Infer file from source

README.md

@@ -18,13 +18,12 @@ Use the following code.
 
 ```ts
 import { scaffold } from "https://deno.land/x/skaffe@v1.0.0/mod.ts";
-import { join } from "https://deno.land/std@0.123.0/path/mod.ts";
 
 const thisFile = import.meta.url;
-const targetFile = join(Deno.cwd(), "target-file.ts");
+const targetDirectory = Deno.cwd(); // using a dir will infer the file name
 
 // Will copy this very source file into the working directory
-await scaffold(thisFile, targetFile);
+await scaffold(thisFile, targetDirectory);
 ```
 
 ## Node Example
@@ -39,13 +38,12 @@ and use the following code.
 
 ```ts
 const { scaffold } = require("skaffe");
-const { join } = require("path");
 
 const thisFile = __filename;
-const targetFile = join(process.cwd(), "target-file.js");
+const targetDirectory = process.cwd(); // using a dir will infer the file name
 
 // Will copy this very source file into the working directory
-scaffold(thisFile, targetFile);
+scaffold(thisFile, targetDirectory);
 ```
 
 ## Why?
@@ -66,5 +64,5 @@ and Node, and let `skaffe` do the nasty part.
 
 ## What's in a Name?
 
-The word _skaffe_ is Norwegian and means _provide_.
-It also looks similar to the prefix of _scaffolding_.
+The word _skaffe_ is Norwegian and means _provide_. It also looks similar to the
+prefix of _scaffolding_.

example.ts

@@ -1,8 +1,7 @@
 import { scaffold } from "https://deno.land/x/skaffe@v1.0.0/mod.ts";
-import { join } from "https://deno.land/std@0.123.0/path/mod.ts";
 
 const thisFile = import.meta.url;
-const targetFile = join(Deno.cwd(), "example.ts");
+const targetDirectory = Deno.cwd(); // using a dir will infer the file name
 
 // Will copy this very source file into the working directory
-await scaffold(thisFile, targetFile);
+await scaffold(thisFile, targetDirectory);

src/platform.deno.ts

@@ -3,6 +3,10 @@ import {
   readerFromIterable,
 } from "https://deno.land/std@0.123.0/streams/mod.ts";
 
+export { basename, join } from "https://deno.land/std@0.123.0/path/mod.ts";
+export const isDirectory = (path: string) =>
+  Deno.stat(path).then((info) => info.isDirectory);
+
 export async function writeData(
   target: string,
   data: AsyncIterable<Uint8Array>,

src/platform.node.ts

@@ -1,5 +1,10 @@
 import { createWriteStream } from "fs";
 import { Readable } from "stream";
+import { lstat } from "fs/promises";
+
+export { basename, join } from "path";
+export const isDirectory = (path: string) =>
+  lstat(path).then((info) => info.isDirectory());
 
 export async function writeData(
   target: string,

src/scaffold.ts

@@ -1,8 +1,9 @@
-import { writeData } from "./platform.deno.ts";
+import { basename, isDirectory, join, writeData } from "./platform.deno.ts";
 
 export async function scaffold(source: string | URL, target: string) {
+  const file = await toFile(source, target);
   const data: AsyncIterable<Uint8Array> = await getFile(source);
-  await writeData(target, data);
+  await writeData(file, data);
 }
 
 export async function getFile(
@@ -15,3 +16,23 @@ export async function getFile(
   }
   return data;
 }
+
+export async function toFile(
+  sourceFile: string | URL,
+  targetDirectoryOrFile: string,
+): Promise<string> {
+  let result = targetDirectoryOrFile;
+  try {
+    // If the given target is an existing directory ...
+    if (await isDirectory(targetDirectoryOrFile)) {
+      // ... use the source file name in the directory.
+      const path = typeof sourceFile === "string"
+        ? sourceFile
+        : sourceFile.pathname;
+      result = join(targetDirectoryOrFile, basename(path));
+    }
+  } catch {
+    // Failed to stat, do not infer filename
+  }
+  return result;
+}

src/shim.node.ts

@@ -1,4 +1,6 @@
 import { createReadStream } from "fs";
+import { URL } from "url";
+export { URL };
 
 interface FetchResult {
   body: AsyncIterable<Uint8Array>;