Implement the resolver

1 files changed, 34 insertions, 0 deletions

diff --git a/packages/resolver/src/resolvers/npm_resolver.ts b/packages/resolver/src/resolvers/npm_resolver.ts
new file mode 100644
index 000000000..2c0a44aad
--- /dev/null
+++ b/packages/resolver/src/resolvers/npm_resolver.ts
@@ -0,0 +1,34 @@
+import * as fs from 'fs';
+import * as path from 'path';
+
+import { ContractSource } from '../types';
+
+import { Resolver } from './resolver';
+
+export class NPMResolver extends Resolver {
+    private _packagePath: string;
+    constructor(packagePath: string) {
+        super();
+        this._packagePath = packagePath;
+    }
+    public resolveIfExists(importPath: string): ContractSource | undefined {
+        if (!importPath.startsWith('/')) {
+            const [packageName, ...other] = importPath.split('/');
+            const pathWithinPackage = path.join(...other);
+            let currentPath = this._packagePath;
+            const ROOT_PATH = '/';
+            while (currentPath !== ROOT_PATH) {
+                const lookupPath = path.join(currentPath, 'node_modules', packageName, pathWithinPackage);
+                if (fs.existsSync(lookupPath)) {
+                    const fileContent = fs.readFileSync(lookupPath).toString();
+                    return {
+                        source: fileContent,
+                        path: lookupPath,
+                    };
+                }
+                currentPath = path.dirname(currentPath);
+            }
+        }
+        return undefined;
+    }
+}