factor out some logical chunks of the main build process

Author: geoffp

core/lib/patternlab.js

@@ -502,53 +502,26 @@ const patternlab_engine = function (config) {
     return PatternGraph.loadFromFile(patternlab);
   }
 
-  function buildPatterns(deletePatternDir) {
-
-    if (patternlab.config.debug) {
-      console.log(
-        chalk.bold('\n====[ Pattern Lab / Node'),
-        `- v${packageInfo.version}`,
-        chalk.bold(']====\n')
-      );
-    }
-
-    patternlab.events.emit('patternlab-build-pattern-start', patternlab);
-
-    const graph = patternlab.graph = loadPatternGraph(deletePatternDir);
-
-    const graphNeedsUpgrade = !PatternGraph.checkVersion(graph);
-
-    if (graphNeedsUpgrade) {
-      plutils.log.info("Due to an upgrade, a complete rebuild is required and the public/patterns directory was deleted. " +
-                       "Incremental build is available again on the next successful run.");
-
-      // Ensure that the freshly built graph has the latest version again.
-      patternlab.graph.upgradeVersion();
-    }
-
-    // Flags
-    const incrementalBuildsEnabled = !(deletePatternDir || graphNeedsUpgrade);
-
-    if (incrementalBuildsEnabled) {
-      plutils.log.info("Incremental builds enabled.");
-    } else {
-      // needs to be done BEFORE processing patterns
-      fs.removeSync(paths.public.patterns);
-      fs.emptyDirSync(paths.public.patterns);
-    }
+  function buildGlobalData() {
+    //
+    // COLLECT GLOBAL LIBRARY DATA
+    //
 
+    // data.json
     try {
       patternlab.data = buildPatternData(paths.source.data, fs);
     } catch (ex) {
       plutils.error('missing or malformed' + paths.source.data + 'data.json  Pattern Lab may not work without this file.');
       patternlab.data = {};
     }
+    // listitems.json
     try {
       patternlab.listitems = fs.readJSONSync(path.resolve(paths.source.data, 'listitems.json'));
     } catch (ex) {
       plutils.warning('WARNING: missing or malformed ' + paths.source.data + 'listitems.json file.  Pattern Lab may not work without this file.');
       patternlab.listitems = {};
     }
+    // load up all the necessary files from pattern lab that apply to every template
     try {
       patternlab.header = fs.readFileSync(path.resolve(paths.source.patternlabFiles['general-header']), 'utf8');
       patternlab.footer = fs.readFileSync(path.resolve(paths.source.patternlabFiles['general-footer']), 'utf8');
@@ -560,6 +533,12 @@ const patternlab_engine = function (config) {
       plutils.error('\nERROR: missing an essential file from ' + paths.source.patternlabFiles + '. Pattern Lab won\'t work without this file.\n');
       process.exit(1);
     }
+
+
+    //
+    // INITIALIZE EMPTY GLOBAL DATA STRUCTURES
+    //
+
     patternlab.patterns = [];
     patternlab.subtypePatterns = {};
     patternlab.partials = {};
@@ -570,6 +549,51 @@ const patternlab_engine = function (config) {
     pattern_assembler.combine_listItems(patternlab);
 
     patternlab.events.emit('patternlab-build-global-data-end', patternlab);
+  }
+
+
+  function cleanBuildDirectory(incrementalBuildsEnabled) {
+    if (incrementalBuildsEnabled) {
+      plutils.log.info("Incremental builds enabled.");
+    } else {
+      // needs to be done BEFORE processing patterns
+      fs.removeSync(paths.public.patterns);
+      fs.emptyDirSync(paths.public.patterns);
+    }
+  }
+
+  function buildPatterns(deletePatternDir) {
+
+    if (patternlab.config.debug) {
+      console.log(
+        chalk.bold('\n====[ Pattern Lab / Node'),
+        `- v${packageInfo.version}`,
+        chalk.bold(']====\n')
+      );
+    }
+
+    patternlab.events.emit('patternlab-build-pattern-start', patternlab);
+
+    //
+    // CHECK INCREMENTAL BUILD GRAPH
+    //
+    const graph = patternlab.graph = loadPatternGraph(deletePatternDir);
+    const graphNeedsUpgrade = !PatternGraph.checkVersion(graph);
+    if (graphNeedsUpgrade) {
+      plutils.log.info("Due to an upgrade, a complete rebuild is required and the public/patterns directory was deleted. " +
+                       "Incremental build is available again on the next successful run.");
+
+      // Ensure that the freshly built graph has the latest version again.
+      patternlab.graph.upgradeVersion();
+    }
+    // Flags
+    const incrementalBuildsEnabled = !(deletePatternDir || graphNeedsUpgrade);
+
+    //
+    // CLEAN BUILD DIRECTORY, maybe
+    //
+    cleanBuildDirectory(incrementalBuildsEnabled);
+    buildGlobalData();
 
     // diveSync once to perform iterative populating of patternlab object
     return processAllPatternsIterative(paths.source.patterns, patternlab).then(() => {