// Termios settings
// https://man7.org/linux/man-pages/man3/termios.3.html

export namespace Termios {
  export enum InputFlag {
    ISTRIP = 0x0020, // Strip off 8th bit
    INLCR = 0x0040, // Map NL to CR on input
    IGNCR = 0x0080, // Ignore CR on input
    ICRNL = 0x0100, // Map CR to NL on input
    IUCLC = 0x0200, // Map uppercase to lowercase on input
    IXON = 0x0400, // Enable XON/XOFF flow control on output
    IXANY = 0x0800, // Enable any character to restart output
    IMAXBEL = 0x2000, // Ring bell when input queue is full
    IUTF8 = 0x4000 // Input is UTF8
  }

  export enum OutputFlag {
    OPOST = 0x0001, // Enable implementation-defined output processing
    OLCUC = 0x0002, // Map lowercase to uppercase on output
    ONLCR = 0x0004, // Map NL to CR-NL on output
    OCRNL = 0x0008, // Map CR to NL on output
    ONOCR = 0x0010, // Don't output CR at column 0
    ONLRET = 0x0020, // NL performs CR on output
    TABDLY = 0x1800 // Horizontal tab delay mask
  }

  export enum LocalFlag {
    ISIG = 0x0001, // Enable signals
    ICANON = 0x0002, // Enable canonical mode on input
    ECHO = 0x0008, // Enable echo
    ECHOE = 0x0010, // ERASE character erases preceding character
    ECHOK = 0x0020, // KILL character erases current line
    ECHONL = 0x0040, // Echo NL even if ECHO not set
    NOFLSH = 0x0080, // Disable flush after interrupt or quite
    ECHOCTL = 0x0200, // Terminal special characters are echoed
    ECHOPRT = 0x0400, // Characters are printed as they are erased
    ECHOKE = 0x0800, // KILL is echoed by erasing each character on the line
    IEXTEN = 0x8000 // Enable implementation-defined input processing
  }

  export enum ControlCharacter {
    VINTR = 0, // INTR (interrupt) character
    VQUIT = 1, // QUIT character
    VERASE = 2, // ERASE character
    VKILL = 3, // KILL character
    VEOF = 4, // EOF (end-of-file) character
    VTIME = 5, // Timeout for non-canonical read
    VMIN = 6, // Minimum number of characters for non-canonical read
    VSWTCH = 7, // SWTCH (switch) character
    VSTART = 8, // Start character restarts output after stopped by Stop character
    VSTOP = 9, // Stop character to stop output until Start character typed
    VSUSP = 10, // SUSP (suspend) character
    VEOL = 11, // Additional EOL (end-of-line) character
    VREPRINT = 12, // Reprint unread characters
    VDISCARD = 13, // Toggle start/stop discards pending input
    VWERASE = 14, // Word erase
    VLNEXT = 15, // Literal next character
    VEOL2 = 16 // Yet another EOL character
  }

  // This is the termios interface used by emscripten.
  export interface IFlags {
    c_iflag: InputFlag;
    c_oflag: OutputFlag;
    c_cflag: number;
    c_lflag: LocalFlag;
    c_cc: number[];
  }

  export function cloneFlags(flags: IFlags): IFlags {
    return {
      c_iflag: flags.c_iflag,
      c_oflag: flags.c_oflag,
      c_cflag: flags.c_cflag,
      c_lflag: flags.c_lflag,
      c_cc: [...flags.c_cc]
    };
  }

  export class Flags implements IFlags {
    c_iflag: InputFlag = 0 as InputFlag;
    c_oflag: OutputFlag = 0 as OutputFlag;
    c_cflag: number = 0;
    c_lflag: LocalFlag = 0 as LocalFlag;
    c_cc: number[] = [];
  }

  export interface ITermios {
    get(): IFlags;
    set(flags: IFlags): void;
  }

  export class Termios implements ITermios {
    constructor() {
      this.setDefaultShell();
    }

    get(): IFlags {
      return this._flags;
    }

    // Log to console for debug purposes.
    log(title: string) {
      const enumHelper = (enumType: any, name: string, enumValue: any) => {
        const s: string[] = [];
        for (const [k, v] of Object.entries(enumType).filter(([k, v]) => k[0].match(/\D/))) {
          if ((enumValue & (v as number)) > 0) {
            s.push(k);
          }
        }
        return `  ${name} = ${enumValue} 0x${enumValue.toString(16)} = ${s.join(' ')}`;
      };

      const log: string[] = ['Cockle ' + title + ':'];
      const flags = this._flags;
      log.push(enumHelper(InputFlag, 'c_iflag', flags.c_iflag));
      log.push(enumHelper(OutputFlag, 'c_oflag', flags.c_oflag));
      log.push(`  c_cflag = ${flags.c_cflag} 0x${flags.c_cflag.toString(16)}`);
      log.push(enumHelper(LocalFlag, 'c_lflag', flags.c_lflag));
      log.push(`  c_cc = ${flags.c_cc}`);
      console.debug(log.join('\n'));
    }

    set(flags: IFlags): void {
      this._flags = flags;
      this.log('Termios set');
    }

    setDefaultShell(): void {
      this.setDefaultWasm();
      this._flags.c_oflag |= OutputFlag.ONOCR;
    }

    /**
     * Set termios settings to the default used in WebAssembly commands.
     */
    setDefaultWasm(): void {
      // This is taken from the default in emscripten-compiled code.
      const flags = this._flags;
      flags.c_iflag = InputFlag.IUTF8 | InputFlag.IMAXBEL | InputFlag.IXON | InputFlag.ICRNL; // 25856 = 0x6500
      flags.c_oflag = OutputFlag.OPOST | OutputFlag.ONLCR; // 5
      flags.c_cflag = 191; // ignored
      flags.c_lflag =
        LocalFlag.IEXTEN |
        LocalFlag.ECHOKE |
        LocalFlag.ECHOCTL |
        LocalFlag.ECHOK |
        LocalFlag.ECHOE |
        LocalFlag.ECHO |
        LocalFlag.ICANON |
        LocalFlag.ISIG; // 35387 = 0x8A3B
      flags.c_cc = [
        3, // VINTR
        28, // VQUIT
        127, // VERASE
        21, // VKILL
        4, // VEOF
        0, // VTIME
        1, // VMIN
        0, // VSWTCH
        17, // VSTART
        19, // VSTOP
        26, // VSUSP
        0, // VEOL
        18, // VREPRINT
        15, // VDISCARD
        23, // VWERASE
        22, // VLNEXT
        0, // VEOL2
        0,
        0,
        0,
        0,
        0,
        0,
        0,
        0,
        0,
        0,
        0,
        0,
        0,
        0,
        0
      ];
    }

    setRawMode(): void {
      // Assume is currently default shell termios.
      const flags = this._flags;
      flags.c_iflag &= ~(
        InputFlag.ISTRIP |
        InputFlag.INLCR |
        InputFlag.IGNCR |
        InputFlag.ICRNL |
        InputFlag.IXON
      );
      flags.c_oflag &= ~OutputFlag.OPOST;
      flags.c_lflag &= ~(
        LocalFlag.ECHO |
        LocalFlag.ECHONL |
        LocalFlag.ICANON |
        LocalFlag.ISIG |
        LocalFlag.IEXTEN
      );
    }

    private _flags: IFlags = new Flags();
  }
}