1 files changed, 175 insertions, 0 deletions
diff --git a/src/game_loop.c b/src/game_loop.c
new file mode 100644
index 0000000..9cbd5e2
--- /dev/null
+++ b/src/game_loop.c
@@ -0,0 +1,175 @@
+#define _GNU_SOURCE
+
+#include <errno.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "othello.h"
+
+#define STREQ(a, b) (strcmp(a, b) == 0)
+
+static player_color other_player(player_color current_player) {
+  switch (current_player) {
+  case WHITE:
+    return BLACK;
+  case BLACK:
+    return WHITE;
+  default:
+    return EMPTY;
+  }
+}
+
+static int player_number_from_color(player_color player) {
+  switch (player) {
+  case WHITE:
+    return 1;
+  case BLACK:
+    return 2;
+  default:
+    return -1;
+  }
+}
+
+static void prompt_player(player_color current_player) {
+  printf("Player %d [h for help] > ", player_number_from_color(current_player));
+}
+
+static void print_help() {
+  puts("To enter a move, enter the two row and column seperated by spaces.\n"
+       "For example `0 0` will select the top left corner.\n\n"
+       "To print the board again, enter `p`\n\n"
+       "To drop into a guile repl enter `g`.\n\n"
+       "In the guile repl you can define an AI to use for the current player.\n\n"
+       "After you define an AI for that player, it will be used for the rest "
+       "of the game instead of prompting for input for that user.");
+}
+
+static struct move get_move(player_color board[8][8],
+                            player_color current_player) {
+  // Initialize move to an invalid move.
+  struct move move = {-1, -1};
+
+  do {
+    prompt_player(current_player);
+    char *input = NULL;
+    size_t input_length = 0;
+
+    errno = 0;
+    while (getline(&input, &input_length, stdin) <= 0) {
+      if (errno != 0) {
+        perror("Error getting input");
+        exit(EXIT_FAILURE);
+      }
+    }
+
+    if (STREQ(input, "h\n")) {
+      print_help();
+    } else if (STREQ(input, "p\n")) {
+      print_board(board);
+    } else if (STREQ(input, "g\n")) {
+      puts("NOT IMPLEMENTED YET!");
+    } else {
+      sscanf(input, "%d %d", &move.row, &move.col);
+    }
+
+    free(input);
+  } while (!is_valid_move(board, current_player, move));
+
+  return move;
+}
+
+static void apply_move(player_color board[8][8], player_color current_player,
+                       struct move move) {
+  if (!is_valid_move(board, current_player, move)) {
+
+    // We should have checked for the validity of the move before we got here.
+    fprintf(stderr, "The move %d %d was not valid for player %d\n", move.row,
+            move.col, player_number_from_color(current_player) + 1);
+    exit(EXIT_FAILURE);
+  }
+
+  // Flip in up direction
+  int up_end = move.row;
+  for (int i = move.row - 1; i > 0; i--) {
+    if (board[i][move.col] == EMPTY) {
+      break;
+    } else if (board[i][move.col] == current_player) {
+      /*up_end = i + 1;*/
+      up_end = i;
+      break;
+    }
+  }
+
+  // Flip in down direction
+  int down_end = move.row;
+  for (int i = move.row + 1; i < 8; i++) {
+    if (board[i][move.col] == EMPTY) {
+      break;
+    } else if (board[i][move.col] == current_player) {
+      /*down_end = i - 1;*/
+      down_end = i;
+      break;
+    }
+  }
+
+  // Flip in left direction
+  int left_end = move.col;
+  for (int i = move.col - 1; i > 0; i--) {
+    if (board[move.row][i] == EMPTY) {
+      break;
+    } else if (board[move.row][i] == current_player) {
+      /*left_end = i + 1;*/
+      left_end = i;
+      break;
+    }
+  }
+
+  // Flip in right direction
+  int right_end = move.col;
+  for (int i = move.col + 1; i < 8; i++) {
+    if (board[move.row][i] == EMPTY) {
+      break;
+    } else if (board[move.row][i] == current_player) {
+      /*right_end = i - 1;*/
+      right_end = i;
+      break;
+    }
+  }
+
+  for (int i = move.row; i > up_end; i--) {
+    board[i][move.col] = current_player;
+  }
+  for (int i = move.row; i < down_end; i++) {
+    board[i][move.col] = current_player;
+  }
+  for (int i = move.col; i > left_end; i--) {
+    board[move.row][i] = current_player;
+  }
+  for (int i = move.col; i < right_end; i++) {
+    board[move.row][i] = current_player;
+  }
+}
+
+char game_loop(player_color board[8][8]) {
+  player_color current_player = WHITE;
+
+  while (has_valid_moves(board, current_player)) {
+    struct move move = get_move(board, current_player);
+    apply_move(board, current_player, move);
+    /*board[move.row][move.col] = current_player;*/
+    current_player = other_player(current_player);
+  }
+
+  int white_score = 0, black_score = 0;
+  for (int row = 0; row < 8; row++) {
+    for (int col = 0; col < 8; col++) {
+      white_score += board[row][col] == WHITE;
+      black_score += board[row][col] == BLACK;
+    }
+  }
+
+  return white_score > black_score   ? WHITE
+         : black_score > white_score ? BLACK
+                                     : EMPTY;
+}