trainsim/dev.ts

/// <reference lib="deno.ns" />

import * as esbuild from "npm:esbuild";
import { denoPlugins } from "jsr:@luca/esbuild-deno-loader";
import { serveDir } from "jsr:@std/http";

async function* crawl(dir: string): AsyncIterable<string> {
  for await (const file of Deno.readDir(dir)) {
    const fullPath = dir + "/" + file.name;

    if (file.isDirectory) {
      yield* crawl(fullPath);
    } else {
      yield fullPath;
    }
  }
}

async function dev() {
  const paths = [];
  const ignoredFiles = ["bundler", "bundle", "dev", "test"];

  for await (const path of crawl("./")) {
    if (
      path.endsWith(".ts") &&
      !ignoredFiles.find((file) => path.includes(file))
    ) {
      paths.push(path);
    }
  }
  await build();

  const watcher = Deno.watchFs(paths);

  for await (const event of watcher) {
    if (event.kind === "modify") {
      console.log("File modified, bundling...");
      await build();
    }
  }
}
async function build() {
  const cfg = await import("./deno.json", {
    with: { type: "json" },
  });
  const importMap = {
    imports: cfg.default.imports,
  };
  const importMapURL = "data:application/json," + JSON.stringify(importMap);
  console.log("File modified, bundling...");
  try {
    const result = await esbuild.build({
      entryPoints: ["./main.ts"],
      bundle: true,
      outfile: "bundle.js",
      plugins: [...denoPlugins({
        importMapURL,
        lockPath: "./deno.lock",
      })],
      loader: {
        ".ts": "ts",
        ".js": "js",
        ".jsx": "jsx",
        ".tsx": "tsx",
      },
    });
    esbuild.stop();
    console.log("Bundled successfully!");
    sendSSE("data: build\n\n");
  } catch (e) {
    console.error(e);
    // Deno.exit(1);
  }
}

let sseStreams: ReadableStreamDefaultController[] = [];

function sendSSE(message: string) {
  sseStreams.filter((stream) => {
    try {
      stream.enqueue(new TextEncoder().encode(message));
      return true;
    } catch {
      return false;
    }
  });
}

function sse(r: Request) {
  let controller: ReadableStreamDefaultController;
  const body = new ReadableStream({
    start(controller) {
      sseStreams.push(controller);
    },
    cancel() {
      sseStreams = sseStreams.filter((stream) => stream !== controller);
    },
  });

  return new Response(body, {
    status: 200,
    headers: {
      "Content-Type": "text/event-stream",
      "Cache-Control": "no-cache",
      Connection: "keep-alive",
    },
  });
}

if (Deno.args.includes("dev")) {
  dev();
  Deno.serve(async (r) => {
    if (r.url.endsWith("sse")) {
      return sse(r);
    }

    const d = await serveDir(r, {
      fsRoot: ".",
      showIndex: true,
    });

    if (d.headers.get("content-type")?.startsWith("text/html")) {
      const body = await d.text();
      return new Response(
        body.replace(
          "</body>",
          `<script defer>
          const source = new EventSource("/sse");
          source.onmessage = (event) => {
            if (event.data === "build") {
              location.reload();
            }
          };
        </script></body>`,
        ),
        {
          status: 200,
          headers: {
            "Content-Type": "text/html",
            "Cache-Control": "no-cache",
          },
        },
      );
    }
    if (d.url.endsWith(".js")) {
      d.headers.set("Cache-Control", "no-cache");
      d.headers.set("Content-Type", "application/javascript");
    }
    return d;
  });
} else {
  await build();
}