import { difference, Sys } from "../deps.ts";

export class Runner {
  constructor(readonly sys = Sys) {
  }

  // Run a tool by its name and args
  async run(args: string[]) {
    const app = args.shift();
    if (!app) {
      throw new Error("Usage: run app [args...]");
    }

    const flags_txt = await this.downloadText(
      `https://code.thunderk.net/typescript/${app}/raw/branch/master/config/run.flags`,
    );
    const flags = flags_txt.split(/\s+/).filter((arg) => arg);
    if (flags.some((arg) => !arg.startsWith("--"))) {
      throw new Error(`Bad run flags: ${flags}`);
    }

    if (!await this.checkStamp(app)) {
      console.log("Reloading sources...");
      flags.unshift("--reload");
    }

    const uri =
      `https://code.thunderk.net/typescript/${app}/raw/branch/master/cli.ts`;
    await this.sys.run({
      cmd: ["deno", "run"].concat(flags).concat([uri]).concat(args),
    }).status();
  }

  // Download a remote text content (empty if not a 200 response)
  async downloadText(uri: string): Promise<string> {
    const response = await fetch(uri);
    if (response.status == 200) {
      const result = await response.text();
      return result;
    } else {
      return "";
    }
  }

  // Check an app timestamp, returning true if it is valid
  async checkStamp(app: string): Promise<boolean> {
    const path = `/tmp/thunderk-run-${app}.stamp`;
    try {
      const stat = await this.sys.stat(path);
      if (stat.isFile && stat.mtime) {
        const age = difference(stat.mtime, new Date()).days ?? 0;
        if (age < 1) {
          return true;
        }
      }
    } catch {
    }

    await this.sys.writeTextFile(path, "");
    return false;
  }
}

// Run a remote program, by its name and args
export async function run(args: string[], sys = Sys) {
  const runner = new Runner(sys);
  await runner.run(args);
}