initial commit (it all starts here...)

src/cli/index.ts

@@ -0,0 +1,113 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at https://mozilla.org/MPL/2.0/.
+ */
+
+import { Command, UsageError } from "./types";
+
+const globalHelpText = `\
+Usage: websnacks [...globalOptions] <command>
+
+Global Options:
+  -r|--require <module>     Module to require before executing the command. May
+                            be specified more than once to load multiple modules.
+
+Commands:
+  build                     Build a static site that uses websnacks templates.
+  dev                       Start the live-reloading development server for a
+                            site.
+`;
+
+interface Options {
+    showHelp: boolean;
+    require: string[];
+}
+
+const parseArgs = (
+    args: string[]
+): { options: Options; commandName?: string; commandArgs: string[] } => {
+    const options: Options = {
+        showHelp: false,
+        require: [],
+    };
+    // Look ahead for the first argument that doesn't start with a "-" to
+    // indicate the end of option parsing.
+    while (args.length > 0 && args[0].indexOf("-") >= 0) {
+        const opt = args.shift();
+        switch (opt) {
+            case "-h":
+            case "--help":
+                options.showHelp = true;
+                break;
+            case "-r":
+            case "--require":
+                const moduleName = args.shift();
+                if (moduleName == null) {
+                    throw new UsageError(
+                        `-r requires a valid module name`,
+                        globalHelpText
+                    );
+                }
+                options.require.push(moduleName);
+                break;
+            default:
+                throw new UsageError(`unknown option ${opt}`, globalHelpText);
+        }
+    }
+    const commandName = args.shift();
+    return { options, commandName, commandArgs: args };
+};
+
+const _main = async (args: string[]): Promise<void> => {
+    const { options, commandName, commandArgs } = parseArgs(args);
+    if (options.showHelp) {
+        console.log(`${globalHelpText}\n`);
+        return;
+    }
+    if (commandName == null) {
+        throw new UsageError(`must specify a valid command`, globalHelpText);
+    }
+    for (const moduleName of options.require) {
+        await import(moduleName);
+    }
+
+    let command: Command;
+    switch (commandName) {
+        case "build":
+            command = await import("./commands/build");
+            break;
+        case "dev":
+            command = await import("./commands/dev");
+            break;
+        default:
+            throw new UsageError(
+                `unknown command ${commandName}`,
+                globalHelpText
+            );
+    }
+    // NOTE: Should this just delegate to the command?
+    for (const arg of commandArgs) {
+        if (arg === "--help" || arg === "-h") {
+            console.log(`${command.helpText}\n`);
+            return;
+        }
+    }
+    await command.execute(commandArgs);
+};
+
+/**
+ * Entrypoint of the CLI app.
+ */
+export const main = (): void => {
+    _main(process.argv.slice(2)).catch((error) => {
+        if (error instanceof UsageError) {
+            console.error(`Error: ${error.message}\n`);
+            console.log(`${error.helpText}\n`);
+        } else {
+            const errorMsg =
+                error instanceof Error ? error.stack : JSON.stringify(error);
+            console.error(`Unexpected error: ${errorMsg}\n`);
+        }
+        process.exit(1);
+    });
+};