From 24adecd9227931ebaec16115e05055e0b580d351 Mon Sep 17 00:00:00 2001
From: Joel Challis <git@zvecr.com>
Date: Sun, 1 Jan 2023 19:16:38 +0000
Subject: [PATCH] Implement XAP style merge semantics for DD keycodes (#19397)

---
 lib/python/qmk/json_schema.py | 40 ++++++++++++++++++++++++---
 lib/python/qmk/keycodes.py    | 52 +++++++++++++++++++++++++----------
 2 files changed, 73 insertions(+), 19 deletions(-)

diff --git a/lib/python/qmk/json_schema.py b/lib/python/qmk/json_schema.py
index 934e2f841f..c886a0d868 100644
--- a/lib/python/qmk/json_schema.py
+++ b/lib/python/qmk/json_schema.py
@@ -1,12 +1,13 @@
 """Functions that help us generate and use info.json files.
 """
 import json
-from collections.abc import Mapping
-from functools import lru_cache
-from pathlib import Path
-
 import hjson
 import jsonschema
+from collections.abc import Mapping
+from functools import lru_cache
+from typing import OrderedDict
+from pathlib import Path
+
 from milc import cli
 
 
@@ -101,3 +102,34 @@ def deep_update(origdict, newdict):
             origdict[key] = value
 
     return origdict
+
+
+def merge_ordered_dicts(dicts):
+    """Merges nested OrderedDict objects resulting from reading a hjson file.
+    Later input dicts overrides earlier dicts for plain values.
+    Arrays will be appended. If the first entry of an array is "!reset!", the contents of the array will be cleared and replaced with RHS.
+    Dictionaries will be recursively merged. If any entry is "!reset!", the contents of the dictionary will be cleared and replaced with RHS.
+    """
+    result = OrderedDict()
+
+    def add_entry(target, k, v):
+        if k in target and isinstance(v, (OrderedDict, dict)):
+            if "!reset!" in v:
+                target[k] = v
+            else:
+                target[k] = merge_ordered_dicts([target[k], v])
+            if "!reset!" in target[k]:
+                del target[k]["!reset!"]
+        elif k in target and isinstance(v, list):
+            if v[0] == '!reset!':
+                target[k] = v[1:]
+            else:
+                target[k] = target[k] + v
+        else:
+            target[k] = v
+
+    for d in dicts:
+        for (k, v) in d.items():
+            add_entry(result, k, v)
+
+    return result
diff --git a/lib/python/qmk/keycodes.py b/lib/python/qmk/keycodes.py
index 600163bab9..d2f2492829 100644
--- a/lib/python/qmk/keycodes.py
+++ b/lib/python/qmk/keycodes.py
@@ -1,6 +1,6 @@
 from pathlib import Path
 
-from qmk.json_schema import deep_update, json_load, validate
+from qmk.json_schema import merge_ordered_dicts, deep_update, json_load, validate
 
 CONSTANTS_PATH = Path('data/constants/')
 KEYCODES_PATH = CONSTANTS_PATH / 'keycodes'
@@ -16,20 +16,13 @@ def _find_versions(path, prefix):
     return ret
 
 
-def _load_fragments(path, prefix, version):
-    file = path / f'{prefix}_{version}.hjson'
-    if not file.exists():
-        raise ValueError(f'Requested keycode spec ({prefix}:{version}) is invalid!')
+def _potential_search_versions(version, lang=None):
+    versions = list_versions(lang)
+    versions.reverse()
 
-    # Load base
-    spec = json_load(file)
+    loc = versions.index(version) + 1
 
-    # Merge in fragments
-    fragments = path.glob(f'{prefix}_{version}_*.hjson')
-    for file in fragments:
-        deep_update(spec, json_load(file))
-
-    return spec
+    return versions[:loc]
 
 
 def _search_path(lang=None):
@@ -40,6 +33,34 @@ def _search_prefix(lang=None):
     return f'keycodes_{lang}' if lang else 'keycodes'
 
 
+def _locate_files(path, prefix, versions):
+    # collate files by fragment "type"
+    files = {'_': []}
+    for version in versions:
+        files['_'].append(path / f'{prefix}_{version}.hjson')
+
+        for file in path.glob(f'{prefix}_{version}_*.hjson'):
+            fragment = file.stem.replace(f'{prefix}_{version}_', '')
+            if fragment not in files:
+                files[fragment] = []
+            files[fragment].append(file)
+
+    return files
+
+
+def _process_files(files):
+    # allow override within types of fragments - but not globally
+    spec = {}
+    for category in files.values():
+        specs = []
+        for file in category:
+            specs.append(json_load(file))
+
+        deep_update(spec, merge_ordered_dicts(specs))
+
+    return spec
+
+
 def _validate(spec):
     # first throw it to the jsonschema
     validate(spec, 'qmk.keycodes.v1')
@@ -62,9 +83,10 @@ def load_spec(version, lang=None):
 
     path = _search_path(lang)
     prefix = _search_prefix(lang)
+    versions = _potential_search_versions(version, lang)
 
-    # Load base
-    spec = _load_fragments(path, prefix, version)
+    # Load bases + any fragments
+    spec = _process_files(_locate_files(path, prefix, versions))
 
     # Sort?
     spec['keycodes'] = dict(sorted(spec.get('keycodes', {}).items()))