From 12959153c18db8f2ce642c1d3203e78ac95f624a Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?J=C3=B6rn-Michael=20Miehe?=
 <40151420+ldericher@users.noreply.github.com>
Date: Wed, 31 Aug 2022 10:41:36 +0000
Subject: [PATCH] download cache

---
 api/ovkiosk/routers/image.py | 41 ++++++++++++++++++++++++++++--------
 api/poetry.lock              | 14 +++++++++++-
 api/pyproject.toml           |  1 +
 3 files changed, 46 insertions(+), 10 deletions(-)

diff --git a/api/ovkiosk/routers/image.py b/api/ovkiosk/routers/image.py
index 0cec0a9..5cda51b 100644
--- a/api/ovkiosk/routers/image.py
+++ b/api/ovkiosk/routers/image.py
@@ -1,8 +1,10 @@
 import io
 import logging
 import re
-from typing import Iterator
+import time
+from typing import Iterator, Optional
 
+from async_lru import alru_cache
 from fastapi import APIRouter, Depends, HTTPException, status
 from fastapi.responses import StreamingResponse
 from PIL import Image
@@ -66,6 +68,32 @@ async def find_images(
     return list(file_names)
 
 
+async def get_ttl_hash(seconds: int = 20) -> int:
+    """
+    Return the same value withing `seconds` time period
+    https://stackoverflow.com/a/55900800
+    """
+    return round(time.time() / seconds)
+
+
+@alru_cache(maxsize=20)
+async def get_image_by_name(
+    file_name: str,
+    ttl_hash: Optional[int] = None,
+) -> io.BytesIO:
+    del ttl_hash
+
+    file = DavFile(CLIENT.resource(f"img/{file_name}"), refresh=False)
+    print(f"Downloading {file_name}")
+    await file.download()
+    img = Image.open(io.BytesIO(file.bytes)).convert("RGB")
+
+    img_buffer = io.BytesIO()
+    img.save(img_buffer, format='JPEG', quality=85)
+
+    return img_buffer
+
+
 @router.get(
     "/get/{prefix}",
     responses={
@@ -85,6 +113,7 @@ async def find_images(
 async def get_image(
     prefix: str,
     file_names: Iterator[str] = Depends(find_file_names),
+    ttl_hash: int = Depends(get_ttl_hash),
 ) -> StreamingResponse:
     file_names = list(file_names)
 
@@ -94,17 +123,11 @@ async def get_image(
     elif len(file_names) > 1:
         raise HTTPException(status_code=status.HTTP_409_CONFLICT)
 
-    file_name = file_names[0]
-    file = DavFile(CLIENT.resource(f"img/{file_name}"), refresh=False)
-    await file.download()
-    img = Image.open(io.BytesIO(file.bytes)).convert("RGB")
-
-    img_buffer = io.BytesIO()
-    img.save(img_buffer, format='JPEG', quality=85)
+    img_buffer = await get_image_by_name(file_names[0], ttl_hash)
     img_buffer.seek(0)
 
     return StreamingResponse(
-        img_buffer,
+        content=img_buffer,
         media_type="image/jpeg",
         headers={
             "Content-Disposition": f"filename={prefix}.jpg"
diff --git a/api/poetry.lock b/api/poetry.lock
index 8b7d05c..4444950 100644
--- a/api/poetry.lock
+++ b/api/poetry.lock
@@ -41,6 +41,14 @@ tornado = ["tornado (>=4.3)"]
 twisted = ["twisted"]
 zookeeper = ["kazoo"]
 
+[[package]]
+name = "async-lru"
+version = "1.0.3"
+description = "Simple lru_cache for asyncio"
+category = "main"
+optional = false
+python-versions = ">=3.6"
+
 [[package]]
 name = "certifi"
 version = "2022.6.15"
@@ -363,7 +371,7 @@ testing = ["func-timeout", "jaraco.itertools", "pytest (>=6)", "pytest-black (>=
 [metadata]
 lock-version = "1.1"
 python-versions = "^3.9"
-content-hash = "b39654ea53ee894dd65fe2217ca58fea259c9fe8a9bbae26f6198c42304608e2"
+content-hash = "04507c7951fd5d6a92767f82635087e15da2eff67f52e22e79b6e1db863e9ed4"
 
 [metadata.files]
 anyio = [
@@ -374,6 +382,10 @@ apscheduler = [
     {file = "APScheduler-3.9.1-py2.py3-none-any.whl", hash = "sha256:ddc25a0ddd899de44d7f451f4375fb971887e65af51e41e5dcf681f59b8b2c9a"},
     {file = "APScheduler-3.9.1.tar.gz", hash = "sha256:65e6574b6395498d371d045f2a8a7e4f7d50c6ad21ef7313d15b1c7cf20df1e3"},
 ]
+async-lru = [
+    {file = "async-lru-1.0.3.tar.gz", hash = "sha256:c2cb9b2915eb14e6cf3e717154b40f715bf90e596d73623677affd0d1fbcd32a"},
+    {file = "async_lru-1.0.3-py3-none-any.whl", hash = "sha256:ea692c303feb6211ff260d230dae1583636f13e05c9ae616eada77855b7f415c"},
+]
 certifi = [
     {file = "certifi-2022.6.15-py3-none-any.whl", hash = "sha256:fe86415d55e84719d75f8b69414f6438ac3547d2078ab91b67e779ef69378412"},
     {file = "certifi-2022.6.15.tar.gz", hash = "sha256:84c85a9078b11105f04f3036a9482ae10e4621616db313fe045dd24743a0820d"},
diff --git a/api/pyproject.toml b/api/pyproject.toml
index 0d5e3f5..61a3f6c 100644
--- a/api/pyproject.toml
+++ b/api/pyproject.toml
@@ -13,6 +13,7 @@ webdavclient3 = "3.14.5"
 Markdown = "^3.4.1"
 APScheduler = "^3.9.1"
 Pillow = "^9.2.0"
+async-lru = "^1.0.3"
 
 [tool.poetry.dev-dependencies]
 # pytest = "^5.2"