perf(anki): skip unchanged files using file hashes

src/anki/parser.py

@@ -1,9 +1,11 @@
 import glob
-import os.path
+import json
 
 from functools import cache
+from pathlib import Path
 from typing import List
 
+import appdirs
 import tree_sitter
 from tree_sitter_language_pack import get_language, get_parser
 
@@ -37,14 +39,17 @@ class FlashcardParser:
     flashcard_query: tree_sitter.Query
 
     file_handlers: List[tuple[FileHandler, List[Flashcard]]]
+    file_hashes: dict[str, str]
+    file_hashes_store_path: Path = Path(appdirs.user_state_dir("typstar") + "/file_hashes.json")
 
     def __init__(self):
         self.typst_language = get_language("typst")
         self.typst_parser = get_parser("typst")
         self.flashcard_query = self.typst_language.query(ts_flashcard_query)
         self.file_handlers = []
+        self._load_file_hashes()
 
-    def parse_file(self, file: FileHandler, preamble: str) -> List[Flashcard]:
+    def _parse_file(self, file: FileHandler, preamble: str) -> List[Flashcard]:
         cards = []
         tree = self.typst_parser.parse(file.get_bytes(), encoding="utf8")
         captures = self.flashcard_query.captures(tree.root_node)
@@ -73,27 +78,51 @@ class FlashcardParser:
 
     def parse_directory(self, root_dir):
         print(f"Parsing flashcards in {root_dir}...")
+        root_dir = Path(root_dir)
         preambles = {}
         flashcards = []
 
         @cache
-        def get_preamble(path) -> str | None:
-            while len(path) > len(root_dir):
+        def get_preamble(path: Path) -> str | None:
+            while path != root_dir:
                 if preamble := preambles.get(path):
                     return preamble
-                path = os.path.dirname(path)
+                path = path.parent
 
         for file in sorted(glob.glob(f"{root_dir}/**/**.typ", include_hidden=True, recursive=True)):
-            if os.path.basename(file) == ".anki.typ":
-                with open(file, encoding="utf-8") as f:
-                    preambles[os.path.dirname(file)] = f.read()
+            file = Path(file)
+            if file.name == ".anki.typ":
+                preambles[file.parent] = file.read_text(encoding="utf-8")
                 continue
             fh = FileHandler(file)
-            cards = self.parse_file(fh, get_preamble(os.path.dirname(file)))
-            self.file_handlers.append((fh, cards))
-            flashcards.extend(cards)
+            if self._hash_changed(fh):
+                cards = self._parse_file(fh, get_preamble(file.parent))
+                self.file_handlers.append((fh, cards))
+                flashcards.extend(cards)
         return flashcards
 
+    def _hash_changed(self, file: FileHandler) -> bool:
+        file_hash = file.get_file_hash()
+        cached = self.file_hashes.get(str(file.file_path))
+        self.file_hashes[str(file.file_path)] = file_hash
+        return file_hash != cached
+
+    def _load_file_hashes(self):
+        self.file_hashes_store_path.parent.mkdir(parents=True, exist_ok=True)
+        self.file_hashes_store_path.touch()
+        content = self.file_hashes_store_path.read_text()
+        if content:
+            self.file_hashes = json.loads(content)
+        else:
+            self.file_hashes = {}
+
+    def save_file_hashes(self):
+        self.file_hashes_store_path.write_text(json.dumps(self.file_hashes))
+
+    def clear_file_hashes(self):
+        self.file_hashes = {}
+        self.save_file_hashes()
+
     def update_ids_in_source(self):
         print("Updating ids in source...")
         for fh, cards in self.file_handlers:
@@ -104,3 +133,4 @@ class FlashcardParser:
                     file_updated = True
             if file_updated:
                 fh.write()
+                self.file_hashes[str(fh.file_path)] = fh.get_file_hash()