/*

drawLine.mjs - <short description TODO>

Copyright (C) 2022 Strudel contributors - see <https://codeberg.org/uzu/strudel/src/branch/main/packages/core/drawLine.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 Fraction, { gcd } from './fraction.mjs';

/**

 * Intended for a debugging, drawLine renders the pattern as a string, where each character represents the same time span.

 * Should only be used with single characters as values, otherwise the character slots will be messed up.

 * Character legend:

 *

 * - "|" cycle separator

 * - "-" hold previous value

 * - "." silence

 *

 * @param {Pattern} pattern the pattern to use

 * @param {number} chars max number of characters (approximately)

 * @returns string

 * @example

 * const line = drawLine("0 [1 2 3]", 10); // |0--123|0--123

 * console.log(line);

 * silence;

 */

function drawLine(pat, chars = 60) {

  let cycle = 0;

  let pos = Fraction(0);

  let lines = [''];

  let emptyLine = ''; // this will be the "reference" empty line, which will be copied into extra lines

  while (lines[0].length < chars) {

    const haps = pat.queryArc(cycle, cycle + 1);

    const durations = haps.filter((hap) => hap.hasOnset()).map((hap) => hap.duration);

    const charFraction = gcd(...durations);

    const totalSlots = charFraction.inverse(); // number of character slots for the current cycle

    lines = lines.map((line) => line + '|'); // add pipe character before each cycle

    emptyLine += '|';

    for (let i = 0; i < totalSlots; i++) {

      const [begin, end] = [pos, pos.add(charFraction)];

      const matches = haps.filter((hap) => hap.whole.begin.lte(begin) && hap.whole.end.gte(end));

      const missingLines = matches.length - lines.length;

      if (missingLines > 0) {

        lines = lines.concat(Array(missingLines).fill(emptyLine));

      }

      lines = lines.map((line, i) => {

        const hap = matches[i];

        if (hap) {

          const isOnset = hap.whole.begin.eq(begin);

          const char = isOnset ? '' + hap.value : '-';

          return line + char;

        }

        return line + '.';

      });

      emptyLine += '.';

      pos = pos.add(charFraction);

    }

    cycle++;

  }

  return lines.join('\n');

}

export default drawLine;