synchronizer: rm redundant get_history call if new block mined unconf

diff --git a/electrum/synchronizer.py b/electrum/synchronizer.py
index 7907645..c231eab 100644
--- a/electrum/synchronizer.py
+++ b/electrum/synchronizer.py
@@ -160,7 +160,18 @@ class Synchronizer(SynchronizerBase):
                 and not self._stale_histories
                 and self.status_queue.empty())
 
-    async def _maybe_request_history_for_addr(self, addr: str) -> List[dict]:
+    async def _maybe_request_history_for_addr(self, addr: str, *, ann_status: Optional[str]) -> List[dict]:
+        # First opportunistically try to guess the addr history. Might save us network requests.
+        old_history = self.adb.db.get_addr_history(addr)
+        def guess_height(old_height: int) -> int:
+            if old_height in (0, -1,):
+                return self.interface.tip  # maybe mempool tx got mined just now
+            return old_height
+        guessed_history = [(txid, guess_height(old_height)) for (txid, old_height) in old_history]
+        if history_status(guessed_history) == ann_status:
+            self.logger.debug(f"managed to guess new history for {addr}. won't call 'blockchain.scripthash.get_history'.")
+            return [{"height": height, "tx_hash": txid} for (txid, height) in guessed_history]
+        # request addr history from server
         sh = address_to_scripthash(addr)
         self._requests_sent += 1
         async with self._network_request_semaphore:
@@ -183,7 +194,7 @@ class Synchronizer(SynchronizerBase):
             self._stale_histories.pop(addr, asyncio.Future()).cancel()
         finally:
             self._handling_addr_statuses.discard(addr)
-        result = await self._maybe_request_history_for_addr(addr)
+        result = await self._maybe_request_history_for_addr(addr, ann_status=status)
         hist = list(map(lambda item: (item['tx_hash'], item['height']), result))
         # tx_fees
         tx_fees = [(item['tx_hash'], item.get('fee')) for item in result]
diff --git a/tests/test_interface.py b/tests/test_interface.py
index 07b1333..06388a1 100644
--- a/tests/test_interface.py
+++ b/tests/test_interface.py
@@ -1,5 +1,6 @@
 import asyncio
 import collections
+from typing import Optional, Sequence, Iterable
 
 import aiorpcx
 from aiorpcx import RPCError
@@ -12,8 +13,13 @@ from electrum.logging import Logger
 from electrum.simple_config import SimpleConfig
 from electrum.transaction import Transaction
 from electrum import constants
+from electrum.wallet import Abstract_Wallet
+from electrum.blockchain import Blockchain
+from electrum.bitcoin import script_to_scripthash
+from electrum.synchronizer import history_status
 
 from . import ElectrumTestCase
+from . import restore_wallet_from_text__for_unittest
 
 
 class TestServerAddr(ElectrumTestCase):
@@ -86,6 +92,10 @@ class MockNetwork:
         pass
     async def switch_lagging_interface(self):
         pass
+    def blockchain(self) -> Blockchain:
+        return self.interface.blockchain
+    def get_local_height(self) -> int:
+        return self.blockchain().height()
 
 
 # regtest chain:
@@ -106,11 +116,11 @@ BLOCK_HEADERS = {
 }
 
 _active_server_sessions = set()
-def _get_active_server_session() -> 'ServerSession':
+def _get_active_server_session() -> 'ToyServerSession':
     assert 1 == len(_active_server_sessions), len(_active_server_sessions)
     return list(_active_server_sessions)[0]
 
