/**
 * KHAELOR
 * File: src/tui/components/sparkline.ts
 * Description: Braille sparkline — 2×4 dots per cell, used by /cost per-turn graphs (TUI v2 §3).
 *
 * Author: Simon-Pierre Boucher
 * Contact: contact@spboucher.ai
 */

// Braille dot bits by (column 0-1, row 0-3), per the Unicode braille block.
const DOT_BITS: number[][] = [
  [0x01, 0x02, 0x04, 0x40],
  [0x08, 0x10, 0x20, 0x80],
];

/**
 * Render a numeric series as a braille sparkline: `⣀⣄⣤⣶⣿⣷⣄`. Two values per
 * cell, four vertical levels per dot column. Empty/flat series render as a
 * flat baseline — no fabricated variance (Absolute Rule #4).
 */
export function brailleSparkline(values: readonly number[], maxCells?: number): string {
  if (values.length === 0) return "";
  const max = Math.max(...values);
  const levels = values.map((value) => {
    if (max <= 0) return 1;
    return Math.max(1, Math.min(4, Math.ceil((value / max) * 4)));
  });
  const cellCount = Math.ceil(levels.length / 2);
  const cells: string[] = [];
  for (let cell = 0; cell < cellCount; cell += 1) {
    let bits = 0;
    for (let column = 0; column < 2; column += 1) {
      const level = levels[cell * 2 + column];
      if (level === undefined) continue;
      for (let row = 4 - level; row < 4; row += 1) {
        bits |= (DOT_BITS[column] as number[])[row] as number;
      }
    }
    cells.push(String.fromCharCode(0x2800 + bits));
  }
  const rendered = cells.join("");
  if (maxCells !== undefined && cells.length > maxCells) {
    return rendered.slice(cells.length - maxCells);
  }
  return rendered;
}