Reorganize project structure

checkaddy_app/validators/btc.py

@@ -0,0 +1,28 @@
+from __future__ import annotations
+
+from .common import base58check_verify, bech32_decode
+
+
+def validate_btc_address(address: str) -> tuple[bool, str]:
+    address = address.strip()
+    if address.lower().startswith("bc1"):
+        hrp, data, spec = bech32_decode(address)
+        if hrp is None:
+            return False, "Invalid Bech32 or Bech32m checksum"
+        if hrp != "bc":
+            return False, "Invalid HRP for BTC"
+        if not data:
+            return False, "Missing witness program"
+        return True, f"Valid {spec} address"
+
+    if not (address.startswith("1") or address.startswith("3")):
+        return False, "BTC Base58 addresses must start with 1 or 3"
+
+    valid, reason, version, payload_len = base58check_verify(address)
+    if not valid:
+        return False, reason
+    if payload_len != 21:
+        return False, "Unexpected Base58 payload length"
+    if version not in (0x00, 0x05):
+        return False, "Invalid BTC version byte"
+    return True, "Valid Base58Check address"