From d284a8733d2efb0ad593de2e964329ad33163f04 Mon Sep 17 00:00:00 2001
From: Muhammad Azeez <muhammad@dylibso.com>
Date: Thu, 12 Dec 2024 17:09:51 +0300
Subject: [PATCH] call with host context

---
 src/CurrentPlugin.php      | 15 +++++++++++++++
 src/Internal/LibExtism.php | 31 ++++++++++++++++++++++++++++++-
 tests/PluginTest.php       | 33 +++++++++++++++++++++++++++++++++
 3 files changed, 78 insertions(+), 1 deletion(-)

diff --git a/src/CurrentPlugin.php b/src/CurrentPlugin.php
index e931a55..64c0ff9 100644
--- a/src/CurrentPlugin.php
+++ b/src/CurrentPlugin.php
@@ -24,6 +24,21 @@ public function __construct($lib, \FFI\CData $handle)
         $this->lib = $lib;
     }
 
+   /**
+     * Get *a copy* of the current plugin call's associated host context data. Returns null if call was made without host context.
+     *
+     * @return mixed|null Returns a copy of the host context data or null if none was provided
+     */
+    public function getCallHostContext()
+    {
+        $serialized = $this->lib->extism_current_plugin_host_context($this->handle);
+        if ($serialized === null) {
+            return null;
+        }
+
+        return unserialize($serialized);
+    }
+
     /**
      * Reads a string from the plugin's memory at the given offset.
      *
diff --git a/src/Internal/LibExtism.php b/src/Internal/LibExtism.php
index aca82f9..5c267fb 100644
--- a/src/Internal/LibExtism.php
+++ b/src/Internal/LibExtism.php
@@ -197,7 +197,23 @@ public function extism_plugin_config(\FFI\CData $plugin, string $json, int $json
     public function extism_plugin_call_with_host_context(\FFI\CData $plugin, string $func_name, string $data, int $data_len, $host_context): int
     {
         $dataPtr = $this->owned("uint8_t", $data);
-        return $this->ffi->extism_plugin_call_with_host_context($plugin, $func_name, $dataPtr, $data_len, $host_context);
+
+        if ($host_context === null) {
+            return $this->ffi->extism_plugin_call_with_host_context($plugin, $func_name, $dataPtr, $data_len, null);
+        }
+
+        $serialized = serialize($host_context);
+        $contextPtr = $this->ffi->new("char*");
+        $contextArray = $this->ownedZero($serialized);
+        $contextPtr = \FFI::addr($contextArray);
+
+        return $this->ffi->extism_plugin_call_with_host_context(
+            $plugin,
+            $func_name,
+            $dataPtr,
+            $data_len,
+            $contextPtr
+        );
     }
 
     /**
@@ -219,6 +235,19 @@ public function extism_plugin_call(\FFI\CData $plugin, string $func_name, string
         return $this->ffi->extism_plugin_call($plugin, $func_name, $dataPtr, $data_len);
     }
 
+    /**
+     * Get the current plugin's associated host context data
+     */
+    public function extism_current_plugin_host_context(\FFI\CData $plugin): ?string
+    {
+        $ptr = $this->ffi->extism_current_plugin_host_context($plugin);
+        if ($ptr === null || \FFI::isNull($ptr)) {
+            return null;
+        }
+
+        return \FFI::string($this->ffi->cast("char *", $ptr));
+    }
+
     public function extism_error(\FFI\CData $plugin): ?string
     {
         return $this->ffi->extism_error($plugin);
diff --git a/tests/PluginTest.php b/tests/PluginTest.php
index 5a21e42..c86bc77 100644
--- a/tests/PluginTest.php
+++ b/tests/PluginTest.php
@@ -98,6 +98,39 @@ public function testHostFunctions(): void
         $this->assertEquals('{"count":3,"total":6,"vowels":"aeiouAEIOU"}', $response);
     }
 
+
+    public function testCallWithHostContext(): void
+    {
+        $multiUserKvStore = [[]];
+
+        $kvRead = new HostFunction("kv_read", [ExtismValType::I64], [ExtismValType::I64], function (CurrentPlugin $p, string $key) use (&$multiUserKvStore) {
+            $ctx = $p->getCallHostContext(); // get a copy of the host context data
+            $userId = $ctx["userId"];
+            $kvStore = $multiUserKvStore[$userId] ?? [];
+
+            return $kvStore[$key] ?? "\0\0\0\0";
+        });
+
+        $kvWrite = new HostFunction("kv_write", [ExtismValType::I64, ExtismValType::I64], [], function (CurrentPlugin $p, string $key, string $value) use (&$multiUserKvStore) {
+            $ctx = $p->getCallHostContext(); // get a copy of the host context data
+            $userId = $ctx["userId"];
+            $kvStore = $multiUserKvStore[$userId] ?? [];
+
+            $kvStore[$key] = $value;
+            $multiUserKvStore[$userId] = $kvStore;
+        });
+
+        $plugin = self::loadPlugin("count_vowels_kvstore.wasm", [$kvRead, $kvWrite]);
+
+        $ctx = ["userId" => 1];
+
+        $response = $plugin->callWithContext("count_vowels", "Hello World!", $ctx);
+        $this->assertEquals('{"count":3,"total":3,"vowels":"aeiouAEIOU"}', $response);
+
+        $response = $plugin->callWithContext("count_vowels", "Hello World!", $ctx);
+        $this->assertEquals('{"count":3,"total":6,"vowels":"aeiouAEIOU"}', $response);
+    }
+
     public function testHostFunctionManual(): void
     {
         $kvstore = [];