previous mistake

README.md

@@ -189,7 +189,8 @@ In addition to shortcuts mentioned above and those shown in the main menu:
 * **[Ctrl-delete]** Delete current node.
 * **[c]** Collapse/Uncollapse the branch from the current node to the previous branching point.
 * **[b]** Go back to the previous branching point.
-* **[n]** As in clicking the red arrow, go to one move before the next mistake (orange or worse) by a human player.
+* **[n]** As in clicking the forward red arrow, go to one move before the next mistake (orange or worse) by a human player.
+* **[Shift-n]** As in clicking the backward red arrow, go to one move before the previous mistake.
 * **[scroll up]**: Undo move. Only works when hovering the cursor over the board.
 * **[scroll down]**: Redo move. Only works when hovering the cursor over the board.
 * **[click on a move]**: See detailed statistics for a previous move, along with expected variation that was best instead of this move.

katrain/__main__.py

@@ -313,9 +313,9 @@ class KaTrainGui(Screen, KaTrainBase):
         self.board_gui.animating_pv = None
         self.game.redo(n_times)
 
-    def _do_next_mistake(self):
+    def _do_find_mistake(self, fn="redo"):
         self.board_gui.animating_pv = None
-        self.game.redo(999, stop_on_mistake=self.config("trainer/eval_thresholds")[-4])
+        getattr(self.game, fn)(9999, stop_on_mistake=self.config("trainer/eval_thresholds")[-4])
 
     def _do_cycle_children(self, *args):
         self.board_gui.animating_pv = None
@@ -480,7 +480,7 @@ class KaTrainGui(Screen, KaTrainBase):
             self.engine, analyze_fast=False
         )  # speed up result for looking at end of game
         self._do_new_game(move_tree=move_tree, analyze_fast=True)
-        self("redo", 999)
+        self("redo", 9999)
         self.log("Imported game from clipboard.", OUTPUT_INFO)
 
     def on_touch_up(self, touch):
@@ -514,7 +514,6 @@ class KaTrainGui(Screen, KaTrainBase):
             "i": ("insert-mode",),
             "p": ("play", None),
             "l": ("play-to-end",),
-            "n": ("next-mistake",),
             "b": ("undo", "branch"),
             "down": ("switch-branch", 1),
             "up": ("switch-branch", -1),
@@ -561,15 +560,17 @@ class KaTrainGui(Screen, KaTrainBase):
         elif keycode[1] in ["`", "~", "f12"]:
             self.zen = (self.zen + 1) % 3
         elif keycode[1] in ["left", "z"]:
-            self("undo", 1 + shift_pressed * 9 + ctrl_pressed * 999)
+            self("undo", 1 + shift_pressed * 9 + ctrl_pressed * 9999)
         elif keycode[1] in ["right", "x"]:
-            self("redo", 1 + shift_pressed * 9 + ctrl_pressed * 999)
+            self("redo", 1 + shift_pressed * 9 + ctrl_pressed * 9999)
         elif keycode[1] == "home":
-            self("undo", 999)
+            self("undo", 9999)
         elif keycode[1] == "end":
-            self("redo", 999)
+            self("redo", 9999)
         elif keycode[1] == "pageup":
             self.controls.move_tree.make_selected_node_main_branch()
+        elif keycode[1] == "n":
+            self("find-mistake", "undo" if shift_pressed else "redo")
         elif keycode[1] == "delete" and ctrl_pressed:
             self.controls.move_tree.delete_selected_node()
         elif keycode[1] == "c" and not ctrl_pressed:

katrain/core/game.py

@@ -257,10 +257,10 @@ class Game:
         self.current_node = node
         self._calculate_groups()
 
-    def undo(self, n_times=1):
+    def undo(self, n_times=1, stop_on_mistake=None):
         # allow undo/delete only in insert mode
         cn = self.current_node  # avoid race conditions
-        if self.insert_mode:
+        if self.insert_mode:  # in insert mode, undo = delete
             if n_times == 1 and cn not in self.insert_after.nodes_from_root:
                 cn.parent.children = [c for c in cn.parent.children if c != cn]
                 self.current_node = cn.parent
@@ -270,7 +270,15 @@ class Game:
         if n_times == "branch":
             n_times = 9999
             break_on_branch = True
-        for _ in range(n_times):
+        for move in range(n_times):
+            if (
+                stop_on_mistake is not None
+                and cn.points_lost is not None
+                and cn.points_lost >= stop_on_mistake
+                and self.katrain.players_info[cn.player].player_type != PLAYER_AI
+            ):
+                self.set_current_node(cn.parent)
+                return
             if cn.shortcut_from:
                 cn = cn.shortcut_from
             elif not cn.is_root:

katrain/gui.kv

@@ -186,9 +186,13 @@
         pos_hint: {'center_x': 0.5,'center_y':0.5}
         Label:
             size_hint: 0.075, 0.5
+        NavIconButton:
+            icon: 'Previous-Mistake.png'
+            color: Theme.MISTAKE_BUTTON_COLOR
+            on_press: root.katrain('find-mistake','undo')
         NavIconButton:
             icon: 'Previous-End.png'
-            on_press: root.katrain('undo',999)
+            on_press: root.katrain('undo',9999)
         NavIconButton:
             icon: 'Previous-5.png'
             on_press: root.katrain('undo',10)
@@ -218,11 +222,11 @@
             on_press: root.katrain('redo',10)
         NavIconButton:
             icon: 'Next-End.png'
-            on_press: root.katrain('redo',999)
+            on_press: root.katrain('redo',9999)
         NavIconButton:
             icon: 'Next-Mistake.png'
-            color: [0.79,0.06,0.06,1]
-            on_press: root.katrain('next-mistake')
+            color: Theme.MISTAKE_BUTTON_COLOR
+            on_press: root.katrain('find-mistake','redo')
     ClickableLabel:
         pos_hint: {'center_x': 0.85,'center_y':0.5}
         size_hint: None, 1

katrain/gui/theme.py

@@ -46,6 +46,7 @@ class Theme:
     MENU_ITEM_SHORTCUT_COLOR = LIGHT_GREY
     PLAY_ANALYZE_TAB_COLOR = YELLOW
     INPUT_FONT_COLOR = WHITE
+    MISTAKE_BUTTON_COLOR = [0.79, 0.06, 0.06, 1]
 
     # gui spacing
     CP_SPACING = 6