From ed540d68256f3f05e86b7880858249a1e8a17c42 Mon Sep 17 00:00:00 2001
From: Keuin <keuinx@gmail.com>
Date: Fri, 2 Jun 2023 00:15:30 +0800
Subject: Cache HTML source on disk

---
 htmlcache.py | 33 +++++++++++++++++++++++++++++++++
 web.py       | 23 +++++------------------
 2 files changed, 38 insertions(+), 18 deletions(-)
 create mode 100644 htmlcache.py

diff --git a/htmlcache.py b/htmlcache.py
new file mode 100644
index 0000000..2f727a7
--- /dev/null
+++ b/htmlcache.py
@@ -0,0 +1,33 @@
+import os
+
+import aiohttp
+
+import main
+
+
+class TexSourceGenerationError(Exception):
+    pass
+
+
+class HtmlCache:
+
+    def __init__(self, cache_path: str):
+        self._cache_path = os.path.abspath(cache_path)
+
+    async def get_utaten_tex_source(self, item_id: str) -> str:
+        cache_file_path = os.path.join(self._cache_path, f'{item_id}.html')
+        if os.path.isfile(cache_file_path):
+            with open(cache_file_path, 'r', encoding='utf-8') as f:
+                html = f.read()
+        else:
+            async with aiohttp.ClientSession() as ses:
+                async with ses.get(f'https://utaten.com/lyric/{item_id}/') as r:
+                    if not r.ok:
+                        raise TexSourceGenerationError('HTTP request failed when reading page source')
+                    html = await r.text()
+                    try:
+                        with open(cache_file_path, 'w', encoding='utf-8') as f:
+                            f.write(html)
+                    except IOError as e:
+                        print(f'Failed to update cache for song `{item_id}`: {e}')
+        return main.html_to_tex(html)
diff --git a/web.py b/web.py
index 007e93d..e2d7fdf 100644
--- a/web.py
+++ b/web.py
@@ -1,36 +1,23 @@
 import re
 
-import aiohttp
 from fastapi import FastAPI, Response
 from fastapi.responses import FileResponse
 
-import main
+import htmlcache
 import texgen
 
 app = FastAPI()
 
 utaten_pattern = re.compile(r'[a-z0-9]+')
 tex_generator = texgen.TexGenerator('pdf_cache', 'temp', 20)
-
-
-class TexSourceGenerationError(Exception):
-    pass
-
-
-async def _get_utaten_tex_source(item_id: str) -> str:
-    async with aiohttp.ClientSession() as ses:
-        async with ses.get(f'https://utaten.com/lyric/{item_id}/') as r:
-            if not r.ok:
-                raise TexSourceGenerationError('HTTP request failed when reading page source')
-            html = await r.text()
-            return main.html_to_tex(html)
+html_cache = htmlcache.HtmlCache('html_cache')
 
 
 @app.get("/utaten/{item_id}.pdf")
 async def get_utaten_lyric_pdf(item_id: str):
     try:
         print('_get_utaten_tex_source')
-        tex = await _get_utaten_tex_source(item_id)
+        tex = await html_cache.get_utaten_tex_source(item_id)
         print('xelatex')
         pdf_path = await tex_generator.xelatex(tex)
         return FileResponse(pdf_path, media_type='application/pdf')
@@ -41,7 +28,7 @@ async def get_utaten_lyric_pdf(item_id: str):
 @app.get("/utaten/{item_id}.tex")
 async def get_utaten_lyric_tex(item_id: str):
     try:
-        tex = await _get_utaten_tex_source(item_id)
+        tex = await html_cache.get_utaten_tex_source(item_id)
         return Response(content=tex, media_type='application/x-tex')
-    except TexSourceGenerationError as e:
+    except htmlcache.TexSourceGenerationError as e:
         return Response(content=str(e), status_code=503)
-- 
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