import { mkdir, readdir, readFile, writeFile } from "node:fs/promises";
import { watch } from "node:fs";
import { dirname, join } from "node:path";
import { transform } from "lightningcss";
import { githubDarkTheme, githubLightTheme } from "../themes";
import { createStylesheet } from "../styles/index";
import { syncLocales } from "./locale";

const root = process.cwd();
const minify = process.argv.includes("--minify");
const watchMode = process.argv.includes("--watch");
const themes = [
  {
    filename: "theme-github-dev.css",
    source: githubLightTheme,
  },
  {
    filename: "theme-github-dev-dark.css",
    source: githubDarkTheme,
  },
];

async function writeIfChanged(output: string, content: Buffer | string) {
  try {
    const current = await readFile(output);
    if (Buffer.compare(current, Buffer.from(content)) === 0) {
      return;
    }
  } catch {
    // Missing files are created below.
  }

  await mkdir(dirname(output), { recursive: true });
  await writeFile(output, content);
}

async function syncDir(source: string, target: string, ignoredNames = new Set<string>()) {
  const entries = await readdir(source, { withFileTypes: true });

  await Promise.all(
    entries.map(async (entry) => {
      if (ignoredNames.has(entry.name)) {
        return;
      }

      const sourcePath = join(source, entry.name);
      const targetPath = join(target, entry.name);

      if (entry.isDirectory()) {
        await syncDir(sourcePath, targetPath);
        return;
      }

      if (entry.isFile()) {
        await writeIfChanged(targetPath, await readFile(sourcePath));
      }
    }),
  );
}

async function build() {
  const cssOutputs = await Promise.all(
    themes.flatMap((theme) => {
      const result = transform({
        filename: theme.filename,
        code: Buffer.from(createStylesheet(theme.source)),
        minify,
        targets: {
          chrome: 108 << 16,
          firefox: 108 << 16,
          safari: 16 << 16,
        },
      });

      return [
        writeIfChanged(join(root, "dist", theme.filename), result.code),
        writeIfChanged(join(root, ".gitea", "custom", "public", "assets", "css", theme.filename), result.code),
      ];
    }),
  );

  await Promise.all([
    syncDir(join(root, "templates"), join(root, ".gitea", "custom", "templates")),
    syncDir(join(root, "options"), join(root, ".gitea", "custom", "options"), new Set(["locale", "locale-overrides"])),
  ]);
  await syncLocales();

  console.log(`built ${cssOutputs.length} css outputs`);
}

await build();

if (watchMode) {
  console.log("watching styles, themes, and src");
  const watchedDirs = [join(root, "styles"), join(root, "themes"), join(root, "src")];
  const watchers = watchedDirs.map((dir) =>
    watch(dir, { recursive: true }, async (_eventType, filename) => {
      if (filename?.endsWith(".ts")) {
        await build();
      }
    }),
  );

  process.on("SIGINT", () => {
    watchers.forEach((watcher) => watcher.close());
    process.exit(0);
  });
}