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import { CommandCode } from "./code.ts";import type {  ConnectConfig,  ConnectConfigWithAuthentication,  SendConfig} from "./config.ts";import { BufReader, BufWriter, TextProtoReader } from "./deps.ts";
const encoder = new TextEncoder();
interface Command {  code: number;  args: string;}
enum ContentTransferEncoding {  "7bit" = "7bit",  "8bit" = "8bit",  "base64" = "base64",  "binary" = "binary",  "quoted-printable" = "quoted-printable",}
interface SmtpClientOptions {  content_encoding?:    | "7bit"    | "8bit"    | "base64"    | "binary"    | "quoted-printable";}
export class SmtpClient {  private _conn: Deno.Conn | null;  private _reader: TextProtoReader | null;  private _writer: BufWriter | null;  private _content_encoding: ContentTransferEncoding;
  constructor({    content_encoding = ContentTransferEncoding["quoted-printable"],  }: SmtpClientOptions = {}) {    this._conn = null;    this._reader = null;    this._writer = null;
    const _content_encoding = String(content_encoding).toLowerCase();    if (!(_content_encoding in ContentTransferEncoding)) {      throw new Error(        `${JSON.stringify(content_encoding)} is not a valid content encoding`,      );    }    this._content_encoding = _content_encoding as ContentTransferEncoding;  }
  async connect(config: ConnectConfig | ConnectConfigWithAuthentication) {    const conn = await Deno.connect({      hostname: config.hostname,      port: config.port || 25,    });    await this._connect(conn, config);  }
  async connectTLS(config: ConnectConfig | ConnectConfigWithAuthentication) {    const conn = await Deno.connectTls({      hostname: config.hostname,      port: config.port || 465,    });    await this._connect(conn, config);  }
  async close() {    if (!this._conn) {      return;    }    await this._conn.close();  }
  async send(config: SendConfig) {    const [from, fromData] = this.parseAddress(config.from);    const [to, toData] = this.parseAddress(config.to);
    await this.writeCmd("MAIL", "FROM:", from);    this.assertCode(await this.readCmd(), CommandCode.OK);    await this.writeCmd("RCPT", "TO:", 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: ", fromData);    await this.writeCmd("To: ", toData);    await this.writeCmd("Date: ", new Date().toString());
    if(config.html) {      await this.writeCmd("Content-Type: multipart/alternative; boundary=AlternativeBoundary", "\r\n");      await this.writeCmd("--AlternativeBoundary");      await this.writeCmd('Content-Type: text/plain; charset="utf-8"', "\r\n");      await this.writeCmd(config.content, "\r\n");      await this.writeCmd("--AlternativeBoundary");      await this.writeCmd('Content-Type: text/html; charset="utf-8"', "\r\n");      await this.writeCmd(config.html, "\r\n.\r\n");    } else {      await this.writeCmd("MIME-Version: 1.0");      await this.writeCmd("Content-Type: text/html;charset=utf-8");      await this.writeCmd(`Content-Transfer-Encoding: ${this._content_encoding}` + "\r\n");      await this.writeCmd(config.content, "\r\n.\r\n");    }
    this.assertCode(await this.readCmd(), CommandCode.OK);  }
  private async _connect(conn: Deno.Conn, config: ConnectConfig) {    this._conn = conn;    const reader = new BufReader(this._conn);    this._writer = new BufWriter(this._conn);    this._reader = new TextProtoReader(reader);
    this.assertCode(await this.readCmd(), CommandCode.READY);
    await this.writeCmd("EHLO", config.hostname);    while (true) {      const cmd = await this.readCmd();      if (!cmd || !cmd.args.startsWith("-")) break;    }
    if (this.useAuthentication(config)) {      await this.writeCmd("AUTH", "LOGIN");      this.assertCode(await this.readCmd(), 334);
      await this.writeCmd(btoa(config.username));      this.assertCode(await this.readCmd(), 334);
      await this.writeCmd(btoa(config.password));      this.assertCode(await this.readCmd(), CommandCode.AUTHO_SUCCESS);    }  }
  private assertCode(cmd: Command | null, code: number, msg?: string) {    if (!cmd) {      throw new Error(`invalid cmd`);    }    if (cmd.code !== code) {      throw new Error(msg || cmd.code + ": " + cmd.args);    }  }
  private async readCmd(): Promise<Command | null> {    if (!this._reader) {      return null;    }    const result = await this._reader.readLine();    if (result === null) return null;    const cmdCode = parseInt(result.slice(0, 3).trim());    const cmdArgs = result.slice(3).trim();    return {      code: cmdCode,      args: cmdArgs,    };  }
  private async writeCmd(...args: string[]) {    if (!this._writer) {      return null;    }    const data = encoder.encode([...args].join(" ") + "\r\n");    await this._writer.write(data);    await this._writer.flush();  }
  private useAuthentication(    config: ConnectConfig | ConnectConfigWithAuthentication,  ): config is ConnectConfigWithAuthentication {    return (config as ConnectConfigWithAuthentication).username !== undefined;  }
  private parseAddress(email: string): [string, string] {    const m = email.toString().match(/(.*)\s<(.*)>/);    return m?.length === 3      ? [`<${m[2]}>`, email]      : [`<${email}>`, `<${email}>`];  }}