fastapi infrastructure

- API/web distrinction
- language code prefixes
- content negotiation for endpoints

1 files changed, 79 insertions, 0 deletions

diff --git a/fatcat_scholar/web.py b/fatcat_scholar/web.py
new file mode 100644
index 0000000..dfebe01
--- /dev/null
+++ b/fatcat_scholar/web.py
@@ -0,0 +1,79 @@
+
+"""
+This file is the FastAPI web application.
+"""
+
+from enum import Enum
+
+from fastapi import FastAPI, APIRouter, Request, Depends
+from fastapi.staticfiles import StaticFiles
+from fastapi.templating import Jinja2Templates
+from fastapi.responses import HTMLResponse
+
+I18N_LANG_DEFAULT = "en"
+I18N_LANG_OPTIONS = ["en", "de", "zh"]
+
+class LangPrefix:
+    """
+    Looks for a two-character language prefix.
+
+    If there is no such prefix, in the future it could also look at the
+    Accept-Language header and try to infer a language from that, while not
+    setting the prefix code.
+    """
+
+    def __init__(self, request: Request):
+        self.prefix : str = ""
+        self.code : str = I18N_LANG_DEFAULT
+        for lang_option in I18N_LANG_OPTIONS:
+            if request.url.path.startswith(f"/{lang_option}/"):
+                self.prefix = f"/{lang_option}"
+                self.code = lang_option
+                break
+
+class ContentNegotiation:
+    """
+    Choses a mimetype to return based on Accept header.
+
+    Intended to be used for RESTful content negotiation from web endpoints to API.
+    """
+
+    def __init__(self, request: Request):
+        self.mimetype = "text/html"
+        if request.headers.get('accept', '').startswith('application/json'):
+            self.mimetype = "application/json"
+
+api = APIRouter()
+
+@api.get("/", operation_id="get_home")
+async def home(request: Request):
+    return {"endpoints": {"/": "this", "/search": "fulltext search"}}
+
+@api.get("/search", operation_id="get_search")
+async def search(request: Request):
+    return {"message": "search results would go here, I guess"}
+
+web = APIRouter()
+templates = Jinja2Templates(directory="fatcat_scholar/templates")
+
+@web.get("/", include_in_schema=False)
+async def web_home(request: Request, lang: LangPrefix = Depends(LangPrefix), content: ContentNegotiation = Depends(ContentNegotiation)):
+    if content.mimetype == "application/json":
+        return await api_home(request)
+    return templates.TemplateResponse("home.html", {"request": request})
+
+@web.get("/search", include_in_schema=False)
+async def web_search(request: Request):
+    if content.mimetype == "application/json":
+        return await api_search(request)
+    return templates.TemplateResponse("search.html", {"request": request})
+
+app = FastAPI()
+
+
+app.include_router(web)
+for lang_option in I18N_LANG_OPTIONS:
+    app.include_router(web, prefix=f"/{lang_option}")
+app.include_router(api)
+app.mount("/static", StaticFiles(directory="fatcat_scholar/static"), name="static")
+