-class ServerSession(aiorpcx.RPCSession, Logger):
+class ToyServerSession(aiorpcx.RPCSession, Logger):
 
     def __init__(self, *args, **kwargs):
         aiorpcx.RPCSession.__init__(self, *args, **kwargs)
@@ -120,6 +130,12 @@ class ServerSession(aiorpcx.RPCSession, Logger):
         self.txs = {
             "bdae818ad3c1f261317738ae9284159bf54874356f186dbc7afd631dc1527fcb": bfh("020000000001010000000000000000000000000000000000000000000000000000000000000000ffffffff025100ffffffff0200f2052a010000001600140297bde2689a3c79ffe050583b62f86f2d9dae540000000000000000266a24aa21a9ede2f61c3f71d1defd3fa999dfa36953755c690689799962b48bebd836974e8cf90120000000000000000000000000000000000000000000000000000000000000000000000000"),
         }  # type: dict[str, bytes]
+        self.txid_to_block_height = collections.defaultdict(int)  # type: dict[str, int]
+        self.subbed_headers = False
+        self.notified_height = None  # type: Optional[int]
+        self.subbed_scripthashes = set()  # type: set[str]
+        self.sh_to_funding_txids = collections.defaultdict(set)  # type: dict[str, set[str]]
+        self.sh_to_spending_txids = collections.defaultdict(set)  # type: dict[str, set[str]]
         self._method_counts = collections.defaultdict(int)  # type: dict[str, int]
         _active_server_sessions.add(self)
 
@@ -136,8 +152,11 @@ class ServerSession(aiorpcx.RPCSession, Logger):
             'blockchain.headers.subscribe': self._handle_headers_subscribe,
             'blockchain.block.header': self._handle_block_header,
             'blockchain.block.headers': self._handle_block_headers,
+            'blockchain.scripthash.subscribe': self._handle_scripthash_subscribe,
+            'blockchain.scripthash.get_history': self._handle_scripthash_get_history,
             'blockchain.transaction.get': self._handle_transaction_get,
             'blockchain.transaction.broadcast': self._handle_transaction_broadcast,
+            'blockchain.transaction.get_merkle': self._handle_transaction_get_merkle,
             'server.ping': self._handle_ping,
         }
         handler = handlers.get(request.method)
@@ -162,9 +181,13 @@ class ServerSession(aiorpcx.RPCSession, Logger):
     async def _handle_estimatefee(self, number, mode=None):
         return 1000
 
-    async def _handle_headers_subscribe(self):
+    def _get_headersub_result(self):
         return {'hex': BLOCK_HEADERS[self.cur_height].hex(), 'height': self.cur_height}
 
+    async def _handle_headers_subscribe(self):
+        self.subbed_headers = True
+        return self._get_headersub_result()
+
     async def _handle_block_header(self, height):
         return BLOCK_HEADERS[height].hex()
 
@@ -186,10 +209,97 @@ class ServerSession(aiorpcx.RPCSession, Logger):
             raise RPCError(DAEMON_ERROR, f'daemon error: unknown txid={tx_hash}')
         return rawtx.hex()
 
