counterfact/dist/server/transpiler.js

a library for building a fake REST API for testing

// Stryker disable all
import { once } from "node:events";
import fs from "node:fs/promises";
import nodePath from "node:path";
import { watch as chokidarWatch } from "chokidar";
import createDebug from "debug";
import ts from "typescript";
import { ensureDirectoryExists } from "../util/ensure-directory-exists.js";
import { CHOKIDAR_OPTIONS } from "./constants.js";
import { convertFileExtensionsToCjs } from "./convert-js-extensions-to-cjs.js";
const debug = createDebug("counterfact:server:transpiler");
export class Transpiler extends EventTarget {
    sourcePath;
    destinationPath;
    moduleKind;
    watcher;
    constructor(sourcePath, destinationPath, moduleKind) {
        super();
        this.sourcePath = sourcePath;
        this.destinationPath = destinationPath;
        this.moduleKind = moduleKind;
    }
    get extension() {
        return this.moduleKind.toLowerCase() === "commonjs" ? ".cjs" : ".js";
    }
    async watch() {
        debug("transpiler: watch");
        this.watcher = chokidarWatch(this.sourcePath, {
            ...CHOKIDAR_OPTIONS,
            ignored: `${this.sourcePath}/js`,
            ignoreInitial: false,
        });
        const transpiles = [];
        this.watcher.on("all", async (eventName, sourcePathOriginal) => {
            debug("transpiler event: %s <%s>", eventName, sourcePathOriginal);
            const JS_EXTENSIONS = ["js", "mjs", "ts", "mts"];
            if (!JS_EXTENSIONS.some((extension) => sourcePathOriginal.endsWith(`.${extension}`)))
                return;
            const sourcePath = sourcePathOriginal.replaceAll("\\", "/");
            const destinationPath = sourcePath
                .replace(this.sourcePath, this.destinationPath)
                .replaceAll("\\", "/")
                .replace(".ts", this.extension);
            if (["add", "change"].includes(eventName)) {
                transpiles.push(this.transpileFile(eventName, sourcePath, destinationPath));
            }
            if (eventName === "unlink") {
                try {
                    await fs.rm(destinationPath);
                }
                catch (error) {
                    if (error.code !== "ENOENT") {
                        debug("error removing %s: %o", destinationPath, error);
                        this.dispatchEvent(new Event("error"));
                        throw error;
                    }
                }
                this.dispatchEvent(new Event("delete"));
            }
        });
        await once(this.watcher, "ready");
        await Promise.all(transpiles);
    }
    async stopWatching() {
        await this.watcher?.close();
    }
    async transpileFile(eventName, sourcePath, destinationPath) {
        ensureDirectoryExists(destinationPath);
        const source = await fs.readFile(sourcePath, "utf8");
        const result = ts.transpileModule(source, {
            compilerOptions: {
                module: ts.ModuleKind[this.moduleKind.toLowerCase() === "module" ? "ES2022" : "CommonJS"],
                target: ts.ScriptTarget.ES2015,
            },
        }).outputText;
        const fullDestination = nodePath
            .join(sourcePath
            .replace(this.sourcePath, this.destinationPath)
            .replace(".ts", this.extension))
            .replaceAll("\\", "/");
        const resultWithTransformedFileExtensions = convertFileExtensionsToCjs(result);
        try {
            await fs.writeFile(fullDestination, resultWithTransformedFileExtensions);
        }
        catch {
            debug("error transpiling %s", fullDestination);
            this.dispatchEvent(new Event("error"));
            throw new Error("could not transpile");
        }
        this.dispatchEvent(new Event("write"));
    }
}