Nearly complete rewrite using MailExtensions with Experiments

LICENSE

@@ -1,6 +1,6 @@
 The MIT License (MIT)
 
-Copyright (c) 2013 eykamp, 2020 Welpy-cw
+Copyright (c) 2013 eykamp, 2024 Hartmut Welpmann [:welpy-cw]
 
 Permission is hereby granted, free of charge, to any person obtaining a copy of
 this software and associated documentation files (the "Software"), to deal in

api/FolderAccount/implementation.js

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+var { ExtensionCommon } = ChromeUtils.importESModule(
+  "resource://gre/modules/ExtensionCommon.sys.mjs"
+);
+
+var { MailServices } = ChromeUtils.importESModule(
+  "resource:///modules/MailServices.sys.mjs"
+);
+
+var FolderAccount = class extends ExtensionCommon.ExtensionAPI {
+  getAPI(context) {
+    return {
+      FolderAccount: {
+        async getDisplayedFolder(tabId) {
+          return context.extension.folderManager.convert(
+            context.extension.tabManager.get(tabId).nativeTab.folder
+          );
+        },
+        async getRelatedMessageFolder(tabId) {
+          const tabObject = context.extension.tabManager.get(tabId);
+          const realTabWindow = tabObject.window;
+          const folder = realTabWindow.gMessenger.msgHdrFromURI(
+            realTabWindow.gMsgCompose.originalMsgURI
+          ).folder;
+          return context.extension.folderManager.convert(folder);
+          },
+        async getFolderAccountSettings() {
+          const folderPrefs = new Map();
+          const branch = Services.prefs.getBranch("extensions.folderaccount.");
+          for (const child of branch.getChildList("")) {
+            let pref;
+            try {
+              pref = branch.getCharPref(child);
+            } catch (e) {
+              continue;
+            }
+            const matches = child.match(
+              /(?<setting>addToCcOnReply|overrideReturnAddress|replyTo(OnReplyForward)?|to)?\.?(?<folder>.*)/
+            );
+            const folderURI = matches.groups["folder"];
+            const settingKey = matches.groups["setting"] ?? "identityId";
+            if (/addToCcOnReply|overrideReturnAddress|replyToOnReplyForward/.test(settingKey)) {
+              pref = pref == "true";
+            }
+            folderPrefs.set(folderURI, {
+              ...folderPrefs.get(folderURI),
+              [settingKey]: pref,
+            });
+          }
+          const mailFolderPrefs = new Map();
+          folderPrefs.forEach((value, key) => {
+            const folder = MailServices.folderLookup.getFolderForURL(key);
+            const mailFolder = context.extension.folderManager.convert(folder);
+            if (mailFolder) {
+              mailFolderPrefs.set(mailFolder.id, value);
+            }
+          });
+          return mailFolderPrefs;
+        },
+      },
+    };
+  }
+};

api/FolderAccount/schema.json

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+[
+  {
+    "namespace": "FolderAccount",
+    "functions": [
+      {
+        "name": "getDisplayedFolder",
+        "description": "Get the currently displayed folder in the tab",
+        "type": "function",
+        "async": true,
+        "parameters": [
+          {
+            "name": "tabId",
+            "description": "The last focused tab",
+            "type": "integer"
+          }
+        ]
+      },
+      {
+        "name": "getRelatedMessageFolder",
+        "description": "Get the folder of the related message of the currently displayed compose window",
+        "type": "function",
+        "async": true,
+        "parameters": [
+          {
+            "name": "tabId",
+            "description": "The current compose tab",
+            "type": "integer"
+          }
+        ]
+      },
+      {
+        "name": "getFolderAccountSettings",
+        "description": "Get all the Folder Account settings from its preference branch for migration.",
+        "type": "function",
+        "async": true,
+        "parameters": []
+      }
+    ]
+  }
+]

api/LegacyPrefs/README.md

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+## Objective
+
+Use this API to access Thunderbird's system preferences or to migrate your own preferences from the Thunderbird preference system to the local storage of your MailExtension.
+
+## Usage
+
+Add the [LegacyPrefs API](https://github.com/thundernest/addon-developer-support/tree/master/auxiliary-apis/LegacyPrefs) to your add-on. Your `manifest.json` needs an entry like this:
+
+```
+  "experiment_apis": {
+    "LegacyPrefs": {
+      "schema": "api/LegacyPrefs/schema.json",
+      "parent": {
+        "scopes": ["addon_parent"],
+        "paths": [["LegacyPrefs"]],
+        "script": "api/LegacyPrefs/implementation.js"
+      }
+    }
+  },
+```
+
+## API Functions
+
+This API provides the following functions:
+
+### async getPref(aName, [aFallback])
+
+Returns the value for the ``aName`` preference. If it is not defined or has no default value assigned, ``aFallback`` will be returned (which defaults to ``null``).
+
+### async getUserPref(aName)
+
+Returns the user defined value for the ``aName`` preference. This will ignore any defined default value and will only return an explicitly set value, which differs from the default. Otherwise it will return ``null``.
+
+### clearUserPref(aName)
+
+Clears the user defined value for preference ``aName``. Subsequent calls to ``getUserPref(aName)`` will return ``null``.
+
+### async setPref(aName, aValue)
+
+Set the ``aName`` preference to the given value. Will return false and log an error to the console, if the type of ``aValue`` does not match the type of the preference.
+
+## API Events
+
+This API provides the following events:
+
+### onChanged.addListener(listener, branch)
+
+Register a listener which is notified each time a value in the specified branch is changed. The listener returns the name and the new value of the changed preference.
+
+Example:
+
+```
+browser.LegacyPrefs.onChanged.addListener(async (name, value) => {
+  console.log(`Changed value in "mailnews.": ${name} = ${value}`);
+}, "mailnews.");
+```
+
+---
+
+A detailed example using the LegacyPref API to migrate add-on preferences to the local storage can be found in [/scripts/preferences/](https://github.com/thundernest/addon-developer-support/tree/master/scripts/preferences).