nginx load balancer and api

app/encoding.py

@@ -0,0 +1,52 @@
+"""
+Base62 encoding for short URL generation.
+
+- Uses 0-9, A-Z, a-z (62 characters)
+- URL-safe (no special characters)
+- More compact than hex (base16) or base64
+
+Length vs Capacity:
+- 6 chars: 62^6 = 56.8 billion unique URLs
+- 7 chars: 62^7 = 3.5 trillion unique URLs
+"""
+
+CHARSET = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz"
+BASE = len(CHARSET)  # 62
+
+
+def base62_encode(num: int) -> str:
+    """
+    Encode an integer to a base62 string.
+    """
+    if num < 0:
+        raise ValueError("Cannot encode negative numbers")
+    if num == 0:
+        return CHARSET[0]
+
+    result = []
+    while num:
+        result.append(CHARSET[num % BASE])
+        num //= BASE
+
+    return "".join(reversed(result))
+
+
+def base62_decode(encoded: str) -> int:
+    """
+    Decode a base62 string back to an integer.
+    """
+    if not encoded:
+        raise ValueError("Cannot decode empty string")
+
+    num = 0
+    for char in encoded:
+        if char not in CHARSET:
+            raise ValueError(f"Invalid character: {char}")
+        num = num * BASE + CHARSET.index(char)
+
+    return num
+
+
+def pad_to_length(encoded: str, length: int = 7) -> str:
+    """Pad encoded string to minimum length with leading zeros."""
+    return encoded.zfill(length)[-length:] if len(encoded) < length else encoded