Assignment2 algorithm solution.

script.js

@@ -1,12 +1,62 @@
 const ASSIGNMENT = 'assignment';
 const ANSWER = 'answer';
+const ALGORITHM_CHECKBOX = 'algorithm';
+const ERROR_MESSAGE_NO_SUCH_CHARACTER_IN_RPS = "Non existant character in rock paper scissor game selected: ";
+const ERROR_MESSAGE_TOO_FEW_CHARACTERS_IN_LINE = "Too few characters in line: ";
 const NEWLINE_CHARACTER = '\n';
+const OPTION_LOSE = 'X';
+const OPTION_TIE = 'Y';
+const OPTION_WIN = 'Z';
+
+const RPS = Object.freeze({
+    ROCK: 1,
+    PAPER: 2,
+    SCISSORS: 3,
+
+    /**
+     * Select winning hand for given hand.
+     * @param hand the chosen hand
+     * @return RPS the winning hand
+     */
+    winning_hand: function(hand) {
+        hand++;
+        if(hand > RPS.SCISSORS) {
+            hand = RPS.ROCK;
+        }
+        return hand;
+    },
+
+    /**
+     * Select losing hand for given hand.
+     * @param hand the chosen hand
+     * @return RPS the losing hand
+     */
+    losing_hand: function(hand) {
+        hand--;
+        if(hand < RPS.ROCK) {
+            hand = RPS.SCISSORS;
+        }
+        return hand;
+    }
+});
+const RPS_ALIAS_MAP = Object.freeze({
+    "A": RPS.ROCK,
+    "B": RPS.PAPER,
+    "C": RPS.SCISSORS,
+    "X": RPS.ROCK,
+    "Y": RPS.PAPER,
+    "Z": RPS.SCISSORS,
+})
+const SCORE_LOSE = 0;
+const SCORE_TIE = 3;
+const SCORE_WIN = 6;
 
 /**
  * Main function
  */
 window.onload = function() {
     document.getElementById(ASSIGNMENT).addEventListener("input", calculateAnswer);
+    document.getElementById(ALGORITHM_CHECKBOX).addEventListener("click", calculateAnswer);
 }
 
 /**
@@ -15,7 +65,9 @@ window.onload = function() {
  */
 function calculateAnswer(event) {
   console.info("Calculating answer for input...");
-  let answer = algorithm(event.target.value);
+  let assignment = document.getElementById(ASSIGNMENT).value;
+  let interpret_as_rps = document.getElementById(ALGORITHM_CHECKBOX).checked;
+  let answer = algorithm(assignment, interpret_as_rps);
 
   document.getElementById(ANSWER).innerText = answer;
 }
@@ -25,9 +77,115 @@ function calculateAnswer(event) {
  * @param assignment the input from the assignment.
  * @return string the answer
  */
-function algorithm(assignment) {
+function algorithm(assignment, interpret_as_rps) {
+    let errors = 0;
     let lines = assignment.trim().split(NEWLINE_CHARACTER);
+    let score = 0;
     console.info("Linecount:" + lines.length);
 
-    // TODO: implement assignment
+    for(let i=0; i<lines.length; i++) {
+        let rps_match = lines[i].replace(/\s/g, ''); // remove all whitespace
+        if(rps_match.length < 2) {
+            console.error(ERROR_MESSAGE_TOO_FEW_CHARACTERS_IN_LINE + i + ", skipped.");
+            errors++;
+            continue;
+        }
+
+        // Assign characters from line
+        let opponent_hand = map_hand_character(rps_match[0]); 
+        let player_input = rps_match[1]; 
+        let player_hand = -1;
+
+        // Validate hand
+        if(opponent_hand<0) {
+            console.error(ERROR_MESSAGE_NO_SUCH_CHARACTER_IN_RPS + rps_match[0] + " for line: " + i);
+            errors++;
+            continue;
+        }
+
+        // How should we interpret input? match_option or Rock Paper Scissors.
+        if(interpret_as_rps) {
+            player_hand = interpret_player_hand_as_rps_input(player_input);
+        } else {
+            player_hand = interpret_player_hand_as_match_input(player_input, opponent_hand);
+        }
+
+        if(player_hand<0) { // Invalid input
+            console.error(ERROR_MESSAGE_NO_SUCH_CHARACTER_IN_RPS + rps_match[1] + " for line: " + i);
+            errors++;
+            continue;
+        }
+
+        score += rps_result(player_hand, opponent_hand);
+    }
+
+    if(errors > 0) {
+        return errors.toString() + " Error(s) in input, see console for details."
+    }
+
+    return "Player score: " + score;
+}
+
+/**
+ * Interpret given input for player as a rock paper scissor character.
+ * @param char input the input for hand character (A,B,C,X,Y,Z)
+ * @return the player hand character or -1 if invalid.
+ */
+function interpret_player_hand_as_rps_input(input) {
+    return map_hand_character(input); 
+}
+
+/**
+ * Interpret given input for player as a match option.
+ * @param char input the input for match option (X,Y,Z)
+ * @return the player hand character or -1 if invalid.
+ */
+function interpret_player_hand_as_match_input(input, opponent_hand) {
+    let player_hand = -1;
+    switch (input) {
+        case OPTION_LOSE:
+            player_hand = RPS.losing_hand(opponent_hand);
+            break;
+        case OPTION_WIN:
+            player_hand = RPS.winning_hand(opponent_hand);
+            break;
+        case OPTION_TIE:
+            player_hand = opponent_hand;
+            break;
+    }
+
+    return player_hand;
+}
+
+/**
+ * Maps the chosen hand character to 
+ * @param hand_character the chosen character
+ * @return RPS the rock paper scissor hand or -1 if invalid
+ */
+function map_hand_character(hand_character) {
+    if(!(hand_character in RPS_ALIAS_MAP)) {
+        return -1;
+    }
+
+    return RPS_ALIAS_MAP[hand_character];
+}
+
+/**
+ * Calculate the result of rock paper scissor match
+ * @param RPS player_hand the player's choice
+ * @param RPS opponent_hand the opponent's choice
+ * @return score
+ */
+function rps_result(player_hand, opponent_hand) {
+    let score = 0;
+    if(player_hand == opponent_hand) {
+        score = SCORE_TIE + player_hand;  // TIE
+    } else if(player_hand == RPS.winning_hand(opponent_hand)) {
+        score = SCORE_WIN + player_hand; // WIN
+    } else {
+        score = SCORE_LOSE + player_hand; // LOSE
+    }
+
+    console.debug("score:" + score + ", player: " + player_hand + ", opponent: " + opponent_hand);
+    return score;
 }