-    async def _handle_transaction_broadcast(self, raw_tx: str):
+    async def _handle_transaction_get_merkle(self, tx_hash: str, height: int) -> dict:
+        # Fake stuff. Client will ignore it due to config.NETWORK_SKIPMERKLECHECK
+        return {
+            "merkle":
+            [
+                "713d6c7e6ce7bbea708d61162231eaa8ecb31c4c5dd84f81c20409a90069cb24",
+                "03dbaec78d4a52fbaf3c7aa5d3fccd9d8654f323940716ddf5ee2e4bda458fde",
+                "e670224b23f156c27993ac3071940c0ff865b812e21e0a162fe7a005d6e57851",
+                "369a1619a67c3108a8850118602e3669455c70cdcdb89248b64cc6325575b885",
+                "4756688678644dcb27d62931f04013254a62aeee5dec139d1aac9f7b1f318112",
+                "7b97e73abc043836fd890555bfce54757d387943a6860e5450525e8e9ab46be5",
+                "61505055e8b639b7c64fd58bce6fc5c2378b92e025a02583303f69930091b1c3",
+                "27a654ff1895385ac14a574a0415d3bbba9ec23a8774f22ec20d53dd0b5386ff",
+                "5312ed87933075e60a9511857d23d460a085f3b6e9e5e565ad2443d223cfccdc",
+                "94f60b14a9f106440a197054936e6fb92abbd69d6059b38fdf79b33fc864fca0",
+                "2d64851151550e8c4d337f335ee28874401d55b358a66f1bafab2c3e9f48773d"
+            ],
+            "block_height": height,
+            "pos": 710,
+        }
+
+    async def _handle_transaction_broadcast(self, raw_tx: str) -> str:
         tx = Transaction(raw_tx)
-        self.txs[tx.txid()] = bfh(raw_tx)
-        return tx.txid()
+        txid = tx.txid()
+        self.txs[txid] = bfh(raw_tx)
+        touched_sh = await self._process_added_tx(txid=txid)
+        if touched_sh:
+            await self._send_notifications(touched_sh=touched_sh)
+        return txid
+
+    async def _process_added_tx(self, *, txid: str) -> set[str]:
+        """Returns touched scripthashes."""
+        tx = Transaction(self.txs[txid])
+        touched_sh = set()
+        # update sh_to_funding_txids
+        for txout in tx.outputs():
+            sh = script_to_scripthash(txout.scriptpubkey)
+            self.sh_to_funding_txids[sh].add(txid)
+            touched_sh.add(sh)
+        # update sh_to_spending_txids
+        for txin in tx.inputs():
+            if parent_tx_raw := self.txs.get(txin.prevout.txid.hex()):
+                parent_tx = Transaction(parent_tx_raw)
+                ptxout = parent_tx.outputs()[txin.prevout.out_idx]
+                sh = script_to_scripthash(ptxout.scriptpubkey)
+                self.sh_to_spending_txids[sh].add(txid)
+                touched_sh.add(sh)
+        return touched_sh
+
+    async def _handle_scripthash_subscribe(self, sh: str) -> Optional[str]:
+        self.subbed_scripthashes.add(sh)
+        hist = self._calc_sh_history(sh)
+        return history_status(hist)
+
+    async def _handle_scripthash_get_history(self, sh: str) -> Sequence[dict]:
+        hist_tuples = self._calc_sh_history(sh)
+        hist_dicts = [{"height": height, "tx_hash": txid} for (txid, height) in hist_tuples]
+        for hist_dict in hist_dicts:  # add "fee" key for mempool txs
+            if hist_dict["height"] in (0, -1,):
+                hist_dict["fee"] = 0
+        return hist_dicts
+
+    def _calc_sh_history(self, sh: str) -> Sequence[tuple[str, int]]:
+        txids = self.sh_to_funding_txids[sh] | self.sh_to_spending_txids[sh]
+        hist = []
+        for txid in txids:
+            bh = self.txid_to_block_height[txid]
+            hist.append((txid, bh))
+        hist.sort(key=lambda x: x[1])  # FIXME put mempool txs last
+        return hist
+
+    async def _send_notifications(self, *, touched_sh: Iterable[str], height_changed: bool = False) -> None:
+        if height_changed and self.subbed_headers and self.notified_height != self.cur_height:
+            self.notified_height = self.cur_height
+            args = (self._get_headersub_result(),)
+            await self.send_notification('blockchain.headers.subscribe', args)
+        touched_sh = set(sh for sh in touched_sh if sh in self.subbed_scripthashes)
+        for sh in touched_sh:
+            hist = self._calc_sh_history(sh)
+            args = (sh, history_status(hist))
+            await self.send_notification("blockchain.scripthash.subscribe", args)
+
+    async def mine_block(self, *, txids_mined: Iterable[str] = None):
+        if txids_mined is None:
+            txids_mined = []
+        self.cur_height += 1
+        touched_sh = set()
+        for txid in txids_mined:
+            self.txid_to_block_height[txid] = self.cur_height
+            touched_sh |= await self._process_added_tx(txid=txid)
+        await self._send_notifications(touched_sh=touched_sh, height_changed=True)
 
 
 class TestInterface(ElectrumTestCase):
@@ -198,6 +308,7 @@ class TestInterface(ElectrumTestCase):
     def setUp(self):
         super().setUp()
         self.config = SimpleConfig({'electrum_path': self.electrum_path})
+        self.config.NETWORK_SKIPMERKLECHECK = True
         self._orig_WAIT_FOR_BUFFER_GROWTH_SECONDS = PaddedRSTransport.WAIT_FOR_BUFFER_GROWTH_SECONDS
         PaddedRSTransport.WAIT_FOR_BUFFER_GROWTH_SECONDS = 0
 
