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// Copyright 2020-present the denosaurs team. All rights reserved. MIT license.
import log from "./log.ts";
import { Denon, DenonEvent } from "../denon.ts";import { CompleteDenonConfig } from "./config.ts";import { ScriptOptions } from "./scripts.ts";
const logger = log.prefix("daem");
/** Daemon instance. * Returned by Denon instance when * `start(script)` is called. It can be used in a for * loop to listen to DenonEvents. */export class Daemon implements AsyncIterable<DenonEvent> {  #denon: Denon;  #script: string;  #config: CompleteDenonConfig;  #processes: { [pid: number]: Deno.Process } = {};
  constructor(denon: Denon, script: string) {    this.#denon = denon;    this.#script = script;    this.#config = denon.config; // just as a shortcut  }
  /** Restart current process. */  private async reload(): Promise<void> {    if (this.#config.logger && this.#config.logger.fullscreen) {      logger.debug("clearing screen");      console.clear();    }
    logger.info("restarting due to changes...");
    this.killAll();
    await this.start();  }
  private async start(): Promise<ScriptOptions> {    const commands = this.#denon.runner.build(this.#script);
    // Sequential execution, one process after another is executed,    // *sequentially*, the last process is named `main` and is the    // one that will actually be demonized.    for (let i = 0; i < commands.length; i++) {      const plog = log.prefix(`#${i}`);      const command = commands[i];      const options = command.options;      let process = command.exe();      plog.debug(`starting process with pid ${process.pid}`);
      if (i === commands.length - 1) {        if (options.watch && this.#config.watcher.match) {          const match = this.#config.watcher.match.join(" ");          logger.info(            `watching path(s): ${match}`,          );        }        if (options.watch && this.#config.watcher.exts) {          const exts = this.#config.watcher.exts.join(",");          logger.info(            `watching extensions: ${exts}`,          );        }        plog.warning(`starting main \`${command.cmd.join(" ")}\``);        this.#processes[process.pid] = process;        this.monitor(process, command.options);        return command.options;      }
      plog.info(`starting sequential \`${command.cmd.join(" ")}\``);      await process.status();      process.close();    }    return {};  }
  private killAll(): void {    logger.debug(      `killing ${Object.keys(this.#processes).length} orphan process[es]`,    );    // kill all processes spawned    let pcopy = Object.assign({}, this.#processes);    this.#processes = {};    for (let id in pcopy) {      const p = pcopy[id];      if (Deno.build.os === "windows") {        logger.debug(`closing (windows) process with pid ${p.pid}`);        p.close();      } else {        logger.debug(`killing (unix) process with pid ${p.pid}`);        Deno.kill(p.pid, Deno.Signal.SIGKILL);      }    }  }
  private async monitor(    process: Deno.Process,    options: ScriptOptions,  ): Promise<void> {    logger.debug(`monitoring status of process with pid ${process.pid}`);    const pid = process.pid;    let s: Deno.ProcessStatus | undefined;    try {      s = await process.status();      process.close();      logger.debug(`got status of process with pid ${process.pid}`);    } catch (error) {      logger.debug(`error getting status of process with pid ${process.pid}`);    }    let p = this.#processes[pid];    if (p) {      logger.debug(`process with pid ${process.pid} exited on its own`);      // process exited on its own, so we should wait a reload      // remove it from processes array as it is already dead      delete this.#processes[pid];
      if (s) {        // logger status status        if (s.success) {          if (options.watch) {            logger.info("clean exit - waiting for changes before restart");          } else {            logger.info("clean exit - denon is exiting ...");          }        } else {          if (options.watch) {            logger.error(              "app crashed - waiting for file changes before starting ...",            );          } else {            logger.error("app crashed - denon is exiting ...");          }        }      }    } else {      logger.debug(`process with pid ${process.pid} was killed`);    }  }
  private async onExit(): Promise<void> {    if (Deno.build.os !== "windows") {      const signs = [        Deno.Signal.SIGHUP,        Deno.Signal.SIGINT,        Deno.Signal.SIGTERM,        Deno.Signal.SIGTSTP,      ];      signs.forEach((s) => {        (async () => {          await Deno.signal(s);          this.killAll();          Deno.exit(0);        })();      });    }  }
  async *iterate(): AsyncIterator<DenonEvent> {    this.onExit();    yield {      type: "start",    };    const options = await this.start();    if (options.watch) {      for await (const watchE of this.#denon.watcher) {        if (watchE.some((_) => _.type.includes("modify"))) {          logger.debug(            `reload event detected, starting the reload procedure...`,          );          yield {            type: "reload",            change: watchE,          };          await this.reload();        }      }    }    yield {      type: "exit",    };  }
  [Symbol.asyncIterator](): AsyncIterator<DenonEvent> {    return this.iterate();  }}