// this file should not have `async` and `await`
import path from "node:path";
import process from "node:process";
import chokidar, { type FSWatcher } from "chokidar";
import { Compiler, type CompilerOptions } from "./compiler.ts";

interface TscxOptions extends CompilerOptions {
  watch: boolean;
}

export class Action {
  private lastUpdateTsconfigTime = Date.now();

  private readonly compiler;
  private watcher?: FSWatcher;
  constructor(private readonly options: TscxOptions) {
    const { watch, ...compilerOptions } = options;
    this.compiler = new Compiler(compilerOptions);
  }

  private watch(paths: string[]) {
    this.watcher = chokidar
      .watch(paths, {
        ignored: [
          "**/node_modules/**",
          "**/.git/**",
          this.compiler.getOutDir(),
        ],
        ignoreInitial: true,
      })
      .on("add", (filepath) => this.cb(filepath))
      .on("unlink", (filepath) => this.cb(filepath))
      .on("change", (filepath) => this.cb(filepath))
      .on("ready", () => this.cb());
  }

  private setupWatcher() {
    const include = this.compiler.getInclude() ?? [];
    const watchFiles =
      include.length <= 0
        ? [process.cwd()]
        : include
            .map((i) => path.resolve(process.cwd(), i))
            .concat(path.resolve(process.cwd(), this.options.project));

    if (this.watcher) {
      // If this method throw an error (I mean the promise rejected), the process will exit with non-zero code.
      // See https://github.com/zanminkian/zanminkian.github.io/issues/54
      this.watcher.close().then(
        () => this.watch(watchFiles),
        (e) => {
          throw new Error("Close watcher fail!", { cause: e });
        },
      );
    } else {
      this.watch(watchFiles);
    }
  }

  private cb(filepath?: string) {
    console.log("File changes detected", filepath);
    // user edit non-tsconfig files
    if (
      !filepath ||
      path.resolve(process.cwd(), filepath) !==
        path.resolve(process.cwd(), this.options.project)
    ) {
      return this.compiler.compile();
    }

    // user edit tsconfig file
    const now = Date.now();
    if (now - this.lastUpdateTsconfigTime < 1000) {
      return;
    }
    try {
      this.compiler.refreshTsConfig();
    } catch (e) {
      console.warn(
        "Refresh ts config fail. You can ignore this small warning.",
        e,
      );
      return;
    }
    this.setupWatcher();
    this.lastUpdateTsconfigTime = now;
  }

  start() {
    if (!this.options.watch) {
      this.compiler.compile();
      return;
    }

    this.setupWatcher();
  }
}