Switch storage to persistent SQLite and add .env configuration

.env

@@ -0,0 +1 @@
+BASE_URL=http://localhost:8000

README.md

@@ -2,9 +2,11 @@
 URL-shortener project to showcase python use
 
 ## Create venv
+```bash
 cd /opt/kjc/int/URL-shortener
 python3 -m venv venv
 source venv/bin/activate
+```
 
 ## Run locally
 ```bash

app/main.py

@@ -2,14 +2,32 @@ from fastapi import FastAPI, HTTPException
 from fastapi.responses import RedirectResponse
 from pydantic import BaseModel
 from app.utils import generate_short_code
+from dotenv import load_dotenv
+import os
+import sqlite3
+
+load_dotenv()
 
 app = FastAPI()
 
-url_store = {}
+DB_PATH = "urls.db"
 
+def get_db_connection():
+    conn = sqlite3.connect(DB_PATH)
+    return conn
+
+# URL schema
 class URLRequest(BaseModel):
     url: str
 
+@app.on_event("startup")
+def startup():
+    conn = get_db_connection()
+    conn.execute('''CREATE TABLE IF NOT EXISTS urls
+                    (id INTEGER PRIMARY KEY, short_code TEXT, original_url TEXT, clicks INTEGER)''')
+    conn.commit()
+    conn.close()
+
 @app.get("/")
 def home():
     return {"message": "URL Shortener API"}
@@ -18,9 +36,30 @@ def home():
 def shorten_url(request: URLRequest):
     short_code = generate_short_code()
 
-    url_store[short_code] = {
-        "original_url": request.url,
-        "clicks": 0
-    }
+    conn = get_db_connection()
+    
+    while conn.execute("SELECT 1 FROM urls WHERE short_code = ?", (short_code,)).fetchone():
+        short_code = generate_short_code()
 
-    return {"short_url": f"http://localhost:8000/{short_code}"}
+    conn.execute("INSERT INTO urls (short_code, original_url, clicks) VALUES (?, ?, ?)",
+                 (short_code, request.url, 0))
+    conn.commit()
+    conn.close()
+
+    return {"short_url": f"{os.getenv('BASE_URL', 'http://localhost:8000')}/{short_code}"}
+
+@app.get("/{short_code}")
+def redirect_to_url(short_code: str):
+    conn = get_db_connection()
+    url_data = conn.execute("SELECT original_url, clicks FROM urls WHERE short_code = ?", (short_code,)).fetchone()
+    
+    if url_data is None:
+        raise HTTPException(status_code=404, detail="Shortened URL not found")
+    
+    original_url, clicks = url_data
+
+    conn.execute("UPDATE urls SET clicks = ? WHERE short_code = ?", (clicks + 1, short_code))
+    conn.commit()
+    conn.close()
+
+    return RedirectResponse(url=original_url)