--- /dev/null
+/*
+ * Copyright (C) 2016 "IoT.bzh"
+ * Author José Bollo <jose.bollo@iot.bzh>
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#define _GNU_SOURCE
+#include <stdio.h>
+#include <string.h>
+#include <json-c/json.h>
+
+#include <afb/afb-plugin.h>
+
+/*
+ * the interface to afb-daemon
+ */
+const struct AFB_interface *afbitf;
+
+/*
+ * definition of a board
+ */
+struct board
+{
+ struct board *next;
+ int refcount;
+ int moves;
+ int history[9];
+ int id;
+ int level;
+ char board[9];
+};
+
+/*
+ * list of boards
+ */
+static struct board *all_boards;
+
+/*
+ * Search a board
+ */
+static struct board *search_board(int id)
+{
+ struct board *board = all_boards;
+ while (board != NULL && board->id != id)
+ board = board->next;
+ return board;
+}
+
+/*
+ * Creates a new board
+ */
+static struct board *get_new_board()
+{
+ struct board *board = calloc(1, sizeof *board);
+ memset(board->board, ' ', sizeof board->board);
+ board->refcount = 1;
+ board->level = 1;
+ board->moves = 0;
+ do {
+ board->id = (rand() >> 2) % 1000;
+ } while(board->id == 0 || search_board(board->id) != NULL);
+ board->next = all_boards;
+ all_boards = board;
+ return board;
+}
+
+/*
+ * Release a board
+ */
+static void release_board(struct board *board)
+{
+ /* decrease the reference count ... */
+ if (--board->refcount == 0) {
+ /* ... no more use */
+ /* unlink from the list of boards */
+ struct board **prv = &all_boards;
+ while (*prv != NULL && *prv != board)
+ prv = &(*prv)->next;
+ if (*prv != NULL)
+ *prv = board->next;
+ /* release the used memory */
+ free(board);
+ }
+}
+
+/*
+ * Checks who wins
+ * Returns zero if there is no winner
+ * Returns the char of the winner if a player won
+ */
+static char winner(const char b[9])
+{
+ int i;
+ char c;
+
+ /* check diagonals */
+ c = b[4];
+ if (c != ' ') {
+ if (b[0] == c && b[8] == c)
+ return c;
+ if (b[2] == c && b[6] == c)
+ return c;
+ }
+
+ /* check lines */
+ for (i = 0 ; i <= 6 ; i += 3) {
+ c = b[i];
+ if (c != ' ' && b[i+1] == c && b[i+2] == c)
+ return c;
+ }
+
+ /* check columns */
+ for (i = 0 ; i <= 2 ; i++) {
+ c = b[i];
+ if (c != ' ' && b[i+3] == c && b[i+6] == c)
+ return c;
+ }
+
+ return 0;
+}
+
+/* get the color (X or 0) of the move of index 'move' */
+static char color(int move)
+{
+ return (move & 1) == 0 ? 'X' : '0';
+}
+
+/* adds the move to the board */
+static void add_move(struct board *board, int index)
+{
+ int imove = board->moves++;
+ board->history[imove] = index;
+ board->board[index] = color(imove);
+}
+
+/* get a random possible move index from the board described by 'b' */
+static int get_random_move(char b[9])
+{
+ int index = rand() % 9;
+ while (b[index] != ' ')
+ index = (index + 1) % 9;
+ return index;
+}
+
+/*
+ * Scores the position described by 'b'
+ * for the player of color 'c' using an analysis of 'depth'.
+ * Returns 1 if player 'c' will win.
+ * Returns -1 if opponent of player 'c' will win.
+ * returns 0 otherwise.
