Add market buy handler with blockchain transaction execution

cli/handlers/market.py

@@ -282,3 +282,108 @@ def handle_market_gpu_list(args, default_coordinator_url, output_format):
     except Exception as e:
         print(f"Error listing GPUs: {e}")
         sys.exit(1)
+
+
+def handle_market_buy(args, default_rpc_url, read_password, render_mapping):
+    """Handle marketplace buy command with blockchain transaction."""
+    rpc_url = getattr(args, 'rpc_url', default_rpc_url)
+    
+    if not args.item or not args.wallet:
+        print("Error: --item and --wallet are required")
+        sys.exit(1)
+    
+    # Get password for signing
+    password = read_password(args)
+    if not password:
+        print("Error: Password is required for signing")
+        sys.exit(1)
+    
+    # Load wallet and get address
+    from pathlib import Path
+    import json
+    from cryptography.hazmat.primitives.asymmetric import ed25519
+    
+    keystore_dir = Path("/var/lib/aitbc/keystore")
+    sender_keystore = keystore_dir / f"{args.wallet}.json"
+    
+    if not sender_keystore.exists():
+        print(f"Error: Wallet '{args.wallet}' not found")
+        sys.exit(1)
+    
+    with open(sender_keystore) as f:
+        sender_data = json.load(f)
+    sender_address = sender_data['address']
+    
+    # Decrypt private key for signing
+    try:
+        sys.path.insert(0, "/opt/aitbc/cli")
+        from aitbc_cli import decrypt_private_key
+        private_key_hex = decrypt_private_key(sender_keystore, password)
+        private_key = ed25519.Ed25519PrivateKey.from_private_bytes(bytes.fromhex(private_key_hex))
+    except Exception as e:
+        print(f"Error decrypting wallet: {e}")
+        sys.exit(1)
+    
+    # Get chain_id
+    try:
+        from sys.path import insert
+        insert(0, "/opt/aitbc")
+        from aitbc_cli.utils.chain_id import get_chain_id
+        chain_id = get_chain_id(rpc_url, override=None, timeout=5)
+    except Exception:
+        chain_id = "ait-testnet"
+    
+    # Get actual nonce from blockchain
+    actual_nonce = 0
+    try:
+        account_data = requests.get(f"{rpc_url}/rpc/account/{sender_address}", timeout=5).json()
+        actual_nonce = account_data.get("nonce", 0)
+    except Exception:
+        actual_nonce = 0
+    
+    # Get GPU listing details
+    try:
+        coordinator_url = "http://localhost:8000"
+        gpu_response = requests.get(f"{coordinator_url}/v1/marketplace/gpu/{args.item}", timeout=10)
+        if gpu_response.status_code == 200:
+            gpu_data = gpu_response.json()
+            price = int(gpu_data.get('price_per_hour', 0) * 1000000)  # Convert to AIT
+        else:
+            price = 1000000  # Default price
+    except Exception:
+        price = 1000000  # Default price
+    
+    # Create transaction with marketplace purchase payload
+    transaction = {
+        "type": "TRANSFER",
+        "chain_id": chain_id,
+        "from": sender_address,
+        "nonce": actual_nonce,
+        "fee": 10,
+        "payload": {
+            "recipient": gpu_data.get('owner_address', 'ait0000000000000000000000000000000000000000'),
+            "amount": price,
+            "item_id": args.item,
+            "action": "buy"
+        }
+    }
+    
+    # Sign transaction
+    message = json.dumps(transaction, sort_keys=True).encode()
+    signature = private_key.sign(message)
+    transaction["signature"] = signature.hex()
+    
+    print(f"Submitting purchase transaction to {rpc_url}...")
+    try:
+        response = requests.post(f"{rpc_url}/rpc/transaction", json=transaction, timeout=30)
+        if response.status_code == 200:
+            result = response.json()
+            print("Purchase transaction submitted successfully")
+            render_mapping("Transaction:", result)
+        else:
+            print(f"Purchase failed: {response.status_code}")
+            print(f"Error: {response.text}")
+            sys.exit(1)
+    except Exception as e:
+        print(f"Error submitting purchase: {e}")
+        sys.exit(1)