Update many files.

Add some description about this project, and now it has a simple UI (made with Qt)

If you don't specify the mode of (interface?) the UI. Launcher will show a crude window that lets you
 select a mode to start the (real) launcher.

Test version data fetching functions. Looks great.

app.py

@@ -1,6 +1,12 @@
-from PySide6.QtWidgets import QApplication, QWidget, QMainWindow
+import logging
+import textwrap
 
-from core_lib.unclassified import move_window_to_center
+from PySide6.QtCore import Qt
+from PySide6.QtWidgets import QApplication, QMainWindow, QPushButton, QVBoxLayout, QWidget, QDialog, QPlainTextEdit, \
+    QHBoxLayout
+from core_lib.qt.hack import move_window_to_center
+from core_lib.unclassified import get_latest_version, get_version_manifest, get_specific_version_manifest_url, \
+    fetch_specific_version_manifest, find_useful_part_in_specific_version_manifest
 
 
 class Launcher(QApplication):
@@ -12,6 +18,73 @@ class Launcher(QApplication):
 
         move_window_to_center(self.main_window)
 
+        self.logger = logging.getLogger("Launcher.MainWindow")
+
+        self.test_dialog = self.TestDialog(self.main_window)
+        self.test_dialog.show()
+
+    class TestDialog(QDialog):
+        def __init__(self, parent):
+            super().__init__(parent)
+            self.parent = parent
+            self.resize(300, 200)
+            self.setWindowFlags(self.windowFlags() | Qt.WindowMaximizeButtonHint)
+
+            self.button = QPushButton("Fetch Version Data")
+            self.button.setObjectName("ActionButton")
+            self.button.clicked.connect(self.run_test)
+
+            self.output = QPlainTextEdit()
+            self.output.setReadOnly(True)
+
+            self.layout = QHBoxLayout()
+            self.layout.addWidget(self.output)
+
+            self.right_layout = QVBoxLayout()
+            self.right_layout.setObjectName("RightLayout")
+            self.right_layout.setAlignment(Qt.AlignmentFlag.AlignRight)
+            self.right_layout.addWidget(self.button)
+            self.right_layout.addStretch()
+            self.right_layout.setContentsMargins(0, 10, 0, 0)
+
+            self.layout.addLayout(self.right_layout)
+
+            self.setLayout(self.layout)
+
+            self.setStyleSheet(
+                textwrap.dedent("""
+                QPushButton#ActionButton {
+                    padding: 6px 12px;
+                }          
+                """))
+
+        @property
+        def app(self):
+            return self.parent.parent
+
+        def run_test(self):
+            data = get_version_manifest()
+            ver = get_latest_version(data)
+            ver_data = fetch_specific_version_manifest(data, ver)
+            arguments, asset_index, downloads, java_version, libraries, main_class = (
+                find_useful_part_in_specific_version_manifest(ver_data))
+
+            content = textwrap.dedent(f"""\
+            Arguments: {arguments}\n
+            
+            Asset: {asset_index}\n
+            
+            Downloads: {downloads}\n
+            
+            Java Version: {java_version}\n
+            
+            Libraries: {libraries}\n
+            
+            Main Class: {main_class}\n
+            """)
+
+            self.output.setPlainText(content)
+
     def exec(self):
         self.main_window.show()
-        self.exec_()
+        self.exec_()