From 397992465eb0eae75c05779bda1d662129657386 Mon Sep 17 00:00:00 2001
From: Joe Robinson <joe@mumsnet.com>
Date: Mon, 21 Jul 2014 12:16:04 +0100
Subject: Only allow users to vote on a poll once

---
 blavote.go | 31 +++++++++++++++++++------------
 poll.go    | 24 ++++++++++++++++++++++--
 2 files changed, 41 insertions(+), 14 deletions(-)

diff --git a/blavote.go b/blavote.go
index 857c904..fb4444b 100644
--- a/blavote.go
+++ b/blavote.go
@@ -14,7 +14,7 @@ var version string
 
 func main() {
 
-    version = "0.4"
+    version = "0.5"
 
     //Command line arguments
     var opts struct {
@@ -86,9 +86,11 @@ func main() {
         }
 
     } else {
-        vote(db, opts.Username, opts.Args.Rest)
-
+        err = vote(db, opts.Username, opts.Args.Rest)
 
+        if (err != nil) {
+            fmt.Println(err)
+        }
     }
 
 }
@@ -157,16 +159,21 @@ func vote(db *sqlite3.Conn, nick string, options []string) error {
         }
     }
 
-    args := sqlite3.NamedArgs{"$a": user.id, "$b": poll.id, "$c": option.id}
-    sql := "INSERT INTO votes (user_id, poll_id, option_id) VALUES ($a, $b, $c)"
+    if (!hasUserVotedInPoll(db, poll, user)) {
 
-    err = db.Exec(sql, args)
+        args := sqlite3.NamedArgs{"$a": user.id, "$b": poll.id, "$c": option.id}
+        sql := "INSERT INTO votes (user_id, poll_id, option_id) VALUES ($a, $b, $c)"
+
+        err = db.Exec(sql, args)
+
+        if (err != nil ) {
+            return err
+        } else {
+            fmt.Println("Vote added")
+            return nil
+        }
 
-    if (err != nil ) {
-        fmt.Print("Failed to vote: ")
-        return err
     } else {
-        fmt.Println("Vote added")
-        return nil
+        return errors.New("You have already voted in this poll")
     }
-}
\ No newline at end of file
+}
diff --git a/poll.go b/poll.go
index 275aa21..0952cd7 100644
--- a/poll.go
+++ b/poll.go
@@ -85,7 +85,7 @@ func getPollFromId(db *sqlite3.Conn, id int) (Poll, error) {
     sql := "SELECT * FROM polls WHERE id = $a"
     s, err := db.Query(sql, args)
     row := make(sqlite3.RowMap)
-    
+
     for ; err == nil ; err = s.Next() {
         var rowid int64
         s.Scan(&rowid, row)     // Assigns 1st column to rowid, the rest to row
@@ -123,5 +123,25 @@ func deletePoll(db *sqlite3.Conn, id int, nick string) error {
         return errors.New("You do not have permission to delete this poll")
     }
 
+}
+
+func hasUserVotedInPoll(db *sqlite3.Conn, poll Poll, user User) bool {
 
-}
\ No newline at end of file
+    args := sqlite3.NamedArgs{"$a": poll.id, "$b": user.id}
+    sql := "SELECT count(*) FROM votes WHERE poll_id = $a AND user_id = $b"
+    s, err := db.Query(sql, args)
+
+    for ; err == nil ; err = s.Next() {
+        var count int64
+        s.Scan(&count)     // Assigns 1st column to rowid, the rest to row
+
+        if (count == 0) {
+            return false
+        } else {
+            return true
+        }
+    }
+
+    //Not sure why we'd get here, but we probably don't want to record a vote if we did
+    return true
+}
-- 
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