Implement schema validation

Author: octogonz

tsdoc-config/src/TSDocConfigFile.ts

@@ -1,17 +1,53 @@
+import * as fs from 'fs';
+import * as path from 'path';
+import * as Ajv from 'ajv';
+
 interface ITSDocConfigFileData {
   filePath: string;
 }
 
+const ajv: Ajv.Ajv = new Ajv({ verbose: true });
+
+function initializeSchemaValidator(): Ajv.ValidateFunction {
+  const jsonSchemaContent: string = fs.readFileSync(path.join(__dirname, 'schemas/tsdoc-config.schema.json'))
+    .toString();
+  const jsonSchema: object = JSON.parse(jsonSchemaContent);
+
+  return ajv.compile(jsonSchema);
+}
+
+// Warning: AJV has a fairly strange API.  Each time this function is called, the function  object's
+// properties get overwritten with the results of the latest validation.  Thus we need to be careful
+// to read the properties before a subsequent call may occur.
+const tsdocSchemaValidator: Ajv.ValidateFunction = initializeSchemaValidator();
+
+interface IConfigJson {
+}
+
 export class TSDocConfigFile {
+
   public readonly filePath: string;
 
   private constructor(data: ITSDocConfigFileData) {
     this.filePath = data.filePath;
   }
 
-  public static load(filePath: string): TSDocConfigFile {
+  public static load(jsonFilePath: string): TSDocConfigFile {
+    const fullJsonFilePath: string = path.resolve(jsonFilePath);
+
+    const configJsonContent: string = fs.readFileSync(fullJsonFilePath).toString();
+
+    const configJson: IConfigJson = JSON.parse(configJsonContent);
+    const success: boolean = tsdocSchemaValidator(configJson) as boolean;
+
+    if (!success) {
+      const description: string = ajv.errorsText(tsdocSchemaValidator.errors);
+      throw new Error('Error parsing config file: ' + description
+        + '\nError in file: ' + jsonFilePath);
+    }
+
     return new TSDocConfigFile({
-      filePath
+      filePath: fullJsonFilePath
     });
   }
 }