refactor: wallet, simplify addressbook migration

Same process written in a cleaner manner.
Removing code duplication.

Author: furszy

src/wallet/wallet.cpp

@@ -4009,52 +4009,41 @@ bool CWallet::ApplyMigrationData(MigrationData& data, bilingual_str& error)
 
     // Check the address book data in the same way we did for transactions
     std::vector<CTxDestination> dests_to_delete;
-    for (const auto& addr_pair : m_address_book) {
-        // Labels applied to receiving addresses should go based on IsMine
-        if (addr_pair.second.purpose == AddressPurpose::RECEIVE) {
-            if (!IsMine(addr_pair.first)) {
-                // Check the address book data is the watchonly wallet's
-                if (data.watchonly_wallet) {
-                    LOCK(data.watchonly_wallet->cs_wallet);
-                    if (data.watchonly_wallet->IsMine(addr_pair.first)) {
-                        // Add to the watchonly. Copy the entire address book entry
-                        data.watchonly_wallet->m_address_book[addr_pair.first] = addr_pair.second;
-                        dests_to_delete.push_back(addr_pair.first);
-                        continue;
-                    }
-                }
-                if (data.solvable_wallet) {
-                    LOCK(data.solvable_wallet->cs_wallet);
-                    if (data.solvable_wallet->IsMine(addr_pair.first)) {
-                        // Add to the solvable. Copy the entire address book entry
-                        data.solvable_wallet->m_address_book[addr_pair.first] = addr_pair.second;
-                        dests_to_delete.push_back(addr_pair.first);
-                        continue;
-                    }
-                }
+    for (const auto& [dest, record] : m_address_book) {
+        // Ensure "receive" entries that are no longer part of the original wallet are transferred to another wallet
+        // Entries for everything else ("send") will be cloned to all wallets.
+        bool require_transfer = record.purpose == AddressPurpose::RECEIVE && !IsMine(dest);
+        bool copied = false;
+        for (auto& wallet : {data.watchonly_wallet, data.solvable_wallet}) {
+            if (!wallet) continue;
+
+            LOCK(wallet->cs_wallet);
+            if (require_transfer && !wallet->IsMine(dest)) continue;
+
+            // Copy the entire address book entry
+            wallet->m_address_book[dest] = record;
+
+            copied = true;
+            // Only delete 'receive' records that are no longer part of the original wallet
+            if (require_transfer) {
+                dests_to_delete.push_back(dest);
+                break;
+            }
+        }
 
-                // Skip invalid/non-watched scripts that will not be migrated
-                if (not_migrated_dests.count(addr_pair.first) > 0) {
-                    dests_to_delete.push_back(addr_pair.first);
-                    continue;
-                }
+        // Fail immediately if we ever found an entry that was ours and cannot be transferred
+        // to any of the created wallets (watch-only, solvable).
+        // Means that no inferred descriptor maps to the stored entry. Which mustn't happen.
+        if (require_transfer && !copied) {
 
-                // Not ours, not in watchonly wallet, and not in solvable
-                error = _("Error: Address book data in wallet cannot be identified to belong to migrated wallets");
-                return false;
-            }
-        } else {
-            // Labels for everything else ("send") should be cloned to all
-            if (data.watchonly_wallet) {
-                LOCK(data.watchonly_wallet->cs_wallet);
-                // Add to the watchonly. Copy the entire address book entry
-                data.watchonly_wallet->m_address_book[addr_pair.first] = addr_pair.second;
-            }
-            if (data.solvable_wallet) {
-                LOCK(data.solvable_wallet->cs_wallet);
-                // Add to the solvable. Copy the entire address book entry
-                data.solvable_wallet->m_address_book[addr_pair.first] = addr_pair.second;
+            // Skip invalid/non-watched scripts that will not be migrated
+            if (not_migrated_dests.count(dest) > 0) {
+                dests_to_delete.push_back(dest);
+                continue;
             }
+
+            error = _("Error: Address book data in wallet cannot be identified to belong to migrated wallets");
+            return false;
         }
     }