProvider] to implement a KVStorage on filesystems and like,
+ *  and `FileDataProvider` class on JVM target.
+ */
+actual fun defaultNamedStorage(name: String): KVStorage =  BrowserKVStorage(name, localStorage)
+
+/**
+ * Default KV storage in browser. Use if with `localStorage` or `sessionStorage`. It uses
+ * prefix for storage values not to collide with other data, beware of it.
+ */
+class BrowserKVStorage(keyPrefix: String, private val bst: Storage) : KVStorage {
+
+    private val prefix = "$keyPrefix:"
+    fun k(key: String) = "$prefix$key"
+    override fun get(key: String): ByteArray? {
+        return bst.getItem(k(key))?.decodeBase64Compact()
+    }
+
+    override fun set(key: String, value: ByteArray?) {
+        val corrected = k(key)
+        if (value == null)
+            bst.removeItem(corrected)
+        else
+            bst.set(corrected, value.encodeToBase64Compact())
+    }
+
+    override val keys: Set<String>
+        get() {
+            val kk = mutableListOf<String>()
+            for (i in 0 until bst.length) {
+                val k = bst.key(i) ?: break
+                if( k.startsWith(prefix)) {
+                    kk += k.substring(prefix.length)
+                }
+            }
+            return kk.toSet()
+        }
+}