From d6fdeec63a01ba43c5468ecc7c77a37347b0c953 Mon Sep 17 00:00:00 2001
From: Santo Cariotti <santo@dcariotti.me>
Date: Fri, 17 Jun 2022 17:21:25 +0200
Subject: Add exercise

---
 Year_3/Blockchain/RockPaperScissor.sol | 124 +++++++++++++++++++++++++++++++++
 1 file changed, 124 insertions(+)
 create mode 100644 Year_3/Blockchain/RockPaperScissor.sol

diff --git a/Year_3/Blockchain/RockPaperScissor.sol b/Year_3/Blockchain/RockPaperScissor.sol
new file mode 100644
index 0000000..528bc4c
--- /dev/null
+++ b/Year_3/Blockchain/RockPaperScissor.sol
@@ -0,0 +1,124 @@
+// SPDX-License-Identifier: MIT
+
+pragma solidity ^0.8.0;
+
+import "TrustworthyRockPaperScissorsTournamentSpecs.sol";
+
+contract TrustworthyRockPaperScissorsTournament is TrustworthyRockPaperScissorsTournamentSpecs {
+    enum Move { ROCK, PAPER, SCISSOR }
+    enum Status { IN_PROGRESS, END }
+    struct PlayerInfo {
+        address payable id;
+        uint8 wins;
+        Move[] games;
+        uint fees;
+    }
+
+    mapping(Player => PlayerInfo) players;
+    uint8 target;
+    uint256 matchFee;
+    Status status;
+    Player winner;
+    address payable owner;
+
+    uint8 override public disputedMatches;
+ 
+    constructor(
+        address payable firstPlayer,
+        address payable secondPlayer,
+        uint8 targetWins,
+        uint256 singleMatchFee
+    ) {
+        require(firstPlayer != secondPlayer, "Players must be two different addresses.");
+        require(firstPlayer != address(0) && secondPlayer != address(0), "Players address are not valid.");
+
+        players[Player.First].id = firstPlayer;
+        players[Player.Second].id = secondPlayer;
+        target = targetWins;
+        matchFee = singleMatchFee;
+        status = Status.IN_PROGRESS;
+        disputedMatches = 0;
+        owner = payable(msg.sender);
+    }
+
+    function moveRock() external override payable {
+        move(Move.ROCK);
+    }
+
+    function movePaper() external override payable {
+        move(Move.PAPER);
+    }
+
+    function moveScissor() external override payable {
+        move(Move.SCISSOR);
+    }
+
+    modifier mustBeAPlayer() {
+        require(msg.sender == players[Player.First].id || msg.sender == players[Player.Second].id, "You're not one of the players.");
+        _;
+    }
+
+    function move(Move move_type) internal mustBeAPlayer {
+        require(status != Status.END, "Game has already finish");
+        require(msg.value >= matchFee, "You need to pass the minimum fee to play");
+
+        Player p = (msg.sender == players[Player.First].id ? Player.First : Player.Second);
+        players[p].games.push(move_type);
+        players[p].fees += msg.value;
+
+        checkGame();
+    }
+
+    function checkGame() internal {
+        uint8 n = uint8(
+                players[Player.First].games.length < players[Player.Second].games.length 
+                ? players[Player.First].games.length
+                : players[Player.Second].games.length
+            );
+
+        for (uint8 i = disputedMatches; i < n; ++i) {
+            Move p1 = players[Player.First].games[i];
+            Move p2 = players[Player.Second].games[i];
+
+            // Fair play
+            if (p1 == p2) continue;
+
+            if (
+                (p1 == Move.ROCK && p2 == Move.SCISSOR) ||
+                (p1 == Move.SCISSOR && p2 == Move.PAPER) ||
+                (p1 == Move.PAPER && p2 == Move.ROCK)
+            ) {
+                players[Player.First].wins++;
+                emit MatchWonBy(Player.First, i);
+            } else {
+                players[Player.Second].wins++;
+                emit MatchWonBy(Player.Second, i);
+            }
+
+            disputedMatches++;
+
+            if (players[Player.First].wins == target) {
+                emit TournamentWonBy(Player.First);
+                winner = Player.First;
+                endGame();
+            } else if (players[Player.Second].wins == target) {
+                emit TournamentWonBy(Player.Second);
+                winner = Player.Second;
+                endGame();
+            }
+        }
+    }
+
+    function endGame() internal {
+        require(status != Status.END, "Game has already finish");
+
+        assert(players[winner].wins == target);
+
+        uint total = players[Player.First].fees + players[Player.Second].fees;
+        assert(total == address(this).balance);
+        players[winner].id.transfer(total);
+
+        status = Status.END;
+        selfdestruct(owner);
+    }
+}
-- 
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