post_to_twitter: only post stories once they have reached a vote threshold

This drops storing twitter:last_story_id in Keystore and stores each
story's tweet id, so we can query which stories meet the threshold
and haven't been posted to twitter yet.

script/post_to_twitter

@@ -7,59 +7,61 @@ require File.expand_path('../../config/boot',  __FILE__)
 require APP_PATH
 Rails.application.require_environment!
 
-LAST_STORY_KEY = "twitter:last_story_id"
+MIN_STORY_SCORE = 2
 
-last_story_id = (Keystore.value_for(LAST_STORY_KEY) || Story.last.id).to_i
-
-Story.where("id > ? AND is_expired = ?", last_story_id, false).
-order(:id).each do |s|
-  if !s.tags.map(&:tag).include?("meta")
-    tags = ""
-    s.sorted_taggings.each do |tagging|
-      tags += ' #' + tagging.tag.tag
-    end
-
-    tco_status = "\n" +
-      (s.url.present?? ("X" * Twitter::TCO_LEN) + "\n" : "") +
-      ("X" * Twitter::TCO_LEN) +
-      tags
-
-    status = "\n" +
-      (s.url.present?? s.url + "\n" : "") +
-      s.short_id_url +
-      tags
-
-    left_len = Twitter::MAX_TWEET_LEN - tco_status.length
-
-    title = s.title
-    if title.match(/^([dm] |@)/i)
-      # prevent these tweets from activating twitter shortcuts
-      # https://dev.twitter.com/docs/faq#tweeting
-      title = "- #{title}"
-    end
-
-    if title.bytesize > left_len
-      status = title[0, left_len - 3] + "..." + status
-    else
-      status = title + status
-    end
-
-    res = Twitter.oauth_request("/1.1/statuses/update.json", :post,
-      { "status" => status })
-
-    begin
-      if res["id_str"].match(/\d+/)
-        s.update_column("twitter_id", res["id_str"])
-      else
-        raise
-      end
-    rescue => e
-      puts "failed posting story #{s.id} (#{status.inspect}): #{e.inspect}\n" +
-        "#{res.inspect}"
-      exit
-    end
+Story.where("is_expired = ? AND #{Story.score_sql} > ? AND " <<
+"twitter_id IS NULL AND created_at >= ?", false, MIN_STORY_SCORE,
+Time.now - 1.days).order(:id).each_with_index do |s,x|
+  if s.tags.map(&:tag).include?("meta")
+    next
   end
 
-  Keystore.put(LAST_STORY_KEY, s.id)
-  sleep 2
+  if x > 0
+    sleep 2
+  end
+
+  tags = ""
+  s.sorted_taggings.each do |tagging|
+    tags += ' #' + tagging.tag.tag
+  end
+
+  tco_status = "\n" +
+    (s.url.present?? ("X" * Twitter::TCO_LEN) + "\n" : "") +
+    ("X" * Twitter::TCO_LEN) +
+    tags
+
+  status = "\n" +
+    (s.url.present?? s.url + "\n" : "") +
+    s.short_id_url +
+    tags
+
+  left_len = Twitter::MAX_TWEET_LEN - tco_status.length
+
+  title = s.title
+  if title.match(/^([dm] |@)/i)
+    # prevent these tweets from activating twitter shortcuts
+    # https://dev.twitter.com/docs/faq#tweeting
+    title = "- #{title}"
+  end
+
+  if title.bytesize > left_len
+    status = title[0, left_len - 3] + "..." + status
+  else
+    status = title + status
+  end
+
+  res = Twitter.oauth_request("/1.1/statuses/update.json", :post,
+    { "status" => status })
+
+  begin
+    if res["id_str"].match(/\d+/)
+      s.update_column("twitter_id", res["id_str"])
+    else
+      raise
+    end
+  rescue => e
+    puts "failed posting story #{s.id} (#{status.inspect}): #{e.inspect}\n" +
+      "#{res.inspect}"
+    exit
+  end
 end