Cache the configuration JSON.

So it is available when the website is down and speeds up startup (I
hope).

Fixes #94.

2 files changed, 133 insertions, 61 deletions

diff --git a/lib/libbugzilla.js b/lib/libbugzilla.js
index 928555e..4e9cdd9 100644
--- a/lib/libbugzilla.js
+++ b/lib/libbugzilla.js
@@ -11,7 +11,9 @@ var passUtils = require("passwords");
 var Request = require("request").Request;
 var selfMod = require("self");
 var urlMod = require("url");
+var xhrMod = require("xhr");
 var panelMod = require("panel");
+var myStorage = require("simple-storage");
 
 var JSONURLDefault = "https://fedorahosted.org/released"+
 "/bugzilla-triage-scripts/Config_data.json";
@@ -357,80 +359,150 @@ var makeJSONRPCCall = exports.makeJSONRPCCall = function makeJSONRPCCall(url, me
   }).post();
 };
 
-exports.initialize = function initialize(config, callback) {
-  var prefJSONURLName = BTSPrefNS+"JSONURL";
-  var urlStr = preferences.get(prefJSONURLName, JSONURLDefault);
-  preferences.set(prefJSONURLName, urlStr);
+/**
+ * Preprocess JSON into config data structure.
+ *
+ * Should be completely side-effects free pure function.
+ */
+function processConfigJSON(rawJSON) {
+  config.gJSONData = rawJSON;
+
+  // Get additional tables
+  if ("downloadJSON" in config.gJSONData.configData) {
+    var URLsList = config.gJSONData.configData.downloadJSON;
+    if (!config.constantData) {
+      config.constantData = {};
+    }
+    URLsList.forEach(function (arr) {
+      var title = arr[0];
+      var url = arr[1];
+      Request({
+        url: url,
+        onComplete: function(response) {
+          if (response.status == 200) {
+            config.constantData[title] = response.json;
+          } else {
+            console.error("Cannot download " + title + " from URL " + url);
+          }
+        }
+      }).get();
+    });
+  }
+
+  config.configData = {};
 
   // should we spit out a lot of debugging output
   var prefDebugName = BTSPrefNS+"debug";
   debugOption = preferences.get(prefDebugName, false);
   preferences.set(prefDebugName, debugOption);
+  config.configData.debuggingVerbose = debugOption;
 
+  // FIXME What are these variables actually good for? Document them.
+  if ("matches" in config.configData) {
+    config.configData.skipMatches = config.configData.matches.map(function(x) {
+      return x.replace("show_bug.cgi.*","((process|post)_bug|attachment)\.cgi$");
+    });
+  }
+
+  config.constantData = {};
+  if ("constantData" in config.gJSONData) {
+    config.constantData = config.gJSONData.constantData;
+    config.constantData.queryUpstreamBug = JSON.parse(
+        selfMod.data.load("queryUpstreamBug.json"));
+    config.constantData.bugzillaLabelNames =
+      JSON.parse(selfMod.data.load("bugzillalabelNames.json"));
+    config.constantData.newUpstreamBug =
+      JSON.parse(selfMod.data.load("newUpstreamBug.json"));
+    config.constantData.ProfessionalProducts =
+      JSON.parse(selfMod.data.load("professionalProducts.json"));
+    config.constantData.BugzillaAbbreviations =
+     JSON.parse(selfMod.data.load("bugzillalabelAbbreviations.json"));
+  }
+
+  if ("CCmaintainer" in config.constantData) {
+    config.configData.defBugzillaMaintainerArr = config.constantData.CCmaintainer;
+  }
+
+  copiedAttributes.forEach(function (attrib) {
+    if (attrib in config.gJSONData.configData) {
+      config.configData[attrib] = config.gJSONData.configData[attrib];
+    }
+  });
+}
+
+function fetchConfigurationJSON(url, callback) {
+  var retValue = null;
   Request({
-    url: urlStr,
+    url: url,
     onComplete: function (response) {
       if (response.status == 200) {
-        config.gJSONData = response.json;
-
-        // Get additional tables
-        if ("downloadJSON" in config.gJSONData.configData) {
-          var URLsList = config.gJSONData.configData.downloadJSON;
-          var dwnldObj = "";
-          URLsList.forEach(function (arr) {
-            var title = arr[0];
-            var url = arr[1];
-            Request({
-              url: url,
-              onComplete: function(response) {
-                if (response.status == 200) {
-                  config.constantData[title] = response.json;
-                } else {
-                  console.error("Cannot download " + title + " from URL " + url);
-                }
-              }
-            }).get();
-          });
-        }
-
-        config.configData = {};
-        config.configData.debuggingVerbose = debugOption;
-        config.configData.matches = config.gJSONData.configData.matches;
-        config.configData.skipMatches = config.configData.matches.map(function(x) {
-          return x.replace("show_bug.cgi.*","((process|post)_bug|attachment)\.cgi$");
-        });
-
-        config.constantData = {};
-        if ("constantData" in config.gJSONData) {
-          config.constantData = config.gJSONData.constantData;
-          config.constantData.queryUpstreamBug = JSON.parse(
-              selfMod.data.load("queryUpstreamBug.json"));
-          config.constantData.bugzillaLabelNames =
-            JSON.parse(selfMod.data.load("bugzillalabelNames.json"));
-          config.constantData.newUpstreamBug =
-            JSON.parse(selfMod.data.load("newUpstreamBug.json"));
-          config.constantData.ProfessionalProducts =
-            JSON.parse(selfMod.data.load("professionalProducts.json"));
-          config.constantData.BugzillaAbbreviations =
-           JSON.parse(selfMod.data.load("bugzillalabelAbbreviations.json"));
-        }
+        processConfigJSON(response.json);
+        myStorage.storage.configJSON.meta.eTag = response.headers['Etag'];
+        myStorage.storage.configJSON.meta.lastModified =
+          response.headers['Last-Modified'];
+        myStorage.storage.configJSON.parsedJSON = config;
+      }
+      else {
+        // If we cannot get JSON from the real URL, we are happy
+        // with getting our fix from anywhere, including (possibly)
+        // expired cache
+        if (myStorage.storage.configJSON &&
+          myStorage.storage.configJSON.parsedJSON) {
+            config = myStorage.storage.configJSON.parsedJSON;
+          }
+      }
+      if ("submitsLogging" in config.gJSONData.configData &&
+        config.gJSONData.configData.submitsLogging) {
+          logger.initialize();
+      }
+      loginToAllBugzillas(callback);
+    }
+  }).get();
+};
 
