hot reloading, plugin instantiation, plugin main method

- The Loader now watches for file changes in the plugin directory, and will (re)import when a new plugin is created, or an existing one is modified. This is implemented by means of the watchdog library
- Plugin classes are now instantiated (and therefore require a self arg in every method). This way they can maintain a state during the runtime of the loader (or until they are reloaded), and share data between methods.
- Plugins can now have a __main() method, which can include long-running code. Every plugin's main method is ran in a separate asyncio task.
- Plugin methods that start from __ are now uncallable from javascript. This can be helpful when implementing unfinished/development versions of methods.

4 files changed, 73 insertions, 21 deletions

diff --git a/plugin_loader/loader.py b/plugin_loader/loader.py
index 0ed58b39..3d234cae 100644
--- a/plugin_loader/loader.py
+++ b/plugin_loader/loader.py
@@ -1,17 +1,43 @@
 from aiohttp import web
 from aiohttp_jinja2 import template
+from watchdog.observers.polling import PollingObserver as Observer
+from watchdog.events import FileSystemEventHandler
 
 from os import path, listdir
 from importlib.util import spec_from_file_location, module_from_spec
 from logging import getLogger
 
-import injector
+from injector import get_tabs
+
+class FileChangeHandler(FileSystemEventHandler):
+    def __init__(self, loader) -> None:
+        super().__init__()
+        self.loader : Loader = loader
+
+    def on_created(self, event):
+        src_path = event.src_path
+        if "__pycache__" in src_path:
+            return
+        self.loader.import_plugin(src_path)
+    
+    def on_modified(self, event):
+        src_path = event.src_path
+        if "__pycache__" in src_path:
+            return
+        self.loader.import_plugin(src_path)
 
 class Loader:
-    def __init__(self, server_instance, plugin_path) -> None:
+    def __init__(self, server_instance, plugin_path, loop, live_reload=False) -> None:
+        self.loop = loop
         self.logger = getLogger("Loader")
         self.plugin_path = plugin_path
-        self.plugins = self.import_plugins()
+        self.plugins = {}
+        self.import_plugins()
+
+        if live_reload:
+            self.observer = Observer()
+            self.observer.schedule(FileChangeHandler(self), self.plugin_path)
+            self.observer.start()
 
         server_instance.add_routes([
             web.get("/plugins/iframe", self.plugin_iframe_route),
@@ -21,29 +47,48 @@ class Loader:
             web.get("/steam_resource/{path:.+}", self.get_steam_resource)
         ])
 
+    def import_plugin(self, file):
+        try:
+            spec = spec_from_file_location("_", file)
+            module = module_from_spec(spec)
+            spec.loader.exec_module(module)
+            if not hasattr(module.Plugin, "name"):
+                raise KeyError("Plugin {} has not defined a name".format(file))
+            if module.Plugin.name in self.plugins:
+                    if hasattr(module.Plugin, "hot_reload") and not module.Plugin.hot_reload:
+                        self.logger.info("Plugin {} is already loaded and has requested to not be re-loaded"
+                        .format(module.Plugin.name))
+                    else:
+                        if hasattr(self.plugins[module.Plugin.name], "task"):
+                            self.plugins[module.Plugin.name].task.cancel()
+                        self.plugins.pop(module.Plugin.name, None)
+            self.plugins[module.Plugin.name] = module.Plugin()
+            if hasattr(module.Plugin, "__main"):
+                setattr(self.plugins[module.Plugin.name], "task",
+                self.loop.create_task(self.plugins[module.Plugin.name].__main()))
+            self.logger.info("Loaded {}".format(module.Plugin.name))
+        except Exception as e:
+            self.logger.error("Could not load {}. {}".format(file, e))
+
     def import_plugins(self):
         files = [i for i in listdir(self.plugin_path) if i.endswith(".py")]
-        dc = {}
         for file in files:
-            try:
-                spec = spec_from_file_location("_", path.join(self.plugin_path, file))
-                module = module_from_spec(spec)
-                spec.loader.exec_module(module)
-                dc[module.Plugin.name] = module.Plugin
-                self.logger.info("Loaded {}".format(module.Plugin.name))
-            except Exception as e:
-                self.logger.error("Could not load {}. {}".format(file, e))
-        return dc
+            self.import_plugin(path.join(self.plugin_path, file))
+    
+    async def watch_for_file_change(self):
+        pass
 
     async def reload_plugins(self, request=None):
-        self.logger.info("Re-importing all plugins.")
-        self.plugins = self.import_plugins()
+        self.logger.info("Re-importing plugins.")
+        self.import_plugins()
 
     async def handle_plugin_method_call(self, plugin_name, method_name, **kwargs):
+        if method_name.startswith("__"):
+            raise RuntimeError("Tried to call private method")
         return await getattr(self.plugins[plugin_name], method_name)(**kwargs)
 
     async def get_steam_resource(self, request):
-        tab = (await injector.get_tabs())[0]
+        tab = (await get_tabs())[0]
         return web.Response(text=await tab.get_steam_resource(f"https://steamloopback.host/{request.match_info['path']}"), content_type="text/html")
 
     async def load_plugin(self, request):
diff --git a/plugin_loader/main.py b/plugin_loader/main.py
index 4ecb5158..da371310 100644
--- a/plugin_loader/main.py
+++ b/plugin_loader/main.py
@@ -12,14 +12,15 @@ from utilities import util_methods
 CONFIG = {
     "plugin_path": getenv("PLUGIN_PATH", "/home/deck/homebrew/plugins"),
     "server_host": getenv("SERVER_HOST", "127.0.0.1"),
-    "server_port": int(getenv("SERVER_PORT", "1337"))
+    "server_port": int(getenv("SERVER_PORT", "1337")),
+    "live_reload": getenv("LIVE_RELOAD", "1") == "1"
 }
 
 class PluginManager:
     def __init__(self) -> None:
         self.loop = get_event_loop()
         self.web_app = Application()
-        self.plugin_loader = Loader(self.web_app, CONFIG["plugin_path"])
+        self.plugin_loader = Loader(self.web_app, CONFIG["plugin_path"], self.loop, CONFIG["live_reload"])
 
         jinja_setup(self.web_app, loader=FileSystemLoader(path.join(path.dirname(__file__), 'templates')))
         self.web_app.on_startup.append(self.inject_javascript)
diff --git a/plugin_template.py b/plugin_template.py
index be477d37..43088b14 100644
--- a/plugin_template.py
+++ b/plugin_template.py
@@ -7,8 +7,13 @@ class Plugin:
 
     tile_view_html = ""
 
-    async def method_1(**kwargs):
+    hot_reload = False
+
+    async def __main(self):
+        pass
+
+    async def method_1(self, **kwargs):
         pass
 
-    async def method_2(**kwargs):
+    async def method_2(self, **kwargs):
         pass
\ No newline at end of file
diff --git a/requirements.txt b/requirements.txt
index 513ec897..c77a53ed 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1,2 +1,3 @@
 aiohttp==3.8.1
-aiohttp-jinja2==1.5.0
\ No newline at end of file
+aiohttp-jinja2==1.5.0
+watchdog==2.1.7
\ No newline at end of file