Empathy: Initial implementation of scoring that considers players' judging

I'm slowly learning more about JavaScript, (such as using
Objects.entries instead of open-coding it, using Set(), etc.), which
is helping as I write progressively more complex code.

But I don't feel _really_ confident that I've written this code in the
best form possible.

diff --git a/empathy.js b/empathy.js
index cb691485c0e928ccef8ae4cf9ac0e478877a74ce..5635c774f18e9fc8d64036df05cdc788b4c19907 100644 (file)
--- a/empathy.js
+++ b/empathy.js
@@ -14,6 +14,7 @@ class Empathy extends Game {
     };
     this.answers = [];
     this.next_prompt_id = 1;
+    this.equivalencies = {};
   }
 
   reset() {
@@ -48,6 +49,7 @@ class Empathy extends Game {
     this.state.scores = null;
 
     this.answers = [];
+    this.equivalencies = {};
 
     this.broadcast_event_object('game-state', this.state);
   }
@@ -136,7 +138,51 @@ class Empathy extends Game {
     this.broadcast_event_object('ambiguities', this.state.ambiguities);
   }
 
-  receive_judging() {
+  receive_judging(prompt_id, session_id, word_groups) {
+    const player = this.players_by_session[session_id];
+    if (! player)
+      return { valid: false, message: "Player not found" };
+
+    const prompt = this.state.prompts.find(p => p.id === prompt_id);
+    if (! prompt)
+      return { valid: false, message: "Prompt not found" };
+
+    if (prompt !== this.state.active_prompt)
+      return { valid: false, message: "Prompt no longer active" };
+
+    /* Each player submits some number of groups of answers that
+     * should be considered equivalent. The server expands that into
+     * the set of pair-wise equivalencies that are expressed. The
+     * reason for that is so that the server can determine which
+     * pair-wise equivalencies have majority support.
+     */
+    for (let group of word_groups) {
+
+      for (let i = 0; i < group.length - 1; i++) {
+        for (let j = i + 1; j < group.length; j++) {
+          let eq = [group[i], group[j]];
+
+          /* Put the two words into a reliable order so that we don't
+           * miss a pair of equivalent equivalencies just because they
+           * happen to be in the opposite order. */
+          if (eq[0].localeCompare(eq[1]) > 0) {
+            eq = [group[j], group[i]];
+          }
+
+          const exist = this.equivalencies[`${eq[0]}:${eq[1]}`];
+          if (exist) {
+            exist.count++;
+          } else {
+            this.equivalencies[`${eq[0]}:${eq[1]}`] = {
+              count: 1,
+              words: eq
+            };
+          }
+
+        }
+      }
+    }
+
     /* And notify players how many players have completed judging. */
     this.state.players_judged++;
     this.broadcast_event_object('judged', this.state.players_judged);
@@ -152,19 +198,56 @@ class Empathy extends Game {
     const word_submitters = {};
     const scores = [];
 
+    /* Perform a (non-strict) majority ruling on equivalencies,
+     * dropping all that didn't get enough votes. */
+    const quorum = Math.floor((this.players.length + 1)/2);
+    const agreed_equivalencies = Object.values(this.equivalencies).filter(
+      eq => eq.count >= quorum);
+
+    /* And with that agreed set of equivalencies, construct the full
+     * groups. */
+    const word_groups = {};
+
+    for (let e of agreed_equivalencies) {
+      let group = word_groups[e.words[0]];
+      if (! group)
+        group = word_groups[e.words[1]];
+      if (! group)
+        group = { words: [], players: new Set()};
+
+      if (! word_groups[e.words[0]]) {
+        word_groups[e.words[0]] = group;
+        group.words.push(e.words[0]);
+      }
+
+      if (! word_groups[e.words[1]]) {
+        word_groups[e.words[1]] = group;
+        group.words.push(e.words[1]);
+      }
+    }
+
+    /* Now go through answers from each player and add the player name
+     * to the set corresponding to each word group. */
     for (let a of this.answers) {
       for (let word of a.answers) {
-        if (word_submitters[word])
-          word_submitters[word].push(a.player.name);
-        else
-          word_submitters[word] = [a.player.name];
+        /* If there's no group yet, this is a singleton word. */
+        if (word_groups[word]) {
+          word_groups[word].players.add(a.player.name);
+        } else {
+          const group = { words: [word], players: new Set() };
+          group.players.add(a.player.name);
+          word_groups[word] = group;
+        }
       }
     }
 
+    /* Finally, go through the answers one more time, this time taking
+     * the length of the player set as a score for the player's
+     * submission of that word. */
     for (let a of this.answers) {
       let score = 0;
       for (let word of a.answers) {
-        score += word_submitters[word].length;
+        score += word_groups[word].players.size;
       }
       scores.push({
         player: a.player.name,
@@ -176,11 +259,23 @@ class Empathy extends Game {
       return b.score - a.score;
     });
 
-    const word_submitters_arr = [];
-    for (let word in word_submitters)
-      word_submitters_arr.push({word: word, players: word_submitters[word]});
+    /* Put the word groups into a form the client can consume.
+     *
+     * Most significantly, we only want one entry for each group (even
+     * though our current "word_groups" object has a property for each
+     * word considered equivalent).
+     */
+    const words_submitted = Object.entries(word_groups).filter(
+      group => group[0] === group[1].words[0]).map(
+        group => {
+          return {
+            word: group[1].words.join('/'),
+            players: Array.from(group[1].players)
+          };
+        }
+      );
 
-    word_submitters_arr.sort((a,b) => {
+    words_submitted.sort((a,b) => {
       return b.players.length - a.players.length;
     });
 
@@ -188,7 +283,7 @@ class Empathy extends Game {
      * be sent to any new clients that join. */
     this.state.scores = {
       scores: scores,
-      words: word_submitters_arr
+      words: words_submitted
     };
 
     /* And broadcast the scores to all connected clients. */