#include "hand.h"

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.
	}
	
	if(!pair_eaten) {
		if(Tiles rest = eat_pair(tiles)) {
			if(basic_format(rest, true)) {
				return true;
			}
		}
	}
	
	if(tiles.size() < 3) {
		return false;
	}
	
	if(Tiles rest = eat_pon(tiles)) {
		if(basic_format(rest, pair_eaten)) {
			return true;
		}
	}
	
	if(Tiles rest = eat_chi(tiles)) {
		return basic_format(rest, 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);
		return tiles;
	}
	return Tiles();
}

Tiles Hand::eat_pon(Tiles tiles) {
	if(tiles[0] == tiles[2]) {
		tiles.erase(tiles.begin(), tiles.begin() + 3);
		return tiles;
	}
	return Tiles();
}

Tiles Hand::eat_chi(Tiles tiles) {
	Tile::Set set = tiles.front().get_set();
	int num = tiles.front().get_num();
	
	if(set == Tile::Honor || num > 7) {
		// Can't be chi-ed.
		return Tiles();
	}
	
	Tiles::iterator it1 = std::find(tiles.begin(), tiles.end(), Tile(set, num + 1));
	if(it1 != tiles.end()) {
		Tiles::iterator it2 = std::find(tiles.begin(), tiles.end(), Tile(set, num + 2));
		if(it2 != tiles.end()) {
			// We can eat a chi of tiles.
			tiles.erase(it2);
			tiles.erase(it1);
			tiles.erase(tiles.begin());
			return tiles;
		}
	}
	return Tiles();
}