Free the npm package from third party dependencies

.gitignore

@@ -1,5 +1,6 @@
 /target
 **/*.rs.bk
 /node_modules
-/bin
-/unpacked_bin
+/packages/*/elm-json
+/packages/*/elm-json.exe
+/unpacked_bin

bin/elm-json

@@ -0,0 +1,9 @@
+#!/usr/bin/env node
+var spawn = require("child_process").spawn;
+
+var binPath = require("../binary.js")();
+
+spawn(binPath, process.argv.slice(2), { stdio: "inherit" }).on(
+    "exit",
+    process.exit
+);

binary.js

@@ -0,0 +1,95 @@
+var fs = require("fs");
+var package = require("./package.json");
+var path = require("path");
+
+module.exports = function () {
+    var os = process.env.BINWRAP_PLATFORM || process.platform;
+    var arch = process.env.BINWRAP_ARCH || process.arch;
+
+    var requested = `${os}-${arch}`;
+    var current = `${process.platform}-${process.arch}`;
+    if (requested !== current) {
+        console.error(
+            `WARNING: Using binaries for the requested platform (${requested}) instead of for the actual platform (${current}).`
+        );
+    }
+
+    var subPackageName = `@zwilias/elm-json-${requested}`;
+
+    if (!(subPackageName in package.optionalDependencies)) {
+        exitFailure(
+            `The elm-json npm package does not support your platform (${requested}).`
+        );
+    }
+
+    var fileName = process.platform === "win32" ? "elm-json.exe" : "elm-json";
+
+    try {
+        var subBinaryPath = require.resolve(`${subPackageName}/${fileName}`);
+    } catch (error) {
+        if (error && error.code === "MODULE_NOT_FOUND") {
+            exitFailure(missingSubPackageHelp(subPackageName));
+        } else {
+            exitFailure(
+                `I had trouble requiring the binary package for your platform (${subPackageName}):\n\n${error}`
+            );
+        }
+    }
+
+    // Yarn 2 and later ("Berry") always invokes `node` (regardless of configuration)
+    // so we cannot do any optimizations there.
+    var isYarnBerry = /\byarn\/(?!1\.)/.test(
+        process.env.npm_config_user_agent || ""
+    );
+
+    // On Windows, npm always invokes `node` so we cannot do any optimizations there either.
+    if (process.platform === "win32" || isYarnBerry) {
+        return subBinaryPath;
+    }
+
+    var binaryPath = path.resolve(__dirname, package.bin.elm);
+    var tmpPath = binaryPath + ".tmp";
+
+    try {
+        // Atomically replace the file with a hard link to the binary as an optimization.
+        fs.linkSync(subBinaryPath, tmpPath);
+        fs.renameSync(tmpPath, binaryPath);
+    } catch (error) {
+        exitFailure(
+            `I had some trouble writing file to disk. It is saying:\n\n${error}`
+        );
+    }
+
+    return binaryPath;
+};
+
+function exitFailure(message) {
+    console.error(
+        `
+-- ERROR -----------------------------------------------------------------------
+
+${message}
+
+NOTE: You can avoid npm entirely by downloading directly from:
+https://github.com/zwilias/elm-json/releases/tag/${package.version}
+All this package does is distributing a file from there.
+
+--------------------------------------------------------------------------------
+    `.trim()
+    );
+    process.exit(1);
+}
+
+function missingSubPackageHelp(subPackageName) {
+    return `
+I support your platform, but I could not find the binary package (${subPackageName}) for it!
+
+This can happen if you use the "--omit=optional" (or "--no-optional") npm flag.
+The "optionalDependencies" package.json feature is used by elm-json to install the correct
+binary executable for your current platform. Remove that flag to use elm-json.
+
+This can also happen if the "node_modules" folder was copied between two operating systems
+that need different binaries - including "virtual" operating systems like Docker and WSL.
+If so, try installing with npm rather than copying "node_modules".
+    `.trim();
+}

index.js

@@ -1,24 +1,12 @@
-var binwrap = require("binwrap");
-var path = require("path");
+function dummy() {
+    return Promise.resolve();
+}
 
-var packageInfo = require(path.join(__dirname, "package.json"));
-var version = packageInfo.version;
-var root =
-    "https://github.com/zwilias/elm-json/releases/download/v" +
-    version +
-    "/elm-json-v" +
-    version;
-
-module.exports = binwrap({
-    dirname: __dirname,
-    binaries: ["elm-json"],
-    urls: {
-        "darwin-arm64": root + "-aarch64-apple-darwin.tar.gz",
-        "darwin-x64": root + "-x86_64-apple-darwin.tar.gz",
-        "linux-x64": root + "-x86_64-unknown-linux-musl.tar.gz",
-        "linux-arm": root + "-armv7-unknown-linux-musleabihf.tar.gz",
-        "linux-arm64": root + "-armv7-unknown-linux-musleabihf.tar.gz",
-        "win32-x64": root + "-x86_64-pc-windows-msvc.tar.gz",
-        "win32-ia32": root + "-x86_64-pc-windows-msvc.tar.gz"
-    }
-});
+module.exports = {
+    paths: {
+        "elm-json": require("./binary.js")(),
+    },
+    install: dummy,
+    prepare: dummy,
+    test: dummy,
+};