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import { CommandCode } from "./code.ts";import { ConnectConfig, SendConfig } from "./config.ts";import { BufReader, BufWriter } from "./deps.ts";
const decoder = new TextDecoder();const encoder = new TextEncoder();
interface Command {  code: string;  args: string;}
export class SmtpClient {  private _conn: Deno.Conn;  private _reader: BufReader;  private _writer: BufWriter;
  async connect(config: ConnectConfig) {    config = { port: 25, ...config };    this._conn = await Deno.dial("tcp", `${config.host}:${config.port}`);    this._reader = new BufReader(this._conn);    this._writer = new BufWriter(this._conn);    let cmd = await this.readCmd();    this.assertCode(cmd, CommandCode.READY);
    await this.writeCmd("EHLO", config.host);    while (true) {      const cmd = await this.readCmd();      if (!cmd.args.startsWith("-")) break;    }    await this.writeCmd("AUTH", "LOGIN");    await this.readCmd();    await this.writeCmd(btoa(config.username));    await this.readCmd();    await this.writeCmd(btoa(config.password));
    this.assertCode(await this.readCmd(), CommandCode.AUTHO_SUCCESS);  }
  public async send(config: SendConfig) {    await this.writeCmd("MAIL", "FROM:", `<${config.from}>`);    this.assertCode(await this.readCmd(), CommandCode.OK);    await this.writeCmd("RCPT", "TO:", `<${config.to}>`);    this.assertCode(await this.readCmd(), CommandCode.OK);    await this.writeCmd("DATA");    this.assertCode(await this.readCmd(), CommandCode.BEGIN_DATA);
    await this.writeCmd("Subject: ", config.subject);    await this.writeCmd("From: ", config.from);    await this.writeCmd("To: ", `<${config.from}>`);    await this.writeCmd("Date: ", new Date().toString());
    await this.writeCmd("MIME-Version: 1.0");    await this.writeCmd("Content-Type: text/html;charset=utf-8");    await this.writeCmd("Content-Transfer-Encoding: quoted-printable");
    await this.writeCmd(config.content, "\r\n.\r\n");    this.assertCode(await this.readCmd(), CommandCode.OK);  }
  public async close() {    await this._conn.close();  }
  private assertCode(cmd: Command, code: string, msg?: string) {    if (cmd.code !== code) {      throw new Error(msg || cmd.code + ": " + cmd.args);    }    // console.log("Read:", cmd);  }
  private async readCmd(): Promise<Command> {    const result = await this._reader.readLine();    if (result === Deno.EOF) return null;    const line = decoder.decode(result.line);    const cmdCode = line.slice(0, 3).trim();    const cmdArgs = line.slice(3).trim();    // console.log("r", line, cmdCode, cmdArgs);    return {      code: cmdCode,      args: cmdArgs    };  }
  private async writeCmd(...args: string[]) {    // console.log("Write:", ...args);    const data = encoder.encode([...args].join(" ") + "\r\n");    await this._writer.write(data);    await this._writer.flush();  }}