Factorize history export code used in GUI and command line.

Add options to export history limits and exchange rate.
Closes: #1752, #2604,
Replaces: #2715, 3724

gui/qt/main_window.py

@@ -2494,32 +2494,13 @@ class ElectrumWindow(QMainWindow, MessageBoxMixin, PrintError):
             plt.show()
 
     def do_export_history(self, wallet, fileName, is_csv):
-        history = wallet.get_history()
+        history = wallet.export_history(fx=self.fx)
         lines = []
         for item in history:
-            tx_hash, height, confirmations, timestamp, value, balance = item
-            if height>0:
-                if timestamp is not None:
-                    time_string = format_time(timestamp)
-                else:
-                    time_string = _("unverified")
-            else:
-                time_string = _("unconfirmed")
-
-            if value is not None:
-                value_string = format_satoshis(value, True)
-            else:
-                value_string = '--'
-
-            if tx_hash:
-                label = wallet.get_label(tx_hash)
-            else:
-                label = ""
-
             if is_csv:
-                lines.append([tx_hash, label, confirmations, value_string, time_string])
+                lines.append([item['txid'], item.get('label', ''), item['confirmations'], item['value'], item['date']])
             else:
-                lines.append({'txid':tx_hash, 'date':"%16s"%time_string, 'label':label, 'value':value_string})
+                lines.append(item)
 
         with open(fileName, "w+") as f:
             if is_csv:
@@ -2529,7 +2510,7 @@ class ElectrumWindow(QMainWindow, MessageBoxMixin, PrintError):
                     transaction.writerow(line)
             else:
                 import json
-                f.write(json.dumps(lines, indent = 4))
+                f.write(json.dumps(lines, indent=4))
 
     def sweep_key_dialog(self):
         d = WindowModalDialog(self, title=_('Sweep private keys'))