4 files changed, 133 insertions, 2 deletions

diff --git a/server/game.h b/server/game.h
index 6c986f5..1de6c73 100644
--- a/server/game.h
+++ b/server/game.h
@@ -50,6 +50,9 @@ class Game : public boost::enable_shared_from_this<Game> {
 				
 				typedef std::vector<int> Targets;
 				
+				//! Check if player can declare riichi.
+				bool can_riichi();
+				
 				//! Check if tile can be called for a chi.
 				Targets can_chi(Tile tile);
 				
diff --git a/server/hand.cpp b/server/hand.cpp
index 393a6c0..abdeb4b 100644
--- a/server/hand.cpp
+++ b/server/hand.cpp
@@ -4,6 +4,10 @@ bool Hand::agari(const Tiles& tiles) {
 	return basic_format(tiles);
 }
 
+bool Hand::tenpai(const Tiles& tiles) {
+	return basic_format_tenpai(tiles);
+}
+
 bool Hand::basic_format(const Tiles& tiles, bool pair_eaten) {
 	if(!tiles) {
 		return true; // All tiles eaten.
@@ -34,6 +38,90 @@ bool Hand::basic_format(const Tiles& tiles, bool pair_eaten) {
 	return false;
 }
 
+bool Hand::basic_format_tenpai(const Tiles& tiles, bool pair_eaten, bool wait_eaten) {
+	if(!tiles) {
+		return true;
+	}
+	
+	if(!pair_eaten && !wait_eaten) {
+		if(basic_format_tenpai(eat_tanki(tiles), true, true)) {
+			return true;
+		}
+	}
+	
+	if(tiles.size() < 2) {
+		return false;
+	}
+	
+	if(!pair_eaten) {
+		if(Tiles rest = eat_pair(tiles)) {
+			if(basic_format_tenpai(rest, true, wait_eaten)) {
+				return true;
+			}
+		}
+	}
+	
+	if(!wait_eaten) {
+		if(Tiles rest = eat_chi_wait(tiles)) {
+			if(basic_format_tenpai(rest, pair_eaten, true)) {
+				return true;
+			}
+		}
+	}
+	
+	if(tiles.size() < 3) {
+		return false;
+	}
+	
+	if(Tiles rest = eat_pon(tiles)) {
+		if(basic_format_tenpai(rest, pair_eaten, wait_eaten)) {
+			return true;
+		}
+	}
+	
+	if(Tiles rest = eat_chi(tiles)) {
+		return basic_format_tenpai(rest, pair_eaten, wait_eaten);
+	}
+	
+	return false;
+}
+
+Tiles Hand::eat_tanki(Tiles tiles) {
+	tiles.erase(tiles.begin());
+	return tiles;
+}
+
+Tiles Hand::eat_chi_wait(Tiles tiles) {
+	Tile::Set set = tiles.front().get_set();
+	int num = tiles.front().get_num();
+	
+	if(set == Tile::Honor || num > 8) {
+		return Tiles();
+	}
+	
+	// Look for T+1.
+	Tiles::iterator it = std::find(tiles.begin(), tiles.end(), Tile(set, num + 1));
+	if(it != tiles.end()) {
+		tiles.erase(it);
+		tiles.erase(tiles.begin());
+		return tiles;
+	}
+	
+	if(num > 7) {
+		return Tiles();
+	}
+	
+	// Look for T+2.
+	it = std::find(tiles.begin(), tiles.end(), Tile(set, num + 2));
+	if(it != tiles.end()) {
+		tiles.erase(it);
+		tiles.erase(tiles.begin());
+		return tiles;
+	}
+	
+	return Tiles();
+}
+
 Tiles Hand::eat_pair(Tiles tiles) {
 	if(tiles[0] == tiles[1]) {
 		tiles.erase(tiles.begin(), tiles.begin() + 2);
@@ -51,8 +139,8 @@ Tiles Hand::eat_pon(Tiles tiles) {
 }
 
 Tiles Hand::eat_chi(Tiles tiles) {
-	Tile::Set set = tiles[0].get_set();
-	int num = tiles[0].get_num();
+	Tile::Set set = tiles.front().get_set();
+	int num = tiles.front().get_num();
 	
 	if(set == Tile::Honor || num > 7) {
 		// Can't be chi-ed.
diff --git a/server/hand.h b/server/hand.h
index 46ae40a..e38a387 100644
--- a/server/hand.h
+++ b/server/hand.h
@@ -7,9 +7,21 @@ namespace Hand {
 	//! Check if the tiles constitute a complete hand. Also valid for the concealed part of an open hand.
 	bool agari(const Tiles& tiles);
 	
+	//! Check if the tiles miss only one from constituting a complete hand. Also valid for the concealed part of an open hand.
+	bool tenpai(const Tiles& tiles);
+	
 	// Check if the tiles is matching the normal format of one pair and rest triplets.
 	bool basic_format(const Tiles& tiles, bool pair_eaten = false);
 	
+	// Check if the tiles is matching the normal format but missing one.
+	bool basic_format_tenpai(const Tiles& tiles, bool pair_eaten = false, bool wait_eaten = false);
+	
+	// Eat a single tile (i.e. the tanki machi) from beginning of list and return rest.
+	Tiles eat_tanki(Tiles tiles);
+	
+	// Eat two tiles waiting for a third to complete a chi (i.e. ryanmen, penchan or kanchan machi) if possible.
+	Tiles eat_chi_wait(Tiles tiles);
+	
 	// Eat a pair from beginning of list if possible and return rest, else return empty list.
 	Tiles eat_pair(Tiles tiles);
 	
diff --git a/server/player.cpp b/server/player.cpp
index 4407095..37dc3bc 100644
--- a/server/player.cpp
+++ b/server/player.cpp
@@ -36,6 +36,9 @@ Actions Game::Player::get_actions_draw() {
 	
 	if(!riichi) {
 		// Check if player can riichi.
+		if(can_riichi()) {
+			possible_actions.push_back(Action(Action::Riichi));
+		}
 		
 		// List all tiles that can be discarded.
 		for(std::size_t i = 0; i < hand.size(); i++) {
@@ -89,6 +92,31 @@ Actions Game::Player::get_actions_discard(Tile tile, PlayerNum discarder) {
 	return possible_actions;
 }
 
+bool Game::Player::can_riichi() {
+	if(open) {
+		return false;
+	}
+	
+	Tiles tiles = hand;
+	
+	// Take first tile out of the set.
+	Tile out = tiles.front();
+	tiles.erase(tiles.begin());
+	
+	// Iterate over the rest of the set, exchanging the tile until a tenpai is found or all is tested.
+	for(Tiles::iterator it = tiles.begin(); it != tiles.end(); it++) {
+		if(Hand::tenpai(tiles)) {
+			return true;
+		}
+		
+		// TODO: Skip unnecessary tests if player got several equal tiles on hand.
+		
+		std::swap(*it, out);
+	}
+	
+	return false;
+}
+
 Game::Player::Targets Game::Player::can_chi(Tile tile) {
 	Targets targets;