@@ -207,7 +318,7 @@ class TestInterface(ElectrumTestCase):
 
     async def asyncSetUp(self):
         await super().asyncSetUp()
-        self._server: asyncio.base_events.Server = await aiorpcx.serve_rs(ServerSession, "127.0.0.1")
+        self._server: asyncio.base_events.Server = await aiorpcx.serve_rs(ToyServerSession, "127.0.0.1")
         server_socket_addr = self._server.sockets[0].getsockname()
         self._server_port = server_socket_addr[1]
         self.network = MockNetwork(config=self.config)
@@ -255,3 +366,35 @@ class TestInterface(ElectrumTestCase):
         rawtx2 = await interface.get_transaction(tx.txid())
         self.assertEqual(rawtx1, rawtx2)
         self.assertEqual(_get_active_server_session()._method_counts["blockchain.transaction.get"], 0)
+
+    async def test_dont_request_gethistory_if_status_change_results_from_mempool_txs_simply_getting_mined(self):
+        """After a new block is mined, we recv "blockchain.scripthash.subscribe" notifs.
+        We opportunistically guess the scripthash status changed purely because touching mempool txs just got mined.
+        If the guess is correct, we won't call the "blockchain.scripthash.get_history" RPC.
+        """
+        interface = await self._start_iface_and_wait_for_sync()
+        w1 = restore_wallet_from_text__for_unittest("9dk", path=None, config=self.config)['wallet']  # type: Abstract_Wallet
+        w1.start_network(self.network)
+        await w1.up_to_date_changed_event.wait()
+        self.assertEqual(_get_active_server_session()._method_counts["blockchain.scripthash.get_history"], 0)
+        # fund w1 (in mempool)
+        funding_tx = "01000000000101e855888b77b1688d08985b863bfe85b354049b4eba923db9b5cf37089975d5d10000000000fdffffff0280969800000000001600140297bde2689a3c79ffe050583b62f86f2d9dae5460abe9000000000016001472df47551b6e7e0c8428814d2e572bc5ac773dda024730440220383efa2f0f5b87f8ce5d6b6eaf48cba03bf522b23fbb23b2ac54ff9d9a8f6a8802206f67d1f909f3c7a22ac0308ac4c19853ffca3a9317e1d7e0c88cc3a86853aaac0121035061949222555a0df490978fe6e7ebbaa96332ecb5c266918fd800c0eef736e7358d1400"
+        funding_txid = await _get_active_server_session()._handle_transaction_broadcast(funding_tx)
+        await w1.up_to_date_changed_event.wait()
+        while not w1.is_up_to_date():
+            await w1.up_to_date_changed_event.wait()
+        self.assertEqual(_get_active_server_session()._method_counts["blockchain.scripthash.get_history"], 1)
+        self.assertEqual(
+            w1.adb.get_address_history("bcrt1qq2tmmcngng78nllq2pvrkchcdukemtj5jnxz44"),
+            {funding_txid: 0})
+        # mine funding tx
+        await _get_active_server_session().mine_block(txids_mined=[funding_txid])
+        await w1.up_to_date_changed_event.wait()
+        while not w1.is_up_to_date():
+            await w1.up_to_date_changed_event.wait()
+        # see if we managed to guess new history, and hence did not need to call get_history RPC
+        self.assertEqual(_get_active_server_session()._method_counts["blockchain.scripthash.get_history"], 1)
+        self.assertEqual(
+            w1.adb.get_address_history("bcrt1qq2tmmcngng78nllq2pvrkchcdukemtj5jnxz44"),
+            {funding_txid: 7})
+