-        if ("CCmaintainer" in config.constantData) {
-          config.configData.defBugzillaMaintainerArr = config.constantData.CCmaintainer;
-        }
+exports.initialize = function initialize(callback) {
+  var prefJSONURLName = BTSPrefNS+"JSONURL";
+  var urlStr = preferences.get(prefJSONURLName, JSONURLDefault);
+  preferences.set(prefJSONURLName, urlStr);
 
-        copiedAttributes.forEach(function (attrib) {
-          if (attrib in config.gJSONData.configData) {
-            config.configData[attrib] = config.gJSONData.configData[attrib];
-          }
-        });
+  if (!myStorage.storage.configJSON) {
+    myStorage.storage.configJSON = {};
+    myStorage.storage.configJSON.meta = {
+      eTag: "",
+      lastModified: null
+    };
+  }
 
-        if ("submitsLogging" in config.gJSONData.configData &&
+  var req = new xhrMod.XMLHttpRequest();
+  req.open("HEAD", urlStr, true);
+  req.onreadystatechange = function (aEvt) {
+    if (req.readyState == 4) {
+      if(req.status == 200) {
+        var _curETag = req.getResponseHeader("ETag");
+        var _curLastModified = new Date(req.getResponseHeader("Last-Modified"));
+        console.log("_curLastModified = " + _curLastModified);
+        console.log("cache.lastModified = " +
+          myStorage.storage.configJSON.meta.lastModified);
+        if ((_curETag == myStorage.storage.configJSON.meta.eTag)
+            || (_curLastModified <=
+              myStorage.storage.configJSON.meta.lastModified)) {
+          console.log("Loading from cache!");
+          // use cached values
+          config = myStorage.storage.configJSON.parsedJSON;
+          if ("submitsLogging" in config.gJSONData.configData &&
             config.gJSONData.configData.submitsLogging) {
-          logger.initialize();
+              logger.initialize();
+          }
+          console.log("config.gJSONData = " + config.gJSONData);
+          console.log("config.config = " + config.configData);
+          loginToAllBugzillas(callback);
+        }
+        else { // cache is not up-to-date
+          console.log("Too old cache!");
+          fetchConfigurationJSON(urlStr, callback);
         }
       }
-      loginToAllBugzillas(callback);
     }
-  }).get();
+  };
+  req.send();
 }
diff --git a/lib/main.js b/lib/main.js
index 0beb947..b7875c3 100644
--- a/lib/main.js
+++ b/lib/main.js
@@ -117,7 +117,7 @@ var contentScriptLibraries = [
 var mainPMRE = new RegExp("http[s]?:\\/\\/bug(zilla|s)\\.[^\\/]*?" +
   "\\/show_bug.cgi\\?id=.*");
 
-libbz.initialize(libbz.config, function() {
+libbz.initialize(function() {
   pageMod.PageMod({
     include : [ mainPMRE ],
     contentScriptWhen : 'ready',