/*

serial.mjs - <short description TODO>

Copyright (C) 2022 Strudel contributors - see <https://codeberg.org/uzu/strudel/src/branch/main/packages/serial/serial.mjs>

This program is free software: you can redistribute it and/or modify it under the terms of the GNU Affero General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Affero General Public License for more details. You should have received a copy of the GNU Affero General Public License along with this program.  If not, see <https://www.gnu.org/licenses/>.

*/

import { Pattern, isPattern } from '@strudel/core';

var writeMessagers = {};

var choosing = false;

export async function getWriter(name, br) {

  if (choosing) {

    return;

  }

  choosing = true;

  if (name in writeMessagers) {

    return writeMessagers[name];

  }

  if ('serial' in navigator) {

    const port = await navigator.serial.requestPort();

    await port.open({ baudRate: br });

    const encoder = new TextEncoder();

    const writer = port.writable.getWriter();

    writeMessagers[name] = function (message, chk) {

      const encoded = encoder.encode(message);

      if (!chk) {

        writer.write(encoded);

      } else {

        const bytes = new Uint8Array(4);

        bytes[0] = 124; // | symbol

        bytes[1] = (chk >> 8) & 0xff;

        bytes[2] = chk & 0xff;

        bytes[3] = 59; // semicolon

        const withchk = new Uint8Array(encoded.length + 4);

        withchk.set(encoded);

        withchk.set(bytes, encoded.length);

        writer.write(withchk);

      }

    };

  } else {

    throw 'Webserial is not available in this browser.';

  }

}

const latency = 0.1;

// crc16 (CCITT-FALSE) https://gist.github.com/tijnkooijmans/10981093

function crc16(data) {

  const length = data.length;

  if (length == 0) {

    return 0;

  }

  var crc = 0xffff;

  for (var i = 0; i < length; ++i) {

    crc ^= data.charCodeAt(i) << 8;

    for (var j = 0; j < 8; ++j) {

      crc = (crc & 0x8000) > 0 ? (crc << 1) ^ 0x1021 : crc << 1;

    }

  }

  return crc & 0xffff;

}

Pattern.prototype.serial = function (br = 115200, sendcrc = false, singlecharids = false, name = 'default') {

  return this.withHap((hap) => {

    if (!(name in writeMessagers)) {

      getWriter(name, br);

    }

    const onTrigger = (t_deprecate, hap, currentTime, cps, targetTime) => {

      var message = '';

      var chk = 0;

      if (typeof hap.value === 'object') {

        if ('action' in hap.value) {

          var action = hap.value['action'];

          if (singlecharids) {

            action = action.charAt(0);

          }

          message += action + '(';

          var first = true;

          for (var [key, val] of Object.entries(hap.value)) {

            if (key === 'action') {

              continue;

            }

            if (first) {

              first = false;

            } else {

              message += ',';

            }

            if (singlecharids) {

              key = key.charAt(0);

            }

            message += key + ':' + val;

          }

          message += ')';

          if (sendcrc) {

            chk = crc16(message);

          }

        } else {

          for (const [key, val] of Object.entries(hap.value)) {

            message += `${key}:${val}`;

          }

        }

      } else {

        message = hap.value;

      }

      const offset = (targetTime - currentTime + latency) * 1000;

      window.setTimeout(function () {

        writeMessagers[name](message, chk);

      }, offset);

    };

    return hap.setContext({ ...hap.context, onTrigger, dominantTrigger: true });

  });

};