+ */
+static int score_position(char b[9], char c, int depth)
+{
+ int i, t, r;
+
+ /* check if winner */
+ if (winner(b) == c)
+ return 1;
+
+ /* when depth of analysis is reached return unknown case */
+ if (--depth == 0)
+ return 0;
+
+ /* switch to the opponent */
+ c = (char)('O' + 'X' - c);
+
+ /* inspect opponent moves */
+ r = 1;
+ for (i = 0 ; i < 9 ; i++) {
+ if (b[i] == ' ') {
+ b[i] = c;
+ t = score_position(b, c, depth);
+ b[i] = ' ';
+ if (t > 0)
+ return -1; /* opponent will win */
+
+ if (t == 0)
+ r = 0; /* something not clear */
+ }
+ }
+ return r;
+}
+
+/* get one move: return the computed index of the move */
+static int get_move(struct board *board)
+{
+ int index, depth, t, f;
+ char c;
+ char b[9];
+
+ /* compute the depth */
+ depth = board->level - 1;
+ if (board->moves + depth > 9)
+ depth = 9 - board->moves;
+
+ /* case of null depth */
+ if (depth == 0)
+ return get_random_move(board->board);
+
+ /* depth and more */
+ memcpy(b, board->board, 9);
+ c = color(board->moves);
+ f = 0;
+ for (index = 0 ; index < 9 ; index++) {
+ if (board->board[index] == ' ') {
+ board->board[index] = c;
+ t = score_position(board->board, c, depth);
+ board->board[index] = ' ';
+ if (t > 0)
+ return index;
+ if (t < 0)
+ b[index] = '+';
+ else
+ f = 1;
+ }
+ }
+ return get_random_move(f ? b : board->board);
+}
+
+/*
+ * get the board description
+ */
+static struct json_object *describe(struct board *board)
+{
+ int i;
+ char w;
+ struct json_object *resu, *arr;
+
+ resu = json_object_new_object();
+
+ json_object_object_add(resu, "boardid", json_object_new_int(board->id));
+ json_object_object_add(resu, "level", json_object_new_int(board->level));
+
+ arr = json_object_new_array();
+ json_object_object_add(resu, "board", arr);
+ for (i = 0 ; i < 9 ; i++)
+ json_object_array_add(arr,
+ json_object_new_string_len(&board->board[i], 1));
+
+ arr = json_object_new_array();
+ json_object_object_add(resu, "history", arr);
+ for (i = 0 ; i < board->moves ; i++)
+ json_object_array_add(arr, json_object_new_int(board->history[i]));
+
+ w = winner(board->board);
+ if (w)
+ json_object_object_add(resu, "winner", json_object_new_string_len(&w, 1));
+ else if (board->moves == 9)
+ json_object_object_add(resu, "winner", json_object_new_string("none"));
+
+ return resu;
+}
+
+/*
+ * signals a change of the board
+ */
+static void changed(struct board *board, const char *reason)
+{
+ /* TODO */
+ WARNING(afbitf, "changed is unimplmented (reason was %s)", reason);
+}
+
+/*
+ * retrieves the board of the request
+ */
+static struct board *board_of_req(struct afb_req req)
+{
+ return afb_req_context(req, (void*)get_new_board, (void*)release_board);
+}
+
+/*
+ * start a new game
+ */
+static void new(struct afb_req req)
+{
+ struct board *board;
+
+ /* retrieves the context for the session */
+ board = board_of_req(req);
+
+ /* reset the game */
+ memset(board->board, ' ', sizeof board->board);
+ board->moves = 0;
+
+ /* replies */
+ afb_req_success(req, NULL, NULL);
+
+ /* signal change */
+ changed(board, "new");
+}
+
+/*
+ * get the board
+ */
+static void board(struct afb_req req)
+{
+ afb_req_success(req, describe(board_of_req(req)), NULL);
+}
+
+/*
+ * move a piece
+ */
+static void move(struct afb_req req)
+{
+ struct board *board;
+ int i;
+ const char *index;
+
+ /* retrieves the context for the session */
+ board = board_of_req(req);
+
+ /* retrieves the parameters of the move */
+ index = afb_req_value(req, "index");
+ i = index == NULL ? -1 : atoi(index);
+
+ /* checks validity of parameters */
+ if (i < 0 || i > 8) {
+ afb_req_fail(req, "error", "bad request");
+ return;
+ }
+
+ /* checks validity of the state */
+ if (winner(board->board) != 0) {
+ afb_req_fail(req, "error", "game terminated");
+ return;
+ }
+
+ /* checks validity of the move */
+ if (board->board[i] != ' ') {
+ afb_req_fail(req, "error", "occupied");
+ return;
+ }
+
+ /* applies the move */
+ add_move(board, i);
+
+ /* replies */
+ afb_req_success(req, NULL, NULL);
+
+ /* signals change */
+ changed(board, "move");
+}
+
+/*
+ * set the level
