add output file tracking and remove obsolete files

recipes.py

@@ -1,9 +1,10 @@
-from typing import Dict, List, Any, Optional
+from typing import Dict, List, Any, Optional, Set
 import os
 
 import yaml
 import jinja2
 
+
 class Context:
     def __init__(self) -> None:
         self.units = Units()
@@ -36,6 +37,7 @@ class Units:
 class Ingredient:
     def __init__(self, ctx: Context) -> None:
         self.ctx = ctx
+
     def load(self, dct: Dict[str, Any]) -> List[str]:
         issues = []
         issues += assert_dict(dct, ["name"], ["wdid", "pricedb", "aliases"])
@@ -178,6 +180,7 @@ class IngredientInstance:
 class RecipePart:
     def __init__(self, ctx: Context) -> None:
         self.ctx = ctx
+
     def load(self, dct: Dict[str, Any]) -> List[str]:
         issues = []
         issues += assert_dict(dct, ["title", "ingredients", "steps"], [])
@@ -263,6 +266,8 @@ class Builder:
             autoescape=jinja2.select_autoescape(),
         )
         self.ctx = Context()
+        # list of output files that will be built
+        self.outfiles: Set[str] = set()
 
     def load_file(self, file: str) -> Any:
         print(f"loading {file}")
@@ -281,6 +286,7 @@ class Builder:
 
         with open(f"out/{format}/{file}", "w", encoding="utf-8") as f:
             f.write(outstr)
+        self.outfiles.add(file)
 
     def load(self) -> None:
         issues: List[str] = []
@@ -322,10 +328,27 @@ class Builder:
 
         self.rendertemplate("index.html", "html", "index.html", {"recipes": recipes})
         for recipe in recipes:
-            self.rendertemplate( "recipe.html", "html", recipe.outpath, {"recipe": recipe})
+            self.rendertemplate(
+                "recipe.html", "html", recipe.outpath, {"recipe": recipe}
+            )
+
+    def finish(self) -> None:
+        files = set()
+        for _, _, filesx in os.walk("out/html"):
+            files = set(filesx)
+
+        # files we did not generate, probably left by a previous run, but not valid anymore
+        extra_files = files - self.outfiles
+        for file in extra_files:
+            print(f"removing obsolete {file}")
+            os.remove(f"out/html/{file}")
+
+    def main(self) -> None:
+        self.load()
+        self.run()
+        self.finish()
 
 
 if __name__ == "__main__":
     builder = Builder()
-    builder.load()
-    builder.run()
+    builder.main()