chore: Fully comment @css-blocks/glimmer's Resolver.ts.

Author: amiller-gh

Diff for: packages/@css-blocks/glimmer/src/Resolver.ts

@@ -11,6 +11,14 @@ import { ResolvedFile } from "./Template";
 
 const DEBUG = debugGenerator("css-blocks:glimmer:resolver");
 
+/**
+ * Convert constituent template path parts to an Ember Classic style Block path.
+ *
+ * @param base The base path of the project to discover files relative from.
+ * @param templatePath The template's filesystem path relative to `base`.
+ * @param ext The extension to look for.
+ * @return Where the associated Block should be located on the filesystem.
+ */
 function toClassicPath(base: string, templatePath: string, ext: string): string {
   // TODO: There is a more robust way to do all this path munging!
   let classic = path.parse(templatePath.replace("templates/", "styles/"));
@@ -19,6 +27,14 @@ function toClassicPath(base: string, templatePath: string, ext: string): string
   return path.join(base, path.format(classic));
 }
 
+/**
+ * Convert constituent template path parts to an Ember Pods style Block path.
+ *
+ * @param base The base path of the project to discover files relative from.
+ * @param templatePath The template's filesystem path relative to `base`.
+ * @param ext The extension to look for.
+ * @return Where the associated Block should be located on the filesystem.
+ */
 function toPodsPath(base: string, templatePath: string, ext: string): string {
   let pods = path.parse(templatePath);
   delete pods.base; // Required for path.format to pick up new extension.
@@ -28,18 +44,29 @@ function toPodsPath(base: string, templatePath: string, ext: string): string {
 }
 
 /**
- * The Glimmer CSS Blocks Resolver deals in three
+ * The Glimmer CSS Blocks Resolver currently supports three
  * kinds of project structure modes:
  *  - Component Names as Paths (Module Config)
  *  - Relative Template Paths (Classic Ember)
  *  - Relative Template Paths (Ember Pods)
+ *
+ * It provides abstractions for interacting with the three project
+ * structures, so the rest of the Glimmer analyzer code can operate
+ * independently of the filesystem structure.
+ *
 */
 export class Resolver {
 
   private depAnalyzers: Map<string, DependencyAnalyzer> = new Map();
   private moduleConfig?: ResolverConfiguration;
   private fileEndings: Set<string>;
 
+  /**
+   * Creates a new Resolver for this project.
+   *
+   * @param cssBlocksConfig  The CSS Blocks configuration object.
+   * @param moduleConfig  If applicable, the Glimmer module config for static analysis.
+   */
   constructor(cssBlocksConfig: ResolvedConfiguration, moduleConfig?: ResolverConfiguration) {
     if (moduleConfig) {
       this.moduleConfig = moduleConfig;
@@ -48,23 +75,39 @@ export class Resolver {
     DEBUG(`Discovering all Block files that end with ("${[...this.fileEndings].join(`|`)}")`);
   }
 
-  private dependencyAnalyzerFor(dir: string): DependencyAnalyzer | undefined {
+  /**
+   * If appropriate, returns the `DependencyAnalyzer` for a given project.
+   * If no module config exists for the project (aka: is not a full, statically
+   * analyzable Glimmer app) it returns undefined.
+   *
+   * @param base  The base path of the project to analyze.
+   * @return The DependencyAnalyzer, or undefined.
+   */
+  private dependencyAnalyzerFor(base: string): DependencyAnalyzer | undefined {
     if (!this.moduleConfig) { return undefined; }
-    if (this.depAnalyzers.has(dir)) {
-      return this.depAnalyzers.get(dir)!;
+    if (this.depAnalyzers.has(base)) {
+      return this.depAnalyzers.get(base)!;
     }
     let src = this.moduleConfig.app && this.moduleConfig.app.mainPath || "src";
-    let depAnalyzer = new DependencyAnalyzer(dir, {
+    let depAnalyzer = new DependencyAnalyzer(base, {
       config: { moduleConfiguration: this.moduleConfig },
       paths: {
         src,
       },
     });
-    this.depAnalyzers.set(dir, depAnalyzer);
+    this.depAnalyzers.set(base, depAnalyzer);
     return depAnalyzer;
   }
 
