feat: marking cards no longer clogs the undo history

src/main.zig

@@ -11,9 +11,20 @@ const Response = union(enum) {
     page: Element,
     transition: struct {
         game_state: GameState,
-        can_undo: bool,
+        history_type: HistoryType,
         reset_selection: bool = false,
     },
+
+    pub const HistoryType = enum {
+        /// This game state should act as the start of history, and all previous history should
+        /// be removed.
+        start,
+        /// This game state shouldn't be added to the history.
+        transient,
+        /// This game state should be added to the history, as a point in time that can be reverted
+        /// to.
+        important,
+    };
 };
 
 const GameState = struct {
@@ -204,6 +215,7 @@ pub fn main() !void {
         history.deinit();
     }
     try history.append(try GameState.init(gpa.allocator(), std.crypto.random.int(u64), 1));
+    var history_type = Response.HistoryType.start;
 
     var root_element: ?Element = null;
     var response_arena = std.heap.ArenaAllocator.init(gpa.allocator());
@@ -312,6 +324,7 @@ pub fn main() !void {
 
         if (input_state.undo and history.items.len > 1) {
             var discarded_state = history.pop();
+            history_type = .important;
             discarded_state.deinit();
             root_element = null;
             hovered_action = null;
@@ -369,13 +382,25 @@ pub fn main() !void {
                     if (transition.reset_selection) {
                         hovered_action = null;
                     }
-                    if (!transition.can_undo) {
+                    const new_game_state = try transition.game_state.clone(gpa.allocator());
+                    if (history_type == .transient) {
+                        var transient_state = history.pop();
+                        transient_state.deinit();
+                    }
+                    switch (transition.history_type) {
+                        .start => {
                             for (history.items) |*state| {
                                 state.deinit();
                             }
                             history.clearRetainingCapacity();
+                            try history.append(new_game_state);
+                        },
+                        .important => try history.append(new_game_state),
+                        .transient => {
+                            try history.append(new_game_state);
+                        },
                     }
-                    try history.append(try transition.game_state.clone(gpa.allocator()));
+                    history_type = transition.history_type;
 
                     if (request_command) |command| gpa.allocator().free(command);
                     request_command = null;
@@ -1021,7 +1046,7 @@ fn drawCardHandler(arena: std.mem.Allocator, request: Request) HandlerError!Resp
             new_game_state.handler = &playerTurnHandler;
             return Response{ .transition = .{
                 .game_state = new_game_state,
-                .can_undo = false,
+                .history_type = .start,
             } };
         } else if (std.mem.eql(u8, command, "draw discard_pile")) {
             var new_game_state = try request.game_state.clone(arena);
@@ -1029,7 +1054,7 @@ fn drawCardHandler(arena: std.mem.Allocator, request: Request) HandlerError!Resp
             new_game_state.handler = &playerTurnHandler;
             return Response{ .transition = .{
                 .game_state = new_game_state,
-                .can_undo = true,
+                .history_type = .important,
             } };
         }
     }
@@ -1085,7 +1110,7 @@ fn playerTurnHandler(arena: std.mem.Allocator, request: Request) HandlerError!Re
 
             return Response{ .transition = .{
                 .game_state = new_game_state,
-                .can_undo = true,
+                .history_type = .transient,
                 .reset_selection = false,
             } };
         } else if (std.mem.eql(u8, command, "discard")) {
@@ -1109,7 +1134,7 @@ fn playerTurnHandler(arena: std.mem.Allocator, request: Request) HandlerError!Re
 
                 return Response{ .transition = .{
                     .game_state = new_game_state,
-                    .can_undo = true,
+                    .history_type = .important,
                     .reset_selection = false,
                 } };
             }
@@ -1165,7 +1190,7 @@ fn endOfTurnConfirmHandler(arena: std.mem.Allocator, request: Request) HandlerEr
 
             return Response{ .transition = .{
                 .game_state = new_game_state,
-                .can_undo = false,
+                .history_type = .start,
             } };
         }
     }