Add a migration script for Renoise

Now all migration scripts are done.

tools/migration/README.md

@@ -53,3 +53,15 @@ chmod +x migrate-reaper.py
 # migration process
 ./migrate-reaper.py /path/to/some/project.RPP
 ```
+
+## Renoise
+
+```shell
+# First download the script
+curl -o migrate-renoise.py https://raw.githubusercontent.com/robbert-vdh/yabridge/master/tools/migration/migrate-renoise.py
+chmod +x migrate-renoise.py
+
+# And then run it on any old .xrns files, the script will guide you through the
+# migration process
+./migrate-renoise.py /path/to/some/project.xrns
+```

tools/migration/migrate-renoise.py

@@ -0,0 +1,107 @@
+#!/usr/bin/env python3
+
+import argparse
+import os
+import shutil
+import textwrap
+from xml.etree import ElementTree
+import zipfile
+
+
+# Renoise project files are zip archives that contain an XML file
+RENOISE_XML_FILENAME = "Song.xml"
+
+
+parser = argparse.ArgumentParser(
+    description="Migrate old yabridge VST3 plugin instances in Renoise project files."
+)
+parser.add_argument("filename", type=str, help="The .xrns project file to migrate.")
+
+# As a safety measure we want to limit the file names we accept
+args = parser.parse_args()
+
+filename = args.filename
+file_stem, file_extension = os.path.splitext(filename)
+if file_extension.lower() != ".xrns":
+    print("For safety reasons, only '*.xrns' files are accepted")
+    exit(1)
+if file_stem.endswith("-migrated"):
+    print("This project file has already been migrated to the new format")
+    exit(1)
+
+migrated_filename = file_stem + "-migrated" + file_extension
+if os.path.exists(migrated_filename):
+    print(
+        f"'{migrated_filename}' already exists, back it up and move it elsewhere "
+        "if you want to redo the migration"
+    )
+    exit(1)
+
+print(
+    "\n".join(
+        textwrap.wrap(
+            f"This script will go through '{filename}' to migrate old yabridge VST3 plugin instances. "
+            f"The output will be saved to '{migrated_filename}', but make sure to still create a backup of the original file in case something does go wrong. "
+            f"For every VST3 plugin found you will be prompted with the question if you want to migrate it. "
+            f"Answer 'yes' for all old yabridge VST3 plugin instances, and 'no' for any other VST3 plugin."
+            f"Make sure to test whether the new project works immediately after migration.",
+            width=80,
+            break_on_hyphens=False,
+        )
+    )
+)
+print()
+
+# We'll search through the original file, and prompt to replace all VST3 class
+# IDs we come across. See `WineUID` in yabridge's source code for an
+# explanation of this conversion. In all other migration scripts we could
+# simply do this with regular expressions, but Renoise uses XML files where
+# every attribute is stored on its own line, so we cannot
+with zipfile.ZipFile(filename, "r") as in_archive, zipfile.ZipFile(
+    migrated_filename, "w"
+) as out_archive:
+    # I don't know if Renoise uses this field, probably not
+    out_archive.comment = in_archive.comment
+
+    migrated_xml = ElementTree.fromstring(in_archive.read(RENOISE_XML_FILENAME))
+    for element in migrated_xml.iter():
+        # Renoise uses different tags for plugins, so we'll identify VST3
+        # plugins based on the attributes instead
+        plugin_name = element.find("PluginDisplayName")
+        plugin_type = element.find("PluginType")
+        plugin_uid = element.find("PluginIdentifier")
+        if (
+            plugin_name is not None
+            and plugin_type is not None
+            and plugin_uid is not None
+            and plugin_type.text == "VST3"
+            and plugin_uid.text is not None
+        ):
+            wine_uid = bytearray.fromhex(plugin_uid.text)
+            converted_uid = bytearray.fromhex(plugin_uid.text)
+
+            converted_uid[0] = wine_uid[3]
+            converted_uid[1] = wine_uid[2]
+            converted_uid[2] = wine_uid[1]
+            converted_uid[3] = wine_uid[0]
+
+            converted_uid[4] = wine_uid[5]
+            converted_uid[5] = wine_uid[4]
+            converted_uid[6] = wine_uid[7]
+            converted_uid[7] = wine_uid[6]
+
+            print(
+                f"Found '{plugin_name.text}' with class ID '{wine_uid.hex().upper()}'"
+            )
+            while True:
+                answer = input("Should this plugin be migrated? [yes/no] ").lower()
+                if answer == "yes":
+                    plugin_uid.text = converted_uid.hex().upper()
+                    break
+                elif answer == "no":
+                    break
+                else:
+                    print("Please answer only 'yes' or 'no'")
+
+    print(f"\nMigration successful, writing the results to '{migrated_filename}'")
+    out_archive.writestr(RENOISE_XML_FILENAME, ElementTree.tostring(migrated_xml))