-  // TODO: We need to automatically discover the file ending here – its not guaranteed to be a css file.
+  /**
+   * Converts a template file path to its associated Block filepath, if present.
+   * All file endings associated with a preprocessor are attempted.
+   * If no block exists, returns undefined.
+   *
+   * @param base  The base path of the project to lookup Block files relative to.
+   * @param template  The template name we're attempting to discover block files for.
+   * @return A promise that resolves with the discover Block path, or undefined.
+   */
   private async tmplPathToStylesheetPath(base: string, template: string): Promise<string | undefined> {
     let triedPaths = [];
     // For every supported block extension:
@@ -75,13 +118,16 @@ export class Resolver {
         DEBUG(`Discovered classic Block for template ${template}: ${classic}`);
         return classic;
       }
+      // Else attempt to fetch at the pods path.
       let podsPath = toPodsPath(base, template, ext);
       if (fs.pathExistsSync(podsPath)) {
         DEBUG(`Discovered pods Block for template ${template}: ${podsPath}`);
         return podsPath;
       }
       triedPaths.push(path.relative(base, classic), path.relative(base, podsPath));
     }
+
+    // If we get here, there is no Block file at any standard Ember location, for any support file ending.
     DEBUG(`No Block discovered for template ${template}. Attempted at:${triedPaths.join(`\n  - `)}`);
     return undefined;
   }
@@ -92,22 +138,30 @@ export class Resolver {
    * "Module Map" mode where we can statically analyze application
    * dependencies. In "Classic Ember" or "Ember Pods" mode we just
    * return the same ident.
+   *
+   * @param base The base of the project to analyze.
+   * @param identifier  The Glimmer identifier to discover recursive dependencies for.
+   * @return The list of recursive dependencies for this identifier.
    */
-  recursiveDependenciesForTemplate(dir: string, identifier: string): string[] {
-    let depAnalyzer = this.dependencyAnalyzerFor(dir);
+  recursiveDependenciesForTemplate(base: string, identifier: string): string[] {
+    let depAnalyzer = this.dependencyAnalyzerFor(base);
     if (!depAnalyzer) { return [identifier]; }
     return depAnalyzer.recursiveDependenciesForTemplate(identifier).components;
   }
 
   /**
    * Given a template identifier, resolve the Block file associated
    * with the template, if any.
+   *
+   * @param base The base of the project to analyze.
+   * @param identifier  The Glimmer identifier to discover recursive dependencies for.
+   * @return The resolved Block file if present, or undefined.
   */
-  async stylesheetFor(dir: string, identifier: string): Promise<ResolvedFile | undefined> {
-    let depAnalyzer = this.dependencyAnalyzerFor(dir);
+  async stylesheetFor(base: string, identifier: string): Promise<ResolvedFile | undefined> {
+    let depAnalyzer = this.dependencyAnalyzerFor(base);
 
     if (!depAnalyzer) {
-      let stylesheet = await this.tmplPathToStylesheetPath(dir, identifier);
+      let stylesheet = await this.tmplPathToStylesheetPath(base, identifier);
       if (!stylesheet) { return undefined; }
       return new ResolvedFile(
         (fs.readFileSync(stylesheet)).toString(),
@@ -120,7 +174,7 @@ export class Resolver {
     identifier = depAnalyzer.project.resolver.identify(`stylesheet:${identifier}`);
     let file: string = depAnalyzer.project.resolver.resolve(identifier);
     if (!file) { return undefined; }
-    file = path.join(dir, depAnalyzer.project.paths.src, file);
+    file = path.join(base, depAnalyzer.project.paths.src, file);
     if (!fs.existsSync(file)) { return undefined; }
     let content = (fs.readFileSync(file)).toString();
     return new ResolvedFile(content, identifier, file);
@@ -129,12 +183,15 @@ export class Resolver {
   /**
    * Given a template identifier, resolve the actual template file associated
    * with it, if any.
+   * @param base The base of the project to analyze.
+   * @param identifier The template identifier to discover recursive dependencies for.
+   * @return The resolved Block file if present, or undefined.
   */
-  async templateFor(dir: string, identifier: string): Promise<ResolvedFile | undefined> {
-    let depAnalyzer = this.dependencyAnalyzerFor(dir);
+  async templateFor(base: string, identifier: string): Promise<ResolvedFile | undefined> {
+    let depAnalyzer = this.dependencyAnalyzerFor(base);
 
     if (!depAnalyzer) {
-      let template = path.join(dir, identifier);
+      let template = path.join(base, identifier);
       return new ResolvedFile(
         (fs.readFileSync(template)).toString(),
         identifier,