#!/usr/bin/env node
import fs from "node:fs/promises";
import path from "node:path";
import { fileURLToPath } from "node:url";
import { build } from "esbuild";

const modulePath = fileURLToPath(import.meta.url);
const pluginDir = path.resolve(path.dirname(modulePath), "..");
const repoRoot = path.resolve(pluginDir, "../..");
const outfile = path.join(pluginDir, "chrome-extension", "modules", "copilot-runtime.js");

async function writeCopilotRuntimeIfChanged(filePath, contents) {
  try {
    if ((await fs.readFile(filePath, "utf8")) === contents) {
      return false;
    }
  } catch (error) {
    if (error?.code !== "ENOENT") {
      throw error;
    }
  }

  await fs.mkdir(path.dirname(filePath), { recursive: true });
  await fs.writeFile(filePath, contents, "utf8");
  return true;
}

/** Builds the copilot runtime without rewriting an identical generated asset. */
export async function buildCopilotRuntime(params = {}) {
  const buildImpl = params.build ?? build;
  const outputPath = params.outputPath ?? outfile;
  const result = await buildImpl({
    entryPoints: [path.join(pluginDir, "scripts", "copilot-runtime-entry.ts")],
    outfile: outputPath,
    bundle: true,
    format: "esm",
    legalComments: "inline",
    minifyIdentifiers: false,
    minifySyntax: true,
    minifyWhitespace: true,
    platform: "browser",
    target: "chrome125",
    tsconfig: path.join(repoRoot, "tsconfig.json"),
    write: false,
  });

  const outputFile = result.outputFiles?.[0];
  if (!outputFile) {
    throw new Error("esbuild did not produce the Browser copilot runtime bundle");
  }

  return writeCopilotRuntimeIfChanged(outputPath, outputFile.text);
}

if (process.argv[1] === modulePath) {
  await buildCopilotRuntime();
}