From 3b20dcb41a23238434dd04bb84f7e36e01c259e1 Mon Sep 17 00:00:00 2001
From: Stefan Oltmann <github@stefan-oltmann.de>
Date: Sat, 16 Dec 2023 00:20:45 +0100
Subject: [PATCH] WASM Zlib support (#47)

Use pako library for WASM zlib to fully support PNG
---
 README.md                                     |  3 +--
 build.gradle.kts                              | 20 +++++++++++++-
 kotlin-js-store/yarn.lock                     | 23 ++++++++++++++++
 .../com/ashampoo/kim/common/ZLib.wasm.kt      | 27 +++++++++++++++++--
 4 files changed, 68 insertions(+), 5 deletions(-)
 create mode 100644 kotlin-js-store/yarn.lock

diff --git a/README.md b/README.md
index 55383a7a..1cc7dbe5 100644
--- a/README.md
+++ b/README.md
@@ -34,7 +34,7 @@ of Ashampoo Photos, which, in turn, is driven by user community feedback.
 ## Installation
 
 ```
-implementation("com.ashampoo:kim:0.8")
+implementation("com.ashampoo:kim:0.8.1")
 ```
 
 ## Sample usages
@@ -139,7 +139,6 @@ val newBytes = Kim.updateThumbnail(
 ## Limitations
 
 * Inability to update EXIF, IPTC and XMP in JPG files simultaneously.
-* There is no implementation of WebAssembly (WASM) for ZLib compression, which means that PNG files utilizing this compression cannot be processed.
 
 ## Contributions
 
diff --git a/build.gradle.kts b/build.gradle.kts
index d4a2d1e8..dbacf8e2 100644
--- a/build.gradle.kts
+++ b/build.gradle.kts
@@ -1,6 +1,7 @@
 import org.jetbrains.kotlin.gradle.plugin.mpp.NativeBuildType
 import org.jetbrains.kotlin.gradle.plugin.mpp.apple.XCFramework
 import org.jetbrains.kotlin.gradle.targets.js.dsl.ExperimentalWasmDsl
+import org.jetbrains.kotlin.gradle.targets.js.nodejs.NodeJsRootExtension
 
 plugins {
     kotlin("multiplatform") version "1.9.21"
@@ -146,7 +147,11 @@ kotlin {
     }
 
     @OptIn(ExperimentalWasmDsl::class)
-    wasmJs()
+    wasmJs {
+        // All tests reading from files fail, because kotlinx-io
+        // has no Path support for WASM (yet?).
+        // nodejs()
+    }
 
 //  Note: Missing support in kotlinx-datetime
 //    @OptIn(ExperimentalWasmDsl::class)
@@ -278,6 +283,10 @@ kotlin {
 
         wasmJsMain.dependsOn(this)
         // wasmWasiMain.dependsOn(this)
+
+        dependencies {
+            implementation(npm("pako", "2.1.0"))
+        }
     }
 }
 
@@ -450,3 +459,12 @@ publishing {
     }
 }
 // endregion
+
+//rootProject.the<NodeJsRootExtension>().apply {
+//    nodeVersion = "21.0.0-v8-canary202309143a48826a08"
+//    nodeDownloadBaseUrl = "https://nodejs.org/download/v8-canary"
+//}
+//
+//tasks.withType<org.jetbrains.kotlin.gradle.targets.js.npm.tasks.KotlinNpmInstallTask>().configureEach {
+//    args.add("--ignore-engines")
+//}
diff --git a/kotlin-js-store/yarn.lock b/kotlin-js-store/yarn.lock
new file mode 100644
index 00000000..87aee93f
--- /dev/null
+++ b/kotlin-js-store/yarn.lock
@@ -0,0 +1,23 @@
+# THIS IS AN AUTOGENERATED FILE. DO NOT EDIT THIS FILE DIRECTLY.
+# yarn lockfile v1
+
+
+"@js-joda/core@3.2.0":
+  version "3.2.0"
+  resolved "https://registry.yarnpkg.com/@js-joda/core/-/core-3.2.0.tgz#3e61e21b7b2b8a6be746df1335cf91d70db2a273"
+  integrity sha512-PMqgJ0sw5B7FKb2d5bWYIoxjri+QlW/Pys7+Rw82jSH0QN3rB05jZ/VrrsUdh1w4+i2kw9JOejXGq/KhDOX7Kg==
+
+format-util@^1.0.5:
+  version "1.0.5"
+  resolved "https://registry.yarnpkg.com/format-util/-/format-util-1.0.5.tgz#1ffb450c8a03e7bccffe40643180918cc297d271"
+  integrity sha512-varLbTj0e0yVyRpqQhuWV+8hlePAgaoFRhNFj50BNjEIrw1/DphHSObtqwskVCPWNgzwPoQrZAbfa/SBiicNeg==
+
+pako@2.1.0:
+  version "2.1.0"
+  resolved "https://registry.yarnpkg.com/pako/-/pako-2.1.0.tgz#266cc37f98c7d883545d11335c00fbd4062c9a86"
+  integrity sha512-w+eufiZ1WuJYgPXbV/PO3NCMEc3xqylkKHzp8bxp1uW4qaSNQUkwmLLEc3kKsfz8lpV1F8Ht3U1Cm+9Srog2ug==
+
+typescript@5.0.4:
+  version "5.0.4"
+  resolved "https://registry.yarnpkg.com/typescript/-/typescript-5.0.4.tgz#b217fd20119bd61a94d4011274e0ab369058da3b"
+  integrity sha512-cW9T5W9xY37cc+jfEnaUvX91foxtHkza3Nw3wkoF4sSlKn0MONdkdEndig/qPBWXNkmplh3NzayQzCiHM4/hqw==
diff --git a/src/wasmMain/kotlin/com/ashampoo/kim/common/ZLib.wasm.kt b/src/wasmMain/kotlin/com/ashampoo/kim/common/ZLib.wasm.kt
index b848d948..173cee90 100644
--- a/src/wasmMain/kotlin/com/ashampoo/kim/common/ZLib.wasm.kt
+++ b/src/wasmMain/kotlin/com/ashampoo/kim/common/ZLib.wasm.kt
@@ -15,8 +15,31 @@
  */
 package com.ashampoo.kim.common
 
+import org.khronos.webgl.Uint8Array
+import org.khronos.webgl.get
+import org.khronos.webgl.set
+
 actual fun compress(input: String): ByteArray =
-    TODO("NOT implemented!") // FIXME
+    Pako.deflate(input).toByteArray()
 
 actual fun decompress(byteArray: ByteArray): String =
-    TODO("NOT implemented!") // FIXME
+    Pako.inflate(byteArray.toUint8Array(), toStringOptions)
+
+private val toStringOptions: JsAny = js("({to: 'string'})")
+
+private fun Uint8Array.toByteArray(): ByteArray =
+    ByteArray(length) { this[it] }
+
+private fun ByteArray.toUint8Array(): Uint8Array {
+    val result = Uint8Array(size)
+    forEachIndexed { index, byte ->
+        result[index] = byte
+    }
+    return result
+}
+
+@JsModule("pako")
+private external object Pako {
+    fun deflate(data: String): Uint8Array
+    fun inflate(data: Uint8Array, options: JsAny): String
+}