Reorganize project structure

checkaddy_app/validators/bch.py

@@ -0,0 +1,33 @@
+from __future__ import annotations
+
+from ..constants import BCH_CASHADDR_RE
+from .common import base58check_verify
+
+
+def validate_bch_address(address: str) -> tuple[bool, str]:
+    address = address.strip()
+    lower = address.lower()
+    if lower.startswith("bitcoincash:"):
+        payload = lower.split(":", 1)[1]
+    else:
+        payload = lower
+
+    if payload.startswith("q") or payload.startswith("p"):
+        if not BCH_CASHADDR_RE.fullmatch(payload):
+            return False, "Invalid characters in BCH CashAddr payload"
+        if len(payload) < 30:
+            return False, "BCH CashAddr payload is too short"
+        # Future improvement: replace this with full BCH CashAddr checksum verification.
+        return True, "CashAddr format (checksum not verified)"
+
+    if address.startswith("1") or address.startswith("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 BCH legacy version byte"
+        return True, "Valid legacy Base58Check address"
+
+    return False, "BCH addresses must be CashAddr or legacy Base58"