+ */
+static void level(struct afb_req req)
+{
+ struct board *board;
+ int l;
+ const char *level;
+
+ /* retrieves the context for the session */
+ board = board_of_req(req);
+
+ /* retrieves the parameters */
+ level = afb_req_value(req, "level");
+ l = level == NULL ? -1 : atoi(level);
+
+ /* check validity of parameters */
+ if (l < 1 || l > 10) {
+ afb_req_fail(req, "error", "bad request");
+ return;
+ }
+ board->level = l;
+
+ /* replies */
+ afb_req_success(req, NULL, NULL);
+
+ /* signals change */
+ changed(board, "level");
+}
+
+/*
+ * Join a board
+ */
+static void join(struct afb_req req)
+{
+ struct board *board;
+ const char *id;
+
+ /* retrieves the context for the session */
+ board = board_of_req(req);
+
+ /* retrieves the parameters */
+ board = board_of_req(req);
+ id = afb_req_value(req, "boardid");
+ if (id == NULL)
+ goto bad_request;
+
+ /* check validity of parameters */
+ if (strcmp(id, "none")) {
+ board = get_new_board();
+ goto success;
+ }
+ board = search_board(atoi(id));
+ if (board == NULL)
+ goto bad_request;
+
+ board->refcount++;
+success:
+ afb_req_context_set(req, board, (void*)release_board);
+
+ /* replies */
+ afb_req_success(req, NULL, NULL);
+ return;
+
+bad_request:
+ afb_req_fail(req, "error", "bad request");
+ return;
+}
+
+/*
+ * Undo the last move
+ */
+static void undo(struct afb_req req)
+{
+ struct board *board;
+ int i;
+
+ /* retrieves the context for the session */
+ board = board_of_req(req);
+
+ /* checks the state */
+ if (board->moves == 0) {
+ afb_req_fail(req, "error", "bad request");
+ return;
+ }
+
+ /* undo the last move */
+ i = board->history[--board->moves];
+ board->board[i] = ' ';
+
+ /* replies */
+ afb_req_success(req, NULL, NULL);
+
+ /* signals change */
+ changed(board, "undo");
+}
+
+/*
+ * computer plays
+ */
+static void play(struct afb_req req)
+{
+ struct board *board;
+ int index;
+
+ /* retrieves the context for the session */
+ board = board_of_req(req);
+
+ /* checks validity of the state */
+ if (winner(board->board) != 0 || board->moves == 9) {
+ afb_req_fail(req, "error", "game terminated");
+ return;
+ }
+
+ /* gets the move and plays it */
+ index = get_move(board);
+ add_move(board, index);
+
+ /* replies */
+ afb_req_success(req, describe(board), NULL);
+
+ /* signals change */
+ changed(board, "play");
+}
+
+/*
+ * array of the verbs exported to afb-daemon
+ */
+static const struct AFB_verb_desc_v1 verbs[] = {
+ /* VERB'S NAME SESSION MANAGEMENT FUNCTION TO CALL SHORT DESCRIPTION */
+ { .name= "new", .session= AFB_SESSION_NONE, .callback= new, .info= "Starts a new game" },
+ { .name= "play", .session= AFB_SESSION_NONE, .callback= play, .info= "Tells the server to play" },
+ { .name= "move", .session= AFB_SESSION_NONE, .callback= move, .info= "Tells the client move" },
+ { .name= "board", .session= AFB_SESSION_NONE, .callback= board, .info= "Get the current board" },
+ { .name= "level", .session= AFB_SESSION_NONE, .callback= level, .info= "Set the server level" },
+ { .name= "join", .session= AFB_SESSION_NONE, .callback= join, .info= "Join a board" },
+ { .name= "undo", .session= AFB_SESSION_NONE, .callback= undo, .info= "Undo the last move" },
+ /* marker for end of the array */
+ { .name= NULL }
+};
+
+/*
+ * description of the plugin for afb-daemon
+ */
+static const struct AFB_plugin plugin_description =
+{
+ /* description conforms to VERSION 1 */
+ .type= AFB_PLUGIN_VERSION_1,
+ .v1= { /* fills the v1 field of the union when AFB_PLUGIN_VERSION_1 */
+ .prefix= "tictactoe", /* the API name (or plugin name or prefix) */
+ .info= "Sample tac-tac-toe game", /* short description of of the plugin */
+ .verbs = verbs /* the array describing the verbs of the API */
+ }
+};
+
+/*
+ * activation function for registering the plugin called by afb-daemon
+ */
+const struct AFB_plugin *pluginAfbV1Register(const struct AFB_interface *itf)
+{
+ afbitf = itf; // records the interface for accessing afb-daemon
+ return &plugin_description; // returns the description of the plugin
+}
+
Code Review / src / app-framework-binder.git / commitdiff