From 15503cb45b604350296318d964a93e0e22ce490d Mon Sep 17 00:00:00 2001
From: Neale Pickett <neale@lanl.gov>
Date: Sun, 24 Feb 2019 11:53:22 -0700
Subject: [PATCH] Check user-supplied answers for possible correctness

---
 devel/devel-server.py |  2 --
 devel/moth.py         |  6 +++---
 theme/puzzle.html     |  2 +-
 theme/puzzle.js       | 44 ++++++++++++++++++++++++++++++++++++++++++-
 4 files changed, 47 insertions(+), 7 deletions(-)

diff --git a/devel/devel-server.py b/devel/devel-server.py
index 3d2de63..2be469a 100755
--- a/devel/devel-server.py
+++ b/devel/devel-server.py
@@ -40,8 +40,6 @@ def get_puzzle(request, data=None):
     puzzle = cat.puzzle(points)
     return puzzle
 
-# OMG what is this I hate Python now
-@asyncio.coroutine
 async def handle_answer(request):
     data = await request.post()
     puzzle = get_puzzle(request, data)
diff --git a/devel/moth.py b/devel/moth.py
index 9820783..ee13f46 100644
--- a/devel/moth.py
+++ b/devel/moth.py
@@ -15,9 +15,9 @@ import tempfile
 
 messageChars = b'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ'
 
-def djb2hash(buf):
+def djb2hash(str):
     h = 5381
-    for c in buf:
+    for c in str.encode("utf-8"):
         h = ((h * 33) + c) & 0xffffffff
     return h
 
@@ -277,7 +277,7 @@ class Puzzle:
     def hashes(self):
         "Return a list of answer hashes"
 
-        return [djb2hash(a.encode('utf-8')) for a in self.answers]
+        return [djb2hash(a) for a in self.answers]
 
 
 class Category:
diff --git a/theme/puzzle.html b/theme/puzzle.html
index fc03cfa..2a8dcba 100644
--- a/theme/puzzle.html
+++ b/theme/puzzle.html
@@ -22,7 +22,7 @@
       <input type="hidden" name="cat">
       <input type="hidden" name="points">
       Team ID: <input type="text" name="id"> <br>
-      Answer: <input type="text" name="answer" id="answer"> <br>
+      Answer: <input type="text" name="answer" id="answer"> <span id="answer_ok"></span><br>
       <input type="submit" value="Submit">
     </form>
     <div id="devel"></div>
diff --git a/theme/puzzle.js b/theme/puzzle.js
index f129a51..6ab5f07 100644
--- a/theme/puzzle.js
+++ b/theme/puzzle.js
@@ -44,7 +44,17 @@ function devel_addin(obj, e) {
   }
 }
 
+// The routine used to hash answers in compiled puzzle packages
+function djb2hash(buf) {
+  let h = 5381
+  for (let c of (new TextEncoder).encode(buf)) { // JavaScript is weird.
+    h = ((h * 33) + c) & 0xffffffff
+  }
+  return h
+}
 
+
+// Pop up a message
 function toast(message, timeout=5000) {
   let p = document.createElement("p")
   
@@ -56,7 +66,7 @@ function toast(message, timeout=5000) {
   )
 }
 
-
+// When the user submits an answer
 function submit(e) {
   e.preventDefault()
   fetch("answer", {
@@ -92,6 +102,9 @@ function loadPuzzle(categoryName, points, puzzleId) {
     // Populate authors
     document.getElementById("authors").textContent = obj.authors.join(", ")
     
+    // Make the whole puzzle available
+    window.puzzle = obj
+    
     // If answers are provided, this is the devel server
     if (obj.answers) {
       devel_addin(obj, document.getElementById("devel"))
@@ -139,6 +152,32 @@ function loadPuzzle(categoryName, points, puzzleId) {
   document.querySelector("input[name=points]").value = points
 }
 
+function answerCheck(e) {
+  let answer = e.target.value
+  let ok = document.querySelector("#answer_ok")
+  
+  // You have to provide someplace to put the check
+  if (! ok) {
+    return
+  }
+  
+  let possiblyCorrect = false
+  let answerHash = djb2hash(answer)
+  for (let correctHash of window.puzzle.hashes) {
+    if (correctHash == answerHash) {
+      possiblyCorrect = true
+    }
+  }
+  
+  if (possiblyCorrect) {
+    ok.textContent = "🙆"
+    ok.title = "Possibly correct"
+  } else {
+    ok.textContent = "🙅"
+    ok.title = "Definitely not correct"
+  }
+}
+
 function init() {
   let params = new URLSearchParams(window.location.search)
   let categoryName = params.get("cat")
@@ -154,6 +193,9 @@ function init() {
     document.querySelector("input[name=id]").value = teamId
   }
   
+  if (document.querySelector("#answer")) {
+    document.querySelector("#answer").addEventListener("input", answerCheck)
+  }
   document.querySelector("form").addEventListener("submit", submit)
 }