cache forecasts on filesystem

1 files changed, 32 insertions, 0 deletions

diff --git a/fscache.py b/fscache.py
new file mode 100644
index 0000000..d52ff62
--- /dev/null
+++ b/fscache.py
@@ -0,0 +1,32 @@
+import os
+import time
+from pathlib import Path
+
+class CacheMiss(Exception):
+    pass
+
+class Cache:
+    def __init__(self, name, ttl=3600):
+        self.ttl = ttl
+        try:
+            self.cache_dir = Path(os.environ['XDG_CACHE_HOME'])/name
+        except KeyError:
+            self.cache_dir = Path(os.environ['HOME'])/'.cache'/name
+        self.cache_dir.mkdir(exist_ok=True)
+
+    def write(self, key, value):
+        # TODO gracefully handle keys with '/' by creating directories or rewriting
+        loc = self.cache_dir/key
+        loc.write_text(value, errors='ignore')
+
+    def read(self, key):
+        loc = self.cache_dir/key
+
+        if not loc.exists():
+            raise CacheMiss
+
+        age = time.time() - loc.stat().st_mtime
+        if age > self.ttl:
+            raise CacheMiss
+        
+        return loc.read_text()