Highlight the previous move.

This is particularly helpful when using the game to play on a real board

1 files changed, 37 insertions, 10 deletions

diff --git a/src/move.c b/src/move.c
index 2f96ca3..9f8df44 100644
--- a/src/move.c
+++ b/src/move.c
@@ -36,8 +36,10 @@ static void print_help() {
        "p - Print the board again\n");
 }
 
-static char *prompt_player(enum player_color current_player) {
-  print_board(get_board());
+static char *prompt_player(enum player_color current_player,
+                           struct move *flipped_last_turn,
+                           size_t flipped_last_turn_length) {
+  print_board(get_board(), flipped_last_turn, flipped_last_turn_length);
   switch (current_player) {
   case WHITE:
     return "Player 1 [h for help] > ";
@@ -49,11 +51,14 @@ static char *prompt_player(enum player_color current_player) {
   }
 }
 
-struct move prompt_get_move(enum player_color current_player) {
+struct move prompt_get_move(enum player_color current_player,
+                            struct move *flipped_last_turn,
+                            size_t flipped_last_turn_length) {
   // Initialize move to an invalid move.
   struct move move = {-1, -1};
 
-  char *prompt = prompt_player(current_player);
+  char *prompt = prompt_player(current_player, flipped_last_turn,
+                               flipped_last_turn_length);
   do {
     char *input = readline(prompt);
 
@@ -64,7 +69,7 @@ struct move prompt_get_move(enum player_color current_player) {
       if (STREQ(input, "h")) {
         print_help();
       } else if (STREQ(input, "p")) {
-        print_board(get_board());
+        print_board(get_board(), flipped_last_turn, flipped_last_turn_length);
       } else {
         sscanf(input, "%d %d", &move.row, &move.col);
       }
@@ -82,8 +87,9 @@ struct move prompt_get_move(enum player_color current_player) {
 
 // Returns non-zero number if the move was valid.
 // Returns the number of flipped tiles.
-int apply_move(enum player_color **board, enum player_color current_player,
-               struct move move) {
+size_t apply_move(enum player_color **board, enum player_color current_player,
+                  struct move move, struct move **flipped_spots,
+                  size_t *flipped_spots_capacity) {
 
   // The move must be a positive position.
   if (move.row < 0 || move.col < 0) {
@@ -107,6 +113,17 @@ int apply_move(enum player_color **board, enum player_color current_player,
        done_flipping_up_left = false, done_flipping_up_right = false,
        done_flipping_down_left = false, done_flipping_down_right = false;
 
+#define add_flipped_spot(row_in, col_in)                                       \
+  if (flipped_spots != NULL && flipped_spots_capacity != NULL) {               \
+    if (num_flipped == *flipped_spots_capacity) {                              \
+      *flipped_spots_capacity *= 2;                                            \
+      *flipped_spots = reallocarray(*flipped_spots, *flipped_spots_capacity,   \
+                                    sizeof(struct move));                      \
+    }                                                                          \
+    (*flipped_spots)[num_flipped].row = (row_in);                              \
+    (*flipped_spots)[num_flipped].col = (col_in);                              \
+  }
+
   for (int i = 1; i < 8; i++) {
     if (!done_flipping_up && (move.row - i >= 0) &&
         board[move.row - i][move.col] == current_player) {
@@ -122,6 +139,7 @@ int apply_move(enum player_color **board, enum player_color current_player,
         if (flippable) {
           for (int j = 0; j < i; j++) {
             board[move.row - j][move.col] = current_player;
+            add_flipped_spot(move.row - j, move.col);
             num_flipped++;
           }
         }
@@ -143,6 +161,7 @@ int apply_move(enum player_color **board, enum player_color current_player,
         if (flippable) {
           for (int j = 0; j < i; j++) {
             board[move.row + j][move.col] = current_player;
+            add_flipped_spot(move.row + j, move.col);
             num_flipped++;
           }
         }
@@ -164,6 +183,7 @@ int apply_move(enum player_color **board, enum player_color current_player,
         if (flippable) {
           for (int j = 0; j < i; j++) {
             board[move.row][move.col - j] = current_player;
+            add_flipped_spot(move.row, move.col - j);
             num_flipped++;
           }
         }
@@ -185,6 +205,7 @@ int apply_move(enum player_color **board, enum player_color current_player,
         if (flippable) {
           for (int j = 0; j < i; j++) {
             board[move.row][move.col + j] = current_player;
+            add_flipped_spot(move.row, move.col + j);
             num_flipped++;
           }
         }
@@ -206,6 +227,7 @@ int apply_move(enum player_color **board, enum player_color current_player,
         if (flippable) {
           for (int j = 0; j < i; j++) {
             board[move.row - j][move.col - j] = current_player;
+            add_flipped_spot(move.row - j, move.col - j);
             num_flipped++;
           }
         }
@@ -227,6 +249,7 @@ int apply_move(enum player_color **board, enum player_color current_player,
         if (flippable) {
           for (int j = 0; j < i; j++) {
             board[move.row - j][move.col + j] = current_player;
+            add_flipped_spot(move.row - j, move.col + j);
             num_flipped++;
           }
         }
@@ -248,6 +271,7 @@ int apply_move(enum player_color **board, enum player_color current_player,
         if (flippable) {
           for (int j = 0; j < i; j++) {
             board[move.row + j][move.col - j] = current_player;
+            add_flipped_spot(move.row + j, move.col - j);
             num_flipped++;
           }
         }
@@ -269,6 +293,7 @@ int apply_move(enum player_color **board, enum player_color current_player,
         if (flippable) {
           for (int j = 0; j < i; j++) {
             board[move.row + j][move.col + j] = current_player;
+            add_flipped_spot(move.row + j, move.col + j);
             num_flipped++;
           }
         }
@@ -278,6 +303,8 @@ int apply_move(enum player_color **board, enum player_color current_player,
     }
   }
 
+#undef add_flipped_spot
+
   return num_flipped;
 }
 
@@ -294,7 +321,7 @@ SCM scm_apply_move(SCM scm_move, SCM scm_board, SCM scm_player) {
 
   SCM res_board;
 
-  if (apply_move(board, player, move)) {
+  if (apply_move(board, player, move, NULL, NULL)) {
     res_board = scm_board_from_c_board(board);
   } else {
     res_board = SCM_EOL;
@@ -314,7 +341,7 @@ SCM scm_get_num_flipped_by_move(SCM scm_move, SCM scm_board, SCM scm_player) {
   enum player_color player = SCM_UNBNDP(scm_player)
                                  ? get_current_player()
                                  : scm_player_to_c_player(scm_player);
-  SCM res_num = scm_from_int(apply_move(board, player, move));
+  SCM res_num = scm_from_int(apply_move(board, player, move, NULL, NULL));
   free_board(board);
 
   return res_num;
@@ -409,7 +436,7 @@ bool is_valid_move(enum player_color **board,
   // necessarily mutate the board yet though.
   enum player_color **b = copy_board(board);
   // Apply the move to the copy of the board.
-  bool res = apply_move(b, current_player, move);
+  bool res = apply_move(b, current_player, move, NULL, NULL);
 
   free_board(b);