Can create, edit, and delete an alias in the UI

In particular:
* Add NewAliasDialog

Resolves #201

Author: davidfstr

RELEASE_NOTES.md

@@ -12,6 +12,15 @@ Release Notes ⋮
 
 ### main
 
+* Workflow improvements
+    * Aliases are now supported for redirecting similar patterns of URLs,
+      such as `https://www.folklore.org/ → https://folklore.org/`.
+        * Use the "New Alias..." menuitem in the "Entity" menu to create an Alias.
+    * Aliases can be used to redirect to external URLs outside the project,
+      on the live internet.
+        * This can be useful if a subset of a project's URLs are hosted in
+          a different internet-accessible subsystem, such as AWS Glacier.
+
 * Shell improvements
     * Uses the new [interactive interpreter] from Python 3.13.
     * Supports using `await` with Crystal's testing utilities

src/crystal/browser/__init__.py

@@ -6,6 +6,7 @@
 from crystal.app_preferences import app_prefs
 from crystal.browser.entitytree import EntityTree
 from crystal.browser.icons import TREE_NODE_ICONS
+from crystal.browser.new_alias import NewAliasDialog
 from crystal.browser.new_group import NewGroupDialog
 from crystal.browser.new_root_url import ChangePrefixCommand, NewRootUrlDialog
 from crystal.browser.preferences import PreferencesDialog
@@ -316,6 +317,11 @@ def _create_actions(self) -> None:
             enabled=(not self._readonly),
             button_bitmap=dict(DEFAULT_FOLDER_ICON_SET())[wx.TreeItemIcon_Normal],
             button_label='New &Group...')
+        self._new_alias_action = Action(wx.ID_ANY,
+            'New &Alias...',
+            wx.AcceleratorEntry(wx.ACCEL_CTRL | wx.ACCEL_SHIFT, ord('A')),
+            self._on_new_alias,
+            enabled=(not self._readonly))
         self._edit_action = Action(wx.ID_ANY,
             self._EDIT_ACTION_LABEL if not self._readonly else self._GET_INFO_ACTION_LABEL,
             accel=wx.AcceleratorEntry(wx.ACCEL_NORMAL, wx.WXK_RETURN),
@@ -438,6 +444,7 @@ def _create_menu_bar(self, raw_frame: wx.Frame) -> wx.MenuBar:
         entity_menu.AppendSeparator()
         self._new_root_url_action.append_menuitem_to(entity_menu)
         self._new_group_action.append_menuitem_to(entity_menu)
+        self._new_alias_action.append_menuitem_to(entity_menu)
         self._edit_action.append_menuitem_to(entity_menu)
         self._forget_action.append_menuitem_to(entity_menu)
         entity_menu.AppendSeparator()
@@ -1413,16 +1420,56 @@ def _on_edit_group_dialog_ok(self,
 
         assert download_immediately == False
 
-    def _saving_source_would_create_cycle(self, rg: ResourceGroup, source: ResourceGroupSource) -> bool:
-        ancestor_source = source  # type: ResourceGroupSource
-        while ancestor_source is not None:
-            if ancestor_source == rg:
-                return True
-            if isinstance(ancestor_source, ResourceGroup):
-                ancestor_source = ancestor_source.source  # reinterpret
-            else:
-                ancestor_source = None
-        return False
+    # === Entity Pane: New/Edit Alias ===
+    
+    def _on_new_alias(self, event: wx.CommandEvent) -> None:
+        restore_menuitems = self._disable_menus_during_showwindowmodal()
+        NewAliasDialog(
+            self._frame,
+            self._on_new_alias_dialog_ok,
+            alias_exists_func=self._alias_exists,
+            on_close=restore_menuitems,
+        )
+    
+    def _alias_exists(self, source_url_prefix: str) -> bool:
+        return self.project.get_alias(source_url_prefix) is not None
+    
+    @fg_affinity
+    def _on_new_alias_dialog_ok(self,
+            source_url_prefix: str,
+            target_url_prefix: str,
+            target_is_external: bool,
+            ) -> None:
+        if source_url_prefix == '':
+            raise ValueError('Invalid blank source URL prefix')
+        if target_url_prefix == '':
+            raise ValueError('Invalid blank target URL prefix')
+        
+        try:
+            alias = Alias(self.project, source_url_prefix, target_url_prefix,
+                         target_is_external=target_is_external)
+        except Alias.AlreadyExists:
+            raise ValueError('Invalid duplicate source URL prefix')
+    
+    @fg_affinity
+    def _on_edit_alias_dialog_ok(self,
+            alias: Alias,
+            source_url_prefix: str,
+            target_url_prefix: str,
+            target_is_external: bool,
+            ) -> None:
+        if source_url_prefix != alias.source_url_prefix:
+            raise ValueError(
+                'Attempted to change source_url_prefix of existing Alias. '
+                'Source URL prefix cannot be changed after alias is created.'
+            )
+        
+        if target_url_prefix == '':
+            raise ValueError('Invalid blank target URL prefix')
+        
+        # NOTE: Entity tree update will be triggered by property setters
+        alias.target_url_prefix = target_url_prefix
+        alias.target_is_external = target_is_external
 
     # === Entity Pane: Other Commands ===
 
@@ -1487,9 +1534,38 @@ def _on_edit_entity(self, event) -> None:
                     raise
             except CancelLoadUrls:
                 pass
+        elif isinstance(selected_entity, Alias):
+            alias = selected_entity
+            restore_menuitems = self._disable_menus_during_showwindowmodal()
+            try:
+                NewAliasDialog(
+                    self._frame,
+                    partial(self._on_edit_alias_dialog_ok, alias),
+                    alias_exists_func=self._alias_exists,
+                    initial_source_url_prefix=alias.source_url_prefix,
+                    initial_target_url_prefix=alias.target_url_prefix,
+                    initial_target_is_external=alias.target_is_external,
+                    is_edit=True,
+                    readonly=self._readonly,
+                    on_close=restore_menuitems,
+                )
+            except:
+                restore_menuitems()
+                raise
         else:
             raise AssertionError()
 
+    def _saving_source_would_create_cycle(self, rg: ResourceGroup, source: ResourceGroupSource) -> bool:
+        ancestor_source = source  # type: ResourceGroupSource
+        while ancestor_source is not None:
+            if ancestor_source == rg:
+                return True
+            if isinstance(ancestor_source, ResourceGroup):
+                ancestor_source = ancestor_source.source  # reinterpret
+            else:
+                ancestor_source = None
+        return False
+    
     def _on_forget_entity(self, event) -> None:
         selected_entity = self.entity_tree.selected_entity
         assert selected_entity is not None